Susceptibility of different life stages of kudzu bug Megacopta cribraria (F.) (Hemiptera: Plataspidae) to two different strains of Beauveria bassiana

Authors: Glover, James; Portilla, Maribel; Allen, Clint; George, Justin; Parys, Katherine; Reddy, Gadi V.P.

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2022
Publication Date: 9/9/2022
Citation: Glover, J.P., Portilla, M., Allen, K.C., George, J., Parys, K.A., Reddy, G.V. 2022. Susceptibility of different life stages of kudzu bug Megacopta cribraria (F.) (Hemiptera: Plataspidae) to two different strains of Beauveria bassiana. Pathogens. 11:1-10. https://doi.org/10.3390/pathogens11091028.
DOI: https://doi.org/10.3390/pathogens11091028

Interpretive Summary: The objective of this study was to compare the survival, mortality, and lethal dose on the different life stages of Kudzu bug, Megacopta cribraria (F.) (Hemiptera: Plataspidae) to two different pathogenic fungal strains of Beauveria bassiana (Cordycipitaceae). Kudzu bug is an introduced urban and agricultural pest of soybeans (Glycine max (L.) Merrill) (Fabales: Fabaceae) grown in the southeastern United States. The geographic range of kudzu bugs has expanded rapidly within the United States, spreading as far west as Louisiana, north to Maryland and occupying 652 counties in the United States by 2017, and west into Texas by 2021. Kudzu bugs, both adults and nymphs, feed on kudzu variety lobata (Pueraria montana) (Fabales: Fabaceae) (Willd), along with soybeans and a variety of other legumes causing yield losses in untreated soybean across the Southeastern United States. Significant reduction in survival times for kudzu bugs were observed in all instars on and after day five post exposure to the fungal isolates. Late instars and adults saw a marked reduction in survival ten days post exposure to each isolate at the highest concentrations investigated. However, individuals exposed to the KUDSC isolate irrespective of concentration experienced the highest mortality rates across the study.

Technical Abstract: Kudzu bug is an introduced urban and agricultural pest of soybeans (Fabales: Fabaceae) grown in the southeastern United States. Kudzu bugs feed on a variety of other legumes causing yield losses in untreated soybean across the Southeastern United States. In this study we examine and compare the survival, mortality, LC50, and RR50 estimates of Megacopta cribraria exposed to four concentrations of two fungal pathogenic B. bassiana isolates. Survival of kudzu bugs were not affected by either of the B. bassiana isolates or concentrations assayed for all life stages in this experiment one day post exposure, and differences in survival regardless of treatment combination never increased from day 15 through day 20 in this study. The greatest reduction in all experimental parameters, (i.e., survival, mortality, and sporulation) were observed primarily on or after 10 days post-exposure to the Beauveria bassiana isolates. Survival of early instars were not affected by either strain or concentration investigated at 3 and 5 days post exposure, with the exception of 3rd instar kudzu bugs that experienced significantly reduced survival (<65%) when exposed to the KUDSC strain at the highest concentration in the study. Survival of late instars and adults ranged from 77% to 14% on day 10 and 64% to 16% on day 15 through 20. Comparison of dose-mortality values (LC50) using resistance ratios (RR50) were not significantly different between the two strains of B. bassiana for any life stage. The lowest survival rates were observed on or after day 5 for 5th instar and adults exposed to either B. bassiana isolates at the highest concentration investigated in this study.