You are what you eat: fungal metabolites and host plant affect the susceptibility of diamondback moth to entomopathogenic fungi

Sereyboth Soth; Travis R Glare; John G Hampton; Stuart D Card; Jenny J Brookes; Josefina O Narciso

doi:10.7717/peerj.14491

You are what you eat: fungal metabolites and host plant affect the susceptibility of diamondback moth to entomopathogenic fungi

PeerJ. 2022 Dec 19:10:e14491. doi: 10.7717/peerj.14491. eCollection 2022.

Authors

Sereyboth Soth^{1

2}, Travis R Glare¹, John G Hampton¹, Stuart D Card³, Jenny J Brookes¹, Josefina O Narciso¹

Affiliations

¹ Bio-Protection Research Centre, Lincoln University, Christchurch, Canterbury, New Zealand.
² Department of Science, Technology and Innovation Training, National Institute of Science, Technology and Innovation, Chak Angre Leu, Mean Chey, Phnom Penh, Cambodia.
³ Grasslands Research Centre, AgResearch Limited, Palmerston North, Manawatū-Whanganui, New Zealand.

Abstract

Background: Beauveria are entomopathogenic fungi of a broad range of arthropod pests. Many strains of Beauveria have been developed and marketed as biopesticides. Beauveria species are well-suited as the active ingredient within biopesticides because of their ease of mass production, ability to kill a wide range of pest species, consistency in different conditions, and safety with respect to human health. However, the efficacy of these biopesticides can be variable under field conditions. Two under-researched areas, which may limit the deployment of Beauveria-based biopesticides, are the type and amount of insecticidal compounds produced by these fungi and the influence of diet on the susceptibility of specific insect pests to these entomopathogens.

Methods: To understand and remedy this weakness, we investigated the effect of insect diet and Beauveria-derived toxins on the susceptibility of diamondback moth larvae to Beauveria infection. Two New Zealand-derived fungal isolates, B. pseudobassiana I12 Damo and B. bassiana CTL20, previously identified with high virulence towards diamondback moth larvae, were selected for this study. Larvae of diamondback moth were fed on four different plant diets, based on different types of Brassicaceae, namely broccoli, cabbage, cauliflower, and radish, before their susceptibility to the two isolates of Beauveria was assessed. A second experiment assessed secondary metabolites produced from three genetically diverse isolates of Beauveria for their virulence towards diamondback moth larvae.

Results: Diamondback moth larvae fed on broccoli were more susceptible to infection by B. pseudobassiana while larvae fed on radish were more susceptible to infection by B. bassiana. Furthermore, the supernatant from an isolate of B. pseudobassiana resulted in 55% and 65% mortality for half and full-strength culture filtrates, respectively, while the filtrates from two other Beauveria isolates, including a B. bassiana isolate, killed less than 50% of larvae. This study demonstrated different levels of susceptibility of the insects raised on different plant diets and the potential use of metabolites produced by Beauveria isolates in addition to their conidia.

Keywords: Biopesticide; Brassicaceae; Glucosinolates; Median lethal concentration (LC50); Median lethal time (LT50); Metabolites.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Beauveria*
Biological Control Agents / pharmacology
Humans
Insecta / microbiology
Larva / microbiology
Moths* / microbiology
Pest Control, Biological / methods

Substances

Biological Control Agents

Grants and funding

Sereyboth Soth was supported by a New Zealand Ministry of Foreign Affairs and Trade scholarship. Additional funding was supplied by Lincoln University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.