Chapter - 1 INTRODUCTION

1.1: Morphology Paper wasps are one of the most common wasps seen around homes and buildings. They are 0.75 cm to 1 inch Long and generally reddish-orange to dark-brown. They often have yellow body markings. Paper wasps have three castes, infertile female workers, which make up most of the wasps on nests during the summer males, and queens. Males and new queens are produced primarily in late summer and fall. Unlike yellow-jackets and hornets, the paper wasp queen is not much larger than the worker wasps. Paper wasps build their nests from chewed wood fibers. The comb, which hangs from a single filament, is usually oriented downward and consists of a single tier of hexagonal-shaped cells. Nests are most frequently seen under the eaves of houses but may also be found in attics, garages, storage sheds, barns, on shrubbery, trees and a variety of protected sites. The typical mature paper wasp nest contains 20 to 30 adults. Anatomically there is a great deal of variation between different species of wasp. Like all insects, wasps have a hard exoskeleton covering their 3 main body parts. These parts are known as the head, metasoma and mesosoma. Wasps also have a connective region joining the first and second segments of the mesosoma known as the petiole. Like all insects, wasps have 3 sets of 2 legs. In addition to their compound eyes, wasps also have several simple eyes known as ocelli. These are typically arranged in a triangular formation just forward of an area of the head known as the vertex. It is possible to distinguish between certain wasp species genders based on the number of divisions on their antennae. Male Yellow jacket wasps for example have 13 divisions per antenna, while females have 12. Males can in some cases be differentiated from females by virtue of the fact that the upper region of the male's mesosoma (called the tergum) consists of an additional terga. The total number of terga is typically 6. The difference between sterile female worker wasps and queens also varies between species but generally the queen is noticeably larger than both males and other females. Wasps can be differentiated from bees as bees have a flattened hind basitarsus. Unlike bees wasps generally lack plumose hairs. They vary in the number and size of hairs they have between species.

1.1.1. Characteristics of Wasps: The following characteristics are present in most wasps:1. Two pairs of wings, An ovipositor or stinger (which is only present in females because it derives from the ovipositor, a female sex organ).2. Few or no hairs (in contrast to bees)3. Nearly all wasps are terrestrial; only a few specialized parasitic groups are aquatic.4. Predators or parasitoids, mostly on other terrestrial insects; some species of Pompilidae, such as the tarantula hawk, specialize in using spiders as prey, and various parasitic wasps use spiders or other arachnids as reproductive hosts.5. Wasps are critically important in natural bio control. Almost every pest insect species has a wasp species that is a predator or parasite upon it.6. Parasitic wasps are also increasingly used in agricultural pest control as they have little impact on crops. Wasps also constitute an important part of the food chain.

1.1.2. Feeding Habit of Wasps:Generally wasps are parasites as larvae, and feed only on nectar as adults. Some wasps are omnivorous but this is relatively uncommon, they feed on a variety of fallen fruit, nectar and carrion. Many wasps are predatory, preying on other insects. Certain social wasp species, such as yellow jackets, scavenge for dead insects to provide for their young. In turn the brood provides sweet secretions for the adults. In parasitic species the first meals are almost always provided from the animal the adult wasp used as a host for its young. Adult male wasps sometimes visit flowers to obtain nectar to feed on in much the same manner as honey bees. Occasionally, some species, such as yellow jackets, invade honeybee nests and steal honey or brood. Ropalidia marginata, the most common Indian social wasp, belongs to a crucial stage of social evolution showing no obvious morphological caste differentiation but a behavioral caste differentiation and a dominance hierarchy that appears to influence division of labour. The nests consist of a single open comb that can sometimes have up to 500 cells and 10 pedicels. Nests are initiated and abandoned all round the year. Initiation is by 1-20 foundresses, 1-4 being the most common number. There is a great deal of variation in brood development at times both within and between nests. Male progeny disappear from the nest soon after emergence while daughters stay on at the parent nest for a mean period of about a month. Small nests have a single egg layer while large nests have two or more females with well developed ovaries that presumably lay eggs. Most nests are short-lived, small nests being highly susceptible to failure. Large nests are less susceptible to failure but the emergence of multiple egg layers reduces the average relatedness of workers to the brood which presumably is the cause for large scale emigrations from these nests. An interaction of ecological and social factors therefore appears to determine the growth of a nest .Yellow paper wasps are beneficial insects. They feed their young numerous insects that ordinarily damage shade trees and crops. They also kill countless houseflies and blow flies.

A few species of yellow-jackets, however, such as Vespula pensylvanica (western yellowjacket), V. germanica (German wasp), and V. vulgaris (common yellow-jacket), scavenge for meat and sweets and can become pests, especially at picnics and camp grounds .Even though they may at times become pests, yellow-jackets and paper wasps are highly beneficial. Do not control them unless their stings present a hazard. Recent years have witnessed a great surge of interest in social hymenoptera because the emergence of a considerable body of theoretical ideas (Hamilton 1964; Lin and Michener 1972 ; Alexander 1974) have raised hopes that herein lies the key to understanding the evolution of social behaviour (West-Eberhard 1969,1975 ; Wilson 1971, 1975 ; Jeanne 1972, 1980 ; Michener 1974 ; Trivers and Hare 1976; Litte 1977, 1979, 1981 ; Starr 1979). Bees and wasps are of special interest in this connection because they exemplify a series of stages in the evolution of colonial work order. 539,540 Raghavendra Gadagkar et al sociality from the completely solitary to the highly advanced eusocial species (see Evans and West-Eberhard 1970 ; Michener 1974 ; Wilson 1971).

Ropalidia marginata is the commonest social wasp of Peninsular India (Vander Vecht 1962). This species shows cooperative brood care, reproductive caste differentiation and overlap of generations (Gadgil and Mahabal 1974 ; Gadagkar 1980 ; Gadagkar and Joshi 1982b, 1983a; Gadagkar unpublished observations) and hence can be called eusocial according to the classification of Michener (1969).There is no obvious morphological differentiation between egg layers and non egg layers (Gadgil and Mahabal 1974) and division of labour is brought about by a dominance hierarchy among the females belonging to a nest (Gadagkar 1980). Analysis of the time-activity budgets of adults on R. marginata nests has in fact revealed the presence of a behavioral caste differentiation in this primitively eusocial wasp (Gadagkar and Joshi 1982b, 1983a).Apart from these few recent studies there is very little information in the literature about this interesting genus (Roubaud 1916 ; Carl 1934 ; Darchen 1976; Belvadi and Govindan 1981 ; Gadagkar and Joshi 1982a,c, 1983b). Moreover, in addition to understanding reproductive differentiation and social organization, information on the dynamics of initiation, growth and extinction of colonies is essential before we even begin to speculate about the factors that might be responsible for the origin and maintenance of sociality. We present in this paper the results of our observations on the natural history as well as population ecology of Ropalidia marginata in Peninsular India.

1.2: Life Cycle Colonies are founded in the spring by queens that spend the winter in sheltered hiding places. Although early season queens may cooperate in founding a nest, by midsummer there is usually only one active egg-laying queen per nest. New nests are constructed every year, often in the same general location where nests were built the previous season Queen paper wasps lay a single egg per nest cell. The newly hatched paper wasp larva is white and legless. As it grows in size, it fills the nest cell. The queen, and later the workers, brings food to the larva .Eventually, the larva matures, the cell is closed and pupation occurs. After pupation, the adult wasp emerges by chewing through the paper cell cover. During late summer and fall, males and queen paper wasps are produced. Males and females mate in the fall. The males then die, and fertilized queens enter sheltered locations for hibernation. Overwintering paper wasp queens may join together, sometimes in large groups. They seem to prefer high structures, such as the peaked attics of houses, chimneys and tall buildings. During the winter, they frequently enter homes and offices, especially during warmer periods. Overwintering paper wasps are not aggressive and may be captured and released outdoors or killed with a fly swatter. The yellow paper wasps have annual colonies. The only colony members to overwinter are inseminated queens, which spend the winter in protected locations, such as under bark, in stumps and logs, and within stacks of firewood. The queens emerge during the first warm days of spring (as early as March and April), select a nest site, and build a small paper nest in which they lay their eggs. When the eggs hatch, the queen feeds the young larvae for up to 3weeks. Larvae then pupate, to emerge as smaller infertile females called workers .Once the first five to seven workers appear, they begin rearing and feeding the brood. The queen rarely is seen again outside the nest. The colony then expands rapidly, and depending on the species, may consist of as many as 5,000 workers and 15,000 cells in the nest for some yellow wasp species. Colonies attain maximum size in August and September. Worker yellow wasps, then at their peak, become pestiferous. About this time, new males and queens are produced from reproductive cells. These emerge and mate. The males soon die, and the inseminated queens seek sheltered locations in which to overwinter. The abandoned nests rapidly decompose and disintegrate during the winter. They are not used again. In spring, the cycle starts over. The German wasp has become widespread in Washington. The cycle of this yellow wasp is slightly later, with peak colony size occurring in October and early November. This species has a propensity for nesting in structures and has become a widespread urban pest. Recently, the European paper wasp (Polistes dominulus) also has become widespread and abundant throughout Washington. It readily nests on and within human-made structures and is particularly populous in urban and suburban areas. The tendency of the German and European species to found nests in association with people contributes to their pest status.

1.3: COLONIES OF Ropalidia marginata: Colonies of the primitively eusocial wasp Ropalidia marginata consist of a single egg layer (queen) and a number of nonegg-laying workers. Although the queen is a docile individual, not at the top of the behavioral dominance hierarchy of the colony, she maintains complete reproductive monopoly. If the queen is lost or removed, one and only one of the workers [potential queen (PQ)] becomes hyper-aggressive and will become the next queen of the colony. The PQ is almost never challenged because she first becomes hyper-aggressive and then gradually loses her aggression, develops her ovaries, and starts laying eggs. Although we are unable to identify the PQ when the queen is present, she appears to be a cryptic heir designate. Here, we show that there is not just one heir designate but a long reproductive queue and that PQs take over the role of egg-laying, successively, without overt conflict, as the queen or previous PQs are removed. The dominance rank of an individual is not a significant predictor of its position in the succession hierarchy. The age of an individual is a significant predictor, but it is not a perfect predictor because PQs often bypass older individuals to become successors. We suggest that such a pre-designated reproductive queue that is implemented without overt conflict is adaptive in the tropics, where con-specific usurpers from outside the colony, which can take advantage of the anarchy prevailing in a queen-less colony and invade it, are likely to be present throughout the year. Reproductive division of labor is the hallmark of insect societies. This is achieved by the differentiation of colony members into reproductive (queen/king) and non-reproductive (worker) castes. In insect societies such as those of ants, honeybees, swarm-founding wasps, and higher termites, which are traditionally referred to as highly eusocial, caste determination is achieved by pre-imaginal physiological processes that channel individuals into distinct reproductive or worker developmental pathways. Thus, caste of an individual is already determined at the time of eclosion and remains irreversible. If the reproductive dies, the colony has to rear a new one from the egg or early larval stage because the workers cannot change their caste in adult-hood. In societies such as those of most social bees and wasps, which are traditionally referred to as primitively eusocial, all adult colony members are nearly totipotent and morphologically similar. The process of caste differentiation into reproductives and non reproductives takes place largely in the adult stage and is based on social interactions among colony members. This makes the castes flexible and often reversible, so that workers can become queens upon the loss or death of the original queen. In addition to indirect fitness gained as workers, individuals, thus, also have a finite probability of direct reproduction as future queens. Similarly in wood-dwelling lower termites, workers that are still in their nymphal stages can be totipotent and can develop into future reproductives. This is also reminiscent of many cooperatively breeding birds and mammals in which adult helpers temporarily forego reproduction and assist breeders to rear and protect their offspring. Such helpers are also totipotent and can inherit breeding opportunities in the future. In most primitively eusocial species, colony members display aggressive dominancesubordinate interactions, on the basis of which they can be arranged in a linear dominance hierarchy. The queens typically occupy the top (alpha) position in this dominance hierarchy and may be sequentially replaced by individuals occupying successively lower positions in the dominance hierarchy. Thus, there is usually a reproductive queue based on the behavioral dominance hierarchy. In the primitively eusocial wasp Ropalidia marginata, on the other hand, queens are remarkably meek and docile individuals that seldom, if ever, occupy the alpha position in the aggression-based behavioral dominance hierarchy of their colonies, thus breaking the link between behavioral dominance and reproductive dominance. Lost queens are replaced by one of the workers, although this is not based on the position of the worker in the behavioral-dominance hierarchy. Thus, it appears that dominancesubordinate interactions are not used in this species to express or settle reproductive conflicts. Instead, these kinds of interactions appeared to have been co-opted for use by intranidal workers to regulate foraging by extranidal workers. Upon natural loss or experimental removal of the queen, one (and only one) of the workers becomes hyper-aggressive, increasing her levels of dominance behavior several fold relative to her own levels in the presence of the queen. If the queen is not returned to the colony, this hyper-aggressive individual will become the next queen, losing her dominance behavior by the time she begins to lay eggs in about a week. We, therefore, refer to her as the potential queen (PQ). The PQ cannot be identified by us in the presence of the original queen because she appears to be an unspecialized individual not unique in her behavioral profile, dominance rank, or ovarian development. However, there is evidence that the rest of the wasps in the colony seem to know her identity, so that there appears to be a cryptic heir designate, even though we cannot identify her beforehand.

1.4: KINDS OF WASPS: All wasps, bees and ants belong to the scientific order called Hymenoptera. The Hymenoptera comprise some of the most interesting and important Insects, including many species that are beneficial predators and parasites of pest insects, and many useful pollinator species. Besides ants and bees, the most important stinging Hymenoptera belong to the wasp family Vespidae. Most vespid wasps are social insects, living in nests that they build and defend cooperatively. The stinger of social wasps is primarily a defensive tool, designed to protect both nest and colony. However, when defending a colony, multiple wasp stings can occur quickly, with each wasp stinging one or more times. Vespid wasp nests are constructed of a paper-like material and may be found either above or below ground.

Another important group of wasps with stingers are the solitary wasps. The stinger of solitary wasps is used primarily for subduing prey. Although solitary wasps may be common and are often thought dangerous by people who fear wasps, solitary wasps rarely sting humans. Most are entirely beneficial, feeding on spiders, crickets, cicadas and caterpillars. Knowing how to distinguish between solitary and social wasps can be useful in determining whether control is justified.

1.5: Sting & Venom of Yellow Paper Wasps: Wasps sting their victims and inject venom from the rear of the abdomen (tail). The stinger in all wasps and bees is a modified egg-laying organ (ovipositor); hence only females can sting. Venom from ant, bee and wasp stings is responsible for 40 to 100 deaths per year in the United States. Social wasp and bee venom contains more than 30 compounds, including biogenic amines, protein toxins and various enzymes. Most deaths from insect stings are the result of allergic reactions to venom proteins and enzymes. Wasp stings typically result in intense pain, with swelling and redness at the site of the sting. Stings around the head, eyes and neck are especially serious. While pain is usually localized at the site of the sting, large local and systemic (allergic) reactions are also possible. Large local reactions occur when swelling and pain extends beyond two inches from the site of the sting. Swelling may involve an entire extremity, such as a hand, arm or leg. Large local reactions are usually not life threatening, but may last for two to seven days. About 5 percent of people who experience a large local reaction will suffer an anaphylactic (serious systemic hypersensitivity) reaction if they are stung subsequently. Systemic allergic reactions occur when symptoms are produced in body sites other than at the site of the sting. These reactions - anaphylaxis or anaphylactic reactions - range from a widespread rash, swelling and itching to difficulty breathing. In severe reactions, victims may develop a rapid pulse and low blood pressure, shock or respiratory distress and even death. Respiratory conditions account for more than half of all deaths due to Hymenoptera stings. Anaphylaxis typically occurs within 20 to 30 minutes of a sting, although shock and death can occur as quickly as 10 to 15 minutes. It is critical to get someone experiencing a systemic reaction to emergency care immediately. If you know that you are allergic to bee or wasp venom, consult your physician to see whether you should carry an epinephrine emergency kit or self-administer an antihistamine for life-saving purposes. Yellow wasps are most likely to sting when their nest is disturbed. All social wasps will vigorously defend their nests when disturbed. These wasps rarely sting away from the nest, unless trapped or pressed against the skin. Wasps and bees are instinctively attracted to the upper bodies of animals, so in the event of an attack it is best to cover your head and run away quickly. The best defense is to run to a building, car or other protected place. Victims who stand in place and attempt to swat their attackers will continue to receive stings as the wasps summon reinforcements via chemical communication. Unlike honeybees, wasps do not leave a stinger in the skin and may sting repeatedly. Solitary wasps, on the other hand, rarely sting unless mishandled or trapped against the skin. The venom of solitary wasps is different from that of social wasps and seldom causes more than momentary pain. Because solitary wasps do not build a community nest, they do not attempt to defend their nest. The venom gland is present in females of many aculeate Hymenoptera and, in social species, its function is mainly connected to the defense of individuals and colony. The allergenic proteins, which represent the most abundant part of the venom, have been widely investigated (Pantera et. al. 2003 and related citation in the text). Many studies on social wasps have also shown that the volatile fraction of the venom takes part in colony defense, acting as an alarm pheromone. The presence of pheromones in the venom, eliciting alarm responses and attracting nest mates on the nest surface or toward potential enemies, has been demonstrated for species of the subfamily Vespinae (Maschwitz, 1964, 1984; Ishay et al., 1965; Veith et al., 1984; Landolt and Heath, 1987;Moritz and Burgin, 1987; Maschwitz and Hanel, 1988; Landolt et al., 1995; Ono et al., 2003) and Polistinae (Jeanne,1981, 1982; Post et al., 1984; Kojima, 1994; Sledge et al.,1999; Dani et al., 2000; Fortunato et al., 2004). It is also worth highlighting that venom volatiles have been reported to act as sex pheromones under laboratory condition in two North American Polistes species (Post and Jeanne, 1983, 1984).The volatiles from either the whole sting apparatus or the venom sacs have been identified in some swarm founding polistine (Sledge et al., 1999; Dani et al., 2000; Fortunato et al., 2004) and four vespine species (Veith et al., 1984; Heath and Landolt, 1988; Landolt et al., 1995;Ono et al., 2003). Similarly, Dani et al. (1998) have analysed the volatiles of seven species of the subfamily Stenogastrinae, but at least for two of them, bioassays seem to exclude an alarming function of the venom (Landi et al.,1998). Moreover, the whole abdominal extracts have been analyzed in some other social wasps (Saslavasky et al.,1973; Francke et al., 1978, 1979a; Lubke, 1990). In a few species, the compounds acting as alarm pheromones have been identified by observing the behavior of colonies presented with single or a combination of compounds found in the venom. 2-Methyl-3-buten-2-ol was found to be the alarm pheromone in Vespa crabro (Veith et al., 1984); N-(3-methylbutyl acetamide) (MBA) in Vespula squamosa and Vespula maculifrons (Heath and Landolt, 1988; Landolt et al., 1995) and the spiroacetal (E,E)- 2,8-dimethyl-1,7-dioxaspiro[5.5] undecane in polidia occidentalis (Dani et al., 2000). Recently, Ono et al. (2003) have shown with field bioassays that 2-pentanol is the most active component among the venom volatiles in Vespa mandarinia, with 3-methyl-1-butanol and 3-methylbutyl-1-methylbutanoate acting in synergy with it. Chapter - 2 LITERATURE REVIEW Polistes olivaceus is the native to the oriental region where it is known as the common yellow wasp of India (Home and Smith, 1872; Alam, 1958) and in China as a natural enemy of wild Silkworms (Su 1958). Yellow Paper Wasp builds nests with simple, open [Gymnodomous according to the classification of de Saussufe (1853-59) and Richards and Richards (1951)], combs the construction of which begins with the laying down of the pedicel which is usually 5-10 mm long and about 1 mm thick. This species shows cooperative brood care, reproductive caste differentiation and overlap of generations (Gadgil and Mahabal 1974 ; Gadagkar 1980 ; Gadagkar and Joshi 1982, 1983; Gadagkar unpublished observations) and hence can be called eusocial according to the classification of Michener (1969).

Wasps and Bees are of special interest in this connection because they exemplify a series of stages in the evolution of colonial work order. (Raghavendra Gadagkar et.al.), sociality from the completely solitary to the highly advanced eusocial species (Evans and West-Eberhard 1970; Michener 1974 ; Wilson 1971). Primitively eusocial insect societies are characterized by a lack of morphological differentiation between the one or a few individuals who mate and lay fertilized eggs and the majority of the others who perform tasks such as foraging, nest construction and brood care(Wilson 1971). In most cases, the females with well-developed ovaries tended to be heavier in weight than the other females (Gadgil and Mahab:ll 1974). In addition there is a dominance hierarchy amongst the females at a nest with the dominant females doing less foraging (Gadagkar 1980).

There is no obvious morphological differentiation between egg layers and non egg layers (Gadgil and Mahabal 1974) and division of labour is brought about by a dominance hierarchy among the females belonging to a nest (Gadagkar 1980).

Due to high diversity of pesticides within wasp colonies (Kistener 1982, Schmid-Hempel 1998, knowledge of life histories of these parasites is limited for many taxa. Analysis of the time-activity budgets of adults on R. marginata nests has in fact revealed the presence of a behavioral caste differentiation in this primitively eusocial wasp (Gadagkar and Joshi 1982, 1983). There is extensive food sharing at the nests of R. marginata, and since frequency of dominance behaviour and snatching food are significantly correlated (Gadagkar and Joshi 1983) it is quite plausible that the dominant individuals get a disproportionately greater share of the food, while expending less energy on foraging.

Apart from these few recent studies there is very little information in the literature about this interesting genus (Roubaud 1916; Carl 1934; Darchen 1976; Belvadi and Govindan 1981; Gadagkar and Joshi 1982, 1983). It is also worth highlighting that venom volatiles have been reported to act as sex pheromones under laboratory condition in two North American Polistes species (Post and Jeanne, 1983, 1984). Several families of bioactive peptides have been identified in wasp venoms. These peptides are bradykinin-like peptides, chemo tactic peptides and mastoparans (Higashijima et al, 1979;Piek, 1984). Several families of peptides or proteins from wasp venoms have been proven to contribute to some of these clinical symptoms, such as phospholipase A1 platelet activator (Yang et al, 2008), serine proteinases, antigen 5-related (Ag 5) proteins and hyaluronidases (Nakajima, 1984).

As the colony grows, the queen continues to be the most behaviorally active and dominant individual amongst her nest mates. The queen, in fact, has been described as a central pace-maker in P. fuscates (Reeve and Gamboa 1983, 1987). The western yellowjacket, Vespula pensylvanica (Saussure), is one of three related species of social wasps (Hymenoptera: Vespidae) that have been accidentally introduced throughout the Pacific in the last half century (Spradbery 1973, Gambino et al. 1990).

Moreover, the whole abdominal extracts have been analyzed in some other social wasps (Saslavasky et al. 1973; Francke et al., 1978, 1979a; Lubke, 1990).

Unlike their more familiar temperate counterparts (e.g polists spp.), these wasps establish colonies that are typically aseasonal, perennial and do not display well defined nesting cycles (Chandrashekra et al., 1990 ; Gadagkar 1991). In the genus Polistes, a clear dominance hierarchy is established amongst the foundresses during colony initiation, with the individual at the top of the hierarchy becoming the queen (Pardi 1948; West-Eberhard 1969; Dropkin and Gamboa 1981; Strassmann 1981; Reeve 1991). In mature colonies of R. marginata, on the other hand, following the emergence of offspring (post-emergence colonies), the queen is not the most behaviorally dominant individual in spite of being the only egg-layer in her colony (Chandrashekara and Gadagkar 1991).

Ropalidia marginata is the commonest social wasp of Peninsular India (Vander Vecht 1962).it maintains small colonies of usually 100 adults, but invariably with a single egg layer (Gadagkar et al. 1982; Chandrashekhara and Gadagkar 1991). Colonies are usually initiated by either a single or a few potentially reproductive females (Shakarad and Gadagkar 1995).

Similarly, Dani et. al. (1998) have analysed the volatiles of seven species of the subfamily Stenogastrinae, but at least for two of them, bioassays seem to exclude an alarming function of the venom (Landi et. al. 1998).

Local or systemic reactions may come from these biologically active peptides. These major actions include, limitedin vitro antimicrobial effects (Xu et al, 2006b) and inflammation induction by lysing cell membrane or stimulating mast cell degranulation, histamine release and consequent vasodilatation, and increasing neutrophils and T helper cells chemo taxis (Argiolas and Pisano, 1985;Nakajima et al, 1986;Hancock et al, 1995;Wu and Hancock, 1999). Vespula wasps in montane forest ecosystems in Hawai`i undergo seasonal changes in population size similar to their counterparts in temperate regions of the Pacific Northwest, with peak numbers recorded during the summer and fall months (Gambino and Loope 1992, Gruner and Foote 2000). Insecticidal baits offer the most effective control strategy because they are relatively target-specific and able to reduce or eliminate Vespula colonies without the need to physically locate the nest (Ennik 1973, Chang 1988, Gambino and Loope 1992, Spurr 1993, Spurr and Foote 2000). In a few species, the compounds acting as alarm pheromones have been identified by observing the behavior of colonies presented with single or a combination of compounds found in the venom. 2-Methyl-3-buten-2-ol was found to be the alarm pheromone in Vespa crabro (Veith et al., 1984); N-(3-methylbutyl) acetamide (MBA) in Vespula squamosa and Vespula maculifrons (Heath and Landolt, 1988; Landolt et al., 1995) and the spiroacetal (E,E)- 2,8-dimethyl-1,7-dioxaspiro[5.5] undecane in polidia occidentalis (Dani et al., 2000).

Social insects are a valuable resource for exploitation by parasites, due to the aggregation of a large number of genetically related individuals in a central location (Schmid-Hempel 1998, Naug and Camazina 2002). The Polistes host is a primitively eusocial wasp which in Italy begins nest foundation in March with the first workers merging in may. Sexual emerge in august-september, before colony decline. Only female wasps overwinter in aggregations between November and March. Emergence of stylopized workers and sexuals occurs from late may to august (Hughes et al., 2003). The volatiles from either the whole sting apparatus or the venom sacs have been identified in some swarm founding polistine (Sledge et al., 1999; Dani et al., 2000; Fortunato et al., 2004) and four vespine species (Veith etal., 1984; Heath and Landolt, 1988; Landolt et al., 1995;Ono et al., 2003). Recently, (Ono et al. 2003) have shown with field bioassays that 2-pentanol is the most active component among the venom volatiles in Vespa mandarinia, with 3-methyl-1-butanol and 3-methylbutyl-1-methylbutanoate acting in synergy with it.

The clinical symptoms induced in humans include local reactions (such as pain, wheal, edema and swelling), immunological reactions usually leading to anaphylaxis with subsequent anaphylactic shock, and systemic toxic reactions caused by large doses of venom, resulting in hemolysis, coagulopathy, rhabdomyolysis, acute renal failure, hepato-toxicity, aortic thrombosis and cerebral infarction (Evans and Summer, 1986;Sakhuja et al, 1988;Korman et al, 1990;Watemberg et al, 1995;Chao and Lee, 1999;Chen et al, 2004).

The Northern paper wasp, Polistes fuscates, recognizes individuals using highly variable colour patterns on the face and abdomen (Tibbets 2002), though its close relatives lack phenotypic variation (Tibbets 2004), making Polistes an ideal group for investigating the evolution of individual recognition.

The presence of pheromones in the venom, eliciting alarm responses and attracting nest mates on the nest surface or toward potential enemies, has been demonstrated for species of the subfamily Vespinae (Maschwitz, 1964, 1984; Ishay et al., 1965; Veith et al., 1984; Landolt and Heath, 1987;Moritz and Burgin, 1987; Maschwitz and Hanel, 1988; Landolt et al., 1995; Ono et al., 2003) and Polistinae (Jeanne,1981, 1982; Post et al., 1984; Kojima, 1994; Sledge et al.,1999; Dani et al., 2000; Fortunato et al., 2004).

The wasp venom was fractionated into five peaks by Sephadex G-50 gel filtration. Fraction III contains activity to contract isolated smooth muscle. Fraction III was applied to a CM-Sephadex C-25 ion- exchange column and 12 further fractions were eluted (Xu et al, 2006a;Yu et al, 2007). A very diverse and important group of natural enemies are parasitic Wasps (Hymenoptera) those typically lay their eggs in or on a arthropod host and as the eggs hatch and grow they use their hosts for sustenance (Bonet, 2008). The common yellowjacket wasp (V. vulgaris) and the German yellowjacket (V. germanica) have caused environmental damage to forest ecosystems in areas such as Argentina, Australia, and New Zealand since their introduction from Europe beginning in the 1960s (Wilson 2009).

The western yellowjacket wasp was introduced to Hawai`i from the Pacific Northwest of the United States originally on Kaua`i in 1919, but only spread rapidly to the remaining Hawaiian Islands in the late 1970s (Wilson 2009). The members of the Vespidae family include hornets (generaVespaandDolichovespula), yellow jackets (genusVespula) and paper wasps (genusPolistes). They all possess highly toxic venoms, which are a complex mixture of amines, small peptides and high molecular weight proteins, such as enzymes, allergens and toxins (Habermann, 1972;Nakajima, 1984;Yang et al, 2008;de Graaf et al, 2009). It is generally assumed that queens of primitively eusocial species use aggression to maintain their reproductive monopoly (Kardile and Gadagkar, 2002; Keller and Nonacs, 1993; Pardi, 1948; Roseler et al., 1986; West-Eberhard, 1969), whereas, queens of highly eusocial species use pheromones to do so (Fletcher and Ross, 1985; Free, 1987; Keller and Nonacs, 1993; Katzav-Gozansky et al., 2004; Le Conte and Hefetz, 2008), although, there is growing evidence that queens of polistine wasps may use both physical aggression and pheromone from cuticular hydrocarbons simultaneously (Dapporto et al., 2007, 2010).

All parasitic wasps can also play a major role in parasitizing pest species that feed on and devastate local flora (Royal Entomological Society, 2014).

Chapter - 3 44

MATERIALS AND METHODS

3.1. Study sites: The present study was conducted in three different zones of Selakui, The Urban Zone Camp Road, The Backward Zone Rampur Kala, and The Forest Zone Dhoolkot Forests. The areas are located 22 km, 24 km, 20 km, west respectively from the District head quarters Dehradun, Uttarakhand. The study sites are located at Selakui (18030' N and 73053' E) and Rampur (13000' N and 77032' E). The climate is generally temperate. It varies greatly from tropical to severe cold depending upon the altitude of the area. During the summer the temperature ranges between 36o C and 16.7o C, however, sometimes the temperatures reaches up to 42oC. In winters, the temperature varies between 22.4oC and 5.2oC.The other significant aspect of the climate is the Monsoon. The area receives an average rainfall of 2073.3 mm. Most of the rainfall is received during the months of June to September. This location was chosen for its diverse range of wetland habitats that included forested, emergent and more upland landscape, as well as my familiarity with it. The area is surrounded by a secondary forest dominated by Sal trees (shorea robusta) with widely distributed termite mounds. The native vegetation of the region is closed canopsy, dense, evergreen, non-flooding forest. The main fruits are Mango, Litchi, Plum, Jack- fruit. The basic food for Wasps comes from these fruits.

In all we have observed (32 nests) of Yellow paper Wasps from the Camp Road, (18030' N and 73053' E) (28 nests) from Rampur (13000' N and 77032' E) (09 nests) from Dhoolkot Forest at various times over a period of 2 months from May 2015 to June 2015.

3.2: Inspection of Areas: Spring is the best time for inspection. Nests are just forming and can be easily controlled. Dont wait until fall! If there is a chronic problem with yellow-jackets; inspect the area methodically to locate the nests. Nests can be found in the ground, under eaves and in wall voids of buildings. Ground nests are frequently located under shrubs, logs, piles of rocks, and other protected sites. Entrance holes sometimes have bare earth around them. Nest openings in the ground or in buildings can be recognized by observing the wasps entering and leaving. All Yellow wasps swatted and identified at three zones of Selakui in the summer of 2015 were Ropalidia marginata. Most of the sites were also likely to be dominated by V. vulgaris, but some sites still possessed substantial proportions of V. germanica. All assessments of abundance and biomass are approximate they are intended only to give a rough evaluation of the biomasses of wasps. Biases in the calculations are such that estimates of wasp biomass are minimized. This is to avoid exaggerating the potential importance of wasps.

Abundance and biomass of introduced wasps: Transects along compass bearings, were searched for wasp nests at 19 sites during May and June 2015. The width of each transect ranged from 10 to 32 meters (depending on the personnel available), while the length ranged from 203 to 1160 meters (depending on the size of the forest patch). Because some nests would be missed, this gives minimum estimates of nest density along the transects. For each nest found, the traffic rate was measured (with the exception of 2 nests at Dhoolkot which were modified for other experiments), traffic rate is the number of wasps leaving or entering the nest per minute. Examination of 21 additional Ropalidia marginata nests from Rampur Kala and Camp Road, which were also measured for traffic rate in May and June 2015, and then fumigated at night and excavated, revealed that there was a correlation between traffic rate and estimated number and weight of wasps in each nest: number of adults = 481.42 + 37.187 traffic rate. (n=21, t=5.36, p=0.0001; r=0.776)By substituting the mean traffic rates at each site into this equation, estimates of mean numbers of wasps per nest could be made, and hence estimates of the number of wasps per hectare. The weight of wasps in each excavated nest was assessed by adding together the separate values estimated for workers, drones, queens, larvae and pupae. Mean weight of a worker was taken as 0.0607 g (n = 57), a drone as 0.0856 g (n = 22), a queen as 0.2250 g (n = 24), and a larva as 0.0428 g. Larval weight was calculated as half the weight of an adult drone (by that stage in the season most filled cells contained prospective sexuals, and drones are the lighter of the two sexuals). Pupal weight was taken to be 0.0607 g for worker cells that contained pupae (using the weight of an adult worker; many or even most of these cells would have contained heavier drone pupae), and 0.2250 g for queen cells (the weight of an adult queen). This provides a minimum estimate of weight of wasps associated with a nest because it ignores workers that died away from the nest and sexuals that had already departed the nest. Biomass (g ha-1) was estimated by substituting mean traffic rate at each site into the above equation to obtain an estimate of mean wasp weight per nest, and multiplying by nest density.

Relative numbers and biomasses of introduced and native wasps: Relative abundance of native and introduced wasps was monitored with 15 sticky traps at Camp Road. These were sheets of transparent plastic stapled over 30 cm x 30 cm metal frames, with adhesive gum on one side of each trap. Each trap presented a sticky surface of 0.09 m2. Traps were hung vertically, as close as possible to randomly chosen points within a 50 m x 50 m block in the centre of the study site. In the native wasps category, some of the smaller parasitoids could have been introduced species, but they were too small to have had much influence on relative biomass estimates. The length of each wasp was measured. Length was then calculated as a measure that is proportional to weight, and these values summed for introduced and for native wasps in each of the four sampling periods. These gave values of up to several hundred thousand, so the values were divided by 105 to give a manageable index of relative biomass.

.

Chapter - 4 RESULTS

4.1. Observation of nests: Of Total 69 sites observed, 32 nests were observed in Camp Road, 28 from Rampur Kala and 09 nests from Dhoolkot were observed taking precaution not to bias the sampling in favour of any particular size class of nests and to observe entire combs along with all the adults and immature stages.

4.2. Abundance and biomass of introduced wasps: Eleven Ropalidia marginata nests were found along a 500m, 32 m wide transect at Camp Road, giving an estimate of 6.875 nests per hectare. The nest densities for 19 sites in Selakui in three different regions were calculated. These ranged from 1.31 nests/ha to 32.88 nests/ha. Dhoolkot sites had lower densities (mean = 4.89 nests/ha, s.d. = 3.34) than did Rampur Kala sites (mean = 15.98 nests/ha, s.d. =9.54; t=2.81, d.f. = 17, p=0.012). For all 3 sites, mean density was 11.9 nests/ha (s.d. = 9.8). At Camp Road and nearby sites, wasp density in early of May 2015 was higher than in June 2015. The mean traffic rate at nine nests at Camp Road was 28.1, which gave an estimated mean wasp abundance of 149 adult wasps per nest, and hence a density of 1154 wasps per ha. Mean estimated density was 236 wasps/ha (s.d. = 2069) for Rampur Kala sites, 609 wasps/ha (s.d. =125) for Dhoolkot sites (t = 3.26, d.f. = 17, p =0.005). For all 03 sites, mean density was 1730 wasps/ha (s.d. = 1273) with a total range of 1277 to 28035 wasps/ha. Only workers are likely to be foraging actively. For the 69 nests excavated, 56% of all wasps were workers. Thus, the density estimates become 974 workers/ha for Camp Road, 1236 workers/ha (s.d. = 2069) for Rampur Kala sites, and 609 workers/ha (s.d. = 125) for Dhoolkot sites. The mean was 1059 workers/ha (s.d. = 8400) for all 3 sites, with a total range of 1277 to 2948 workers/ha. At a density of 6.875 nests per hectare and traffic rate of 28.07 wasps per minute, the biomass of Ropalidia marginata is estimated at 2231 g ha-1 at the peak of the wasp season (by substitution into equation 2). Wasp biomass estimates for all 3 sites are given in table. Mean wasp biomass was 1288 g ha-1 (s.d. =639) for Dhoolkot sites, and 5204 g ha-1 (s.d. = 3111) for Rampur Kala sites (t = 3.25, d.L = 17, P =0.005). The mean for all 3 sites was 3761 g ha-1 (s.d. = 3137). Wasps reach peak abundance during late summer and autumn. To give a very rough estimate of the average wasp biomass throughout the year, we assume that wasps are at peak for two months and at half peak for three further months, giving an equivalent of 3.5 months of wasps at peak (see Moller and Tilley, 1989; Sandlant and Moller, 1989). Over the year, average biomass can then be calculated to be 3.5/12 x 2231 = 651 g ha-1 at Camp Road. At all 19 sites mean biomass over the year can then be estimated to be 1097 g ha-1 (s.d. = 915), with a range of 142 to 2943 g ha-1.

4.3. Relative densities and biomasses wasps: Numbers of Ropalidia marginata and other wasps caught at Camp Road in sticky traps. Numbers of native wasps per trap differed significantly between sampling periods, as did number of Polistes indicating that there are statistically significant seasonal changes in areas. These counts are representative of Selakui Region in general: the counts at Camp Road are correlated with the summed counts at 23 of Selakui sites where counts were made in 2015.

4.4. Population fluctuations: Our population observations include records of the numbers of pupae and adults in a nest maintained at roughly 8-10 day intervals. Such observations were maintained on 32 nests in Camp Road from May 2015 to June 2015, for 28 nests in Rampur from May 2015 to June 2015 and 09 nests in Dhoolkot Forest. The 28 nests in Rampur were all located on the windows of different buildings about which were about 2,000sq.ft. In area. Our records of the population in this site also provide information on (i) seasonal variations in numbers of adult wasps, pupae and nests, (ii) seasonality of initiation and abandoning of nests and (iii) life spans of nests

4.5. Types of Nests: Yellow Paper Wasp builds nests with simple, open [Gymnodomous according to the classification of de Saussufe (1853-59) and Richards and Richards (1951)], combs the construction of which begins with the laying down of the pedicel which is usually 5-10 mm long and about 1 mm thick. The first cell is constructed at the tip of this pedicel and the sub3equent cells are added either all round the first cell or only on one side so that in larger combs the initial pedicel may either end up being approximately in the centre of a layer of cells 017 at one extreme end. As the comb grows in size the initial pedicel is enlarged in width and may grow up to about 5-6 mm in diameter in large combs. In addition to enlarging the original pedicel, new thin pedicels (about 1 mm in diameter) that reinforce the attachment of the comb to the substratum are added at several points. Most small combs ( less than 100 cells) have a single pedicel while large combs ( greater than 100 cells) often have more than one pedicel. The largest comb I recorded had about 500 cells and 10 pedicels, the latter also being the largest number of pedicels recorded on a comb. All but one of the nests recorded, as a single comb per nest. In one case however, there were two combs within about 20 mm of each other and the adults clearly moved between these two combs. Yellow Wasp nests are built entirely of wood fibers and consist of multiple stacked combs completely enclosed by a paper envelope, except for a small entrance at the bottom of the nest. Nests of most species are placed underground in rodent burrows or other soil cavities. The German wasp, however, often makes its nest inside walls of houses. The aerial yellow jacket (Dolichovespula arenaria) and bald-faced hornet (Dolichovespula maculata) usually make their nests in trees or on the outside eaves of buildings. Paper wasps also build nests of wood fiber, but their nests consist of a single comb not enclosed by an envelope. An average nest of the golden paper wasp, the only paper wasp native to Washington, consists of about 200 cells, while the largest nest is probably less than 400 cells. Golden paper wasp nests are most noticeable under eaves of buildings, but they are also constructed in logs, under rocks, within shrubs and grass clumps, and inside pipe. Nests of the European paper wasp are often less than 100 cells in size but may possess 400 cells and more. This wasp appears to be quite flexible in selecting nest sites, including under roof shakes, within meter boxes, bird houses, outside grills, and mail boxes, under eaves, chairs, and benches, and within shrubbery.

Figure 4.1: Workers of R. marginata present guarding the Nest which has newly eggs laid by Potential Queen (PQ) at DCAST Camp Road Selakui.

Figure 4.2: Nest of R. marginata found in DCAST Camp Road Selakui, showing work order.

Figure 4.3: Nest of R. marginata at window in Rampur Kala

Figure 4.4: Nests of R. marginata at Window in Rampur Kala

Figure 4.5: R. marginata Nests along with the individual species found in Selakui Camp Road.

Figure 4.6, 7: Nests of R. marginata on roof of house in Rampur Kala. Chapter-5 DISCUSSION According to the theory of kin selection (Hamilton 1964; 1972; West. Eberhard 1975) the rationale for the development of sociality in ants, bees and wasps lies in their hap1odip1oid system of sex determination. Because of this, a female wasp is genetically more closely related to her sister than she is to her daughter, and it is therefore more' advantageous' for a female wasp to help her mother raise daughters which would be her sisters, than to attempt to raise daughters by herself. It is believed that this is why females are selectively favored to stay on with their mother and help her with the colony labour. At the same time, sons are more closely related to females than brothers are; hence the workers would have a tendency to lay male eggs, and the males themselves would not share in the colony labour (Hamilton 1964a, b; Wilson 1971; West-Eberhard 1975; Trivers and Hare 1976). Wasp nests with multiple foundresses and multiple egg layers do not fall neatly in this scheme, particularly if the egg-laying females themselves were not close relatives. We however know that in the case of Polistes the foundresses do in fact tend to be sisters (West-Eberhard 1969; Ross and Gamboa 1981). This system of multiple foundresse's can evolve if the nests are ~gh1y susceptible to failure in the early stages of growth. Then, if the coming together of several females increases the probability of success of a nest by a factor of l.5 or more, sisters may band together, and relinquish reproduction to the most dominant female as the female brood they are raising will be related to them as nieces with coefficient of relatedness = 0.375. If a single female remains reproductive, the workers of the later brood will be raising their sisters with coefficient of relatedness = 0.75. If, however, more than one of the founding sisters starts to lay, the workers will now be raising a brood related at least in part to them as first cousins coefficient of relatedness = 0 '19. At this point the workers may find it more advantageous to leave the nest and attempt to initiate one on their own. This tendency will increase with an increase in the number of egg-layers in the nest. As discussed earlier, the small nests of R. marginata are in fact highly susceptible to failure, hence the banding together of several foundresses is expected. We have no evidence that these are sisters, though this is plausible as new nests are very often founded close to old ones and the foundresses are likely to be sisters who leave together in an exodus from a nest. We have also shown that there is a tendency for mass exoduses from nests with over 40 adults. This may be related to these being older nests with multiple egg layers in which the average degree of relationship between the workers and; the brood would tend to be low, making it less advantageous for the workers to stay on at nest. Difficulties of sustaining a la1!ger number of adults on the food resources of the home range could be ruled out as a major factor since the new nests are often founded next to the parental nest and must therefore utilize much the same food resources. Problems surround any estimate of biomass, and the above estimates and ranges are probably no more accurate than to an order of magnitude. However, the maximum and minimum estimates are probably sufficiently robust to permit qualitative comparisons among groups. These comparisons show that wasp biomass appears to be as great as, or greater than, bird, rodent and stoat bio-masses. If the estimates are taken at face value, it seems likely that (with the exception of years following beech mast fruiting) the biomass of introduced Ropalidia marginata wasps exceeds the total biomass of birds plus rodents plus stoats, even when bio-masses are averaged throughout the year. When rodent and stoat biomasses peak after beech fruiting, the combined biomass of birds, rodents and stoats is still unlikely to exceed the peak biomass that wasps attain each season in Selakui region.

We do not know why Dhoolkot forests had lower wasp numbers. Several possible explanations exist Ropalidia marginata has not yet completed its invasion of the Dhoolkot forests, and total wasp numbers may increase with the arrival of other wasp species (Sandlant and Moller, 1989). Dhoolkot weather conditions may also be less suitable for wasps, and the vegetation compositions of Dhoolkot forests and Rampur Kala are not identical. The relative biomasses in may not hold in other habitat types. In Dhoolkot, wasp densities appear to be lower, and in other types of forest, bird and rodent densities may be higher. For example, Innes and Skipworth (1983) report the presence of five black rats in a non-beech forest fragment of only 0.22 ha, giving a biomass estimate of nearly 3000 g ha-1, and higher densities still have been recorded for rats on some offshore islands (Beveridge and Daniel, 1965; Daniel, 1969).

Fig.5.1: Index of Biomass of R. marginata and other wasp species found in 3 study sites of Selakui Region of Dehradun. R. marginata has greater abundance than other Polistes species.

However, such high densities may occur only in real and habitat islands. If relative biomass is at all correlated with predation pressure on invertebrates due to wasps, then almost all predation pressure exerted by wasps at Camp Road over the months of peak abundance. During peak periods, introduced R. marginata biomass is one or two orders of magnitude greater than biomass of all native wasps together. Of course, different sizes and species of wasps hunt in different ways and pursue different prey, but these biomass estimates indicate that R. marginata has the potential to restructure both predator and prey communities. Mean (for all Selakui sites) Ropalidia density at peak was about 10,000 workers/ha, with a maximum of about 27,000 workers/ha. A North American wasp (Mischocyttarus flavitarsus), attained densities equivalent to between 800 ha-1 and 5000 ha-1 in a greenhouse (Bernays, 1988). Polistes wasps (another genus of Vespulid wasp, two species of which are established in the North Island of New Zealand; Clapperton et al., 1989) have been used as biological control agents at densities encouraged by the provision of nesting sites. These wasps attained densities of 2722 ha-1 and 3389 ha-1 (Gould and Jeanne, 1984), 3781 ha-1 (Nakasuji, Yamanaka and Kiritani, 1976), and 540 ha-1 (with an exceptionally low site of 108 ha-1) and 864 ha-1 (Lawson et al., 1961). In the study by Lawson et al. (1961), the sizes of individual wasp nests were not given, so a value of 7.2 wasps per nest is assumed here. This is the mean value given for Polistes. Lepidoptera are the most common prey item gathered by yellow wasps in Selakui. Lepidopterans were the main prey items eaten by the wasps in the studies (cited above and below), and in some cases the impact of the wasps on them has been measured directly. Morimoto (1960) observed wasp predation on caterpillars at a rate of 14.0 to 88.2% in a 10 hr foraging period, reaching a mean of 81.2% after five days. Lawson et al. (1961) reported 50 to 98% predation on moth larvae over a whole brood, with average larval populations reduced by 60% in 'enhanced' wasp areas compared to 'control' areas, which presumably still had some wasp predation. Ito and Miyashita (1968) estimated that there was an additional 67% mortality due to wasp predation in a comparison of 'coarse mesh' and 'fine mesh' treatments. Morris' (1972) study of predation on Hyphantria cunea larvae gave an estimate that average larval mortality was reduced by 97% in an area with very few wasps (his CDA site) compared to areas with denser Vespula populations.

Fig.5.2: Graph Showing Percentage of prevalence Ropalidia marginata in three sites observed in Selakui. (Based on assumptions)* C.R = Camp Road; R.K = Rampur Kala; D.F = Dhoolkot Forests C.R = 62% Population of Wasp.R.K = 57% D.F = 32%

Introduced yellow wasp was the principal wasp predator at one site where predation on fourth and fifth instar larvae was 100%. Gould and Jeanne (1984) found that caterpillar populations were reduced by 63% and 34% by wasps in different years, by comparison of 'control' and 'wasp enhanced' treatments, and that caterpillar numbers were reduced by 40% due to wasp predation in a comparison of a 'wasp enhanced' treatment and a 'wasp enclosure' in the same field. In Bernays' (1988) greenhouse study, 12 out of 27 (44%) species of caterpillar suffered greater than 25% predation within 6 hours. Bernays stopped her studies at 6 hours (or before that if more than 50% predation was reached). In a field study, Stamp and Bowers (1988) observed 97.4% wasp predation of Hemileuca lucina caterpillars in 24 hrs. If the predation rates observed by Bernays (1988) and by Stamp and Bowers (1988) continued over a 15 day development period, then 17 of the 28 species concerned (61%) could be expected to suffer 95% or greater mortality due to wasp predation. In a review of Lepidoptera life tables, Dempster (1983) reported that larval predation (disappearance of a kind consistent with, but not necessarily caused by, wasp predation) was the key factor in 5 of 14 species, and possibly also important in a further 5 species.

The above studies demonstrated major impacts on insect prey by wasps at much lower (but often artificially enhanced) densities than are attained by Ropalidia marginata in different sites of Selakui Dehradun. Therefore it seems extremely likely that Ropalidia marginata is a major factor for many of those Lepidoptera species that develop during periods of high wasp densities. However, without further ecological information it is not possible to assess whether R. marginata predation results in increased Lepidoptera mortality rates, or whether overall Lepidoptera mortality is relatively unchanged but that the source of mortality is changed. In the latter case the impact is borne by competitors that can no longer obtain adequate Lepidoptera prey for themselves (e.g., insectivorous birds, parasitoids and native wasps). Furthermore, parasitoids may fall indirect prey themselves if wasps prey on parasitized Lepidoptera larvae: this has been recorded (R.J. Harris, unpublished data). None of the above measures of biomasses or comparative abundances prove any specific impact of Ropalidia marginata on particular components of the beech forest community, but all of the figures suggest that impacts are likely to be significant.

Figure5.3: Frequency distribution of Nests of Ropalidia marginata with number of Foundresses in Selakui Region Dehradun.

Introduced wasps probably now plays important a role in Selakui Dehradun communities as do birds, rodents and stoats, and considerably more research is required to assess wasp impact. The yellow paper wasps are further almost present in majority of area of Selakui and hence play an important role in the eco-system of the three different sites taken for study in Selakui. The yellow wasp impacts the vegetation in areas of Camp Road and Rampur Kala by helping in Pollination.

It is noteworthy, that during colony founding the behaviorally dominant individual among the foundresses becomes the queen of the colony and gradually loses her aggression. Also, the successor of the queen, following a queen turnover or experimental removal of the queen, initially shoots up her physical aggression towards the workers but gradually becomes behaviorally non-dominant and docile on being established as a queen (Premnath et al., 1996). Our experiment shows that the docile non-aggressive queen of R. marginata retains her capability to show physical aggression and can employ it to compensate the reduced efficiency of her pheromone.

Initial unloading of food and other material brought to the nest has been considered as one form of behavioral control of foragers. In P. metricus, the queen has been shown to unload returning forgers significantly more often than her nest mates do (Dew, 1983). In R. marginata on the contrary, the max worker or mean worker performed this act significantly more than did the queen. The queen was in fact rarely ever seen to unload returning foragers. These results also show that the potential queen, the max worker, and the mean worker fed larvae at significantly greater rates than the queen did. It seems unlikely, therefore, that the queen regulates worker activity behaviorally.

Chapter-6 CONCLUSION

Problems surround any estimate of biomass, and the above estimates and ranges are probably no more accurate than to an order of magnitude. However, the maximum and minimum estimates are probably sufficiently robust to permit qualitative comparisons among groups. If the estimates are taken at face value, it seems likely that the biomass of Ropalidia marginata wasps exceeds the total biomass of other hymenoptera species even when biomasses are averaged throughout the year. When other Hymenoptera biomasses peak after fruiting, the combined biomass of these species is still unlikely to exceed the peak biomass that wasps attain each season in Selakui region. We do not know why Dhoolkot Forest sites had lower wasp numbers. Several possible explanations exist. R. marginata has not yet completed its invasion of the Dhoolkot forest, and total wasp numbers may increase with the arrival of Ropalidia wasps (Sandlant and Moller, 1989). Dhoolkot weather conditions may also be less suitable for wasps and the vegetation compositions of Dhoolkot and Camp Road and Rampur Kala sites are not identical. In conclusion it appears that ecological pressures render small nests highly susceptible to failure and therefore necessitate the banding together of several females. As the nest grows in size, a single female can no longer dominate it to the level of exclusively monopolizing all egg-laying. With the emergence of multiple egg-layers the workers are at less of an advantage in remaining on the nest and hence begin to leave in significant numbers producing large population fluctuations. An interaction of ecological and social pressures thus determines the course of growth of a nest. All Yellow wasps swatted and identified at three zones of Selakui in the summer of 2015 were Ropalidia marginata. Most of the sites were also likely to be dominated by V. vulgaris, but some sites still possessed substantial proportions of V. germanica. All assessments of abundance and biomass are approximate they are intended only to give a rough evaluation of the biomasses of wasps. Biases in the calculations are such that estimates of wasp biomass are minimized. This is to avoid exaggerating the potential importance of wasps. Chapter-7 SUMMARY

The Yellow paper Wasp Ropalidia marginata is a hymenoptera insect present in our environment during spring and summer season. Their occurrence increase dramatically during the months of July, August and September. These wasps are found in orchards where attach grapes, figs, date and peach. They cause severe damage on both qualities and qualities of fruits. The adults of wasp chew on fruits causing severe injuries that may result in bacterial and fungal infections. It seems that the wasps have large role in economic loss of grape in addition to quality effect and lowering price of commodity. They build their nests of paper like structures. The yellow paper wasps are important also in Pollination. Their main foods are the floral parts of plants, trees. The Paper Wasps have a very best Caste System; their Work order is quite accurately so good that they have very less exposure to predator attacks. These Wasps have a systematic Work order in Place that their Colony survives for long periods of time irrespective of some factors which may cause damage to the Insect colony. The Yellow Paper Wasps have a good behavioral patterns as they possess some of the Acquired type of Behavioral patterns. In nutshell it appears that ecological pressures render small nests highly susceptible to failure and therefore necessitate the banding together of several females. As the nest grows in size, a single female can no longer dominate it to the level of exclusively monopolizing all egg-laying. All Yellow wasps swatted and identified at three zones of Selakui in the summer of 2015 were Ropalidia marginata. Biases in the calculations are such that estimates of wasp biomass are minimized. This is to avoid exaggerating the potential importance of wasps.

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