Sublethal Effects Of SYP-9080 Applied On Plutella Xylostella (Lepidoptera: Yponomeutidae)

Plutella xylostella is one of the main pests to endanger cruciferous vegetables, is a worldwide pest. Plutella xylostella is distributed in every province and regions of our country, especially outbreak seriously In the Yangtze river basin and southern coastal areas, has caused a severe impact on vegetable production of China. For a long time, mainly through chemical control of Plutella xylostella, but due to the frequent heavy use of chemical pesticide, Plutella xylostella has developed strong resistance to all used and the most using pesticides. SYP-908 is a new type of damide pesticides, because of its unique insecticidal mechanism, SYP-908 had not developed resistance of interaction with other modes of action pesticides, and has good control effect on lepidoptera pests, therefore has a good application prospect. the different concentrations of SYP-908 effects on biology characteristics of plutella xylostella,and sublethal concentrations of SYP-908 has the impact of sensitive strain biological characteristics and detoxifying enzyme, and the influence of three synergistic agent and four SYP-908 on the prevention and cure effect of diamondback moth. The main results were as followed:?1? The different concentrations of SYP-908 have effects on living, emergence and pupation of Plutella xylostella. With increasing of the concentration and time, mortality rates increased significantly, pupation rate pupa weight and emergence rate decreased significantly, the mortality rate of CK was 2% after 48h,the mortality before pupation of the CK was 28%,the pupation rate was 72%,the emergence rate was 64% and pupa weight is 4.825 mg.when the lowest processed concentration is 0.00625 mg/L, the mortality rate of it was 6% after 48h,the mortality before pupation was 46%, the pupation rate was 54%, the emergence rate was 44%, the highest processed concentration of 0.8 mg/L, the mortality rate of it was 82% after 48 h, the mortality before pupation was 100%. This showed that with the increase of the concentration and time, SYP-908 would gradually strengthen the lethality of Plutella xylostella, and had a very strong consequent effect, also had a great influence of the pupa rate and eclosion rate, presents the obvious dose effect.?2? sublethal concentrations,LC₁₀ and LC₂₅ of SYP-908 have effects on biological characteristics of the parent and offspring plutella xylostella. After dealing sensitive populations of plutella xylostella,3rdinstar with LC₁₀ and LC₂₅ of SYP-908, its development period, survival rate were influenced,but adult longevity, fecundity and pupa weight were not affected.In summary, the influence plutella xylostella dealing with LC₂₅ was more obvious, plutella xylostella dealing with LC₂₅ extended 1.87 days compared to development period, adult survival rate decreased by 27.7%. LC₁₀ treatment group-development period shortened 0.43 days, adult survival rate decreased by 15.2%, compared with control group. After dealing sensitive populations of plutella xylostella,3rdinstar with LC₁₀ and LC₂₅ of SYP-908, it still had a certain influence to the offspring, but it was recovered in the offspring,compared with the dealing parental groups, the adult survival rate decreased by 6.0% offspring groups dealing with LC₂₅ compared with the control group, and it increased by 42.0% compared to the parental groups dealing with LC₂₅. The laying of single females decreased by 35.2, compared with the control groups, it increased by 17.7, compared with the parental groups dealing with LC₂₅. the adult survival rate decreased by 24% of offspring groups dealing with LC₁₀ compared with the control group, and it increased by 30.5%, compared to the parental groups dealing with LC₁₀. The laying of single females decreased by 39.0, compared with the control groups, it increased by 16.9, compared with the parental groups dealing with LC₁₀.The offspring intrinsic rate of increase, finite rate of increase, net reproduction rate of two treatments were inferior to control group after dealing sensitive populations of plutella xylostella,3rdinstar with LC₁₀ and LC₂₅ of SYP-908.especially the net reproduction rate decreased obviously, LC₁₀ and LC₂₅ group decreased by 8.73% and 8.16% compared with the control group respectively. The mean generation time extended 0.86 days and 0.79 days. It shows that the sublethal concentration of SYP-908 has a lethal effect on Plutella xylostella, so as to achieve the aim to inhibite plutella xylostella population development, but with the generations of plutella xylostella increasing, the influence will gradually weaken.?3? Synergism of 3 Synergists with SYP-9080 against DBM. To reduce the dosage of active ingredient, and raise use efficiency of diafenthiuron,toxicity ratio and synergistic ratio of synergists ?DEM, DEF and PBO? with diafenthiuron were determinated by leaf-dipping method. The results showed that DEM, TPP and PBO could raise toxicity ratio and synergistic ratio of diafenthiuron against DBM. While ratios of DEM, DEF and PBO with diafenthiuron were 1:5,1:3,1:4, toxicity ratios were 2.55,3.30 and 3.18, respectively. Synergisms of DEM, DEF and PBO with diafenthiuron increased to different extent, with synergistic ratios were 3.67,3.20 and 5.80, respectively.?4? The sublethal concentration of SYP-908 has effects on the plutella xylostella'detoxification enzyme system. Deal plutella xylostella 3rdinstar with LC₁₀ and LC₂₅ of SYP-908, respectively determine the activity of EST, GST and MFOs after 1,6,12,24,48 and 72 hours. Overall, the activity of the treatment group of EST was lower than the control group, the activity of LC₂₅ dealing group was lower than LC₁₀ dealing group, the activity of the treatment group of GST is higher than the control group, sublethal concentrations of SYP-908 has a certain inhibitory effect on the activity of EST and inductive effect of GST of plutella xylostella. For the MFOs, as the time went on, the activity of LC₁₀ and LC₂₅ was lower than the control group. And the group of LC₂₅ was obviously.On the whole, sublethal concentrations of LC₁₀ and LC₂₅ had showed inhibitory effect on plutella xylostella.