| The main food of honeybee larvae（over 3 days old）is beebread and honey.The long-term intake of low-dose pesticide residues in food will produce sublethal effect and lead to the decrease of honeybee population.In order to investigate the effects of insecticides on the growth and development of honeybee larvae and quantitatively analyze the dietary exposure risk level of honeybee larvae caused by pesticide residues in beebread and honey samples from major honey and powder producing areas in China,five pyrethroid insecticides residues in beebread and honey samples were detected for three years.The results provide more scientific guidance and practical value for the rational use of pyrethroid insecticides on honey-sourced plants,and provide a basis for effectively avoiding the risk of exposure of pyrethroid insecticides to bee larvae.The main findings are as follows:1、Confirmation of five pyrethroid pesticide residues in beebread and honeyThe results of the added recovery experiment show that the linear relationship between bifenthrin,lambda-cyhalothrin,beta-cypermethrin,fenvalerate and deltamethrin is good in the range of 2.5-500 ng/m L concentration,and the linear relationship is 0.9961-0.9993,check-out limits and quantitative limits of 0.47-0.67ng/m L and 1.61-2.66 ng/m L,respectively.At the added concentrations of 10,100,1000μg/kg,theaveragerecoveryrateofbifenthrin,lambda-cyhalothrin,beta-cypermethrin and fenvalerate in beebread and honey was70%-114%.The relative standard deviation was 6-12%,and the average recovery rate of deltamethrin in beebread and honey was 97-114%and the relative standard deviation was 5-16%at the added concentration of 5,50,500μg/kg.The accuracy,accuracy and sensitivity of the method can meet the requirements of pesticide residue analysis.2、Residue analysis of five pyrethroid insecticides in beebread samplesThe pesticide residues in 331 beebread samples collected from six major honey and powder producing areas in China for three consecutive years,and the results showed that 54.7%of the actual samples of beebread detected the pyrethroids,containing one kind of pyrethroid accounted for 32.6%,containing two kinds and above accounted for 22%.The detection rates of the five insecticides were lambda-cyhalothrin（23.3%）,bifenthrin（22.7%）,fenvalerate（12.7%）,deltamethrin（12.4%）and beta-cypermethrin（10.9%）.Among them,the maximum residue,average residue and median residue of lambda-cyhalothrin were 188.14 mg/kg,4.4 mg/kg and 0.6 mg/kg,respectively.3、Residue analysis of five pyrethroid insecticides in honey samplesThe pesticide residues in 364 honey samples collected from six major honey and powder producing areas in China for three consecutive years,and the results showed that the actual sample of honey 43.4%of the samples detected the proposed pyrethroids,containing one kind pyrethroid accounted for 20.3%,containing 2 kinds and above accounted for 23.1%.The detection rates of the five insecticides were deltamethrin（20.9%）,lambda-cyhalothrin（20.6%）,bifenthrin（17%）,fenvalerate（15.1%）and beta-cypermethrin（9.1%）.Among them,the average and maximum concentrations of deltamethrin were the highest,at 0.3 mg/kg and 12.8 mg/kg,respectively.4、Effects of pyrethroid insecticides on the growth and development of bee larvaeThe safety evaluation of the acute toxicity and feathering rate and feathering rate of 5 kinds of pyrethroids on bee larvae showed that the acute toxicity of 5 insecticides to bee larvae was from large to small deltamethrin（0.053μg/bee）),beta-cypermethrin（0.16μg/bee）,lambda-cyhalothrin（0.22μg/bee）,bifenthrin（0.45μg/bee）,fenvalerate（2.08μg/bee）.0.35 mg/L of deltamrthrin will reduce the rate of larvae and feathering of bee larvae respectively by 75%and 77%。5、Risk assessment of bee larvae from trial pesticide residues in bee food and honeyRisk assessment of bee larvae using no observed effect level（NOEL）and residual ratio methods recommended by EFSA,using pyrethroids residues in beebread and honey and acute toxicity parameters for bee larvae as toxicological data,assess the exposure risk of five pyrethroid pesticides to bee larvae,The results show that Risk entropy of bifenthrin,fenvalerate,beta-cypermethrin,lambda-cyhalothrin and deltamethrin are 0.046×10-3,0.096×10-3,0.259×10-3,1.540×10-3and2.128×10-3.The risk entropy of five pyrethroid insecticides to honeybee larvae was less than 1,and the risk was acceptable. |
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