Efficacy of an oil‐based formulation combining Metarhizium rileyi and nucleopolyhedroviruses against lepidopteran pests of soybean

Abstract

A biopesticide that combines Metarhizium rileyi and nucleopolyhedrovirus (NPV) in an oil dispersion (OD) was developed. Its efficacy against Anticarsia gemmatalis and Chrysodeixis includens was evaluated under laboratory and field conditions. First, each of the two selected fungal strains, combined or not in OD preparations with AgMNPV or ChinNPV, was tested in the laboratory against A. gemmatalis and C. includens, respectively. AgMNPV–fungus combinations had similar effect on overall mortality of A. gemmatalis compared to each pathogen used alone. C. includens was less susceptible to infection by M. rileyi strains, and ChinNPV became the major cause of larval death. The OD formulations with M. rileyi and/or NPV were applied in infested soybean fields. ChinNPV + M. rileyi caused 50.8% of overall mortality six days after spraying in a soybean crop infested by both pests, whereas for treatments with the fungus or the virus alone the percentages were 41.2% and 8.8%, respectively. In another field infested solely by A. gemmatalis, insect mortality was similar for the AgMNPV–fungus combination and the virus used alone. Larval parasitism by wasps and dipterans was not affected following biopesticide spraying. Our results suggest that the performance of a dual‐action biopesticide is related to the NPV and fungal strains that are combined and the proportion of host populations simultaneously infesting the crop.

Evaluation of key parameters for developing a Metarhizium rileyi‐based biopesticide against Spodoptera frugiperda (Lepidoptera: Noctuidae) in maize: laboratory, greenhouse, and field trials

“…The absence of a synergistic effect has already been reported in laboratory experiments when selected isolates of M. rileyi and NPV were used in combination against S. frugiperda or A. gemmatalis 31 . However, Lopes et al 50 . discussed the potential positive effect that a dual‐action biopesticide would have to manage mixed populations of lepidopteran pests through the combination of NPV and M. rileyi .…”

“…The absence of a synergistic effect has already been reported in laboratory experiments when selected isolates of M. rileyi and NPV were used in combination against S. frugiperda or A. gemmatalis. 31 However, Lopes et al 50 discussed the potential positive effect that a dual-action biopesticide would have to manage mixed populations of lepidopteran pests through the combination of NPV and M. rileyi. Field experiments in that study suggested that a fungal isolate in the mixture capable of infecting a wide range of hosts may kill caterpillars not susceptible to the virus, or those insects that may not have ingested the virus.…”

Soybean Roots and Soil From High- and Low-Yielding Field Sites Have Different Microbiome Composition

“…Moreover, rhizosphere soils from high yield sites at both SGS contained greater percentages of genus Metarhizium ( M. anisopliae and M. marquandii ) compared to low yield sites. The beneficial entomopathogenic behavior of Metarhizium including M. anisopliae and M. marquandii is widely documented in relation to soybean production ( Clifton et al, 2018 ; Baron et al, 2020 ; Lopes et al, 2020 ). Therefore, the greater occurrence of beneficial fungal genera such as Trichoderma and Metarhizium can potentially eases the soilborne pathogen and insect pressure.…”

Susceptibility of Spodoptera frugiperda and Chrysodeixis includens (Lepidoptera: Noctuidae) to infections caused by Metarhizium rileyi

“…Therefore, M. riley is an entomopathogenic fungus with a great potential to control noctuid pests in several agricultural systems. For instance, C. includens and S. frugiperda larvae are susceptible to this entomopathogen, and the occurrence of natural epizootics caused by M. rileyi on these pest species is often observed in soybean and corn crops, respectively (Pavone et al 2009, Sosa-Gómez 2017, Souza et al 2019, Lopes et. al.…”