Host selection by virgin and inseminated females of the parasitic wasp, Dinarmus basalis (Pteromalidae, Hymenoptera)

1. Fitness is related to reproduction and survival. There apparently exists a negative correlation between the numbers of male and female offspring. There also exists a trade-off between survival and reproduction. This paper investigates optimal decisions with the reproduction and survival trade-off in host selection by wasps.
2. Whereas inseminated female wasps could manipulate the sex of their offspring, virgin females produced only male offspring. I surveyed behavioural differences and the consequences of oviposition by inseminated and virgin females of a solitary parasitic wasp in host choice situations.
3. Two host types were available at the same time to both inseminated and virgin female wasps: one (a 17-day-old host in one bean) presenting difficulties for the laying of eggs, but more benefits for the offspring and the other (five 12- or 13-day-old hosts in one bean) easier for the female wasp for laying of eggs but less beneficial for the offspring.
4. Inseminated female wasps chose more 17-day-old hosts than 12-day-old hosts, but more 13-day-old hosts than 17-day-old hosts in each pair-wise choice. Virgin females chose the smaller hosts in both situations.
5. Virgin females, having greater longevity than inseminated females, laid larger numbers of eggs than the inseminated females during their lifetime by adopting an energy-saving host choice that had little effect on male offspring fitness.