Non-lethal effects of entomopathogenic nematode infection

Abstract

Entomopathogenic nematodes are typically considered lethal parasites of insect hosts. Indeed they are employed as such for biological control of insect pests. The effects of exposure to entomopathogenic nematodes are not strictly limited to mortality, however. Here we explore non-lethal effects of exposure to entomopathogenic nematodes by introducing the relatively non-susceptible pupal stage of Delia antiqua to thirteen different strains. We specifically chose to inoculate the pupal stage because it tends to be more resistant to infection, yet resides in the soil where it could come into contact with EPN biological control agents. We find that there is no significant mortality at the pupal stage, but that there are a host of strain-dependent non-lethal effects during and after the transition to adulthood including altered developmental times and changes in risk of death compared to controls. We also find that exposure to specific strains can reduce risk of mortality. These results emphasize the strain-dependent nature of entomopathogenic nematode infection and highlight the positive and negative ramifications for non-lethal effects for biological control of insect pests. Our work emphasizes the need for strain-specific screening of biological control agents before wide-spread adoption.

Exploring the Use of Entomopathogenic Nematodes and the Natural Products Derived from Their Symbiotic Bacteria to Control the Grapevine Moth, Lobesia botrana (Lepidoptera: Tortricidae)

“…In addition, we observed that the presence of EPNs drove miniature EGVM adult emergences from the pupae (I. Vicente-Díez, personal observation). A recent study has shown that the presence of EPNs can alter developmental times and changes in the risk of death of the non-susceptible pupal stage of Delia antiqua (Diptera: Anthomyiidae) [47]. As such, this possible alteration in size as well as potential alterations in other metabolic parameters might be of interest in the context of the preventive and biological control of EGVMs.…”

Soil moisture conditions alter behavior of entomopathogenic nematodes

“…Further, the presence of nematodes is associated with higher biomass concentrations, microbial communities, plant growth and soil nutrients 21 . These benefits occur as exposure to an EPN will severely limit the fitness and increase the mortality rate of agricultural pests 22 . However, numerous studies have shown that EPNs are sensitive to fluctuations in environmental conditions which reduces the survival and efficacy of these organisms 23‐25 .…”

“…21 These benefits occur as exposure to an EPN will severely limit the fitness and increase the mortality rate of agricultural pests. 22 However, numerous studies have shown that EPNs are sensitive to fluctuations in environmental conditions which reduces the survival and efficacy of these organisms. [23][24][25] This sensitivity becomes a major concern in the biological control of agricultural pests in regard to the unpredictability of climate change.…”

Influence of Asafoetida Extract on the Virulence of the Entomopathogenic Nematode Steinernema carpocapsae and Its Symbiotic Bacterium Xenorhabdus nematophila in the Host Pyrrhocoris apterus

“…Unfortunately, the virulence factors of EPNs are less explored and investigated. This is due to the significant gaps in our knowledge of the metabolic mechanisms that may control their pathogenicity, i.e., host–nematode interactions, symbiotic bacterial virulence, host immunity, and environmental factors [ 12 ]. The interaction between EPNs/symbionts and any other external factors of interest may be additive, antagonistic, or synergistic.…”