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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #286170
Title: Entomopathogenic nematodes: effects of the soil agroecosystem on biological control potential

Author
item Shapiro Ilan, David
item Leskey, Tracy
item Wright, Starker
item BROWN, IAN - Georgia Southwestern State University
item FALL, LEIGHANN - Georgia Southwestern State University

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2012
Publication Date: N/A
Citation: N/A

Interpretive Summary: Beneficial nematodes are used as natural environmentally friendly bio-pesticides. The soil environement affects the fitness of various organisms including these beneficial (a.k.a.entomopathogenic) nematodes, e.g., affecting their survival, foraging, and infection behavior, which has a profound effect on the nematodes ability to achieve pest control. We provide an overview of some of the biotic and abiotic components that affect beneficial nematode fitness. Additionally, we focus specifically on strain differences, relationships with other biotic agents, and foraging behavior. Nematode species or strains vary in their ability to survive in the soil and infect target insect pests. For example, we recently conducted a broad screening of beneficial nematodes for potential to control the plum curculio (a major pest of stone and pome fruit in North America) and discovered major differences in virulence (killing ability) at different temperatures and in different soil types. Nematode relationships with other soil biotic agents can be beneficial, neutral or detrimental. Recently we investigated phoretic relationships between beneficial nematodes and earthworms, and detected advantages in pest control efficacy when earthworms were present; the nematode catch a ride on the earthworms, like hitchikers, which helps the nematodes disperse through soil and find insect pests to attack. Understanding how beneficial nematodes find insects in the soil will help us use these nematodes more effectively in pest control applications. We recently discovered that benefical nematodes respond directionally to electrical fields; thus electrical fields in the soil may assist nematodes in navigation or host-recognition. Additional characterization of diverse soil biotic and abiotic factors and their impact on nematode fitness is necessary for the expansion of beneficial nematodes in biological pest control.

Technical Abstract: The soil agroecosystem affects entomopathogenic nematode (EPN) fitness, e.g., survival, foraging, and infection behavior, which has a profound effect on the biocontrol potential of EPNs. In this presentation we provide an overview of some of the biotic and abiotic components that affect EPN fitness. Additionally, we focus specifically on two biotic factors (strain differences and relationships with other biotic agents) and two abiotic factors (soil moisture and foraging behavior). Nematode species or strains vary in their ability to survive in the soil and infect target pests. For example, we recently conducted a broad screening of EPNs for potential to control the plum curculio, Conotrachelus nenuphar (a major pest of stone and pome fruit in North America) and discovered major differences in virulence at different temperatures and in different soil types. EPN relationships with other soil biotic agents can be beneficial, neutral or detrimental. Recently we investigated phoretic relationships between EPNs and earthworms, and detected advantages in EPN pest control efficacy when earthworms were present (due to enhanced nematode dispersal). Soil moisture is considered a critical factor in achieving biocontrol efficacy with EPNs. In 2011, we conducted mini-plot field trials in West Virginia and Massachusetts to determine the ability of Steinernema riobrave and S. feltiae to control C. nenuphar at varying soil moisture levels. S. riobrave caused high levels of C. nenuphar mortality (more so than S. feltiae) and interestingly, in one of the trials, S. riobrave performed equally well in soil with or without irrigation. Elucidating EPN foraging behavior and host-finding cues will lead to greater understanding of nematode infection dynamics and result in improved biological control. We recently discovered that EPNs respond directionally to electrical fields; thus electrical fields in the soil may assist EPNs in navigation or host-recognition. Additional characterization of diverse soil biotic and abiotic factors and their impact on EPN fitness is necessary for the expansion of EPN biocontrol utility.