N.Chinese Species of Phlebotomus. 533 - Home |...

(9) Jeffreys, H., “ Some Problems of Evaporation.” ‘ Phil. Mag.,’ vol. 35, pp. 270-280(1918).

(10) Knight, R. C., “ On the Use of the Porometer in Stomatal Investigation.” ‘ Ann.of Bot.,’ vol. 30, pp. 50-76 (1916).

(11) Lundegardh, H., “ Ecological Studies in the Assimilation of Certain Forest Plantsand Shore Plants.” ‘ Svensk Bot. Tidsk.,’ vol. 15, pp. 46-95 (1921).

(12) Maskell, E. J., “ The Diurnal Rhythm of Assimilation in Leaves of Cherry Laurelat ‘ limiting ’ Concentrations of Carbon Dioxide.” ‘ Roy. Soc. Proc.,’ B, vol. 102, p. 467.

(13) Matthaei, G. L. C., “ On the Effect of Temperature on Carbon Dioxide Assimilation.”4 Phil. Trans.,’ B, vol. 197, pp. 47-105 (1904).

(14) Renner, O., “ Beitrage zur Physik der Transpiration.” ‘ Flora,’ vol. 100, pp. 451-547(1910).

(15) Warburg, O., “ Uber die Geschwindigkeit der photochemischen Kohlensaurezersetz-ung in lebenden Zellen, 1.” ‘ Biochem. Zeitschr.,’ vol. 100, pp. 230-270 (1919).

N. Chinese Species o f Phlebotomus. 533

The North Chinese Species o f the Genus Phlebotomus (Psychodidce).

By W. S. Patton and E dward H indle, Members of the Kala Azar Commissionof the Royal Society.

(Communicated by Dr. H. H. Dale, Sec. R.S.—Received January 21, 1928.)

In an earlier paper (1926) we noted the more important differential characters of the adults of the three Chinese species of the Genus Phlebotomus, but, as in 1925, we arrived too late in the country to study their early stages, we were unable to record any observations on them. In the present paper we propose to complete our studies of the three species, by describing the differential characters of their early stages, and also we are now able to settle the status of the species with recumbent hairs, which was recorded in the paper noted above as a variety of P. perturbans de Meijere. Recently, Prof, de Meijere very kindly sent to one of us (W.S.P.) co-types of his species, and permitted the making of microscopic preparations of the male terminalia and the female pharynx. A study of these preparations has enabled us to settle the identity of the Chinese species allied to P. perturbans, and as it proves to be distinct from the Javanese species we propose for it the name P . taianensis. Unfortunately we have not been able to settle the identity of the erect-haired species allied to P. sergenti Parrot, as it has not been possible to examine and compare the pharynx of a typical female of the latter.

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534 W. S. Patton and E. Hindle.

The classification of the species of Phlebotomus is at present in a state of flux owing to certain new taxonomic characters recently noted by Adler and Theodor (1926), which promise to be of considerable value in distinguishing the females of this genus.

It is well known that although the males of Phlebotomus can be identified by the characters of the terminalia, it is almost impossible to be sure of the identity of the females unless these are either bred or taken in In the past,emales have been identified, with difficulty, mainly on the characters of the

antennae and palps, and also by the venation. Sinton (1925) failed to find any reliable taxonomic characters in the structure of the female terminalia. Adler and Theodor (1926), when studying the species of the inPalestine, noted that the structure of the mid-pharynx (buccal cavity) varied in the species they examined, as did also that of the spermatheca ; they noted some correlation between the palpal formula and the characters of the midpharynx in the females, but in the males, on the other hand, there was no correlation between the characters of these two structures.

Sinton (1927), following up the work of Adler and Theodor, applied these new taxonomic characters in classifying the Indian species of Phlebotomus. He notes that in the erect-haired group the characters of the spermatheca are of use in separating the females, as in this group the organ is well chitinized and has a crenulated outline. I t varies within wide limits in the species and affords a certain means of separating the females. In the recumbent-haired group, on the other hand, the spermatheca is lightly chitinized, so that its structure affords no reliable characters for separating the females; in this group, however, the structure of the pharynx is of use in identification.

Comparative Notes on the Early Stages op the Chinese Species of

the Genus Phlebotomus.

The Egg.As the general structure of the egg, larva and pupa of Phlebotomus have been

fully described by Grassi (1907) and Newstead (1911), no useful purpose would be served by redescribing them ; consequently, we shall merely note the characters of taxonomic importance in separating the early stages of the three Chinese species known at present.

The egg (fig. 1, b) of P. major chinensis measures 0-44 mm. in length. The chorion exhibits elongated areas of varying length and width, clearly demarcated from each other by dark lines, as illustrated in fig. 1, b. The



535JV. Chinese Species o f Phlebotomus.

e8S fig' c) of P. sergenti var. measures 0-35 mm. in length and the chorion is divided into small, somewhat hexagonal areas, separated from each other

a.

b.Fig. 1. Eggs of the three Chinese species of Phlebotomus. a, P. tai ; b, P. major

chinensis ; c, P. sergenti var.

by raised lines which project from the surface of the egg, as depicted in fig. 1, c. The egg of P. taianensis n. sp. measures 0 • 39 mm. in length, is narrower than either of the eggs of the other two species, and the ends are more pointed ; the surface is marked by smaller, regular, quadrilateral areas, as shown in fig. 1, a.

First LarvalThe general structure of the larva of Phlebotomus is represented in the various

figures. The head is well developed, the mouth parts adapted for biting (man- dibulate), and eyes are absent. The three thoracic segments are distinct, and there are ten abdominal segments ; the posterior spiracle is located on the eighth and the caudal bristles on the ninth abdominal segment. Ventrally, abdominal segments one to eight inclusive are provided each with a fleshy pseudopod.

The first larval instar of P. major chinensis (fig. 2) measures about 0 • G mm. in length. The important taxonomic characters, by which it can be distinguished from the first larval instar of the other two species, are found in the structure and arrangement of the bristles. The two posterior frontal bristles




(fig. 2, p.f.b.) are long and finely branched to the tip, which ends in a small, clear, globular swelling ; they are situated in front of the egg-breaker, which

Fig. 2. First larval instar of P. major chinensis. a.b., anal bristles ; a.cl.b., anterior clypeal bristle ; a.f.b., anterior frontal b r i s t l e a.ep.s., arm of epicranial suture; an., antenna; c.b., caudalbristles ; cl., clypeus ; d.pr.b., dorsal prothoracic bristle; e.b., egg-breaker; lb., labrum; m., mandible ; mx., first maxilla ; p.cl.b., posterior clypeal bristle ; pd., pseudopod ; p.f.b., posterior frontal bristle; p.s., posterior spiracle; 1st a.s., IXth a.s., and Xth a.s., first, ninth, and tenth abdominal segments.

is always well developed in the first larval instar of Phlebotomus. This type of bristle is present on the body of the larva of this species in all its instars, but the globular end is better developed in the body bristles. The pair of anterior frontal bristles (fig. 2, a.f.b.) is situated on the front, nearer the middle line just behind the level of the antennae; they differ from, the posterior pair as they are not so thickly branched, and end in points. The posterior clypeal bristles (fig. 2, p.cl.b.) are long and unbranched, and are situated on each side of the middle line of the most prominent part of the clypeus ; the anterior pair (fig. 2, a.cl.b.) is very short, and situated just posterior to the clypeo- labral suture. The vertical bristles, upper and lower, are similar in structure to the posterior frontal bristles. The dorsal genal bristle is long and similar in structure to the frontal bristles ; the remaining genal bristles are simple, as shown in fig. 2.

The twenty-two prothoracic bristles are arranged in two bands, an anterior and posterior, and in each there are dorsal, lateral and ventral bristles. The dorsal bristles of the second (outer) pair of the anterior band of the prothorax are short, unbranched and spine-like. The ventral bristles of both bands, as in



N. Chinese Species o f Phlebotomus. 537

all the larvae of the three species, are pointed and not globular at their apices. All the remaining prothoracic bristles are finely branched, and end in small, clear globules. The arrangement of the bristles on the meso- and meta-thorax, and on the abdominal segments is clearly shown in the figure ; except for the length of the dorsal and lateral pairs, these bristles afford no special characters of taxonomic value. The posterior spiracle is situated close to the posterior border of the eighth abdominal segment. The two caudal bristles are strongly developed in all the first stage larvae of Phlebotomus, and vary in length in the different species. In the first stage larva of P. major chinensis both bristles are a little longer than the larva itself, and in the egg are folded back. The two large unbranched postero-ventral anal bristles on the tenth abdominal segment are long, and the lower is approximately twice the length of the upper.

The bristles on the head of the first larval instar of P. sergenti var. (fig. 3) differ from those of the first larva of P. major chinensis in that they are shorter. The frontal and vertical bristles are not thickly branched, and end in points. The other head bristles are shown in the figure. The thoracic and abdominal bristles are in marked contrast with those of the first larva of P . major chinensis,

Fig. 3. First larval instar of P. sergenti var. armof epicranial suture; a.b., anal bristles; caudalbristles; e.b., egg-breaker; p-f.b., posterior frontal bristle; p.s., posterior spiracle.

f e.b. r pf b

as they are all short, especially the dorsal and lateral bristles. The second dorsal bristle of the anterior prothoracic band is small and branched, not spine-like. The dorsal bristles are shortest on the eighth abdominal segment. The two caudal bristles on the ninth segment are a little shorter than the body of the larva.




The bristles on the head of the first larval instar of taianensis (fig. 4) are somewhat similar to the corresponding bristles on the first stage larva of

P. major chinensis. The posterior frontal pair and the upper vertical are finely branched and each bristle ends in a globular swelling. The bristles of the anterior frontal pair are markedly elongated and unbranched ; and their structure renders identification of the larva of this species easy. The middle dorsal bristle of the anterior prothoracic band is long and thickly branched at its distal end ; the outer dorsal bristle of the anterior prothoracic band is similar to that of the first larva of P. major chinensis, but is a little smaller. The remaining dorsal thoracic and abdominal bristles are short and decrease in length from before backwards, those on the eighth abdominal segment being the shortest. The lateral thoracic and abdominal bristles are long. The lower of the two unbranched lateral anal bristles on the tenth abdominal segment is about three times the length of the upper bristle. The caudal bristles are extremely long, and are about one and one-third as long again as the body of the larva. These taxonomic characters are clearly shown in the figure (fig. 4).

Fourth Larval Instar.

The head bristles of this stage of P. major chinensis (fig. 5) are a little shorter than those of the first instar, and the posterior,

cb'-'-'

Fig. 4. First larval instar of P. taianensis. a.b., anal bristles ; a.f.b. anterior frontal bristle ; c.6., caudal bristles; e.b., egg-breaker; p.f.b., J —p.f.b. posterior frontal bristle ; p.s., posterior spiracle. j

p.s.

M

frontal, and upper vertical bristles are pointed at their extremities. In the fourth instar of all three species there are three pairs of dorsal bristles on each of the thoracic and abdominal segments, and the prothorax has a well-



N". Chinese Species o f Phlebotomus. 539

developed anterior band. In the fourth larval stage of major thereis a small, spine-like bristle in the anterior prothoracic band directly in front of

Fig. 5. Fourth larval instar of major chinensis. a.h., anal bristles ; a.ep.s., anterior arm of epicranial suture ; a.s.,anterior spiracle; m.d.L,mid-dorsal line; posterior spiracle. .

the anterior spiracle, and a minute branched bristle between the lower lateral bristles of each band on the prothorax. On the meso- and meta-thorax there is a similar branched bristle between the two lateral bristles. The structure and arrangement of the bristles is illustrated in fig. 5. Four caudal bristles are present in the second, third and fourth larval stages of Phlebotomus and are arranged as shown in the drawing ; the outer pair is always shorter than the inner, and in the fourth stage larva of P. major chinensis the bristles of the inner pair are about two-thirds the length of the larva itself and about one- third as long again as those of the outer pair.

In the fourth stage larva of P. sergenti var. (fig. 6) the head bristles are also similar to those of the first larval stage. The small bristle of the anterior

Fig. 6. Fourth larval instar of P. sergenti var. Lettering as in fig. 5.

prothoracic band directly in front of the anterior spiracle is minutely branched, and not spine-like as in the fourth larval stage of P. major chinensis, and this character alone is sufficient to differentiate the two larvae. In the meso- and




meta-thorax the minute branched bristle is absent above and behind the larger lateral bristle, as shown in fig. 6. The dorsal abdominal bristles are a little more than half the length of the corresponding bristles of the fourth stage larva of P. major chinensis. The caudal bristles are comparatively short, the inner pair being about twice the length of the outer.

In the fourth larval instar of P. taianensis n.sp. (fig. 7) the head bristles are similar to those of the first instar, but the unbranched anterior frontal bristle,

Fig. 7. Fourth larval instar of P. taianensis.

which is so characteristic of this larva, is shorter than the corresponding bristle of the first larva. The middle dorsal bristle of the anterior prothoracic band is only about half the length of the other two, and the small internal bristle is spine-like, as in the corresponding larva of P. major chinensis. All the branched thoracic and abdominal bristles are club-shaped, the branches being more numerous towards the distal end, whilst the basal end of the shaft is almost bare. The dorsal abdominal bristles decrease in length from before backwards and are shortest on the eighth abdominal segment. The unbranched, lower lateral anal bristle on the tenth abdominal segment is very long, as in the first larval instar. The caudal bristles are also long and the outer pair is only a little shorter than the inner one.

The Pupa.I t is well known that in the pupa of Phlebotomus, the last larval skin is always

attached to the end of the abdomen, and therefore having noted the larval chaetotaxy, there should be no difficulty in identifying the pupae of the three Chinese species. The pupa of P. major chinensis has a pair of long, stout unbranched bristles close together on the side of the meso-thorax. The pupa



541

of P. sergentivar. lias a single small bristle in the same situation. No bristlewas found in this situation on the three pupae of P. taianensis examined by us.

Adults.The main distinguishing characters of the adults have already been noted

in our previous paper (1926). Except in the case of rubbed specimens, it is possible after a little practice to identify the females of the two species of the erect-haired group with the aid of a pocket lens; in P. major chinensis the thoracic hairs are much darker than those of P. sergenti var. As the characters of the wing venation are not very reliable, and are always subject to variation, and as in order to be certain of the relation of the veins to each other, it is necessary to remove the wing and mount it separately, it is better to examine the structure of the spermatheca in any doubtful specimen, since it affords a very reliable means of separating these two species. The fly, preferably a dry specimen, should be placed in weak caustic potash for several hours, and after washing and dehydration, the spermatheca should be dissected out and mounted on a slide in carbol alcohol, ringing the coverslip with Canada balsam.

The spermatheca of P. major chinensis, two of which from separate specimens are illustrated in fig. 8 a and b, is elongated and torpedo-shaped, with a crenu-

N . Chinese Species Phlebotomus.

Fig. 8. Spermathecse of P. major chinensis ( and b), and of P. sergenti var. (c and d).

lated outline, and the body of the organ seems to be partitioned by dark lines, varying in number from 11 to 13. Its length varies from 98 to llOp., excluding the tuft of fine hairs at the distal end. The spermatheca of P. sergenti var. (fig. 8, c and d)is very much smaller, and varies in length from 18-5 to 22 usually it has three lines apparently dividing it into separate partitions. The




spermatheca of the recumbent-haired species P. taianensis can at once be distinguished from that of either of the other two species, as it is a long sausage-shaped organ without any crenulated margin and also with no dark lines.

The male of P. major chinensis can be readily distinguished from P. sergenti var. by its darker thoracic hairs, and by the presence in the latter of a brush of hairs on each side at the base of the inner surface of the superior clasper. There are five macrochsetse on the distal segment of the superior clasper of P. major chinensis, whereas there are only four on the corresponding segment of P. sergenti var.

As already noted above, we have now been able to satisfy ourselves that the small recumbent-haired species is distinct from P. de Meijere. Thefemales can be readily separated by the characters of the mid-pharynx (buccal cavity). In the mid-pharynx of P. taianensis the pigmented area on the dorsal wall is shaped like a half moon (fig. 9, b), and along its nearly straight posterior border there is a single row of about 56 minute spines. The pigmented area varies in length from 30 to 37 p, and is 75p wide. The spines measure from 3-7 to 4p in length. The mid-pharynx measures 92• 5p at its widest point.

The mid-pharynx of P. perturbans de Meijere (fig. 9, a) is very much smaller measuring 74 p at its widest point in the single specimen examined. The dorsal

Fig. 9. Mid-pharynx (buccal cavity) of P. p de Meijere (a) and of P. taianensis(b).

pigmented area is small and of a much lighter colour than that of P. taianensis ; it barely reaches to the lateral margins of the mid-pharynx, and measures 18*5p in length and 37p in width. The mid-pharynx at this point has a single



row of 18 rather widely separated stout spines; the longest measures l ip in length.

The male terminalia of P. taianensis are illustrated in fig. 10. The distal segment ( d.sp.c.) of the superior clasper measures about 0*14 mm. in length, and is armed with four macrochsetae, two situated at the apex, and two close together on a tubercle nearer the distal than the proximal end of the segment. The two distal macrochsetse measure 100 p and 112 p respectively ; their structure and relation to each other is shown in the drawing. The other two macrochaetse measure 85 p and 107 p respectively. The proximal segment (p.sp.c.) of the superior clasper is broad, and measures 0*29 mm. in length,

N . Chinese Species o f Phlebotomus. 543

LTl.C.

Fig. 10. Terminalia of male P. taianensis. c., cerci or submedian lamellae ; d.sp.c., distal segment of superior clasper ; La., intermediate appendage ; in.c., inferior

clasper ; it.o.,intromittent organ ; p.sp. c., proximal segment of superior clasper ;p., pompetta.

almost exactly double the length of the distal segment. The inferior clasper [in.c.) is long and narrow and is 0*25 mm. in length. It is armed at its

apex with about ten long hairs, the calyces of which are shown in the drawing. The submedian lamella, or cercus (c.), a paired appendage, is broad and pointed and bears numerous hairs. The intermediate appendage is broad basally, and narrows apically, ending in a beak-like point; it measures 24 mm. in length. The paired penis-guards (intromittent organ) are each about 100 p long; the genital filaments are well protruded. The pompetta (p) measures 92 p in length.




The male terminalia of P. perturbans de Meijere are illustrated in fig. 11. The distal segment ( d.sp.c.) of the superior clasper measures about 0-9 mm. in length, and is armed with four long terminal macrochsetae, two dorsal and two ventral, situated on prominent tubercles.

The ventro-external and the dorsal macrochsetae each measure 100 pt. in length. The ventro-internal macrochseta is spathuliform, and measures llOp, in length. The proximal segment ( p.sp..) of the superior clasper is a little wider than that of P. taianensis, and measures 0-24 mm. in length. The inferior clasper (in.c.)is longer and wider than that of P. taianensis and slightly club-shaped ; it measures 0 • 19 mm. in length and, like that of P. ,is armed at its apex with a group of about ten long hairs. The submedian lamella, or cercus (c), another paired appendage, is leaf-like, and in side view appears club-shaped. The intermediate appendage ( .) is long and broadfor more than half its length, becoming narrow distally and ending in a broad beak ; it measures 0 • 18 mm. in length. The paired penis-guard (it.o.) is about 82 g in length; in the specimen the genital filaments are withdrawn. The pompetta (p.) measures 112 p, in length. From the above description of the terminalia of the two species it will be noted that the Chinese species, belonging to the recumbent-haired group, is distinct from the Javanese species.

The question naturally occurs as to whether the Chinese species is identical with the Indian species named P. perturbans by Annandale. A comparison of the characters of the male terminalia of the Indian species, which Sinton has described in great detail, shows that they are most probably distinct, as will



N. Chinese Species Phlebotomus. 545

be noted from a comparison of the measurements of the different appendages of the two species given below in tabular form :—

P. per turbans. P. taianensis.(Indian form.)

„ . , f Proximal segmentSuperior clasper <[ Distal segment ..

0 • 42 mm. 0-25 „

Intermediate appendage 0-25 „Intromittent organ 0*14 „Inferior clasper 0-33 „Apical macrochaetae of superior clasper 90 fxMedian „ ,, ,, 60 & 90 pi.

0-29 mm. 0-14 „ 0-24 „ 0-10 „ 0-25 „

100 & 112[x 85 & 107 fx.

The shape of the distal segment of the superior clasper, as depicted by Sinton, is markedly different from that of P. , and the two apicalmacrochsetse are equal in length, while those of the Chinese species are unequal. As far as we are aware, Sinton has not depicted, or described, the characters of the mid-pharynx of the Indian form of P.

The following is a more complete description of P. taianensis than given in our previous paper :—

Phlebotomus taianensis n. sp.

Male.—A medium-sized dark-brown species with dark recumbent hairs on the dorsal surface of the abdomen, and measuring from 2 to 2-2 mm. in length. Palpal formulae 1, 2, (3, 4), 5 ; segment 5 is long and slender, about equal in length to segments 3 and 4. Antennal formulae 1/III-XV.

The legs are long, and the second tarsal segment is about half the length of the first. The wing is lancet-shaped, and the posterior border is not more arched than the anterior. Vein Rx overlaps vein R2 by about half the length of the latter. Vein R2 is equal in length to the radial stem between the origins of veins R2 and R3, and that of vein R4. The origin of the latter is much nearer the base of the wing than the origin of the branches of the median.

The male terminalia are not particularly prominent. The proximal segment of the superior clasper is long and very broad, and is about twice as long as the distal segment; it bears numerous long hairs. The distal segment is narrow and has a marked prominence about two-thirds the distance from its base. I t is armed with two long apical macrochsetae unequal in length, and two situated close together on the prominence, also unequal in length ; all the macrochaetae are dilated at their extremities when seen from their concave sides, but appear




pointed when seen laterally ; one of the distal macrochsetae is distinctly spathuliform. The intermediate appendage is about two-thirds the length of the proximal segment of the superior clasper. The inferior clasper is long and narrow, and is only slightly dilated at its distal extremity ; it is about as long as the proximal segment of the superior clasper. The submedian lamella is broad and bluntly pointed. The pompetta measures 92 pt. in length.

Female.—The female is similar in colour to the male, but, if anything, is darker, the hairs markedly so, and the recumbent hairs on the dorsal surface of the abdomen form a thick layer. The pigmented area on the dorsal wall of the midpharynx is half-moon shaped, and along its posterior border is armed with about 56 spines ; it varies from 30 to 37 p in length and is 75pt broad. The spines measure from 3-7-4p in length. Palpal formulae 1, 2, 3, 4, 5, and segment 5 is longer than segments 2 and 4 together. Antennal formulae 2/III-XV. Legs similar to those of the male. The wing, on the other hand, is broader in the female. Vein R2 overlaps vein R2 by about two-thirds the length of the latter. Vein R2 is longer than the portion of the radial stem between the origins of the veins R2 and R3, and that of vein R4, and the latter portion is equal to the part of the radial stem between the origin of vein R4 and the vein R3. The origin of vein R4 is nearer the base of the wing than the origin of the branches of the median.

Notes on the Bionomics of Chinese Species of Phlebotomus.

P. Major chinensis.In nature, this species normally seems to have only a single brood each year

and passes the winter in the larval stage. In 1926 the first specimen was brought to the laboratory at Tsinan on May 22, after which date the numbers gradually increased until about the middle of June, when several hundred were caught each day. Towards the end of the month the numbers began to fall rapidly, and after the middle of July only occasional specimens were obtained, which continued until September 12. The following year at Wei-hsien, a town between Tsinan and the coast, the occurrence of P. major chinensis closely agreed with that at Tsinan, the flies first appearing at the end of May and lasting for about six weeks, after which only occasional specimens were seen. In Chihli Province, north of Shantung, the season is one or two weeks later, but all our records agree with the generally expressed Chinese statement that the sandfly is only prevalent during the early summer, and disappears about the time of wheat harvest, when the summer rains result in the formation of pools



Report from Kola Commission. 547

and streams, that afford plenty of opportunity for the multiplication of the mosquitoes which take their place.

In the laboratory no difficulty was experienced in getting the females to lay eggs in the breeding pots described previously (Patton and Hindle, 1927). As in all stages of Phlebotomus, the eggs are rapidly killed by desiccation and have to be kept moist in order to ensure their hatching. Excessive moisture does not seem to affect the early development, for a batch of eggs which was totally submerged for twenty-four hours produced as large a proportion of larvae as eggs kept under more normal conditions.

At room temperature, 25°-30° C., the larvae generally emerged after 10-11 days’ incubation period. In our experiments the larvae were usually fed on bat faeces, but some were reared on rabbit dung, and in Peking, Young and Hertig employed hamster faeces. I t is probable that any decaying or partially digested organic matter would serve as food. In our experience it was found advantageous to keep a fairly large number of larvae—at least a hundred—in each pot. When fewer numbers were present, moulds often grew in great abundance over the surface of the food material, with fatal results, whilst in pots containing many individuals the larvae seemed to be able to keep down the growth of these fungi by feeding on them.

As in other species of Phlebotomus there are four larval stages, and under laboratory conditions the duration of the various stages is shown in the followingtable:—

Egg to first larval instar................................... 10—11 days.First larval stage......... ...................... .'............. 7— 8 ,,Second larval stage........................................... 6— 7 ,,Third larval stage.............................................. 5—• 6 ,,Fourth larval stage ........................................... 7— 9 „Pupal stage ...................................................... 7—10 ,,

Total cycle from egg to adult ....... . 42—51 days.

In view of the fact that under laboratory conditions the life-cycle may be completed in six or seven weeks, and since the females begin to lay eggs early in June, one might have expected two broods a year, for the summer continues at least until the end of September, July and August being the hottest months. In the laboratory during 1926, adults first emerged about the middle of July, and occasional individuals continued to hatch out until the end of August. All

2 sVOL. CII.— B.




larvae which had not pupated by the middle of August remained as such and passed the winter in this stage.

Pupae from these larvae were first noticed the following February, and adults began to emerge during the latter half of the month and in March. I t should be noted, however, that these individuals were kept in an incubator at a temperature of 16°-24° C., consequently the acceleration in the normal rate of development may be attributed to the higher temperature. I t is a curious fact that from eggs laid by the same females and kept under apparently identical conditions, some should complete their development in six or seven weeks whilst others take nine months.

We are convinced that under natural conditions the life-cycle is rarely completed in one season. In the laboratory the larvae are supplied with an unlimited supply of food material, whilst in nature they live in cracks in the ground, in holes, under bricks, etc., and under such circumstances food has to be searched for, and when found the supply is apt to be limited. Consequently, it is reasonable to assume that the length of the larval stages is much longer than under the artificial conditions of our experiments. From the occurrence of the adult flies it is evident that very few individuals complete their whole development during the summer. The flies which appear at the end of May and early in June probably come from larvae which had reached the fourth larval stage before the onset of the previous winter. The adrdts appearing later in June may come from larvae which had only managed to reach the third stage the previous year, and it is just possible that the isolated individuals seen in August and September represent a second brood, which under exceptionally favourable conditions have managed to complete their development in one season.

The larvae which hibernated in the laboratory in 1926-27 were mostly in the fourth stage, and whenever examined were noted to be active. They were kept at a temperature of 18°-24° C. throughout the winter. On December 6, some of these larvae were exposed to a temperature of —11° C., and were all dead by the morning. On December 9, some wrere exposed to a temperature of 0° C. overnight, and next morning were all alive and active. On December 12, other larvae were placed in the ice chest until the 28th, when it was noted that all were alive ; on January 7, most of them were dead, the last one being found dead on January 15. From these few experiments it is evident that the larva of this species can withstand occasional freezing. Mr. Harkness, Professor of Physics, Shantung Christian University, informed us that at Tsinan the ground did not freeze below a depth of 10 inches during the winter of 1926-27, although



Report from Kala Azar Commission. 549

it was considered a very cold season. The larva, therefore, would not need to go very deep into cracks and holes, in order to avoid being frozen.

In contrast with the larvae of P. sergenti var., that of P. major chinensis is much hardier and more active, and can live under conditions of dryness and excessive moisture that are inimical to the former.

When the larvae are full grown and ready to pupate they generally come to the surface of the food material, or if the latter is too damp, climb up the wall of the breeding pot until they reach a drier locality as the pupa requires less moisture than the larva. Once the pupa has been formed the adult insect emerges after a comparatively short interval (7-10 days), and there is no evidence to support the view that this sandfly ever passes the winter in the pupal stage.

At the beginning of the season males are always the first to appear and for the first week or so exceed the females in number, but early in June the latter increase until the proportion of the two sexes is not very dissimilar. As a general rule, the number of females brought to the laboratory greatly outnumbered the males, but as we were paying more for the females and as, owing to their blood-sucking propensities, they would be more liable to be caught, it is probable that our records of wild sandflies do not give a fair indication of the natural ratio. In our breeding experiments the males were also the first to appear, suggesting that their development takes a shorter length of time than the female ; the proportion of the two sexes was approximately equal, however, when all the flies had hatched.

The adults of P. major chinensis are much more active and quick in their movements than the other two species and also markedly differ in their feeding habits. As a general rule the female seems to take only one feed of blood and digestion proceeds comparatively slowly, traces of the meal still being present after six or seven days, a feature which probably favours the development of flagellates. Although we succeeded in feeding a number of the females of this species a second time, these only comprised a small percentage of the total. The flies readily copulate in the breeding pots and the female lays its eggs in one batch—about fifty in number—on the sixth or seventh day after feeding and then dies. The average duration of life in the males is slightly shorter than in the female.

P. Sergenti var.In China this species seems to have at least two broods a year, for although

it appears simultaneously with P. major chinensis about the end of May, it continues without much diminution in numbers until well on into August,and throughout September occasional specimens can be obtained.

2 s 2




The larva is very sluggish and under adverse conditions, such as excessive moisture or dryness, or an overgrowth of mould, it easily succumbs. It seems unable to become adapted to changes in its environment, which is rather surprising in view of the fact that this species is more abundant than the hardier P. major chinensis.The first stage larva, in particular, is very sluggish, hardlymoving from the place where it emerges from the egg, in contrast with the active corresponding stage of the former species.

The duration of the various developmental stages is approximately the same as that of P. major chinensis. Eggs laid in June gave rise to adults seven or eight weeks later, and we assume that the large numbers of adults occurring in nature during August belong to this second brood.

The adults of P. sergentiare much easier to keep in captivity and they will readily feed three, four, and occasionally even five times, before laying their eggs. As a rule, the digestion of blood is very rapid, all traces of it usually having disappeared on the third day after a full meal. Occasionally, however, traces of blood may remain in the gut as long as five days after a meal.

On the whole, this species is the commonest sandfly of North China and in many localities occurs in large numbers. On five occasions we observed the male of P. sergenti in copula with the female of P. major chinensis ; the reverse was never seen. Unfortunately, owing to lack of time, we were not able to follow the result of this abnormal mating. As it was not specially looked for and could only take place in the few hours before the flies were sorted out, it is probable that such crossing is commoner in nature than the above figures would indicate.

P. Taianensis.This species is common in the temples in and around Taian, where it was

first collected, and occurs from the end of May to the middle of September. Although somewhat local, this species seems to have a wider distribution than the other two, as it is not dependent on human beings for its food supply. At Tsingtao, with the exception of isolated examples of P. major ,which all came from one house, this was the only species of sandfly to be found.

In the laboratory the duration of the life-cycle is similar to that of the other two species, and like P. sergenti it seems to have at least two broods each year. The larva is much more hardy and active than the other two and can withstand desiccation for a considerable period. Pupal cases of this species were found in November, 1926, by Dr. Hertig and one of the writers (E.H.), at Wo-Fu-Ssu, a temple on the Western Hills about eighteen miles from Peking.



Report from Kola Commission'. 551

They were in loose earth, attached to small pieces of tiles, at a depth of 6-8 inches below the surface.

P. taianensisseems to feed normally on batrachian or reptilian blood andreadily feeds on frogs, toads, lizards and snakes. We have,also succeeded in feeding a few individuals on a fowl and on a hamster, so it is possible that it may sometimes feed on man, although we were never able to get any specimens to feed on ourselves. When feeding, this sandfly ingests so much blood that its abdomen becomes almost spherical and afterwards it is very sluggish. The process of digestion is even more rapid than in P. and it is possibleto get them to feed every day or two.

In concluding these notes on the North Chinese species of weshould like to point out again that we have been unable to obtain any evidence of their existence from the Yangtse River Valley southwards, and the present distribution agrees with what is known about the incidence of Kala Azar in China, which also seems to be restricted to the Provinces north of the Yangtse.

We should like to express our heartiest thanks to Mrs. Patton, to whom we are indebted for the drawings illustrating this paper.

REFERENCES.

Adler, S., and Theodor, O. (1920).. “ On the of the Genus Phlebotomus inPalestine.” ‘ Bull. Entom. Res.,’ vol. 16, pp. 399-405.

Grassi. B. (1907). “ Ricerehe sui Flebotomi,” ‘ Mem. d. Soc. Ital. d. Sci.,’ Ser. 3a, vol. 14,pp. 353-394.

Newstead, R. (1927). “ The Papataci Flies ( P)of the Maltese Islands.” ‘ Bull.Entom. Res.,’ vol. 2, pp. 47-48.

Patton, W. S., and Hindle, E. (1926). “ Reports from the Kala Azar Commission of theRoyal Society. No. 6. Notes on the Species of the Sandflies (Genus Phlebotomus) of North China.” ‘ Roy. Soe. Proc.,’ B, vol. 100, pp. 405-412.

---------------(1927). “ Reports from the Kala Azar Commission of the Royal Society.The Development of Chinese Leislimania in Phlebotomus var. andP. sergenti var.” ‘ Roy. Soc. Proc.,’ B, vol. 10l, pp. 369-390.

Sinton, J. A. (1925). “ Notes on some Indian species of the Genus Part XIV.The hypopygium of the female Phlebotomus. ‘ Ind. Jl. Med. Res., vol. 13, pp. 97— 108.

----- (1927). “ Some Indian Species of the Genus Phlebotomus, with Special Reference toNew Aids to the Differentiation of Species. Designation of a New Species.” ‘ Trans. Roy. Soc. Trop. Med. and ETyg.,’ vol. 21, pp. 5-7.



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