Individual sex ratios and offspring emergence patterns in a parasitoid wasp, Melittobia australica (Eulophidae), with superparasitism and lethal combat among sons

Evolution of extraordinary female-biased sex ratios: The optimal schedule of sex ratio in local mate competition

“…We have confirmed that the result remains true in the generalized models. Most of our results are consistent with experimental data in Melittobia wasps (Abe et al, 2003a(Abe et al, , 2005. Observed emergence patterns show that males emerge earlier than females on average.…”

“…When the group size (the number of foundresses) is variable, the sex ratio is predicted to be very female-biased when the average group size is close to one (Nunney and Luck, 1988). However, the sex ratio of this species can neither be explained by this model because more than one foundress often attack a host in nature (Cooperband et al, 2003;Abe et al, 2005). In this study, we consider the following two points that may explain the extraordinary small sex ratios.…”

“…Haplo-diploid wasps might also be able to control their primary sex ratio at each stage of their reproduction period. In Melittobia wasps, a foundress continues to lay eggs in the same host for long reproduction period and thus the scheduled game (when to lay male eggs) may play an important role in superparasitism (Abe et al, 2005). Female wasps disperse soon after copulation while males stay at a host and are able to mate many females until they die.…”

“…The latter effect might be stronger when male-male combat is more severe and lethal. Actually, Melittobia wasps lay male eggs intermittently rather than intensively (Abe et al, 2005). There are some theoretical studies on the schedule of sex ratio (e.g.…”

Functional response and mutual interference ofPeristenus spretus(Hymenoptera: Braconidae), a parasitoid ofApolygus lucorum(Heteroptera: Miridae)

“…If two or more eggs were laid on one host, competition between the larvae of solitary parasitoids results in all but one dying (Abe, Kamimura, & Shimada, 2005;Darrouzet, Boivin, & Chevrier, 2008;Hegazi, El-Minshawy, & Shaaban, 1984). In P. spretus, only one parasitoid developed per nymph, and supernumerary larvae were most likely killed by larval physical combat during the first instar.…”