Effect of age and hunger on host-feeding behaviour by femaleTrichogramma euproctidis(Hymenoptera: Trichogrammatidae)

Abstract

AbstractAdult parasitoid females can obtain proteins and lipid by consuming the haemolymph of their host. InTrichogrammaWestwood (Hymenoptera: Trichogrammatidae) species, host feeding on the host egg occurs after oviposition and leads to smaller offspring. We tested the effect of age and hunger on host-feeding behaviour of femaleTrichogramma euproctidisGirault. Young and old females, either starved, water fed, or honey fed, were observed and the host-feeding frequency, duration, distribution, and number of hosts used for nutrition were measured. The sex ratio (proportion of males) allocated to parasitised hosts where host feeding occurred and time taken to parasitise 10 hosts (indicator of female mobility) were also noted. The majority of females host fed on the first host encountered. Age had no impact on frequency, duration, number of hosts used, and mobility ofT. euproctidis. Starved females host fed longer and were less mobile. The sex ratio of the progeny emerging from the first host parasitised was more male biased when host feeding occurred. Host feeding had no effect on the sex ratio deposited elsewhere in the sequence of hosts encountered. Age of female had no effect on host feeding, possibly because host feeding incurs little cost for this species. To host feed on the first host parasitised, in which a male is allocated, is less costly in terms of fitness and represents a strategic choice for the female.