Methods in Anopheles Research - MR4

Chapter 2 : Anopheles Laboratory Biology and Culture2.4 Anopheles Culture2.4.7 Separating Larvae and PupaePage 4 of 4Gentle vortex: Separate by both activity and buoyancyThe vortex method not using chilled water ranges from greatto poor depending on the mosquito strain. A variation is tocollect pupae and larvae in a strainer and washing them intoa Florence flask with fresh water (Figure 2.4.7.9). Swirl asyou fill to the top. Most of the larvae will dive and most of thepupae will rise to the neck. When separation is maximal,pour the pupae off. This method is seldom 100% effective,so some hand-picking is required. This can also work withan Imhoff funnel (as shown in Figure 2.4.7.6) in which casethe larvae are drained from the bottom. Cool water willimprove the separation, but take care that repeated chillingis avoided as much as possible to prevent mortality.Figure 2.4.7.9. An. gambiae larvae andpupae in the process of separation basedon activity and buoyancy. Pupae arefloating to the surface.ReferencesFay RW, Morlan HB (1959) A mechanical device for separating the developmental stages, sexes, andspecies of mosquitoes. Mosq News 19 144-147Hazard EI (1967) Modification of the ice water method for harvesting Anopheles and Culex pupae. Mosq.News 27 115-116Lin CS, Georghiou GP (1976) Tolerance of mosquito larvae and pupae to carbon dioxide anesthesia.Mosq News 36:460-461McCray EM (1961) A mechanical device for the rapid sexing of Aedes aegypti pupae. J Econ Entomol 54819Weathersby AB (1963) Harvesting mosquito pupae with cold water. Mosqss News 23:249 -251