Host recognition and acceptance behaviour in Cotesia sesamiae and C. flavipes (Hymenoptera: Braconidae), parasitoids of gramineous stemborers in Africa

Abstract

The host recognition and acceptance behaviour of two braconid larval parasitoids (Cotesia sesamiae and C. flavipes) were studied using natural stemborer hosts (i.e., the noctuid Busseola fusca for C. sesamiae, and the crambid Chilo partellus for C. flavipes) and a non-host (the pyralid Eldana saccharina). A single larva was introduced into an arena together with a female parasitoid and the behaviour of the wasp recorded until it either stung the larva or for a maximum of 5 min if it did not sting the larva. There was a clear hierarchy of behavioural steps, which was similar for both parasitoid species. In the presence of suitable host larvae, after a latency period of 16–17 s, the wasp walked rapidly drumming the surface with its antennae until it located the larva. After location and antennal examination of the host, which lasted 60–70 s and 30 s, respectively, the parasitoid inserted its ovipositor. Stinging that resulted in successful oviposition usually lasted 5–6 s. In the presence of non-host larvae, the latency period was between 25–70 s, and parasitoids spent significantly more time walking and antennal drumming on larvae without ovipositing. It is likely that these two parasitoid species use their antennae for host recognition, and both their antennae and tarsi for final acceptance of a host for oviposition.In both C. sesamiae and C. flavipes tactile and contact-chemoreception stimuli from the hosts seemed to play a major role in the decision to oviposit.