Host Finding by Heat Perception in Coeloides Brunneri (Hymenoptera: Braconidae)

Coeloides brunneri Viereck females were interrupted in the act of oviposition into Douglas-fir logs and the oviposition site marked. Thermistor probe temperature readings revealed that C . brunneri invariably oviposited over "hotspots" on the bark surface associated with subcortical Douglas-fir beetle larvae. Artificial hotspots were created by placing heated resistance wire probes underneath the bark of an uninfested log. In the absence of all other stimuli, these artificial hotspots induced the parasites to exhibit normal search behavior and to make ovipositional probes, the final phase of host finding. These data augment observations of antennal posture of a searching parasite and the discovery of a possible infrared radiation receptor on the antennae, and support the argument that C . brunneri locates its host through perception of infrared radiation.