Can rearing Sclerodermus brevicornis (Hymenoptera: Bethylidae) on a factitious host affect behavior?

Wasps in the genus Sclerodermus are quasi-social ectoparasitoids that typically attack coleopteran larvae that live inside the wood. Interest in these species is increasing as they are used in programs to control wood boring longhorn beetles of economic importance in China and could also be used in Europe. However, the mass rearing systems are affected by the host used to produce new offspring and rearing Sclerodermus on its natural hosts is time consuming and physically demanding. There is thus a need for factitious hosts with lower production costs and that are easier to rear. The present research focuses on Sclerodermus brevicornis which was found in association with Psacothea hilaris hilaris and can be reared on both this longhorn beetle and on a factitious lepidopteran host, Corcyra cephalonica. As it is known that the biology of natural enemies can be influenced by the host they emerge from, and that the behaviour of S. brevicornis is quite complex due to its degree of sociality (multiple females cooperate to paralyze the host and produce offspring communally), we explored whether and how performance and behavioural traits are influenced by the rearing host. Choice tests were set up using parasitoids with different origins (the host species they emerged from) when offered different host species. Aspects of parasitoid performance, the timing of development, movements between hosts and aggregation on hosts were evaluated. Significant effects were not detected in timing and performance but were found in the number of movements and in aggregation behaviour. As a preliminary conclusion, this research indicates that the overall success of S. brevicornis is not influenced by the host of origin, even if some aspects of its relatively complex social behaviours may be.