Host-parasitoid density relationships between Hypera postica (Coleoptera: Curculionidae) and Bathyplectes curculionis (Hymenoptera: Ichneumonidae) [Insect pests of alfalfa]

The effect of Hypera postica density on attack rate by Bathyplectes curculionis was tested using an open-choice experimental design. Host density had no significant effect on the proportion of hosts parasitized. Host mortality not attributable to normal parasite development was positively correlated with parasite density, suggesting some form of host injury by the parasite. Parasite densities of 1, 2, 4, 8 and 16 parasites per experiment (12.25 sq. ft searching area) had no significant effect on the average success per parasite, indicating that little or no interference occurred at these densities.