Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

The parasitic wasp Achrysocharoides zwoelferi (Hymenoptera, Eulophidae) produces clutches consisting of only one sex. Moreover, male clutch size is invariably one while female clutches are in the range one to four. We designed field experiments to determine the effect of host quality on clutch composition. We found that solitary male and solitary female clutches were reared from the same size mines, and that larger mines tended to produce gregarious female clutches. A higher proportion of male clutches were placed in older hosts, despite their large size. Variation in body size, both between and within clutches, was measured in order to test the predictions of models that take into account the constraint that clutch size is an integer trait, something of potential importance when absolute clutch size is low. Our data supported several predictions of these models, including the trade-off-invariant rule for optimal offspring size developed by Charnov and Downhower. However, while most invertebrate clutch size models assume equal resource share among members of the same clutch, we found an increase in inequality in larger clutches.


Journal article


Behavioral Ecology

Publication Date





577 - 583