Evaluation of Spore Acquisition, Spore Production, and Host Survival Time for Tea Shot-Hole Borer, Euwallacea perbrevis, Adults after Exposure to Four Commercial Products Containing Beauveria bassiana

SIMPLE SUMMARY: The tea shot-hole borer (TSHB) is an invasive ambrosia beetle that vectors several fungal plant pathogens that cause Fusarium branch dieback in avocado trees. This study assessed the potential of four commercial products containing the entomopathogenic fungus Beauveria bassiana (Bb) for managing and mitigating the spread of the TSHB. The formulated fungal products tested were BioCeres WP, BotaniGard WP, BotaniGard ES and Velifer ES. Acquisition of spores by adult beetles dipped in the product suspensions with 2.5 ± 0.1 × 10(6) spores/mL was assessed. Survival time of beetles after residual exposure to the products in an in vivo avocado bark plug bioassay was also determined. Controls consisted of water only, BotaniGard ES and Velifer ES suspension supernatants with the spores removed. Production of Bb spores on beetles was assessed. Beetles exposed to Velifer ES and BotaniGard ES acquired significantly more spores than those exposed to the other fungal products. Beetles exposed to Velifer ES and BotaniGard ES died faster (6–8 days) compared to beetles treated with the other fungal products (10–11 days) and controls (12 days). Percentage mycosis was highest with beetles exposed to Velifer ES (63%). Spore production on cadavers of beetles dipped in Velifer ES was the highest among all treatments, whereas it was lowest on cadavers of beetles dipped in BotaniGard ES. All fungal products in this laboratory study demonstrated potential for use in management of the TSHB, especially Velifer ES. These Bb-based fungal products should be tested under field conditions to confirm these laboratory results. ABSTRACT: Euwallacea perbrevis, the tea shot-hole borer (TSHB), is an invasive ambrosia beetle that vectors several fungal pathogens that cause Fusarium branch dieback in avocado trees in southern Florida. This study assessed the potential of four commercial products containing the entomopathogenic fungus Beauveria bassiana (Bb) for managing adult TSHB beetles. Formulated products containing Bb strains to which adult beetles were exposed were BioCeres WP, BotaniGard WP, BotaniGard ES, and Velifer ES. Controls consisted of water only and BotaniGard ES and Velifer ES supernatant with spores removed. Acquisition of spores by adult beetles dipped in product suspensions with 2.5 ± 0.1 × 10(6) spores/mL was assessed. Survival time of beetles after residual exposure to the Bb-based products in an in vivo avocado bark plug bioassay was determined. Production of Bb spores on beetles after being dipped in product suspensions and placed in a moistened bark-plug assay with water only was assessed. Significantly more spores were acquired by beetles exposed to Velifer ES and BotaniGard ES than beetles exposed to the other fungal products. Beetles exposed to Velifer ES and BotaniGard ES died faster (6–8 days) compared to beetles dipped in the other fungal products (10–11 days) and controls (12 days). Percentage of mycosis was highest with beetles exposed to Velifer ES (63%). Spore production on cadavers of beetles dipped in Velifer ES (20 ± 6.4 × 10(5) spores/cadaver) was the highest among all treatments, whereas it was the lowest on cadavers of beetles dipped in BotaniGard ES (1 ± 0.2 × 10(5) spores/cadaver). All Bb-based products, especially Velifer ES, demonstrated potential to manage TSHB populations under laboratory conditions. These Bb-based fungal products should be tested under field conditions to confirm these laboratory results.