Efficiency of Some Chemical and Bio-Insecticides Against Onion Thrips, Thrips Tabaci Lindeman (Thysanoptera: Thripidae)

Onion thrips, Thrips tabaci (Thysanoptera: Thripidae) is one of the main problems and yields limiting factors in the onion fields (Allium cepa L.). In the present work, an effort was made to study the relative susceptibility of different onion cultivars to infestation with the onion thrips, evaluation of some chemical and bio-insecticides against T. tabaci and to study the effect of meteorological factors on its population density. The results showed that T. tabaci infest all the tested cultivars more or less, however cultivar Red Giza showed to be the most tolerant against T. tabaci infestation among the other cultivars. Giza 6 was the most susceptible among the cultivars followed by Beheri, Giza 20 and finally White Giza. However, there were no significant different among the White Giza and Red Giza cultivars.The tested insecticides can be arranged according to their efficacyagainst nymphs of T. tabaci in descending order as follows; spinetoram, pyridalyl,imidacloprid, thiamethoxam, lambda-cyhalothrin, dinotefuran, pyriproxyfen, malathion, azadirachtin and finally Beauvaria bassiana. On the other hand, these insecticides can be arranged according to the general means of reduction percentages of T. tabaci adults in a descending order as follows; pyridalyl, spinetoram, thiamethoxam, imidacloprid, lambda-cyhalothrin, dinotefuran, pyriproxyfen, malathion, Beauvaria bassiana and azadirachtin.The results of the population trends of T. tabaci revealed that the onion thrips had two generations during the onion growing period. There was a significantly negative correlation (P˂0.05) between population density of onion thrips and relative humidity. The results also revealed that the temperature positively and significantly affect T. tabaci population in both seasons2020 and 2021.