Preliminary survey of genetic determinism controlling the expression of the bimodal emergence of Delia radicum L-(Diptera : Anthomyiidae)

In horlarctic region, at the beginning of the growing season, many phytopha gous insect species show a polymodal emergence in post-diapause against the unfavorable environmental conditions. Within the populations of Delia radi cum, two biotypes are observed, early and late, which differ for the timing of adult emergence in diapausing and non-diapausing conditions. These biot ypes cause a bimodal emergence of the adults. In this preliminary survey, i n non-diapausing condition, we demonstrate that the bimodal emergence is co ntrolled genetically, that the late biotype is recessive and that there is a significant maternal effect of late biotype on the mortality of the eggs. Also, our results also suggest that the females of late biotype have a sim ilar average length of oviposition to those of early biotype.