Synergistic efficacy of β-sitosterol on the growth inhibitory impacts of triflumuron on an indian strain of cotton boll worm, Helicoverpa armigera (Lepidoptera: Noctuidae).

The study investigated the synergism between a phytosterol, β-sitosterol (BS) and a chitin synthesis inhibitor, triflumuron (TFM) to manage Helicoverpa armigera larvae. Both dietary TFM and dietary BS imparted significant growth inhibitory effects on the larvae resulting in diminished growth and adult emergence; more pronounced effects were imparted by TFM-diet. Binary combinations of TFM and BS (1:1, 1:5 and 1:10) augmented the effects with respect to BS-diet, while only TFM + BS (1:1)-diet exerted higher efficacy than TFM-diet, indicating synergism when BS and TFM are in equal proportion. Compared to the BS-diet and TFM-diet, the combined diet reduced the IE30, IE50, and IE90 values by 0.048, 0.064, and 0.019-fold and by 0.51, 0.36, and 0.15-fold, respectively. Larvae reared on IE30 TFM + BS (1:1) gained just 54.37% weight until pupation, as against the those reared on TFM-diet (81.30%), BS-diet (140.83%), and control diet (216.44%). The larvae showed moulting disruptions, underdeveloped cuticle and declined survival. The TFM + BS (1:1) diet caused 30% adult emergence as against 94%, 70% and 48% with control, BS-diet and TFM-diet, respectively. This is the first report demonstrating the synergism between β-sitosterol and triflumuron for Helicoverpa management. [ABSTRACT FROM AUTHOR]

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