Antifungal effects of entomopathogenic symbiotic bacteria for use in biological control of Pythium myriotylum

Authors: Shapiro Ilan, David; LEWIS, EDWIN - University Of Idaho

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/2018
Publication Date: 8/16/2020
Citation: Shapiro Ilan, D.I., Lewis, E.E. 2020. Antifungal effects of entomopathogenic symbiotic bacteria for use in biological control of Pythium myriotylum. Journal of Nematology. 1.

Interpretive Summary: Entomopathogenic nematodes (small round worms), also known as beneficial nematodes, kill insect pests and are safe to humans and the environment. These nematodes are used to control a wide variety of economically important insect pests in various crops such as pecan , peach, and citrus. However, the efficacy of beneficial nematodes is often challenged by abiotic factors such as sensitivity to UV radiation and desiccation, and biotic factors such as predation, and the inability to disperse and find hosts. To overcome these challenges, we have developed novel formulations and application methods to protect beneficial nematodes from adverse environmental conditions. We have also developed methods to enhance nematode dispersal through phoretic associations and to improve nematode strains by creating superior purebred lines. These approaches improve the use of beneficial nematodes so that they can be applied more effectively in controlling insect pests.

Technical Abstract: Entomopathogenic nematodes in the genera Steinernema and Heterorhabditis are potent biocontrol agents. Their efficacy is influenced substantially by various biotic and abiotic stress factors. The ability of entomopathogenic nematodes to withstand environmental stress varies greatly among species and strains. This is evidenced in variable longevity in the soil. Stress factors that contribute to differential longevity include temperature, desiccation and UV radiation. Biotic factors in the soil also contribute to entomopathogenic nematode foraging and infection efficiency (which in turn impacts biocontrol success). Two biotic elements that contribute to nematode dispersal and foraging behavior are phoresy and group dynamics. With the knowledge that certain biotic and abiotic components impact biocontrol efficacy, several approaches can be used to enhance the potential for biocontrol success. Some of these approaches include improved formulation (such as with protective gels), leveraging phoretic or synergistic interactions with other organisms, application of nematodes in their infected hosts, and strain improvement such as hybridization and stabilization via homozygous inbred lines.