Self-superparasitism in the solitary parasitoid Monoctonus paulensis (Hymenoptera: Braconidae, Aphidiinae):: Proximate mechanisms

Monoctonus paulensis (Ashmead) was reared in the laboratory on the four nymphal instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Females frequently laid clutches of two eggs during a single ovipositor probe; however, clutches of more than two eggs were rare. The time needed to capture and position an aphid for oviposition increased with aphid instar but was independent of the number of eggs laid. Oviposition time was proportional to egg number, which shows that eggs were laid one at a time rather than clumped together as a package. Intensity of parasitism (i.e., number of eggs per parasitized host) increased with host instar but declined with the number of hosts attacked in quick succession. Our results suggest that clutch size in M. paulensis is not accidental but controlled by the female.