Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 2001
Publication Date: N/A
Interpretive Summary: Insect-killing nematodes (small round worms) are natural pesticides that offer an environmentally friendly solution to controlling many harmful insects. The nematodes invade insects and then reproduce inside of them. In commercial applications, insect-killing nematodes are mixed with water and applied using standard agricultural equipment. It may also be possible to apply the cadavers of insects that were killed by nematodes. In this approach, insect pest suppression would be achieved by the progeny nematodes emerging from the insect cadavers that were applied. Application of nematode-killed insect cadavers, however, may entail problems in storage and ease of handling. Our objective was to determine if formulating the cadavers would overcome these problems. We found that cadavers that were formulated (in a starch-clay combination) had increased desiccation tolerance and a reduced tendency to rupture or stick together. Therefore, formulation is likely to facilitate the novel approach of applying nematode-infected-cadavers to control insect pests.
Technical Abstract: Entomopathogenic nematodes are commercially applied in aqueous suspension. These biocontrol agents may also be applied in nematode-infected insect cadavers, but this approach may entail problems in storage and ease of handling. We determined the feasibility of formulating nematode-infected insect cadavers to overcome these hindrances. All experiments were conducted with Heterorhabditis bacteriophora Poinar and Galleria mellonella (L.). Non formulated cadavers were used as controls. Out of 19 formulations tested (including combinations of starches, flours, clays, etc.), two (starch-clay combinations) were found to adhere to the cadaver and have no significant effect on nematode reproduction and infectivity; other formulations exhibited poor adhesion or reduced nematode reproduction. Two formulations enabled cadavers to be partially desiccated without affecting reproduction; other formulations and non-formulated cadavers exhibited reduced reproduction upon desiccation. Four-day-old cadavers were more amenable to desiccation than eight-day-old ones. Formulated cadavers were more resistant to rupturing or sticking together during agitation than non-formulated cadavers.