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SCI 355B: Lecture 12Predation & Parasitism

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Vertebrate Animals that EatInsects

• Class Osteichthyes: Bony Fishes• Class Aves: Birds• Class Reptilia: snakes, lizards, turtles• Class Amphibia: frogs & salamanders• Class Mammalia: mammals

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Mammals that Eat Insects

Mammals that Eat Insects

Mammals that Eat Insects

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Plants that eat Insects• 600 different species “eat” insects. But why?

• Plants can prepare their own food. Howeversome grow in bogs or marshes, and the soildoes not contain enough minerals, for theplants to grow well.

• Carnivorous plants make up for nutrientdeficiencies in soil by eating insects. Theycatch their food by creating some uniquetraps. Then slowly digest it.

Plants that eat Insects

The tips of the leaves of this plant areactually small traps with spines alongthe edges.

On the trap is a bright redish spotcovered with nectar which insects areattracted to.

Three tiny hairs on each leaf act astriggers. When insect touchesthese hairs the trap snaps shut. Thendigestive enzymes are secreted andthe food is slowly digested by the plant.

Invertebrates that eat insects

• Class Chilopoda: centipedes• Class Diplopoda: millipedes• Class Arachnida: spiders, etc.• Class Nematoda: round worms

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Chewing

Insects that eat insects

Predation by Insects• Insects live in a world of attack and

defense between predators and prey• Predator = free living, kills more than

one prey for food in order to completedevelopment and/or life cycle. Insectsmay be predaceous at alldevelopmental stages or restricted toone stage only

• Predatory diet = high amounts of protein(not present in plants) that can bereadily converted into own tissue.

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Strategies

• Most predators are larger than prey• Active searchers• Sit and wait/ambush style• Specialized structures/adaptations for

handling prey

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Parasites & Hosts

Some terms• Parasite -a type of symbiotic relationship between

two different organisms where one organism, theparasite, takes from the host, sometimes for aprolonged time. They are ususally smaller than theirhosts, show a high degree of specialization for theirmode of life, and reproduce more quickly and ingreater numbers than their hosts.

– Endoparasite - feed internally (e.g., tapeworm)– Ectoparasite - feed externally (e.g., pubic louse, mosquito)

Some terms• Parasitoid -an organism that spends a significant

portion of its life history attached to or within a singlehost organism which it ultimately kills (and oftenconsumes) in the process. This type of relationshipseems to occur only in organisms that have fastreproduction rates, such as insects.– Idiobiont parasitoid-are those which prevent any further

development of the host after initial parasitization, and thistypically involves a host life stage which is immobile (e.g., anegg or pupa), and almost without exception they live outsidethe host.

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Some terms• Parasitoid -an organism that spends a significant portion of its

life history attached to or within a single host organism which itultimately kills (and often consumes) in the process. This type ofrelationship seems to occur only in organisms that have fastreproduction rates, such as insects.– Koinobiont parasitoid -allow the host to continue its

development and often do not kill or consume the host untilthe host is about to either pupate or become an adult; thistherefore typically involves living within an active, mobilehost. Koinobionts can be further subdivided intoendoparasitoids, which develop inside of the prey, andectoparasitoids, which develop outside the host body.

Some terms

• Hyperparasitoid - a parasitoid of aparasitoid.

Host Immune Response

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Insect Parasitoid Orders

• Hymenoptera*• Diptera*• Strepsiptera• Coleoptera

*major parasitoid groups

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Other Characteristics

• they are smaller than host• only the female searches for host• different parasitoid species can attack

different life stages of host• eggs or larvae are usually laid in, on, or near

host• immatures remain on or in host; adults are

free-living, mobile, and may be predaceous

Some Parasites of Humans

Ectoparasites: fleas, lice, ticks, bot flies, mosquitoes

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Lice

• Transfer from host to host occurs whenhosts are mating/brooding

• Eggs glued to hair/feathers, excepthuman body louse.

• Rarely leave host• One family (Echinopthiriidae) restricted

to seals

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Pubic Lice: (a.k.a. crabs)