Studies On The Controlling Effect Of Tea Saponin Against Ectropis Obliqua

Ectropis obliqua,as one of the main destructive tea insect pests,is harmful to tea planting?centralized occur?difficult to be prevented and cured.The main method of prevention and cure at this stage is chemical control,which is easily lead to environmental pollution and humans and animals poisoning.This thesis research the botanical activity to E.obliqua by using tea saponin solution as botanical insecticides.We used tea saponin solution to determine the biological activity of the 3rd instar larvaes of Ectropis obliqua by using leaf disc medicine feeding method:the toxicity with the 30%tea saponin solution on 3rd instar larvaes had been measured,and determined the effect on some kinds of enzymes of E,obliqua 3rd instar larvaes in the body;explored the effect of 30%tea saponin solution on the natural predatory spiders of E.obliqua;the field trial was been tested.The results were as follows:1.The study on an artificial diet of Ectropis obliqua:consisted of tea powder,yearst powder,Vitamins,sucrose and agar,can support development of E.obliqua.Compared with those fed on natural diet(the tea tender tip),the female ratio was 0.42?egg hatching percentage was 90.50%?pupation rate wsa 94.67%and emergence rate was 94.54%,there were no significant difference with the 0.43?92.00%?90.52%and 91.20%(P>0.05),but the lifetime of adult moth was 6.40d,per pupal weight was 111.66mg and the number of egg laying was 263.3 per female,were highly significant higher than artificial diet which was 5.83d?100.48mg?223.0(P<0.01).Life parameters kept stable.2.The indoor toxicity determination of 30%tea saponin solution against larvae of Ectropis obliqua and spiders:the provided solution showed toxic action on 3rd instar larvaes,after taking solution treated blades,the activity of insect had been reduced and their stings had no obvious reaction,the whole body getting strinking and turning black and finally died.The effect became obvious as time goes by.The corrected mortality rose up to 74.08%after 96h dealed with 30%tea saponin solution.The repellent effect of residual insecticides to Ebrechtella tricuspidata and Evarcha paralbaria shows that:there were repellent effect to Ebrechtella tricuspidata than CK(P=0.003),but the repellent effect of 30%tea saponin solution on Ebrechtella tricuspidata was highly lower than 50%diafenthiuron EC(1500x×)?2.5%bifenthin emulsifiable EC(1500×)(P<0.01),and no repellent effect toEvarcha paralbaria(P=0.69).3.The control efficiency of 30%tea saponin solution against Ectropis obliqua in field and the effect on spiders in tea garden:after having taking field efficacy trails in the plot with 20m2,by setting 50%diafenthiuron EC(1500×)and 2.5%bifenthrin emulsifiable EC(750×)as chemicals control and water as the control check,showed that the field control effect of 30%tea saponin against E.obliqua increased as time went by,and reached its highest at 5th day,with its relative control effect was 77.95%,with significant difference between the 50%diafenthiuron EC(1500×)and 2.5%bifenthrin emulsifiable EC(750×)concentrates.The spider's quantily and species in the 30%tea saponin sparying area were no difference than the CK,significant higher than those of the spraying chemical insecticide area,the number of spiders was 14,including Araneidae sp.?Thomisidae sp.?Salticidae sp.?Theridiidae sp.?Lepthyphantes sp.?Clubionidae sp.?Agelenidae sp..No direct influence of 30%tea saponin on the number and distribution of the spiders in tea garden.4.The effect of tea saponin solution on the target enzyme?detoxifying enzyme and protective enzyme in the 3rd instar larvaes of Ectropis obliqua:after being fed by different concentration of tea saponin,the change in activities of GSTsn AChE?CarE?POD in the body of the 3rd instar larva of E.obliqua were determined,indicated that:30%tea saponin solution revealed dose effect on the activity of GSTs,and induced the activity of GSTs when the concentration are low,when reached to a0020certain concentration,the activity of GSTs had been reduced as time goes by,150mg/mL tea saponin water solution has high inducement rate was 92.94%to GSTs on 24h,and the inhibition rate to GSTs was 4.71%on 96h,and the inducement rate of 300mg/mL tea saponin water solution to GSTs was 88.23%on 12h,the inhibition rate reached 16.15%on 96h.Revealed dose effect and inhibitory activity on the activity of AChE,the highest inhibition rate was 37.83%by 75mg/mL tea saponin water solution to AChE on 48h.Showed inhibitory activity on the activity of CarE and the highest inhibition rate was 39.84%by 300mg/mL tea saponin water solution to AChE on 48h.No evident effect of tea saponin solution on POD.