Insecticidal efficacy of pithraj (Aphanamixis polystachya) leaf and seed powders against Tribolium castaneum larvae in treated wheat

Abstract Background The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is recognized as one of the most prevalent and destructive pests infesting stored grain products. A wide range of studies has explored the use of various plant powders for their potential to manage infestations of T. castaneum and other storage pests. In response to growing concerns over the safety and environmental impact of synthetic insecticides, researchers have increasingly turned their attention to botanical alternatives. In this context, the present study investigates the insecticidal potential of leaf and seed powders derived from pithraj (Aphanamixis polystachya), a medicinally important plant, against the larval stage of T. castaneum under laboratory conditions. Results For the experiment, larvae of different ages (1, 3, and 5 days old) were exposed to varying doses (1.25–20 mg/g) of treated wheat (Kanchan and Pradip varieties), and their developmental parameters were monitored. Treatments significantly reduced pupal and adult recoveries in a dose-dependent manner, with seed powders exhibiting stronger inhibitory effects than leaf powders. The highest dose (20 mg/g) of seed powder caused complete inhibition of pupation in 1- and 3-day-old larvae. Both powders also significantly prolonged larval and pupal developmental periods and induced deformities in pupae and adults, particularly at higher doses and in younger larvae. Factorial ANOVA confirmed significant interactions among larval age, dose, and wheat variety. The inhibition rate (IR) was calculated to quantify reductions in pupal and adult emergence. The seed powder was more potent in inhibiting the formation of pupae and adult emergence, and lengthening the developmental period. Conclusion These findings demonstrate that A. polystachya powders possess strong insecticidal and growth-disrupting properties, highlighting their potential as eco-friendly alternatives to synthetic insecticides for the management of storage pests like T. castaneum.