Combined usage of microbials with neonicotinoides to combat spider mite resurgence in hybrid roses

The purpose of this research is to develop a biointensive pest management system for thrips, Scirtothrips dorsalis and spider mite, Tetranychus urticacae resurgence, by incorporating microbial pesticides (Spinosad; Emamectin Benzoate, Beauveria bassiana) with neonicotinoides (Imidacloprid, and Acetamiprid) on hybrid roses. There were total 13 treatments with three replicates each. During experimental year, 2009-2010 total seven sprays were done at „l 45 days interval. Imidacloprid (drench and spray) and acetamiprid gave significant thrips control throughout the year. In Spinosad treatment thrips number begins to decrease after fourth spray, though, spinosad + imidacloprid 0.5x and spinosad + acetamiprid 0.5x treatments were as effective as imidacloprid. Emamectin benzoate and B. bassiana alone or in combination with neonicotinoides were moderately effective for thrip control however; Emamectin caused highest mortality in spider mites among all the treatments. Imidacloprid and acetamiprid were proved non-toxic for mites. Imidacloprid drench treatments (15„b1.8) gave significantly more number of mites than control (10„b1.1) at 11DAT (days after treatment). Spinosad (1„b2.4) alone and with combination to neonicotinoides provided significantly less number of mites than control at 11DAT. These bioassay results showed that if imidacloprid0.5x and acetamiprid0.5x were combined with Spinosad even at half the labeled rate (x), they provided significant control of thrips as well as spider mites. In addition, glutathione reductase activity was also checked in imidacloprid treated plants and found that up to 5 days after insecticidal treatment it increases and than it becomes constant. However, these observations need further research to make any conclusions.