Abstract:
Bifenthrin suspension concentrate (SC), bifenthrin capsule suspension (CS), acetamiprid emulsifiable concentrate (EC), and acetamiprid CS were applied separately on cucumber plants to evaluate the toxicity of their leaf residues to honeybees and to compare the dissipation dynamics of the two insecticides on cucumber leaves and flowers applied in different formulation types. The results indicated that the residue of bifenthrin on leaves caused evident toxicity to honeybees, with a 24-h leaf-contact mortality time to 25% (RT
25) of > 120 h for SC and 65.6 h for CS, whereas the residue of acetamiprid exhibited no observable toxicity, with RT
25 < 3 h. Dissipation of both insecticides in leaves and flowers followed first-order kinetics, with half-lives ranging from 1.7 to 3.9 d for bifenthrin and 0.6 to 0.9 d for acetamiprid on leaves, and from 0.4 to 0.8 d and 0.5 to 0.7 d on flowers, respectively. A significant positive correlation was observed between the residue levels and the toxicity to honeybees, indicating that both formulation type and environmental factors exerted certain influences on residue persistence and toxicity. This research comprehensively investigated the residue dynamics of two pesticides under natural conditions and their potential harm to honeybees, providing technical support for objectively assessing their actual ecological risks and helping to protect bee resources and to promote sustainable agricultural development.