Effect of bee-vectored Beauveria bassiana on greenhouse beneficials under greenhouse cage conditions

Beauveria bassiana ([Balsamo] Vuillemin [Ascomycota: Hypocreales] Botanigard 22WP® formulation]) shows potential as a bee-vectored microbial control agent for control of insect pests on greenhouse tomato and sweet pepper. To integrate this control strategy with existing beneficials used in greenhouse vegetable production, it is important to determine the impact of bee vectored Beauveria on commonly used biocontrol agents in greenhouse crops. Therefore, greenhouse trials were conducted to investigate the impact of bee-vectored B. bassiana on the survivorship and parasitism/predation level of Encarsia formosa Gahan (Hymenoptera: Aphelinidae), Eretmocerus eremicus Rose & Zolnerowich (Hymenoptera: Aphelinidae), Aphidius colemani Viereck (Hymenoptera: Braconidae), Orius insidiosus (Say) (Heteroptera: Anthocoridae) and Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae). Two treatments were evaluated: (bee-vectored inoculum [1.37×10 10conidia/g of inoculum] and a control [bees but no inoculum]). The experimental design was a completely randomized block design with three to four replications per treatment over time. The commercial bumblebee pollinator, Bombus impatiens (Cresson) (Hymenoptera: Apidae), was used to vector the microbial control agent to the crop. Over 95% of the flower and leaf samples from the tomato and sweet pepper crops contained detectable levels of Beauveria spores. No significant differences in mortalities were found between the two treatments for the parasitoid species and A. swirskii. Mortality for O. insidiosus was significantly greater in the Beauveria treatment compared to the control treatment. Parasitism and predation levels were not significantly different between to the two treatments. Also, Beauveria did not significantly impact bee mortality compared to the control treatment. Thus, based on the results presented in the current study, bee vectoring of the entomopathogen, B. bassiana, should be compatible with many of the beneficial arthropod control agents that are used in greenhouse integrated pest management. © 2012.