Mighty fungi to battle weevil: Efficacy of entomopathogenic fungi towards sweetpotato weevil in the greenhouse and field

On-Demand

Presenting Author(s)

Nupur Sarkar

Postdoctoral Researcher
Louisiana State University Agricultural Center
Baton Rouge, Louisiana

Co-Author(s)

SN

Sara Navarro

Research Associate
Louisiana State University Agricultural Center
Baton Rouge, Louisiana
EA

Elka Armstrong

AgBiome
Research Triangle Park, North Carolina
CK

Chad Keyser

Project leader/ Insect Pathologist
AgBiome
Holly Springs, North Carolina
JD

Jeffry A A. Davis

Professor
Louisiana State University Agricultural Center
Baton Rouge, Louisiana

The aim of this study was to evaluate the efficacy of entomopathogenic fungal strains to control sweetpotato weevil (SPW), Cylas formicarius elegantulus (Summers), in greenhouse and field environments. Four strains isolated from Louisiana soil (K048, K056, K082, and K101) were selected based on performance in laboratory assays. In the greenhouse assay, adult SPWs were exposed to potted sweetpotato plants treated with a fungal solution of 10⁷ spores/ml; a licensed strain (ARSEF 1095) was used as a positive control. The field experiment was a randomized-block design with three replications, all four fungal strains were tested alongside a positive-control (bifenthrin) and two negative controls: autoclaved spores and untreated check. Plant materials from the treated plots were brought back to the laboratory at multiple time points (0, 3, 7, and 14 days after application); adult SPWs were exposed to the leaves and mortality was assessed after 7 days. All the fungal treatments in the greenhouse study showed significantly higher SPW mortality than the negative control treatment. In the field experiment, at 0-days after application, there was no significant difference in weevil mortality between fungal strains and bifenthrin, with all treatments killing >80% of weevils. Fourteen days after application, 66% of SPWs exposed to plant material treated with K101 resulted in mortality, this was statistically similar to the positive chemical control. A second season of field trials is underway however, these initial results are a promising step towards developing a biological control agent for SPW.