In Silico and In Vivo Evaluation of Synthesized SCP-2 Inhibiting Compounds on Life Table Parameters of Helicoverpa armigera (Hübner)

SIMPLE SUMMARY: Different crops and vegetables are attacked by a complex of pest insects causing severe losses in their yield and quality, among them Helicoverpa armigera is one of the key pests. Its polyphagous status and extended environmental tolerance, coupled with high fertility, fecundity rate and short generation time, enables it to quickly attain a primary pest status in any suitable host. To minimize losses caused by this notorious pest, multiple applications of chemical pesticides are required. Due to such indiscriminate use of synthetic insecticides, environmental and human health hazards have become a major concern of the modern-day plant protection industry. Novel scaffolds that may regulate insect growth can offer a sustainable alternative to conventional insecticides. In this study, synthesized small molecules, with a tendency to disrupt insect molting, were evaluated against a Helicoverpa armigera. One of the tested compounds significantly reduced larval and pupal weight accumulations and prolonged stadia lengths resulting in disrupted population growth. At the same time, the emerged females had significantly reduced fertility. These findings suggest that further optimization of tested scaffold may lead to help finding new insecticide-like molecules that will reduce the dependence on traditional chemical insecticides. ABSTRACT: For environment-friendly, safe and nonpersistent chemical control of a significant polyphagous insect pest, Helicoverpa armigera, discovery of growth-regulating xenobiotics can offer a sustainable alternative to conventional insecticides. For this purpose, chemically synthesized compounds to inhibit sterol carrier protein (SCP-2) function using in silico and in vivo assays were evaluated to estimate their impact on the survivals and lifetable indices of H. armigera. From nine chemically synthesized compounds, OA-02, OA-06 and OA-09 were selected for this study based on binding poses mimicking cholesterol, a natural substrate of sterol carrier protein and molecular dynamics simulations. In vivo bioassays revealed that all compounds significantly reduced the larval and pupal weight accumulations and stadia lengths. Subsequently, the pupal periods were prolonged upon treatment with higher doses of the selected compounds. Moreover, OA-09 significantly reduced pupation and adult emergence rates as well as the fertility of female moths; however, fecundity remained unaffected, in general. The life table parameters of H. armigera were significantly reduced when treated with OA-09 at higher doses. The population treated with 450 μM of OA-09 had the least net reproductive rates (Ro) and gross reproductive rate (GRR) compared to the control population. The same compound resulted in a declining survival during the early stages of development coupled with reduced larval and pupal durations, and fertility. These results have a significant implication for developing an effective and sustainable chemical treatment against H. armigera infestation.