Our research is focused on insect pathology and entomopathogenic (insect parasitic) nematodes as biological control agents. The overall objectives of our program are to develop entomopathogens as control agents to reduce the pesticide load in the environment and to have a basic understanding of the ecology and behavior of insect parasitic nematodes. The various facets of our research program are documented in the published papers. Current programs include
(1) the effect of stressors on increasing nematode efficacy,
(2) the impact of scavengers on entomopathogenic nematode recycling,
(3) the behavior and ecology of entomopathogenic nematodes, and
(4) the influence of sustained agriculture on entomopathogens.
Our research on stressors have shown that certain pathogens (e.g., Bacillus thuringiensis subspecies japonica and B. popilliae), when combined with entomopathogenic nematodes against white grubs give additive and synergistic effects. More dramatic synergistic effects against white grubs are noted when the chloronicotinyl insecticide, imidacloprid, is combined with entomopathogenic nematodes. This approach of combining agents along with other control tactics may lead to an effective IPM program against white grubs.
Scavengers such as ants will consume nematode-killed insects, particularly those insects killed by steinernematids. Our research has also shown that heterorhabditid-killed insects are less likely to be scavenged by ants. The activity of ants and other scavengers on nematode-killed hosts is being examined as to their impact on the recycling of entomopathogenic nematodes. The area of behavioral ecology of entomopathogenic nematodes has been a major focus in our laboratory. We have examined competition of different nematode species when they occur in the same soil habitat. We have also examined the adaptive behavior of nematode jumping. Some species of nematodes will jump towards host cues, other species do not respond to host cues. Only nematode species that are classified as ambusher or intermediate foragers jump.
We have initiated a research program on the influence of sustained agriculture on insect pathogens. We are surveying an agricultural system for entomopathogenic fungi and nematodes where conventional and organic farming practices as well as different crop rotation schemes are employed. Our initial results, as predicted, show that entomopathogens are more prevalent in the organic than conventional system. More insects occur in the organic systems, and therefore, this system allows the entomopathogens to recycle. We are delineating to what extent the organic system suppresses insect pests.