Abstract Selective insecticide application is one important
strategy for more precisely targeting harmful insects while
avoiding or mitigating collateral damage to beneficial
insects like honey bees. Recently, macrocyclic lactone-class
insecticides have been introduced into the market place as
selective bio-insecticides for controlling many arthropod
pests, but how to target this selectivity only to harmful
insects has yet to be achieved. In this study, the authors
investigated the acute toxicity of fourmacrocyclic lactone
insecticides (commercialized as abamectin, emamectin
benzoate, spinetoram, and spinosad) both topically and
through feeding studies with adult forager honey bees.
Results indicated emamectin benzoate as topically 133.3,
750.0, and 38.3-fold and orally 3.3, 7.6, and 31.7-fold more
toxic, respectively than abamectin, spinetoram and spinosad.
Using Hazard Quotients for estimates of field toxicity,
abamectin was measured as the safest insecticide both
topically and orally for honey bees. Moreover, a significant
reduction of sugar solution consumption by treatment group
honey bees for orally applied emamectin benzoate and
spinetoram suggests that these insecticides may have
repellent properties.