The effects of fenazaquin (a conventional acaricide), challenger (a natural product isolated from a fermentation culture of Streptomyces fummanus), abamectin (a natural product produced by the soil microorganisms Streptomyces avermiti/is) and azadirachtin (a natural product from neemplants), were evaluated against Tetranychus urticae infesting soybean, Glycine max, in Assiut Governorate during the summer seasons of 2005 and 2006. The side effects of these materials on T. urticae, associated predators, Euseius scutalis (a predatory mite) and Chrysoperia carnea (a predatory insect) were also evaluated.
The obtained data revealed that azadirachtin was the most potent compound introducing the population size of T. urticae after two seasons. The general mean reduction percentage was 89.31%, followed by abamectin and challenger (86.01 and 70.98% respectively). However, fenazaquin demonstrated low reduction percentages (60.57%). The tested biopesticids were successfully controlled the number of T. urticae pest, and they could arrange in descending order of azadirachtin > abamectin > challenger > fenazaquin.
Challenger and abamectin demonstrated an acceptable toxic effect on E. scutalis. The general mean reduction percentages were almost 36%. The side effect of the tested acaricides against the predatory mite, E. scutalis could be arranged in ascending order of abamechtin < challenger < azadirachtin < fenazaquin. The reduction percentages were 35.92, 35.99, 41.33 and 50.60%, respectively. The least toxic compound against C. carnea was abamectin, while the most toxic one was fenazaquin; they reduced the predator populations by 29.91 and 45.37% respectively. The general mean reduction percentages in both seasons could be arranged in ascending order of abamectin < azadirachtin < challenger < fenazaquin.
In conclusion, azadirachtin, and abamectin can be applied effectively against T. urticae with minimal impact on the non-target organisms, i.e. the phytoseiid mite E. scuta/is and the thysanopterous insect C. carnea. They may be classified as IPM-compatible acaricides in the integrated pest management programms against T. urticae infesting soybean.
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