A naturally-occurring insecticide; a mixture of the macrocyclic lactones spinosyn A and spinosyn D, which act as agonists of insect nAChRs; induces toxicity in fruit flies including C. capitata, B. curcurbitae, and B. dorsalis (LC50s = 2.8-4.2, 4.3-5.5, and 3.1-3.3 μg/ml, respectively); has low toxicity in vertebrates; inhibits canine P-gp (IC50 = 0.2 μg/ml)