Dissemination of Isaria fumosorosea Spores by Steinernema feltiae and Heterorhabditis bacteriophora

Abstract

Entomopathogenic nematodes and fungi are globally distributed soil organisms that are frequently used as bioagents in biological control and integrated pest management. Many studies have demonstrated that the combination of biocontrol agents can increase their efficacy against target hosts. In our study, we focused on another potential benefit of the synergy of two species of nematodes, Steinernema feltiae and Heterorhabditis bacteriophora, and the fungus Isaria fumosorosea. According to our hypothesis, these nematodes may be able to disseminate this fungus into the environment. To test this hypothesis, we studied fungal dispersal by the nematodes in different arenas, including potato dextrose agar (PDA) plates, sand heaps, sand barriers, and glass tubes filled with soil. The results of our study showed, for the first time, that the spreading of both conidia and blastospores of I. fumosorosea is significantly enhanced by the presence of entomopathogenic nematodes, but the efficacy of dissemination is negatively influenced by the heterogeneity of the testing arena. We also found that H. bacteriophora spread fungi more effectively than S. feltiae. This phenomenon could be explained by the differences in the presence and persistence of second-stage cuticles or by different foraging behavior. Finally, we observed that blastospores are disseminated more effectively than conidia, which might be due to the different adherence of these spores (conidia are hydrophobic, while blastospores are hydrophilic). The obtained results showed that entomopathogenic nematodes (EPNs) can enhance the efficiency of fungal dispersal.

Natural Warriors against Stored-Grain Pests: The Joint Action of Beauveria bassiana and Steinernema carpocapsae

“…Debilitated EPF-infected insects respire more, attracting EPNs that follow a path of CO 2 toward their hosts [ 52 , 106 ]. Steinernema feltiae and H. bacteriophora have been reported to disperse conidia and blastospores of Isaria fumosorosea in agar dishes and soil, suggesting a high ability for EPNs to spread EPF conidia in the shared environment [ 117 ]. These mechanisms of interaction can lead EPF and EPNs to generate a stronger effect than the sum of their individual effects [ 49 , 89 ].…”

Interactions between Entomopathogenic Fungi and Entomopathogenic Nematodes

“…Recently, Nermuť et al [ 63 ] studied the potential of infective juveniles of entomopathogenic nematodes in the transmission of spores of C. fumosorosea . The authors assessed the dispersal of both the conidia and blastospores of C. fumosorosea by entomopathogenic nematodes S. feltiae and H. bacteriophora .…”

A Review of Prospective Biocontrol Agents and Sustainable Soil Practices for Bulb Mite (Acari: Acaridae) Management

“…The authors concluded that although some EPN species are able to invade and kill bulb mites, their efficacy is in general quite low and they do not seem to represent a viable option for bulb mite biocontrol as a standalone approach [31]. EPNs have, however, other important functions in soil as they can disseminate fungal spores [70], serve as prey for invertebrate predators including mites and springtails or as a host for nematode-trapping fungi, such as Orbilia oligospora (Fresen.) Baral and E. Weber, Monacrosporium eudermatum (Drechsler) Subram.…”