| Honey bees are important pollinating insects in nature.The health of honey bee eggs is crucial to the development and growth of honey bee colonies.In recent years,the effects of pesticides on the health of bee colonies have received widespread attention in China and abroad,but little research has been reported on the effects of pesticides on honey bee eggs during their development.In this study,a multi-residue analysis method for 29 pesticides in beeswax was developed.Based on the monitoring data of 29 pesticide residues in beeswax samples from the main honey-producing provinces and cities in China for two consecutive years,bifenthrin and carbendazim with high detection rates and concentrations were selected as test agents.The effects of bifenthrin and carbendazim in beeswax on egg hatching rate and subsequent larval growth and development were investigated.The results of the study are of great theoretical significance and practical application for the scientific evaluation of the effects of pesticide residues in beeswax on bees and the health of bee colonies.The main findings are as follows:1.Confirmation of a multi-residue analytical method for 29 pesticides in beeswaxThe method was developed for the multi-residue analysis of 29 pesticides in beeswax by high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The method showed good linearity in the concentration range of 5-500μg/kg with the coefficients of determination(r~2)greater than 0.9902.The limits of detection(LOD)and limits of quantification(LOQ)of the method were 0.018-0.324μg/kg and 0.053-0.972μg/kg,respectively.The recoveries ranged from 70.4 to 121.3%and the relative standard deviations ranged from 0.6 to 37.9%,indicating that the sensitivity,accuracy and precision of the method could meet the requirements for the analysis of the 29 pesticides in beeswax.2.Pesticide residues in actual samples of beeswaxThe results of pesticide residue testing of 15 fungicides and 14 insecticides in 216beeswax samples collected from 18 provinces and municipalities for 2 consecutive years showed that all 15 fungicides were detected at different residue levels in the actual samples of beeswax,with 88.4%of all samples contaminated with at least one fungicide,of which carbendazim,triadimefon and tebuconazole were the three pesticides with the highest detection rates among the fungicides.Fourteen insecticides were also detected in the samples,with 95.8%of the samples contaminated with at least one insecticide,and bifenthrin,thiamethoxam and deltamethrin were the three insecticides with the highest detection rates.The third pesticides were detected at 65.74%,60.19%and 55.56%,with average residues of 140.15μg/kg,151.88μg/kg and 12.91μg/kg respectively.3.Migration patterns of bifenthrin and carbendazim in the nectar-beeswax processIn the semi-field test,bifenthrin and carbendazim,which have relatively high detection rates and concentrations in the actual samples,were used as test pesticides to simulate the actual pesticide exposure in the beehive by artificially feeding sugar-containing water.The results showed that bifenthrin and carbendazim in nectar contaminated beeswax from the first day of exposure,with mean concentrations of 70.32μg/kg and 51.78μg/kg,respectively,and that residues of bifenthrin and carbendazim in beeswax increased from 1to 7 days,showing a cumulative trend.After 7 d,the residue concentrations of bifenthrin and carbendazim decreased continuously and showed a trend of dissipation,and the residue concentrations leveled off after 18 d and 16 d,respectively,with the average residue concentrations of 134.89μg/kg and 520.74μg/kg in the bifenthrin-treated group and carbendazim-treated group at 16 d,respectively.The average residue concentrations at18 d for bifenthrin and 16 d for carbendazim were 134.89μg/kg and 520.74μg/kg,respectively.The half-lives of bifenthrin and carbendazim in beeswax after 7 d in the hives were 2.6 d and 2.9 d,respectively.4.Effect of bifenthrin and carbendazim in beeswax on the development of honey bee eggsThe effect of bifenthrin and carbendazim in beeswax on the hatching of honey bee eggs and the growth and development of larvae was investigated using beeswax,the main component of the hive,as the matrix.The results showed that when bifenthrin and carbendazim were added at a concentration of 1500μg/kg and 5000μg/kg respectively,the hatching rates were 82.50%,47.00%,65.75%and 32.00%in the control,bifenthrin-treated,carbendazim-treated and combined-treatment groups respectively,with significant differences between the treatment and control groups.The combined treatment groups showed some synergistic toxicity compared to the single pesticide treatment groups.The survival rates of the larval stage were significantly different from the control group except for the carbendazim treatment group,bifenthrin and the combination treatment group,with mean survival rates of 51.83%and 28.28%respectively;the survival rates of the pupal stage were significantly different from the control group,with mean survival rates of51.61%,21.15%and 6.03%respectively.The mean survival rates were 51.61%,21.15%and 6.03%respectively. |
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