Evaluating Beauveria bassiana Mycoinsecticides Against Spotted Lanternfly ( Lycorma delicatula ) Adults, Nymphs, and Eggs in Semi-Urban Areas

Background The spotted lanternfly ( Lycorma delicatula )(SLF) is an invasive planthopper that is spreading in the United States over recent years. Not only is SLF a nuisance pest in urban areas, but its feeding causes millions of dollars in damage to the forestry, ornamental plant, and viticulture industries annually, necessitating research on effective and sustainable control methods. The fungal pathogen Beauveria bassiana was previously found to infect and kill SLF. Our study sought to evaluate commercially available B. bassiana mycoinsecticides against various SLF life stages. Methods In field trials, SLF were either directly sprayed with mycoinsecticides or exposed to 24-hour old mycoinsecticide residues on trees. We documented mortality over time, as well as the percentage of B. bassiana -infected individuals. Results Direct contact sprays of B. bassiana strain GHA killed 95% of SLF adults after 2 weeks. Approximately 34% of early instar nymphs were killed after 9 days. However, laboratory testing confirmed that > 70% of nymphs were infected with the B. bassiana fungus. Late instar nymphs and adults exposed to residuals were infected at averages of 20% and 7% respectively, suggesting that mycoinsecticide tree bark sprays are not effective and quickly deteriorate within 24 hours. There was no effect of B. bassiana applications on egg hatch rate and only 16% of emerging hatchlings were infected. Conclusions Our results indicate that direct contact spray applications of B. bassiana strain GHA can effectively kill SLF adults and nymphs under field conditions.