CLUTCH SIZE IN A PARASITOID WASP - A MANIPULATION EXPERIMENT

1. The reproductive behaviour of a small, gregarious, ectoparasitoid wasp (Goniozus nephantidis (Muesebeck)) in the family Bethylidae was studied in the laboratory. The wasp lays a clutch of up to 20 eggs, with a very female-biased sex ratio, on the caterpillars of microlepidopterans. 2. Clutch size was strongly influenced by host size. 3. Clutches of different size were artificially created on hosts of approximately the same weight. The manipulations had little effect on juvenile survival, but adult female size decreased strongly with clutch size. Male size was also affected, although to a lesser extent. 4. In the laboratory, larger females lived longer and laid more eggs when provided with hosts. When deprived of hosts, smaller females lived slightly longer. 5. The possibility of using laboratory experiments to test clutch size models is discussed.