Toxicity of botanical insecticides on the stingless bee jataí (Tetragonisca angustula)

Abstract

This study aimed to investigate the toxicity of botanical insecticides on the essential pollinator stingless bee Jataí (Tetragonisca angustula). At first, two bioassays were carried out to assess the effect of the botanical insecticides: garlic, marigold, castor bean, Mexican tea, chili pepper, black pepper, clove, eucalyptus, and neem on bees' survival after exposure by ingestion or contact. Then, additional bioassays were carried out to investigate the effects of extraction solvent, concentrations, and use of adjuvants on the toxicity of botanical insecticides on Jataís bees. Results revealed toxicity of Eucalyptus oil to Jataí bees through contact and ingestion exposure even in low concentrations (0.1% v/v). The Neem oil in concentrations above 2.5% v/v and alcoholic extracts of cloves and black pepper in concentrations above 5% v/v are toxic to Jataí. Addition of detergent increases the toxicity of oil insecticides. Garlic extract prepared under the highest concentration of mineral oil and longest exposure time is toxic to jataí bees. Therefore, we can conclude that the use of botanical insecticides should be performed carefully to preserve this vital insect.