A comparative bioefficacy of seed and root extracts of a medicinal plant, Withania somnifera when administered to prepupae of lepidopteran insects, Spodoptera litura (Lepidoptera: Noctuidae) and Pericallia ricini (Lepidoptera: Arctiidae)

Abstract Background The lepidopterans, Spodoptera litura and Pericallia ricini, are polyphagous pests of agricultural importance. The unscrupulous and non-judicious use of chemical pesticides for controlling the insect pests has resulted into severe environmental hazards, threatening non-target organisms and human health. Results Administration of seed and root extracts of a medicinal plant, Ashwagandha (Withania somnifera) to prepupae of two economically important insect pests viz. S. litura and P. ricini resulted into disruption of molting and metamorphosis leading to a number of developmental aberrations such as prolongation of the life span of prepupae, postponement of pupal-adult ecdysis, ecdysial failure, reduced pupation and adult emergence, formation of larval-pupal and pupal-adult intermediates, abnormal pupae, and adultoids. Treatment with seed extracts of W. somnifera was more effective as it alone caused mortality in both the lepidopteran insects viz. S. litura and P. ricini, whereas no such effect was observed when treated with root extracts. P. ricini was more susceptible to W. somnifera as it resulted into formation of larval-pupal-adult chimeras in addition to effects described earlier, whereas this effect was not observed in the case of S. litura. Conclusion These results are similar to these produced by the administration of JHAs and hence mimic their action by the way of interfering with the neuroendocrine system.