The effects of spinosad insecticide to adults of Apis mellifera, Megachile rotundata and Nomia melanderi (Hymenoptera: Apidae)

• Main Authors: D. F. Mayer, G. Kovács, B. L. Brett, B. L. Bisabri
• Format: Article
• Language: English
• Published: University of Debrecen 2001-03-01
• Series: International Journal of Horticultural Science
• Subjects: honey bees; Apis mellifera; alkali bee; Nomia melanderi; alfalfa leafcutter bee; Megachile rotundata
• Online Access: https://ojs.lib.unideb.hu/IJHS/article/view/257
• ISSN: 1585-0404; 2676-931X

The toxicity of spinosad to adult female bees tended to be least to the honey bee (Apis mellifera L.) (LD50 = 0.078 pg/bee), intermediate to the alkali bee (Nomia melanderi) (0.065 pg/bee), and greatest to the alfalfa leafcutter bee (Megachile rotundata (F.)) (0.058 pg/bee), both in topical drop tests and in tests involving spinosad residues on alfalfa (Medicago sativa) foliage. For the calculated LD50 pg/g, the honey bee (LD50 = 0.612 pg/g) was the most susceptible followed by the alkali bee (0.773 pg/g) and the leafcutter bee (1.908 pg/g). The honey bee oral LD50 was 0.063 pg/bee and the calculated LD50 0.492 pg/g. Adding an adjuvant to spinosad sprays did not change the toxicity of spinosad to bees in residue bioassay studies. Spinosad at as high as 500 ppm in feeders containing a sucrose/honey syrup caused no significant reduction in honey bee visitation or total syrup consumed.