Susceptibility of Melipona scutellaris Latreille (Hymenoptera: Apidae) to Biopesticides

Abstract

Products based on entomopathogenic fungi are extensively used to control insect pests. These biopesticides can result in lethal or sublethal effects on non-target organisms. This study aimed to evaluate the survival of Melipona scutellaris Latreille workers exposed to commercial products based on Beauveria bassiana (IBCB 66), Metarhizium anisopliae (IBCB 425), and Isaria fumosorosea (ESALQ 1296). Fifty foragers were exposed to B. bassiana at 8.25 x 106 conidia/mL, M. anisopliae at 1.1 x 107 conidia/mL, and I. fumosorosea at 2.5 x 109 conidia/mL, using three routes of exposure (ingestion, contact with a surface, and topical application). Kaplan-Meier survival curves were estimated to determine the proportion of workers surviving after each application of the biopesticides. Workers exposed to B. bassiana, M. anisopliae, and I. fumosorosea presented survival rates of 74%, 34%, and 42%, respectively, after 168 hours of exposure by ingestion. For exposure via contact with a contaminated surface, survival rates were 64%, 70%, and 78%; for topical application, 68%, 66%, and 72% of the workers survived, respectively. The results highlight the variability in toxicity of biopesticides based on M. anisopliae, B. bassiana, and I. fumosorosea for M. scutellaris workers. Although all biopesticides resulted in mortality, bee survival rates varied depending on the exposure route. Understanding the effect of entomopathogenic fungi-based products on M. scutellaris may facilitate the development of strategies (such as timing and frequency of spraying) to reduce their impact on bees.

Keywords

• stingless bees
• biocontrol agents
• survival
• behavior
• entomopathogenic fungi