Genetic variation in sex allocation in a parasitic wasp: variation in sex pattern within sequences of oviposition

In order to maximize their fitness under Local Mate Competition (LMC), arrhenotokous female wasps have to produce a precise sex ratio when encountering hosts. Recent progress in the theory of hymenopterous parasitoid reproduction suggest that they manage to do it by laying male and female eggs in a particular order and that such reproductive strategies are adaptive. Therefore, the determinism of such sequential patterns would be regulated by genetic control on which natural selection could act. To test this hypothesis, sequences of oviposition were recorded in a set ofTrichogramma brassicae Bezdenko (Hymenoptera; Trichogrammatidae) females and in their daughters by providing themEphestia kuehniella Zeller (Lepidoptera; Pyralidae) eggs. In order to describe accurately sex pattern within these oviposition sequences, I present a joined non-parametric and multivariate statistical method. It is shown thatT. brassicae females do not produce male and female eggs in random sequences. Moreover, the way they organize the sequence of the sexes in their progeny seems to be under a strong genetic control. The evolutionary consequences of such results are discussed.