Oviposition experience promotes active reproductive behaviour in a synovigenic parasitoid

Abstract

Parasitoids are important insects that are commonly released into the environment to reduce the population sizes of pest species. The lifetime reproductive success of parasitoids mainly depends on host availability and the availability of mature eggs. Consequently, it is predicted that female wasps must balance the risk of egg or host (time) limitation with maximized lifetime fecundity. Typically, synovigenic females, which continue to mature eggs throughout their lifetime, have been shown to adjust their egg production rate in response to environmental variations in host availability to reduce the risk of egg limitation. In this study, we found that in a synovigenic egg parasitoid, Anastatus japonicus (Hymenoptera: Eupelmidae), the oviposition experience of Ana. japonicus females significantly enhanced the egg load and increased the rate of mature egg production. However, in contrast to other studies, the experience of contact with a host did not significantly affect the egg load in females. This result suggests that the overall oviposition experience might induce an adjustment and accelerate egg maturation in Ana. japonicus and is likely more important in egg maturation than transitory host contract. In addition to affecting the egg load, oviposition experience influenced Ana. japonicus female reproductive behaviour, which shifted virgin female behavioural preferences from mating to oviposition and laying more eggs per clutch. Our study provides an optimal strategy for the post-oviposition release of Ana. japonicus, an egg parasitoid of several lepidopteran forest pests, to improve biocontrol effectiveness.