| Phyllotreta striolata is one serious pest of cruciferous vegetables and is more difficult to prevent and control in southern China.The special planting model of vegetable in the southern region has accelerated the reproduction of flea beetle.Insecticide application is still the main control measure to control the density of P.striolata and ensure the quality and yield of vegetable production before the emergence of more effective and effective environmental protection measures.In this paper,the author starts with the above-ground adults and underground larvae combining with the damage characteristics of the striped flea-beetle,to search for chemical pesticides that can effectively prevent and control the flea beetle by laboratory bioassay and field trials,and the safety range and protective effect of four seed coating for Brassica campestris L.ssp.chinensis var.utilis Tsen et Lee are also tested.The result is as follows:1.The laboratory toxicity of ten common chemical insecticides that against the flea beetle adults are determined by leaf-leaching feeding.The results showed that Chlorfenapyr,Tolfenpyrad,Emamectin benzoate and Dinotefuran have better toxicity against the adults of the flea beetle after 48 h treatment.The LC50 is 148.21 mg/L,138.35 mg/L,125.53 mg/L and138.68 mg/L and 68.70 mg/L respectively.The results of toxicity evaluation of different combinations of pesticides to Phyllotreta striolata adults showed,the cotoxicity coefficient is131.66 and the LC50 is 57.95% when the dosage ratio of Dinotefuran to Chlorfenapyr is 1: 9,When the mass ratio of the active ingredient of Tolfenpyrad to Dinotefuran is 7:3 and 8:2,the cotoxicity coefficients is151.91 and 132.29,and the LC50 is 92.87 mg/L and 111.08 mg/L,respectively.2.The investigation results of field test of flea beetle adults of 9 pesticides showed that10% Chlorfenapyr suspension(SC),30% Tolfenpyrad suspension(SC)and 20% Dinotefuran soluble granules(SG)for P.striolata control effect of adult is good.,when the active ingredients of the pesticides is 112.5 g(ai)/hm2,202.5 g(ai)/hm2 and 270.0 g(ai)/hm2,and 1 d after application.The control effects is 76.1%,82.89% and 81.35%,respectively,which is significantly higher than the control.3.The field control effects of different combinations of the above-mentioned three medicaments against other medicaments on the flea beetle are compared.The results showed that when the 30% Tolfenamide suspension(SC)is mixed with 20% Dinotefurin-soluble granules(SG)at the active ingredients ratios of 7:3(132.3 g(a.i.)/hm2),8:2(124.95 g(a.i.)/hm2)and 9:1(118.35 g(a.i.)/hm2),the control effect on P.striolata is better.The control effects are ranged from 84.92% to 86.80% after 1 d insecticide application and ranged from86.23% to 91.33% after 3 d pesticides treatment.and ranged from 76.39% to80.89% after 7 d insecticides treatment.Synergistic effects are also observed after application when the 20%Dinotefurin(SG)and the 10% Chlorfenapyr(SC)are mixed in 1:9 118.35g(a.i.)/hm2,2:8 124.95g(a.i.)/hm2 and 3:7 132.3 g(a.i.)/hm2,they have a good control effect on the adults of flea beetle.The control effect of 1 d is 84.01%~85.78% and 3 d is 84.93%~87.62%.4.The safety of four seed treatments on Brassica campestris L.ssp seeds show that 40%Cyantraniliprole·Thiamethoxam flowable concentrate for seed treatment(FS),600g/L Imidacloprid(FS),18% Thiamethoxam(FS)and 44% Imidacloprid·Fipronil(FS)have no difference in seed germination rate of 2 d,germination rate 5 d and germination rate 10 d,plant height and raw weight with contrast,and have no influence in seed germination and growing security in active ingredient rate lower at 5120 g(a.i.)/100 kg seed,9600 g(a.i.)/100 kg seed,2880 g(a.i.)/100 kg seed,7040 g(a.i.)/100 kg seed.5.The safety and protection of four kinds of seed coating on the field of Brassica campestris L.ssp are studied.The results showed that four kinds of seed treatment agents have some protective effects on the Chinese cabbage after 5 days of emergence,the protection of40% bromothiazide.Suspension and 44% imidacloprid suspension seed coating is significant.When the Concentrate of 40% Cyantraniliprole·Thiamethoxam flowable concentrate for seed treatment(FS)between 750 and 3000 g(a.i.)/100 kg seed and 44% Imidacloprid·Fipronil(FS)in 3000 g(a.i.)/100 kg seed,the plant height and fresh weight of the Chinese cabbage growing for 25 days is significantly increased.The 600g/L Imidacloprid(FS)seed coating and the 18%Thiamethoxam(FS)concentrate between 750-3000 g(a.i.)/100 kg seeds,the plant height and fresh weight of Chinese cabbage growing for 25 days are not significantly different from the control.Under four kinds of seed treatment agents,the damage index of Chinese cabbage after25 days of emergence is almost similar to the control,and the protection is bad.It shows that four kinds of seed treatment agent can protect the early emergence period of Brassica campestris L.ssp,and the latter protection should combine with other methods. |
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