Effects of pesticides on Apis cerana from passion fruit in Hainan island
Description
The passion fruit not only has ornamental and edible value but also possesses certain medicinal properties, making it a highly popular tropical fruit. The use of pesticides during its cultivation, the quality and safety of the product, and its impact on wild insects in the ecological environment have always been topics of great concern to consumers. In this study, samples were collected from eight different regions of Hainan Island, including seven types of samples from passion fruit orchards and residual detection was conducted on 12 chemicals. The results showed that the pesticide detection rate of 12 chemicals ranged from 1.41% to 70.59%. Baoting region had the highest total pesticide detection rate (63.16%), with the highest detection rate of thiamethoxam residues, particularly during the first survey period (Time Point 1) (54.5%). The total pesticide detection rate was highest in passion fruit leaves, especially pyraclostrobin in the Time Point 1 (77.5%). Thiamethoxam residues were detected in all sample tissues, but no pesticide residues were detected in honey, and fluopimomide was not detected in all samples. Furthermore, The highest rate of thiamethoxam exceedance occurred in Baoting region especially during Time Point 1 (54.55%). The dietary intake risk assessment of passion fruit and honey is acceptable. Despite this, pesticide use affected honeybee colonies, with the Wuzhishan region most affected. The acute contact toxicity to Apis cerana of the four neonicotinoid insecticides measured showed that thiamethoxam had the highest toxicity, with a 48-hour LD50 value of 0.000754 μg a.i./bee, while acetamiprid had the lowest toxicity, with a 48-hour LD50 value of 0.225195 μg a.i./bee. The toxicity of the four tested neonicotinoid insecticides to adult A. cerana worker bees was all highly toxic. Therefore, it is recommended to use pesticides rationally during the passion fruit flowering period with caution to avoid harm to A. cerana pollination. These results ensure that the fruit consumed by consumers meets food safety standards. Additionally, testing the risk of pesticides to bees can assess the potential impact of pesticide use on bee populations, thereby taking measures to protect bees and maintain ecological balance.