Insemination capacity and dispersal in relation to sex allocation decisions in Goniozus legneri (Hymenoptera : Bethylidae): Why are there more males in larger broods?

Citation
Icw. Hardy et al., Insemination capacity and dispersal in relation to sex allocation decisions in Goniozus legneri (Hymenoptera : Bethylidae): Why are there more males in larger broods?, ETHOLOGY, 106(11), 2000, pp. 1021-1032
Citations number
22
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences","Neurosciences & Behavoir
Journal title
ETHOLOGY
ISSN journal
0179-1613 → ACNP
Volume
106
Issue
11
Year of publication
2000
Pages
1021 - 1032
Database
ISI
SICI code
0179-1613(200011)106:11<1021:ICADIR>2.0.ZU;2-V
Abstract
Models considering sex ratio optima under single foundress strict local mat e competition predict that female bias will be reduced by stochasticity in sex allocation, developmental mortality of males and limited insemination c apacity of males. In all three cases the number of males per brood is expec ted to increase with brood size. Sex ratio optima may also be less female b iased when several mothers contribute offspring to local mating groups or i f non-local mating occurs between members of different broods; again more m ales are expected in larger broods. In the parasitoid wasp Goniozus legneri (Hymenoptera: Bethylidae), sex allocation has only a small stochastic comp onent, developmental mortality is low and non-siblings are unlikely to deve lop in the same brood. However, the number of males per brood increases wit h the size of the brood (produced by a single mother). We investigated the further possibilities of limited insemination capacity and nonlocal mating using a naturalistic experimental protocol. We found that limited inseminat ion capacity is an unlikely general explanation for the increase in number of males with brood size. All males and females dispersed from both mixed a nd single sex broods. Although most females in mixed sex broods mated prior to dispersal, these data suggest that non-local mating is possible, for in stance via male immigration to broods containing virgin females. This may i nfluence sex ratio optima and account for the trend in male number.