478 JounNer- oF THE AunnrcaN Mosqurro Conrnol AssocrerroN Vor,. 2, No. 4
SEASONAL VARIATION IN POPULATIONS OF ANOPHELES MACULIPENNIS. ANOPHELES CLAVIGER AND CULEX PIPIENS IN TURKEY
lrulrivr KASAP MedicalBiology Department,Qukurova University, Adana, Turkey
ABSTRACT. Seasonalvariation in larval populations of three speciesof mosquitoes,Anopheles 'of maculipmnis, An. claaigerand Cutexpipieru, common in th6 vicinity of Ankara, w'erestudied. Pbpulations An. mncuiipennis and Cx.pipiens disappeared in larval habitats by Decemberbut An. elaaiger,overwintering as larvae remained until the middle of March. Animal footprints are densely populated and are preferred by Cx.pifuns and An. claaign over larger water bodies.
INTRODUCTION Station II was a small pool with abundant emergent water plants. The pool has water Changes in environmental conditions affect running it in .through winter but becomes the duration of life cycle and population sagnan[ ln summer. density of mosquitoes. Populations reach a Station III was a marsh outside a village. The maximum level when environmental condi- marsh is large and deep in winter but small and tions are optimum. In south central Turkey, shallow in summer. Emergent and submergent where most malaria cases occur in September vegetation is found all year. and October, populations of Anophebs sacharoai Station IV was a marsh outside a village, Favre, the principal human malaria vector continuously fed by a spring. It was rich in reach a peak before August, (Postiglione et al. vegetation and favored by cattle and other 1973, Ramsdale and Haas 1978). Populations animals. This station had many hoof prints of An. superpicttu Grassi, the second most around the main water body of the marsh. important malaria vector in Turkey, reach a The seasonal abundance of the larvae was maximum level during the hot and dry determined by dipping with a standard level (Ramsdale summer, and Haas 1978). Anopheles dipper, 14 cm in diamerer and 6 cm in depth. maculipennis Meigen and An. claaiger (Meigen) Counts were made every 4th night. At each are also of importance in malaria transmission. station l0 dips were raken. For each dip the There have been malaria cases in the presence Iarvae were sorted into species and then of each of these species alone, i.e., An. counted regardless of instar. maculipennis in Biga Plain (Canakkale) and An. clauiger in Mardin Province, (Postiglione et al. 1973, Ramsdale and Hass 1978). However, in RESULTS most endemic malaria situations, vectorial The species of larvae found in stations I importance of these two species is observed by through III were An. mnculipennis and, Cx. the simultaneous occurrence with An. sacharoai pipiens but in station lY An. claaiger and Cx. and An. superpictus. pipiens were found. pipiens (Linn.) Culex is also very abundant In station l, An. maculipennis lawae were and domestic and is usually responsible for present fromJune through November and Cx. most of the mosquito bites in urban areas. It is fuFi"^ larvae from July through December. important as a possible vector of filariasis, Population density was lower for Cx. pipieru which has been reported by Sipahioglu (1965) than for An. maculipennrs(Fig. la). In station II in southwestern Turkey. Cx.pipiens larvae firsr appeared inJune and An. More biological data are needed to assessthe maculipennis larvae in the middle of July but vectorial capacity of these species in Turkey both persisted through December. Populations and is the reason for this studv. of Ai. maculipennis iarvae were very iow (Fig. lb). In station III larvae of An. maculipennis aid, Cx. pipiens were found from mid-June through MATERIAL AND METHODS December; population density was higher for Cx. pipiens than for An. maculipennis (Fig. lc). For studying the fluctuations of populations In station IV, larvae of An. claaiger and Cx. of mosquito larvae, 4 larval stations were pipieru first appeared in early June; An. claaiger chosen in different directions from Ankara. persisted through March while Cx. pipiens Station I consisted of a series of small, sunlit disappeared in mid-December. The number of pools without vegetation dug by tile and brick An. claaiger larvae was higher than that of Cx. makers. pipiens (Fig. ld). Dncrrrasrn,1986 Sresoual VentatroNs rN Tux.xry 479
Larval populations varied in all stations but ous larvae were found in the ice in these generally were found in high numbers from months. Ice prevented the larvae from breath- June to the end of September. Larval popula- ing atmosphericair through their siphon. In tions of both Anopheles species reached a this situationthe larvaewere found to assemble maximum level in June and July but that of Cx. around the stemsof water plantswhere the ice pipizns in August and September (Fig. l). A does not surround the stem tightly. Pupation decrease was noticed from September through of An. claaigertook place in March and new December. After the middle of December adults hatchedout in April. larvae were scarce, water and air temperatures In summer, where An. claaigerand Cx.pipiens were below zero in Ankara. On December l5 coexistedin footprints as in station IV, shady air temperature was - 4"C and the water froze. footprints weredensely occupied by An. clnaiger After that no larval counts were made in (Fig. 2) and sunny footprints by Cx.pipiens (Fig. stations I through III. 3). The water temperaturein sunny footprints In station IV the counts were carried out was l-3'C higher than in shadyfootprints. The until March, because An. claaiger overwinters as footprints harbored more larvaethan the main larvae. The larval populations of this species body of marsh (Figs.4, 5). also started to decrease in December but remained steady in January and February. In DISCUSSIONAND CONCLUSIONS December, January, and February, the larvae The density of mosquitopopulations differs could be collected by breaking the ice. Numer- according to the speciesand habitats they live
400
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50 10 Months Months Fig. l. Larvalpopulationsof AnophelesandCulcxinstationsl(a),II(b), III(c) andIV(d). 480 Jounxar-oF THEAlrrnrcau Mosqurro CoNrnor Assocrerrox Vor,. 2, No. 4
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JA5 Months Fig 4. Comparisonsof larval populationsof AnophelzsClaviger in footprints and main habitat. Fig. 2. Larval populations of Anophelesclariger and Culexpipiens in shady footprints. footprints. Footprints, which were small water bodies, shallow, without vegetation and rather in. In Ankara, the larval populations of both warm usually harbored only the mosquito An. maculipennis and An. clauiger reached a species An. clauiger and Cx. pipiens. Other maximum level in June and July while that of organisms such as long lived animals which Cx. pipiens reached a peak in August and may be predators of mosquito larvae were not September. A species living in different envi- found. This may imply that such conditions, ronments may reach a maximum density at especially the absence of predators favor different times, (Trpis 1972, Southwood et al. mosquito breeding in these habitats. The 1972, Service 1973). In Ankara Cx. pipieru warmer water shortens the duration of the reached a maximum density in August in immature stages resulting in a rapid popula- Stations I and II but in September maximum tion increase. densities were attained in stations III and Anopheles claaiger overwinters as larvae in IV. Turkey as in other countries where it is found, In this study greater population densities of both Culex and, Anopheleslarvae occurred in the
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Months Fig. 5. Comparisonsof larval populationsof Alropi- Fig. 3. Larvalpopulations of Anophelescl.a,aign and elesclaaiger and Culexpipicns in footprints and main Culexpipiens in sunnyfootprints. habitat. Dncrlrsrn, 1986 SnasoNar-VentarroNs rN Tunxry 481
(Postiglione et al. 1973, Service 1973, Marshall ReferencesCited 1938, Shute 1933). It seems that in Turkey Marshall,J. F. 1938.The British mosquitoes.British breeding of An. clnviger, An. maculipennis and Museum (Natural History) London. Cx. pipiens stops in October (Fig. l). For An. Postiglione,M., B. Tabanla and C. D. Ramsdale. cl.aaigeroverwintering larval population density 1973: The Anophelesof Turkey. Riv. Parassitol. is expected to remain more or less steady from 34:127-159. October to December when the water surface Ramsdale,C. D. and E. Haas. 1978.Some aspects of epidemiology of resurgent malaria in Turkey. freezes. Then the number of larvae drops Trans. R. Soc.Trop. Med. Hyg. 72:570-580. because some larvae are captured in ice. It also Service,M. W. 1973.The biology of Anopheleselaaiger seems that habitats with emergent plants are (Mg.)(Dipt.,Culicidae) in Southern England.Bull. more suitable for hibernating sites of An. Entomol.Res. 63:347-359. clauiger as larvae can freely breathe through Shute, P. G. 1933. The life history and habits of holes around the stems of water plants where British mosquitoes in relation to their conrrol by antilarvaloperations.J. Trop. Med. Hyg. 36:83-88. most of the hibernating larvae were collected in Sipahioglu,N. 1965.Antalya Bolgesifilarya cografyasi the study. ve Alanya'da filarya cografyasi.Turk. T. C. Mec. This study has obtained information regard- 32:49-56. ing population size of mosquito larvae that Southwood,T. R. E., G. Murdie, G. Yasuno, R. J. should be known before any chemical or other Tonn and P. M. Reader. 1972.Studies on the life budget control measures are applied. Small water of Aedzsaegpti in Wat Samphaya,Bangkok, Thailand. Bull. W.H.O. 46:2ll-226. bodies are important mosquito breeding sites Trpis, M. 1972. Seasonalchanges in the larval which cannot be ignored during mosquito populations of Aedesaeg)pti, in two biotopes in Dar control programs. es Salaam,Tanzania. Bull. W.H.O. 4l:245-255.