Toxic Effects Of Flumethrin On Apis Mellifera Ligustica L. (Hymenoptera:Apidae)

Bees have important economic value and social benefits.At the beginning of the last century,Apis mellifera were introduced to Asia.They have become the dominant bee species in many countries.At the same time,they are also suffering from bee mites.At present,the control of bee mites is mainly based on chemical agents,compared with other acaricides.Flumethrin is an efficient and low toxic acaricide,which is popular with bee farmers at home and abroad.However,due to the nonstandard operation and increasing dosage of acaricide by bee farmers,it harms the health of bees invisibly and causes the drug residues of bee products to exceed the standard.Many previous studies have studied on the effects of other acaricides such as tau-fluvalinate and neonicotinoids such as imidacloprid on the growth and development of honeybees.However,as an alternative to other acaricides,the effects of flumethrin on the health of honeybees need to be studied.Therefore,the effects of flumethrin on the growth and development,toxicity,enzyme activity and gene expression of Apis mellifera were studied by feeding method in order to clarify the toxic mechanism of flumethrin on Apis mellifera.The results are as follows:?1?The effect of sublethal dose of flumethrin on the morphological development of Apis mellifera larvaeSublethal dose of flumethrin was used to feed the larvae of Apis mellifera.The results showed that the morphological development of larvae was affected.Poisoning symptoms such as larval growth retardation,body color browning,body collapse and reduced food intake were found during the experiment;while deformities such as disabled wings,yellowing body color,imperfect compound eyes and petite body were found in honeybees from pupal stage to eclosion.The results showed that the pupation rate and eclosion rate were significantly lower than those of the control group.For example,the pupation rate and eclosion rate of the 10^-33 mg/L treatment group decreased significantly by 24.40%and 30.38%.The results showed that sublethal dose of flumethrin caused serious harm to the development of Apis mellifera larvae.By collecting 3-day-old larvae for repeated exposure indoors,the exposure lasted until the 21th day of eclosion of worker bees,during which the number of dead bees was recorded daily.The results showed that the number of dead bee larvae in the treatment group was significantly higher than that in the control group,the mortality of 10^-55 mg/L in low concentration group was 1.57 times higher than that in control group.?2?Acute toxicity of flumethrin to new emergence Apis melliferaThe acute toxicity test of flumethrin to new Apis mellifera was carried out.The results showed that the acute toxicity of flumethrin to new Apis mellifera was high.The acute toxicity data of flumethrin to new emergence bees showed that 48 h-LD₅₀0 was 0.47?g a.i./bee,95%confidence interval was 0.39-0.57?g a.i./bee,and the linear equation between dosage of flumethrin and bee mortality was Y=-0.123+0.120x.The linear correlation coefficient was 0.938.?3?Development toxicity of sublethal dose of flumethrin to adult worker bees of Apis mellifera.Adult Apis mellifera were fed with sublethal doses of flumethrin for 14 days.The number of deaths and food intake were recorded daily.During the experiment,it was found that Apis mellifera had obvious poisoning phenomena:slow movement,lying on their back,trembling,fighting with each other,slow reaction,etc.The results showed that there was no significant difference in the number of deaths between the treatment group and the control group,but the intake of each treatment group increased significantly compared with the control group,indicating that low dose of flumethrin promoted the increase of bee feeding.?4?The effect of sublethal dose of flumethrin on the content and activity of Apis mellifera enzyme.The changes of enzyme activities in head,abdomen and larval tissues of Apis mellifera fed with sublethal dose of flumethrin were determined.The enzymatic activities of:SOD,CAT,POD,GST,GR and AChE,and the content of enzymatic products of GSH,MDA,LPO and ACh,respectively.The results showed that the activities of CAT,POD,GST,GR and other enzymes in the abdominal tissues of adult bees were significantly different from those of control bees,and the changes of these enzymes at 7 days were more significant than those at 14 days,the various antioxidant enzymes may play a more important role in the early stage of bee development in the oxidative stress caused by flumethrin on Apis mellifera.After 14days of treatment,it was found that the AChE activity of bee head in high concentration treatment group was significantly higher than that in control group?61.54%?,indicating that cyhalothrin could significantly induce AChE activity,thereby interfering with the neurotransmission of bees and inducing changes in bee behavior.Compared with the control group,the activity of SOD in the larvae had no significant change,but the activity of other 9 enzymes had significant changes,indicating that the larvae were more sensitive to the influence of external pollutants.?5?Effect of sublethal dose of flumethrin on gene expression of Apis melliferaAfter 14 days of exposure to the sublethal dose of flumethrin,quantitative fluorescence PCR was used to detect the relative expression of 7 genes in the abdomen of Apis mellifera,including Sod,Cat,Gst1,Gst3,CRBXase,CYP6AS14 and CYP306A1,and 14 genes in the head of Apis mellifera,including Sod,Cat,CYP4G11,CYP6AS14,PGRPSC,PGRP-4300,Spaetzle,toll,cactus,dorsal,hopscotch,abaecin,defensin and defensin-2.The results showed:compared with the control group,the relative expression levels of antioxidant genes of Sod and Cat,detoxification genes of Gst and CYP 450 family,carboxylesterase?CRBXase?and immune related genes?defensin,defensin-2,abaecin,toll,spaetzle,etc.?in abdominal and head tissues of bees were significantly affected.To study the sublethal effect of flumethrin on Apis mellifera,the aim was to explore the rational application of the acaricide in bee industry and the harmfulness to Apis mellifera.On the other hand,the study on the sublethal effect of insecticides on honeybees laid a theoretical foundation for exploring honeybees as environmental indicators.