Effets Maternels Et Biologie Des Populations d'INSECTES

Maternal influences on an insect population must be assessed within a numerically and spatially restricted enclave; it is difficult to demonstrate the impact within a large polymorphic group whose qualitative and quantitative evolution is subject to a number of conflicting influences. When a variety of selective factors is involved, the problem is to isolate, from the polymorphism, the portion that can be attributed to maternal effects.In short-lived organisms such as insects, direct maternal effects on the progeny have an advantage over slower, indirect responses to selective pressures. Direct effects allow progeny to adapt sooner to ecological trends that began or were operating during the parental generation. The peculiarities of insect embryonic development allow maternal influences to act directly on the F 1 adults through their deferred effects on the imaginal discs. Species that deposit organized egg masses provide the best material for studying maternal effects.Behaviour at oviposition can lead to special types of progeny distributions that affect the offspring's survival. In parasitoids, for example, maternal behaviour can introduce a kind of "arena selection" generating superparasitism by aggregative oviposition.The next generation's ecological response that is produced by maternal effects is mediated by changes at the behavioural, metabolic and ovarian levels during the mother's reproductive activity. In this way, she provides a key part of the next generation's functional polymorphism.