Efficacy Of Systemic Insecticides Against The Green Plant Bug And Controlling Technique In The Transgenic Bt Cotton Field

Since1990s, the area-wide application of transgenic BT cotton in China has effectivelycontrolled the cotton bollworm Helicoverpa armigera (Hübner) with resulting in thereduction in the amount of broad-spectrum insecticides used in cotton production. Thisdecreased use of insecticides has caused the mirids to be major pest insects on BT cotton inChina. The mirids have a wide host range, and can spread to cottons, grapes, jujube, etc.Because it lacks effective natural enemies controlling green plant bugs in cotton fields, andthe prevention and control of green plant bugs is still in the initial stage, it mainly relies onchemical control in present. Because A. lucorum is highly hiding and mobile, it results in thatspraying insecticides can not play a direct contact action to them. It need spray pesticidesmore than10times in heavily infested areas. While many pesticides used in cotton fields killnatural enemies, they cause a potential harm to the environment and human health. In thispaper, using systemic insecticides at the root of hydroponic cottons determined the stomachtoxicity and holding effect of eleven kinds of pesticides to green plant bugs in order to acquiresome insecticides being highly effective to A. lucorum. Two kinds of the insecticide-applyingway, seed coating and granules broadcasting, in cotton fields, compared control effects ofthree insecticides, imidacloprid, carbofuran and fipronil to green plant bugs. Seed coating,granules broadcasting and spraying on cotton, combining with planting mungbean asattractive crops, compared influences of different applying ways of imidacloprid to populationdynamics of A. lucorum. Using residue analysis methods analysed persistent dynamics ofimidacloprid in cotton leaves with seed coating and granules broadcasting. Main resultsshowed as follows:1Determining eleven kinds of systemic insecticides through the special systemic actionfrom plant roots with water culture cotton method, the results showed that imidacloprid hadthe highest correct mortality to green plant bugs. It had the best persistence and quicknessdetermined by water culture cotton method. Following insecticides were clothianidin,thiamethoxam, carbofuran and methomyl of which the persistence and quickness were betterthan the rest. Control effects of imidacloprid in1mg/L and10mg/L were bad to A. lucorum.The persistence and quickness of imidacloprid in100mg/L to green plant bugs was the best.2Applying seed dressings and granules of imidacloprid, carbofuran and fipronil on cotton, there was no influence to the emergence rate of cotton seedling and no difference withthe control group. Imidacloprid had the best control effect to A. lucorum in these threeinsecticides.3Seed coating, granules broadcasting, spraying on cotton, combining with mungbean astrapping bands, it compared the influence to population dynamics of green plant bugs withdifferent applying ways of imidacloprid. The results showed that the sequence of controleffects of different applying ways to A. lucorum was the granules broadcasting, seed coating,spraying and control. The amount of active ingredient of imidacloprid granules was1.5kg/hm~2, of which the persistence was up to110days. The amount of active ingredient ofimidacloprid seed dressings was0.675kg/hm~2, of which the persistence was up to90days.4Persistent dynamics of imidacloprid in cotton was examined with different applications,namely seed coating and granules broadcasting, respectively. Along with the time going afterapplying imidacloprid by seed coating and granules broadcasting, the persistent amount ofimidacloprid slowly decreased in cotton leaves. There was some imidacloprid in cotton leavesby every applying way in80days after sowing. This result showed that, imidacloprid could beabsorbed from the cotton root and persistently conducted to the top leaves of cotton.