Study On Biological Activities And Insecticidal Mechanism Of The Extracts From Several Plants On Adult Tribolium Confusum

In this experiment,syring oblate,Paeoniasuffruticosa,Kaempferia galangal,Piper nigrum,Piper nigrum,Zanthoxylum bungeanum,Polygonum hydropiper and Rosmarinus officinalis powder were tested against to Tribolium confusum,so as to filter the high-efficiency insecticidal plant;the effective plant powder was extracted with methanol,petroleum ether,ethyl acetate,acetone,and the extracts’ biological activities against to T.confusum were measured through drop method,airtight fumigation and residual film method;moreover,the practical control effect on T.confusum of Z.bungeanum extracts was researched,and the respective influences of extracts on GST and POD activities of T.confusum were assessed.Results are as follow:1 Selection of toxic effect on T.confusum of eight kinds of plant powderEight kinds of plant powder were mixed into wheat at the dose of 10 g/kg and 20 g/kg,and with the same amount of T.confusum adults in each treatment.The death number of T.confusum was checked and recorded after the treatment of 7 and 14 days.Result showed that: the toxic effect of Z.bungeanum powder was the strongest,and the toxic correction mortality rates at the treatment of 20 g/kg dose and 7,14 d were 42.53% and 66.67%respectively,significantly exceeded other seven kinds of plant powder.2 Effects of different organic solvents on the extraction of dried fruit of Z.bungeanumThe dried fruit of Z.bungeanum was extracted by methanol,petroleum ether,ethyl acetate and acetone,and the extract rates from big to small were: methanol(20.30%)>acetone(17.25%)> ethyl acetate(14.86%)> petroleum ether(12.05%).3 Four kinds of Z.bungeanum extracts to T.confusum in biological activities3.1 Contact activityThe Z.bungeanum extracts were diluted into five dosages of 0.25,0.50,1.00,2.00,4.00 mg/L by acetone,and the contact correction mortality rates of Z.bungeanum extracts against to T.confusum adults were assayed by drop method at the treatment of 24,48,72 and 96 h.With the maximal dosage of 4 mg/L and the treatment 96 h,contact correction mortality rates of methanol,ethyl acetate,petroleum ether and acetone were 77.78,87.78,48.89 and 68.89% respectively.The contact effect enhanced with the increase of treatment time,and the methanol,ethyl acetate Z.bungeanum extracts showed obvious dose effect.The LD50 of Z.bungeanum methanol,ethyl acetate,petroleum ether and acetone extracts to T.confusum were 1.20,0.64,3.31 and 1.93 mg/L.The ethyl acetate extract effect was the best on T.confusum and the petroleum ether extract was the weakest.3.2 Fumigant activityThe Z.bungeanum extracts were designed into1.25,2.50,5.00,10.00,20.00 mg/L dose,and the fumigant correction mortality rates of Z.bungeanum extracts against to T.confusum adults were assayed by airtight fumigation method at the treatment of 24,48,72 and 96 h.Result showed: four kinds of Z.bungeanum extracts had lethal effect on T.confusum,and with the maximal dose of 20 mg/L and the treatment 96 h,the fumigant correction mortality rates of methanol,ethyl acetate,petroleum ether and acetone were83.33,93.33,63.33 and75.56 % respectively.The fumigant effect enhanced with the increase of treatment dose and time.The LD50 of Z.bungeanum extracts at 96 h were 3.82,2.38,10.78 and 6.35 mg/L respectively.3.3 Repellent activityThe repellent activities of Z.bungeanum extracts to T.confusum adults were tested by residual film method with the dose of 9.84,19.67,39.32,78.64,and 157.28 μg/cm2.The repellent effect enhanced with the increased of the concentration of Z.bungeanum extracts.With the maximal dose of 157.28 μg/cm2,the average repellent rates of methanol,ethyl acetate,petroleum ether,acetone were 67.41%,75.08%,47.74%,67.41%,and the repellent grade were Ⅳ,Ⅳ,Ⅲ and Ⅲ level respectively.The repellent effect on T.confusum adults from big to small was: ethyl acetate extract > methanol extract> acetone extract > petroleum ether extract.4 The effects of four kinds of Z.bungeanum extract on enzymes activities in T.confusum adults4.1 Dose effectT.confusum adults were treated by drop method with the extracts dose of 0.25,0.50,1.00,2.00,4.00 mg/L,and the activity changes of GSTs,PODs in T.confusum adults were determined at 36 h.Inhibitory effects on GSTs in T.confusum adults of four kinds of Z.bungeanum extracts were tested.With the treatment of 0.25 mg/L dose and 36 h,the inhibitory effects of ethyl acetate and methanol extracts were obvious.With the increase of treatment dose,the inhibitory effects of four kinds of Z.bungeanum extracts enhanced.The inhibition rate on insect’ GSTs activity of ethyl acetate extract was the biggest,and with the treatment dose of 4 mg/L,the inhibition rate was 56.3%;followed by methanol extract,the inhibition rate was 42.2%.The inhibition effects on PODs activity increased with the increase of the extracts treatment concentration.The inhibition effects of petroleum ether extract and acetoneextract were not so obvious at the treatment dose of 0.25 mg/L.With the treatment dose increased,the inhibition effects of four extracts showed significant difference;at the treatment dose of 4mg/L,the inhibition effects of ethyl acetate,methanol,acetone and petroleum ether extracts were 49.2,39.8,22.8 and 31.3% respectively.4.2 Time effectT.confusum adults were treated at the dose of LD50 of four kinds of Z.bungeanum extracts,and activity changes of GSTs and PODs in T.confusum adults were determined on12,24,36,48,60,72 h.Four kinds of Z.bungeanum extract showed inhibition effects on insect’ GSTs.The inhibition effects on GSTs of methanol,ethyl acetate and petroleum ether extracts enhanced with the treatment time increased during 12 ~ 48 h;the inhibition effects decreased and GSTs activities recovered during 48 ~ 60 h;the GSTs activities declined after treatment time of 60 h.Methanol,ethyl acetate extracts showed the highest inhibition effects on GSTs both at the treatment time of 48 h,petroleum ether and acetone extracts were at 60 h and 72 h respectively.The extracts except methanol extract showed certain induction effects on insects’ PODs and PODs activities increased during the treatment time from 12 h to 24 h;after the treatment time of 24 h,four kinds of Z.bungeanum extracts showed inhibition effects on test insects’ PODs,and the inhibition effects enhanced with time going.The methanol extract showed inhibition effects on insects’ PODs all the time.The PODs activities of the tested insects remained stable after treatment time of 48 h.5 Control effect of Z.bungeanum extracts on T.confusum in simulated warehouseSame amount of four kinds of Z.bungeanum extracts diluted with 10 mL of acetone were mixed into 500 g of wheat,and all the treatments were arranged in simulated warehouse with adequate T.confusum adults.The population number of T.confusum were investigated and recorded after the treatment time of 30,60,90 days.Results showed that all of the extracts showed obvious control effects on T.confusum in 60 d,and the control efficiency of ethyl acetate extract was the highest,30,60,90 d average efficiency was85.76%,significantly exceeded other three kinds of Z.bungeanum extracts.