Effects of Pesticides on Apis cerana From Passion Fruit in Hainan Island

The tropical fruit passion fruit, which depends on insect pollinators such as the Apis cerana, is susceptible to risks associated with excessive pesticide application. These risks include detrimental effects on pollinating insects and the issue of pesticide residues. To quantify these impacts, a multidimensional experimental design was implemented: (1) Sampling entailed the collection of diverse samples (fruit, leaves, flowers, soil, honey, pollen, bees) from eight orchards spanning Hainan Island at four key time points, from preflowering to postpollination. (2) Residues of 12 targeted chemical substances, comprising neonicotinoids, organophosphorus, pyrethroid, and fungicides, were analyzed through liquid chromatography-mass spectrometry. (3) The acute contact toxicity of four neonicotinoid insecticides to Chinese honeybee workers was determined using the drop method, calculating the 48-h median lethal dose (LD₅₀). (4) Dietary intake risks for passion fruit and honey were evaluated via the target hazard quotient (THQ) and risk quotient (RQ) models, whereas ecological risks to bees were assessed through the hazard quotient (HQ) and spray exposure risk quotient (RQsp). The results revealed pesticide detection rates ranging from 1.41% to 70.59%, with the highest total detection rate in the Baoting region. Thiamethoxam was the most prevalent residue, particularly during the initial phase of pollination. No residues were detected in honey, and flupyradifurone was absent across all samples. The dietary risk was deemed acceptable; however, pesticide use had a discernible impact on bee colonies, particularly in the Wuzhishan region. All four neonicotinoid insecticides exhibited high toxicity to Chinese honeybees, with thiamethoxam being the most potent. The study advises judicious pesticide usage during the flowering period to preserve bee pollination.