Evaluating the Ecological Relationships among Beauveria bassiana, Kudzu Bug and Kudzu

When kudzu bug, Megacopta cribraria, was identified in the United States in 2009 as an invasive species, populations began to establish, increase, and spread throughout the southeastern region at intense rates. Kudzu bug invades urban structures, causing unpleasant scenes for homeowners, and reduces crop yield, such as soybean. Kudzu bug caused about $2.8 million in soybean yield loss and treatment in Tennessee in 2020. Although initial spread was rapid throughout the southeastern U.S., spatial modeling has shown populations of kudzu bug are declining and reducing risk of crop damage to growers. These local and regional declines in populations appear to be influenced by at least two natural enemies, a naturally-occurring entomopathogenic fungus, Beauveria bassiana, and an accidentally introduced egg parasitoid, Ooencyrtus nezarae. In Tennessee, O. nezarae causes 52% mortality in kudzu bug eggs and B. bassiana causes about 90% and 33% mortality in second-generation immature kudzu bugs and adult kudzu bugs, respectively.

A two-year study designed to evaluate the presence of B. bassiana was initiated in east Tennessee. The primary research goals of this project were to: 1) identify the temporal and seasonal presence of B. bassiana in kudzu bugs on kudzu in east Tennessee, and 2) identify the temporal and seasonal presence of B. bassiana in kudzu in east Tennessee. The results of this study have indicated that over time, B. bassiana increases in entomopathogenic presence in kudzu bugs and endophytic presence in kudzu in late summer to fall. Significant differences (p < 0.05) among sites were identified among entomopathogenic presence in kudzu bugs, but not in endophytic presence in kudzu (p ≥ 0.05). No differences among sampling locations within a site were identified between kudzu bug or kudzu vines (p ≥ 0.05). Differences were found among kudzu bug sex and developmental stage, with males being more likely to become infected with B. bassiana than immatures, and among immatures stages, with late instars being more likely to be infected than early instars (p < 0.05). Further research on mechanisms of dissemination and the interactions among these organisms, as well as in soybean, are essential to improve the use of B. bassiana to manage kudzu bug populations.A two-year study designed to evaluate the presence of B. bassiana was initiated in east Tennessee. The primary research goals of this project were to: 1) identify the temporal and seasonal presence of B. bassiana in kudzu bugs on kudzu in east Tennessee and 2) identify the temporal and seasonal presence of B. bassiana in kudzu in east Tennessee. The results of this study have indicated that over time, B. bassiana increases in entomopathogenic presence in kudzu bugs and endophytic presence in kudzu in later summer to fall. Significant differences (pB. bassianathan immatures, and immatures stages, where late instars were more likely to become infected than early instars. (pB. bassiana to manage kudzu bug populations.