Effects Of Two Biological Pesticides On The Biological Activities And Metabolic Enzymes Of Sitotroga Cerealella And Sitophilus Oryzae

Sitophilus oryzae(Linnaeus)and Sitotroga cerealella(Olivier)are important stored-product insects,causing serious damage to food,including a large amount of postharvest losses and quality degradation.The use of chemical pesticides is currently limited by environmental safety and pest resistance.It is great significance to develop green,safe and efficient biogenic pesticides in controlling stored-product insects.In this study,the filter paper membrance method was used to determine the contact activity of spinetoram and osthole on important storage pests such as S.oryzae and S.cerealella.Toxic activity of S.oryzae and S.cerealella,according to the results of virulence determination,study the changes of different treatment doses and time on the activity of two stored-product insects metabolic enzyme systems,in order to explore the test The biochemical mechanism of insecticidal effect;the main research results are as follows:1 The contact effect of two pesticides on stored-product insectsFive treatment doses of 5.66,11.32,22.64,45.28,and 90.56?g/cm2 were set respectively,and the contact activity of the two pesticides against rice weevil adults and S.cerealella larvae was determined using insecticide-impregnated filter method.The results showed that:The larvae have a strong contact effect.With the increase of the treatment dose,the corrected mortality of the pests also gradually increased,and the contact effect was significantly enhanced.The longer the treatment time,the better the contact effect.After the contact time was extended from 24 h to 72 h,the corrected mortality rate of osthole was increased from 56%to 70%,and the effect of spinetoram was increased from 66%to 74%The control effect of spinetoram is slightly higher than that of osthole.The two pesticides have a very strong contact effect on adult rice weevil.With the increase of treatment time and dose,the corrected mortality rate gradually increases.The high dose treatment for 24 h to 72 h increased the effect of osthole from 68%to 79%The control effect of spinetoram on S.oryzaes increased from 74%to 87%.The virulence regression analysis results showed that after 72 hours of treatment,the LD50 of osthole and spinetoram against S.cerealella larvae were 31.17 and 26.85 ?g/cm2,respectively;the LD50 of the two pesticides against adult S.oryzae was 22.95,18.13 ?g/cm2,showing that the two biological pesticides have a strong contact effect on S.oryzae adults and S.cerealella larvae.2 Toxic effects of two pesticides on stored-product insectsFive treatment doses of 0.25,0.5,1,2,and 4 mg/kg were designed respectively,and the toxic effect of osthole and spinetoram on S.oryzae adults and S.cerealella larvae was determined by the grain mixing method.It has a strong toxic effect on S.oryzae and S.cerealella,and the toxic effect of the two agents is significantly enhanced with the increase of the treatment dose.After treatment with 4 mg/kg for 15 days,the corrected mortality rates of osthole and spinetoram for S.cerealella larvae were 82%and 89%;the corrected mortality rates for adult rice weevil reached 100%.The effect of spinetoram on two test insects is stronger than that of osthole.The LD50 of osthole and spinetoram treated with S.cerealella larvae after 15 days were 1.05 and 0.78 mg/kg,respectively,and the LD50 after treatment with adult rice weevil was 15 days after 0.19 and 0.17 mg/kg,respectively.S.cerealella and S.oryzae have strong toxic effects.3 The effect of two biological pesticides on the metabolic enzyme activities of two stored-product insects3.1 Dose effect of two agents on metabolic enzymes in two stored-product insectsTreated with 0.25,0.5,1,2,4 mg/kg spinetoram and Osthole mixed grains respectively,the AChE,GST and CarE activities of S.oryzae adults and S.cerealella larvae were measured at 24 h The change.The results showed that:(1)spinetoram showed a strong promotion effect on AChE activity in S.cerealella and S.oryzae;it showed a dose effect on the GST and CarE activities in the two test insects.The higher the treatment dose,the more inhibited the enzyme activity strong.(2)Osthole showed inhibitory effects on AChE and GST in the two test insects;after low-dose treatment,it promoted the activity of Miele CarE and had no significant effect on the activity of CarE of S.cerealella effect.3.2 Time effects of two pesticides on metabolic enzymes in two stored grain pestsThe LD50 doses of the two pesticides were used to treat S.oryzae and S.cerealella larvae.The activity of AChE,GST and CarE was detected at 12,24,36,48,60 and 72 h.It promotes the test insect AChE,and then shows an inhibitory effect and becomes stronger.At 72 h,both pesticides had the highest inhibitory effect on the test insects AChE;spinetoram 48 h had the greatest inhibition on the GST activity of the two test insects;72 h had the highest inhibition on the CarE activity of the two test insects;osthole 60 h The inhibitory effect on GST and CarE of the two test insects was the highest.