Sibling rivalry and brood sex ratios in polyembryonic wasps

FEMALE-BIASED Sex ratios are predicted under local mate competition where offspring of one or a few females mate in isolated subpopulations. Haplodiploid sex determination allows parasitic wasps to bias their sex ratios by controlling fertilization, but parental control is not solely responsible for...

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Bibliographic Details
Published in:Nature (London) 1992-11, Vol.360 (6401), p.254-256
Main Authors: Grbic, M, Ode, P.J, Strand, M.R
Format: Article
Language:English
Subjects:
Biological and medical sciences
cannibalism
Copidosoma
Copidosoma floridanum
ecological competition
Encyrtidae
females
Fundamental and applied biological sciences. Psychology
Humanities and Social Sciences
Hymenoptera
Insecta
Invertebrates
larvae
letter
Life cycle. Embryology. Development
multidisciplinary
Physiology. Development
Science
Science (multidisciplinary)
sex ratio
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Summary:FEMALE-BIASED Sex ratios are predicted under local mate competition where offspring of one or a few females mate in isolated subpopulations. Haplodiploid sex determination allows parasitic wasps to bias their sex ratios by controlling fertilization, but parental control is not solely responsible for the broods of polyembryonic wasps. The eggs of these parasites divide to form many offspring and often two larval morphs. Precocious larvae die without pupating while reproductive larvae become adults. Copidosoma floridanum (Hymenoptera: Encyrtidae) produces 1,000-1,400 offspring per host and most broods contain both sexes (mixed). Mixed broods are female-biased and wasps mate before dispersing, but these broods develop from the mother laying one mate and one female egg and adult males probably obtain additional matings away from the host. Thus, intersexual conflict may exist over the number of offspring to produce per host. Here we show that precocious larvae in mixed broods are predominantly female and that they bias the sex ratio by killing males.
ISSN:0028-0836
1476-4687
DOI:10.1038/360254a0