Investigation Of Pesticide Residues In The Pollen And Nectar Of Oilseed Rape And The Risk Assessment Of Three Pesticides On Apis Mellufera L

Honey bees,as important pollinating insects,have an important role in ecological maintenance and agricultural production.In recent years,the species and populations of pollinating insects,including honey bees,have been threatened by numerous factors,and the use of pesticides is considered to be one of the main causes.In this study,the largest nectar source plant in China and also the first nectar source plant in early spring in many places,oilseed rape,was used as a research object to detect the current status of pesticide residues in pollen and nectar by GC-LC and LC-MC/MC methods,and to assess the potential of these pesticides on honey bees by using hazard quotient(HQ)and BeeRex methods.On this basis,researched the individual or combined effects of different concentrations of acetamiprid(10,40,330 μg/kg),chlorpyrifos(16,40,320 μg/kg)and glyphosate(60,160,340 μg/kg)on the development,survival and flight ability of Apis mellifera L..The results of the study were as follows.(1)A total of 52 pesticides were detected in the pollen and nectar of oilseed rape samples.There were 48 and 34 pesticides in pollen and nectar,respectively.Although the residue concentrations of three pesticides exceeded the EU maximum residue limits in honey,the pesticides will be further degraded during the conversion of nectar into honey,and the details are unknown.(2)The risk assessment was carried out using the HQ and BeeRex methods.The assessment found that in the pollen samples,14 and 13 pesticides had a maximum contact and oral PHQ greater than50,respectively;while in the nectar samples,the corresponding NHQ values exceeded 50 for 10 and 8pesticides,respectively,indicating that these pesticides need further research.And according to the BeeRex method assessment,only cyfluthrin and carbofuran require higher-tiered testing.(3)Exposure to three pesticides alone or in combination significantly affected larval survival(p= 0.0004)and significantly reduced larval survival(p =0.002).From the IR values,it was determined that there was a subadditive effect on the survival for the treatments of acetamiprid + chlorpyrifos,acetamiprid + glyphosate,chlorpyrifos + glyphosate and three combinations.Also be exposured to three pesticides individually or in combination significantly reduced the body weight of new emerged workers(p < 0.0001).Of these,only acetamiprid + chlorpyrifos and chlorpyrifos + glyphosate had an additive effect.(4)The life span of newly emerged bees were exposed to the three pesticides or their mixtures for 10 days continuously was significantly reduced(p < 0.0001).There was an additive effect of acetamiprid + glyphosate and chlorpyrifos + glyphosate on the longevity of newly emerged honey bees.All three concentrations of acetamiprid significantly reduced the longevity of honey bees(p < 0.0001).;the three concentrations of chlorpyrifos significantly shortened longevity of honey bees(p < 0.0001);all three concentrations of glyphosate significantly shortened longevity of honey bees(p < 0.000).(5)Exposure of foragers to acetamiprid,chlorpyrifos and glyphosate alone or in combination for24 h affected the flight time(p < 0.0001),flight distance(p < 0.0001)and mean speed(p = 0.045)of bees.From the results,it can be seen that there is a synergistic effect of two-two combined exposure on the reduction of flying duration and flying distance,while when three are exposed at the same time,the effect on these two aspects is additive.Among the three concentrations of acetamiprid,40 and 330μg/kg significantly increased the flying duration and flying distance.Among the three concentrations of chlorpyrifos,40 and 320 μg/kg significantly decreased the flying duration and flying distance,and 320μg/kg significantly decreased the average velocity.Between the three concentrations of glyphosate,160μg/kg significantly increased the flying distance of honey bees,and 340 μg/kg significantly decreased the flying duration and flying distance of honey bees.From the overall results,some of the residual pesticides have a potential threat to the survival of honey bees.Therefore,the use of pesticides should be controlled during the special periods and the relevant authorities should supervise accordingly.The effects of exposures in combination of acetamiprid,chlorpyrifos and glyphosate on the larvae development,the survival of new emerged workers and forager’s flight ability of Apis mellifera L.appeared the subadditive or synergistic effects,i.e.,the toxicity of the three pesticides increased when in combination.This suggests that the simultaneous use of these three pesticides should be avoided during special periods.