Seasonal variation in the reproductive strategy of the parasitic wasp Eulophus larvarum (Hymenoptera: Chalcidoidea: Eulophidae)
Resource type
Journal article
Creator (person)
Godfray, H C
Shaw, Mark R
Date published
1987
Abstract
1. Eulophus larvarum (L.) (Hymenoptera: Eulophidae) is a gregarious parasitoid of lepidopterous larvae feeding on broad-leaved trees. Normally there are two generations a year. 2. Sex ratio in the spring generation of larvae is female biased. The bias is probably due to local mate competition as progeny from one brood emerge from their pupae in close proximity to each other. 3. Sex ratio in the summer generation of larvae is near equality. Local mate competition is absent as individuals from the same brood become separated during the winter. 4. Variation in sex-ratio in the spring generation is consistent with a binomial model. Variation in sex ratio in the summer generation is much greater than expected from a binomial model and there is a large proportion of single-sex broods. 5. Two hypotheses are put forward to explain the summer generation pattern: virgin oviposition, and strong intersexual competition. 6. No differences in clutch size were found between the two generations.
Journal title
Ecological Entomology
Volume
12
Publisher
Wiley-Blackwell on behalf of the Royal Entomological Society
ISSN
0307-6946
Official URL