Ecological and toxicological studies on thrips tabaci lindeman and associated spiders on onion plantations [electronic resource].

Includes reference.

Population fluctuation of Thrips tabaci Lind. and its associated spiders in onion plantations, as influenced by some weather factors, was studied at El-Riad district, Kafr EI-Sheikh Governorate, Egypt in two successive growing seasons 2008/09 and 2009/10. Toxicity of certain compounds; fenitrothion, etoxazole, super misrona, sour orange, acidless orange, baladi mandarin and Bermectine in reducing the population density of T. tabaci were evaluated. Also, the side effect of these compounds on spiders' population was assessed. The population density of T. tabaci and spiders peaked in March and April in both seasons. Surveyed spiders were found belong to seven families; Araneidae, Dictynidae, Lycosidae, Linyphiidae, Philodromidae, Theridiidae and Thomisidae. Temperature had highly significant positive correlation, while the spiders were highly significant negative for T. tabaci in 2008/09 season. Combined effect of spiders and weather factors on the density of thrips was high. All tested compounds under field conditions showed reduction of infestation of T. tabaci. For the residual effect, all tested compounds gave significant reduction of thrips infestation up to day 14th post treatment. Fenitrothion and Bermectine were the most effective, followed by etoxazole, sour orange, super misrona and then, acidless orange and baladi mandarin which induced the lowest reduction in thrips population. Concerning the side effect of these compounds on spiders; Bermectine and plant oil extracts (sour orange, acidless orange and baladi mandarin) had slight effects, whereas etoxazole and super misrona were moderate. Fenitrothion was the highly toxic compound against spiders.

Summary in Arabic.

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