Conséquences des préférences maternelles pour des alcools primaires ou secondaires sur les traits adaptatifs de deux populations géographiques de Drosophila melanogaster

Abstract

Preferences for four primary and two secondary alcohols are studied in two geographical races of Drosophila melanogaster. an African population, very sensitive to the alcohol, and a resistant French population. Experimental insects are offspring of mothers submitted to situations of choice between non alcoholic media and others containing doses of studied alcohols. Eggs laid under these conditions are reared on media chosen or avoided by the mother. The adaptation of offspring to tested media is estimated using the following parameters: the number of emergences, the developmental time, the weight and the length of wings. The study reveals a better adaptation of French animals than African ones to alcoholized resources. This marked tolerance of the French population is particularly observed in the case of media with 0.5 % ethanol added. However this beneficial effect of ethanol is not observed with other alcohols. The adaptation of insects to an alcoholized medium is a complex phenomenon that influences the maternal preference. Thus, females who prefer non alcoholic or slightly alcoholized media have, in general, made a choice which conforms to the requirements of larvae. Those that laid on media containing strong doses of a highly poisonous alcohol (such as 2-propanol) seem, even if it is opposite to the requirements of the progeny, to have a tendency to exploit a new medium at the price of a limited development of the offspring.