Electrophoretic Patterns of Larval Haemolymph-proteins in Autogenous and Anautogenous Forms of Culex pipiens L.

Abstract

THE common house mosquito, Culex pipiens, has two different forms with respect to egg formation. Adult females of the so-called autogenous form can lay the first batch of eggs without taking a blood meal, whereas anautogenous females will not produce mature eggs until they have ingested blood. In spite of the many investigations of these two mosquito forms, very little is known about the physiological and biochemical basis of autogeny or anautogeny^1–3. Egg formation in adult mosquitoes has been considered to depend on the nutritional reserve stored during larval development^4,5; at emergence autogenous females contain more fat reserve than anautogenous females^6,7. But, as Clements has pointed out⁸, the quantity of reserve materials cannot be the deciding factor for initiating ovarian development, because even in the anautogenous form there should be still a sufficient nutritional storage to produce a limited number of eggs. Investigation of the hormonal system revealed that the corpora allata of the autogenous females are active after emergence, whereas the anautogenous females do not secrete the gonadotrophic hormone until after they have fed on blood^9–12. There is now no doubt that ovarian development in mosquitoes, as in all insects, is under hormonal control, but it is not known why the endocrine system is maintained in an active state even without feeding only in the autogenous form, while that in the anautogenous form requires a blood meal for activation.