Dissertation > Agricultural Sciences > Plant Protection > Pest and Disease Control > Crop pests and diseases and their prevention > Economic crop pests and diseases > Fiber crop pests and diseases > Cotton pests and diseases > Insect pest > Pink bollworm

Resistance Selection and Sublethal Effects of Emamectin Benzoate in Cotton Bollworm, Helicoverpa Armigera (H(?)bner)

Author DongLiXia
Tutor ZuoChangHui
School Chinese Academy of Agricultural Sciences
Course Pesticides
Keywords Emamectin benzoate Bollworm Resistance selection Detoxification enzymes Sublethal effects
CLC S435.622.3
Type Master's thesis
Year 2011
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Bollworm Helicoverpa armigera (Hübner) Lepidoptera, Noctuidae, is a worldwide agricultural pests. At present, the cotton bollworm has organochlorine, organophosphate, carbamate and pyrethroid pesticide produce different degrees of resistance. Emamectin benzoate (abbreviation: emamectin benzoate) is a macrolide antibiotic insecticide miticide, bollworm and other lepidopteran pests have good control effect. Insecticides applied to the field, in addition to the direct killing effect on insects, but also there sublethal effects and drug resistance risk. 1 emamectin benzoate bollworm resistance and cross-resistance heritability To assess the cotton bollworm emamectin benzoate resistance risk, indoors bollworm resistance to the drug selection education and realized heritability estimates. Continuous use of emamectin benzoate against bollworm breeding 25 generations, with homologous control population (CP) compared to acquired resistance multiples of 2.974 times the selected population (RP25). Threshold traits analysis methods used to obtain the cotton bollworm resistance to emamectin benzoate realized heritability (h2) is 0.05218. Further predict its resistance to growth rate, assuming an 90% mortality rate subculture processing bollworm, its resistance to 5-fold, 10-fold, respectively, 18.67-and 26.71-generation needs. Determination of cross-resistance found for emamectin benzoate reduced sensitivity 2.974 times selected population of avermectin also reduces the sensitivity of 3.962 times the initial judgment avermectin and emamectin cross resistance exists. 2 emamectin benzoate sublethal doses of different sensitivities bollworm detoxification enzyme activities indoors emamectin bollworm breeding 20 generations, to obtain 2.32-fold reduced susceptibility to selected population (RP20). Emamectin benzoate were used for homologous control population (CP) and RP20 sub-lethal concentration LC25 handle two groups corresponding to the beginning of the third instar larvae of 48 h, measured test insects in three different age age age 1-6 period carboxylesterase ( CarE) and glutathione-S-transferase (GST) activity analysis activity changes dynamically. The results showed that (1) two species (CP and RP20) increased with age growth, CarE specific activity increased significantly, while the GST specific activity decreased first and then stabilized. (2) CK treatments, RP20 compared with CP, CarE specific activity in the 3 to 6 age were increased and the 4-6 age difference was significant, but small changes in GST specific activity, only three and 6th instar increased significantly. (3) Compared with CK treatment, emamectin benzoate LC25 treatment, two species each age CarE specific activity were increased, and the CP test insects in the fourth instar, age 6 GST specific activity increased significantly in the three age, age 5 No significant differences in the RP20's 3rd instar larvae GST specific activity was significantly inhibited in the four age 4-6 age GST specific activity did not change. Preliminary judgment, emamectin benzoate bollworm reduced susceptibility increases with CarE specific activity related; emamectin sublethal doses of bollworm CarE activity induced by a certain. 3 emamectin sublethal doses of the biological characteristics of cotton bollworm and the life table in order to study the formation of emamectin benzoate against bollworm sublethal effects, indoors with emamectin benzoate LC25 subculture treatment of CP early third instar larvae of 10 generations, get Sub10. Comparative analysis of two groups (CP and Sub10) and between various groups of different treatments (emamectin benzoate LC25 and CK) between the biological characteristics, life table parameters. The results showed that emamectin benzoate LC25 compared with CK treatment, and CK treatments Sub10 compared with CP, bollworms are expressed as growth delay, pupation rate, emergence rate, fecundity and egg hatchability, adult Volume winged rate. Emamectin benzoate LC25 treatment on the Population adverse sexual reproduction exists. Emamectin benzoate LC25 treatment to reduce populations of net reproductive rate, intrinsic rate of increase and finite rate, extending the average generation time and population doubling time, and significantly affected the CP on the Sub10 only intrinsic rate and mean generation time was significant. CK treatment, the two species population life table parameters no difference. Description emamectin sublethal doses of bollworm populations exist growth, reproduction and adversely affected and affected by this pest in contact with the pharmaceutical algebra increases.

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