Host Adaptation in Entomopathogenic Nematodes: An Approach to Enhancing Biological Control Potential
The overall objective of our research was to develop methods to match species of entomopathogenic nematodes against the insect pests which they would be best adapted to control. The underlying hypothesis for this work was that entomopathogenic nematodes should be most effective when used against insect species to which they are naturally adapted to parasitize. Toward this end, we undertook a number of related studies focusing primarily on nematode foraging strategies. We found that foraging strategies affected host associations directly and indirectly. Nematodes' responses to host cues, and the role of their sensory organs based on lectin binding, led to new approaches to determining host range for these parasites. Based on this work, we developed a laboratory bioassay of host recognition behavior designed to predict field results. We also determined that nematodes that forage in a stationary manner (ambushers) have a slower metabolic rate than do active forgers (cruisers), thus their infective stage juveniles are longer lived. This study helps predict the duration of field activity after application and may partially explain field distributions of natural populations of entomopathogenic nematodes. The common thread linking all of these studies was that they led to a deeper understanding of the associations between entomopathogenic nematodes and insects as hosts.