| Eocanthecona furcellata(Wolff)is one of the most important predatory natural enemies of the lepidoptera pests,which has a broad application prospect in the biological control of Spodoptera litura(F.).In the production process,Tobacco pests insecticide lead to a certain extent limitation for the popularization and application of E.furcellata.For understanding the influence of tobacco pests insecticides towards the survival rate as well as the predatory function of E.furcellata,and figuring out the application possibility of the united treatment by using both E furcellata and biopesticides,topical application were carried out under the laboratory condition for evaluating the controlling effects of 2 kinds of biopesticides and 5 kinds of commonly used pesticides towards the the survival rate as well as the predation function of E.furcellata.Moreover,the safety of these pesticides were estimated by the evaluation indicators including the survival rate and the functional response of E.furcellata..And on this basis,the controlling effect of the Spodoptera litura multiple nucleopolyhedrovirus towards the S.litura population on the tobacco was also determined with the help of the life table method,aiming to provide the basis for the biological control of tobacco S.litura.The main results are illustrated as follows:1.The influences of different pesticides towards the survival of E.furcellataEgg-immersion method and topical application were carried out under the laboratory condition for evaluating the effects of 2 kinds of biological reagents(including bacillus thuringiensis and Spodoptera litura multiple nucleopolyhedrovirus)and 5 kinds of commonly used pesticides(including the tebufenozide,the chlorfenapyr,the emamectin benzoate,the chlorantraniliprole and the beta-cypermethrin)towards the the survival rate ofE.furcellata.The results indicated that both two biopesticides treated groups show a hatchability of 91.08 % and 89.45 %,respectively,which has no significant difference with that of control group(91.30 %).Similarly,the survival rates of both two biopesticides treated groups under high dose treatment(10 000 mg/L)are as high as 100 % and 98 %,respectively,and these results also show no significant difference with that of control group,revealing that the tested biopesticides have no significant influence on the survival of E.furcellata.For the 5 pesticides,the high dose treated groups(10 000 mg/L)exhibited a hatchability of 91.00 %,88.49,83.51 %,80.17 % and 5.12 %,respectively.Meanwhile,the survival rates of the groups under low dose treatment(1 250 mg/L)were 70 %,97 %,91 %,99 % and 33 %,respectively.The lowest survival rate under high dose treatment(10 000mg/L)in these groups was 1 % and 4 %,in which discovered in beta-cypermethrin treated and emamectin benzoate treated group,respectively.Hence,it can be concluded that the toxicity of beta-cypermethrin would significantly affect the E.furcellata,which should be inhibited during the period of field releasing.2.The influences of different pesticides towards the predation of E.furcellataThe influence of different pesticide towards the predation of the E.furcellata were investigated under the recommended dose.The predation response of biopesticides(the bacillus thuringiensis and the Spodoptera litura multiple nucleopolyhedrovirus)treated E.furcellata towards the 3rd larva of S.litura was studied.It was found that the structure of predation function response model was not changed under both two treatments.Within a certain range of prey,the predation amount of both treatments increased with the increase of predation density.However,when the prey density increased to a certain limitation,the increasing rate of the predation amounts of E.furcellata slowed down and presented a negative acceleration curve.As for the Spodoptera litura multiple nucleopolyhedrovirus treated,the bacillus thuringiensis treated and the non-treated groups,the instantaneous attack rates were 1.1666,1.379 and 1.1882,respectively.And the predation ability were93.33,66.94 and 110.2 while their daily maximum prey capacity were 80,48.54 and 92.59,respectively.The effect of bacillus thuringiensis treatment on the predation of E.furcellata was higher than that of Spodoptera litura multiple nucleopolyhedrovirus treatment.Simultaneously,the predatory functions of the chemical pesticides(including tebufenozide,chlorfenapyr,emamectin benzoate,chlorantraniliprole)treated E.furcellata towards the S.litura on the tobacco were also measured.The results showed that under chemical treatment,the structure of feeding function response model of E.furcellata to the the 3rd larva of S.litura did not change significantly,but the feeding function parameters of E.furcellata to the prey changed significantly.Under the treatment of insecticides tebufenozide,chlorfenapyr,emamectin benzoate,chlorantraniliprole and control,the instantaneous attack rate of the E.furcellata on S.litura was 1.119,1.2263,1.1635,1.1466 and 1.1882,respectively.the predation ability were 98.84,98.90,53.87,86.86 and 92.59 respectively.Their daily maximum prey capacity were 84.75,80.65,46.30,75.76 and 110.02 respectively.Among them,emamectin benzoate has the greatest influence on the E.furcellata,which is reflected in the decrease of instantaneous attack rate by 2.07 % and the prolongation of predation duratio by 100 %.In addition,their daily maximum prey capacity of E.furcellata under the condition of different prey density under different pesticides was measured.The results showed that under the condition of the same prey density,the predation amount of E.furcellata in the control group was the largest,and the predation amount of E.furcellata in the treatment with emamectin benzoate was significantly lower than that in the control group(p < 0.05).Based on the above results,it can be seen that the safety of emamectin benzoate is relatively low for E.furcellata,and the safer predations for E.furcellata include bacillus thuringiensis,Spodoptera litura multiple nucleopolyhedrovirus tebufenozide,chlorfenapyr and chlorantraniliprole.3.The control effect of the united application of the Spodoptera litura multiple nucleopolyhedrovirus-E.furcellata towards the S.litura population on the tobaccoThe life table method was used to evaluate the control effect of the united application of the Spodoptera litura multiple nucleopolyhedrovirus-E.furcellata towards the S.litura population on the tobacco.It is found that the S.litura population trend indexes of the control,the Spodoptera litura multiple nucleopolyhedrovirus treated,the E.furcellata treated and the united treated S.litura groups were 6.208,2.990,1.063 and 0.851,respectively.The interference indexes of population control(IIPC)of the Spodoptera lituramultiple nucleopolyhedrovirus treated,the E.furcellata treated and the united treated S.litura groups were 0.482,0.171 and 0.173,corresponding to the control effects of 51.8 %,82.9 % and 86.3 %,respectively.These above results indicated that the control effects of the E.furcellata is better than that of Spodoptera litura multiple nucleopolyhedrovirus,and the Spodoptera litura multiple nucleopolyhedrovirus-E.furcellata united application possesses the best effects. |
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