COMPARATIVE EFFICACY OF SALICYLIC ACID AND SOME SYSTEMIC INSECTICIDES AGAINST BEMISIA TABACI (GENN.), AND THEIR IMPACT ON COTTON DEFENSE RESPONSE

SA, flonicamid (FLO), imidacloprid (IMD) and thiamethoxam (THM) were evaluted for their efficacy against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) and its associated predators on cotton plants under field conditions during 2017 and 2018 seasons in Kafrelsheikh governorate, Egypt. Changes occurred in the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and polyphe-nol oxidase (PPO), and total protein content after application of the tested compounds were studied as well. IMD proved to be the most effective against adults and immature stages of B. tabaci followed by THM and FLO. SA at 1 mM was more potent than 2 mM, and both indicated a considerable efficacy against B. tabaci. FLO and SA were the most harmless to the associated predators, while IMD was the most harm-ful, Mixing of 1 mM SA with the tested insecticides enhanced their efficacy against B. tabaci and reduced their toxicity to the associated predators. FLO, THM, IMD and 1 mM SA inhibited the activity of CAT, POD and SOD and increased the total protein content of treated cotton plants compared to untreated ones, while 2 mM SA completely showed the opposite results. 2 mM SA, THM and IMD induced the activity of PPO. while FLO and 1 mM SA reduced its activity. Generally, adding 1 mM SA to the tested insecticides did not change their trend of effect on the enzymes activity and total protein content.