Interaction Between The Defense Of Cotton And The Anti-defense Of Bemisia Tabaci (Gennadius)

Induced effects of exogenous signal stimulus to defensive signal substance MeJA, secondarymetatolites quercetin and protease inhibitor in cotton plant as well as the anti-defense from pest were initially probed in this paper.Key points are as the following:1.The induced effects are quite different in the expressive time and quantity of MeJA in cotton leaves between treatments of Bemisia tabaci sucking and MeJA exogenous spraying. The maximum amount of MeJA is 171.27μg/g after 18h in the treatment of Bemisia tabaci sucking,whereas the maximum amount of MeJA is 115.19μg/g after 24h in the treatment of MeJA exogenous spraying.There are big differences existed between the two treatments as well in the inducting of quercetin and protease inhibitor.The induced effect from the treatment of Bemisia tabaci sucking is faster than the treatment of MeJA exogenous spraying, since the effect was inhibited firstly and then was induced in later.The quantities of quercetin by the treatment of Bemisia tabaci sucking and MeJA exogenous spraying are similar,the amounts are 2.09mg/g and 2.21mg/g,respectively,whereas the quantity of protease inhibitor is more in the treatment of Bemisia tabaci sucking than the treatment of MeJA exogenous spraying,the amounts are 1.85 units and 1.05 units,respectively.2.In the study of the induced effects to carboxylesterase in Bemisia tabaci from the treatment of MeJA exogenous spraying on cotton leaves,quercetin and protease inhibitor in artificial breeding of Bemisia tabaci,the results suggested that among of 0.005%～1% concentration,the specific activities of carboxylesterase are induced to raise by both treatments of quercetin and protease inhibitor,and the dosage effects trend are similar in both treatments.The secondary metabolites in cotton leaves were induced after MeJA exogenous spraying,then Bemisia tabaci ingested the secondary metabolites,and the specific activity of carboxylesterase was induced to express.The specific activity of carboxylesterase was inhibited after 1 day sucking of Bemisia tabaci,then was induced to increase after the treatment of 2,3,4 days,and the expressive amount increased along with the time extension within the tested period.3.In the study of the resistance of Bemisia tabaci to natural pyrethrin after ingesting of leaves from the treatment of MeJA exogenous spraying,results suggested that,the resistance of Bemisia tabaci declined obviously after 1 day's sucking,the resistance factors are 0.15 and 0.18 at 24h and 48h,respectively.Results indicated that the secondary metabolites induced by MeJA exogenous spraying poisoned Bemisia tabaci rapidly and effectively.However,the resistance of Bemisia tabaci increased gradually after 3 day's sucking,the resistance factors are 0.33 and 0.43 at 24h and 48h,respectively.Results indicated that the detoxification of Bemisia tabaci was induced,and following the adaptability mechanism built up,the resistance to insecticide recovered gradually.