Cross-resistance And Mechanism Of Imidacloprid-resistance Strain Of Aphis Gossypii(Hemiptera:Aphididae)

In this study, the imidacloprid-resistance strain of Aphis gossypii was continuous selected in the laboratory after we found a mutation in nicotinic acetylcholine receptor (nAChR) β1subunit to clarify the development and stability of resistance to imidacloprid. And we studied the cross-resistance patterns to acetamiprid, nitenpyram, thiamethoxam, clothianidin, clothianidin, endosulfan, carbosulfan, lambda-cyhalothrin, omethoate, pymetrozine and related mechanisms in imidacloprid-resistance strain of Aphis gossypii. And the influence of imidacloprid, acetamiprid and clothianidin to the biological and biochemical characteristics of the Aphis gossypii were investigated. The results were as follows:1. The resistance strain of A. gossypii was continuously selected with imidacloprid from60-generation to75-generation by the leaf dipping method, the resistance ratio reached72.6-fold compared with the susceptible strain. When resistant-selection was suspended in the next successive12generations, the resistances of aphids just decreased to72.0-fold.2. Leaf dipping method was used to test the cross-resistance to the acetamiprid (20.1-fold), nitenpyram (16.0-fold), clothianidin (11.9-fold), thiamethoxam (14.5-fold), lambda-cyhalothrin (7.77-fold), carbosulfan (11.9-fold), omethoate (5.90-fold), pymetrozine (5.27-fold) and endosulfan (9.18-fold).3. The study of resistance mechanism indicated:mixed-functional oxidase inhibitor PBO, carboxylesterase inhibitor TPP and glutathione-S-transferase inhibitor DEM had no obvious synergism to the acetamiprid, nitenpyram, clothianidin, thiamethoxam, carbosulfan, omethoate and pymetrozine in the susceptible strain of aphid. But shower obvious synergism to lambda-cyhalothrin (1.62-fold,1.33-fold and1.28-fold respectively). But in the imidacloprid-resistance strain (RF75+12), PBO showed obvious synergism to these insecticides (>1.5-fold) except endosulfan; TPP showed certain synergism to these insecticides except pymetrozine and endosulfan; DEM show no obvious synergism to these insecticides but endosulfan (2.12-fold). And clothianidin showed obvious effects on CarE, AChE and GST of the imidacloprid-resistant cotton aphid, with the inhibition of62.6%、45.8%and16.1%. 4. In the study of effects to the biological characteristics of imidacloprid, acetamiprid and clothianidin at LC20does, clothianidin could suppress honeydew excretion and weight gain, with the inhibition of59.1%and75.7%in the imidacloprid-resistance strain of A. gossypii.