TOXICITY OF COMMERCIAL PESTICIDE MIXTURES TO HONEY BEES (Apis mellifera L.)

Honey bees play a vital role in maintaining ecological balance and biodiversity, yet they face serious threats from pesticide exposure, particularly from pesticide mixtures whose effects remain insufficiently studied. This study aimed to survey commercially available pesticide mixtures in agricultural stores in El-Beheira Governorate, Egypt and to evaluate their toxicity to honey bees. A field survey was conducted across pesticide retail outlets to identify both registered and unregistered pesticide mixtures. Selected formulations were subsequently assessed through a biological evaluation experiment to determine their acute toxicity to bees. Toxicity levels were analyzed using LDP Line Probit analysis. Survey findings revealed that fungicides were the most commonly encountered pesticide mixtures, followed by insecticides, acaricides, and herbicides in the market. Among the tested formulations, the insecticide Corner Plus®, a combination of Thiamethoxam and Difenoconazole, exhibited the highest toxicity to honey bees, with a notably low LC50 value of 0.317 ppm. In contrast, the fungicide Craft®, containing Propioconazole and Difenoconazole, showed the lowest toxicity, with an LC50 of 119.256 ppm. These results underscore the potential hazards of pesticide mixtures to honey bees and highlight the need for more stringent evaluation and regulation to protect pollinators.