Abstract
Bethylid wasps are a medium sized family of parasitic Hymenoptera, with biological control potential, which have recently proved excellent model systems for testing evolutionary and life history theory. We report observations on a species of Laelius from The Netherlands. The species is morphologically indistinguishable from Laelius pedatus, previously reported only from the 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 Madison by rearing them on Trogoderma glabrum, but found no significant differences. The Dutch wasps successfully parasitize Trogoderma angustum, an invasive 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 developmental 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 died before completing development, surviving members of the brood grew to a larger size and took longer to complete development. The number of males per brood increased with previous oviposition experience, an indication of sperm depletion through life. We discuss the implications of these trends for parasitoid life history theory.
Highlights
Bethylid wasps (Hymenoptera: Bethylidae) are a glob ally distributed family of aculeate ectoparasitoids with about 2,000 known species (Evans, 1978; Gauld & Bol ton, 1988; Gordh & Moczar, 1990)
Two lines were maintained for a full year using three species o f hosts: many T. angustum were captured from an infested dried insect collection at the same site, and these were supplemented with some T. glabrum cultured in the laboratory and some A. verbasci cap tured elsewhere
We observed how death occurred in 451 cases: predatory mites killed 50 eggs or larvae, and hyperparasitoids Melittobia acasta (Walker) (Hymenoptera: Eulophidae) killed 41 larvae or pupae
Summary
Bethylid wasps (Hymenoptera: Bethylidae) are a glob ally distributed family of aculeate ectoparasitoids with about 2,000 known species (Evans, 1978; Gauld & Bol ton, 1988; Gordh & Moczar, 1990). Bethylid species have attracted the attention of applied entomologists because their hosts (the larvae, and more rarely pupae, of Lepidoptera and Coleoptera) include many important pests of crops and stored products Bethylid wasps display behaviours and life histories which have attracted the attention of evolutionary biologists A major barrier to both the effective use of Bethylidae in biological control and to using them to develop evolu tionary theory is that biological details are available only for only a small proportion of species, and even our knowledge is usually very superficial (such as location of collection, host species, and host habitat). We discuss the relevance of our findings to the biological control of host species and to developing life history theory
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call