Acute and sublethal effects of acetamiprid alone and in mixture with emamectin benzoate on honeybee, Apis mellifera

Abstract

The neonicotinoid acetamiprid (ACE) and emamectin benzoate (EMB) are widely utilized agrochemicals worldwide in crop protection. Most previous studies have evaluated on the toxicity of individual insecticides on honeybees. This study evaluated formulation of combined toxicities of acetamiprid (8%) and emamectin benzoate (2.15%) through oral and contact exposures to Apis mellifera. The binary mixture had a lethal dose (LD50) of 1 × 10−3 µg/bee (oral) and 4 × 10−5 µg/bee (contact) to adult honeybees and a lethal concentration (LC50) of 2 × 10−1 µg/ml to larvae. The mixture's oral and contact hazard quotient were significantly greater than ACE, with values of 17,400 and 5000, respectively. The estimated additive indices (AI) showed that ACE and EMB interacted additively with AI values of 0.047 (oral), 0.01 (contact), and 0.02 (larval). The mixture also reduced the survival of larvae, affected proboscis extension response (PER) scores, and impacted the ability of honeybees to discriminate odors. The authors recommend a field study to investigate the mixture's adverse effects on honeybees further.