Mayer, D. F.Kovács, G.Brett, B. L.Bisabri, B. L.2021-06-282021-06-282001-03-21International Journal of Horticultural Science, Vol. 7 No. 1 (2001) , 93-97.1585-0404https://hdl.handle.net/2437/314093The toxicity of spinosad to adult female bees tended to be least to the honey bee (Apis mellifera L.) (LD 50 = 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 LD 50 pg/g, the honey bee (LD 50 = 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 LD 50 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.  application/pdfhoney beesApis melliferaalkali beeNomia melanderialfalfa leafcutter beeMegachile rotundataspinosadfolyóiratcikkOpen Accesshttps://doi.org/10.31421/IJHS/7/1/257International Journal of Horticultural Science17Int. j. hortic. sci.2676-931X