Scavenging behavior and interspecific competition decrease offspring fitness of the entomopathogenic nematode...

Area of Science:

• * Biological Control
• * Nematology
• * Ecology

Background:

• * Entomopathogenic nematodes (EPNs) are vital biocontrol agents against soil pests.
• * Their efficacy is influenced by complex food web interactions.
• * EPNs can utilize freeze-killed insect larvae as a resource, competing with other soil organisms.

Purpose of the Study:

• * To evaluate EPN scavenging efficiency against competing nematodes and fungi.
• * To determine the impact of scavenging on EPN offspring fitness and pathogenicity.
• * To test if competition exacerbates fitness reductions in EPNs.

Main Methods:

• * Two EPN species (Heterorhabditis bacteriophora, Steinernema feltiae) were tested.
• * Larvae of Galleria mellonella (live and freeze-killed) were used as substrates.
• * Competition was introduced using free-living bacterivorous nematodes (Oscheius, Pristionchus) and Aspergillus flavus.

Main Results:

• * Steinernema feltiae showed reduced reproduction scavenging compared to entomopathogenic infection.
• * Heterorhabditis bacteriophora failed to reproduce as a scavenger.
• * S. feltiae offspring from scavenging had lower pathogenicity and reproduction, especially under high competition.

Conclusions:

• * Scavenging is a less efficient life-history strategy for EPNs compared to their primary entomopathogenic role.
• * Competition significantly reduces the fitness and efficacy of EPNs utilizing scavenged resources.
• * Understanding these dynamics is crucial for optimizing EPN-based pest control strategies.