Life history correlates and reproductive biology of Laelius pedatus (Hymenoptera : Bethylidae) in The Netherlands

Bethylid wasps are a medium sized family of parasitic Hymenoptera, with bio logical control potential, which have recently proved excellent model syste ms for testing evolutionary and life history theory. We report observations on a species of Laelius from The Netherlands. The species is morphological ly indistinguishable from Laelius padatus, previously reported only from th e New World. Reciprocal crosses between the Dutch wasps and L, pedatus from Madison, Wisconsin, USA confirmed that the Dutch population belongs to L. pedatus. We compared the life history of the Dutch wasps with those from Ma dison by rearing them on Trogoderma glabrum, but found no significant diffe rences. The Dutch wasps successfully parasitize Trogoderma angustum, an inv asive museum and domestic pest found in situ, but suffer high developmental mortality on T. glabrum. Wasp egg size was positively correlated with the size of ovipositing female, which was also negatively correlated with the d evelopmental mortality of offspring. Larger wasps also carried more mature eggs. Time taken to lay the clutch increased with the size of the eventual clutch laid and was longer in unmated than mated females. When some wasps d ied before completing development, surviving members of the brood grew to a larger size and took longer to complete development. The number of males p er brood increased with previous oviposition experience, an indication of s perm depletion through life. We discuss the implications of these trends fo r parasitoid life history theory.