The control of storage insect pests is largely based on synthetic pesticides. However, due to fast growing resistance in the targeted insects, negative impact on humans and non-target organisms as well as the environment, there is an urgent need to search some safer alternatives of these xenobiotics. Many essential oils (EOs) and their bioactive compounds have received particular attention for application as botanical pesticides, since they exhibited high insecticidal efficacy, diverse mode of action, and favourable safety profiles on mammalian system as well as to the non-target organisms. Data collected from scientific articles show that these EOs and their bioactive compounds exhibited insecticidal activity via fumigant, contact, repellent, antifeedant, ovicidal, oviposition deterrent and larvicidal activity, and by inhibiting/altering important neurotransmitters such as acetylcholine esterase (AChE) and octopamine or neurotransmitter inhibitor γ-amino butyric acid (GABA), as well as by altering the enzymatic [superoxide dismutase (SOD), catalase (CAT), peroxidases (POx), glutathione-S-transferase (GST) and glutathione reductase (GR)] and non-enzymatic [glutathione (GSH)] antioxidant defence systems. However, in spite of promising pesticidal efficacy against storage pests, the practical application of EOs and their bioactive compounds in real food systems remain rather limited because of their high volatility, poor water solubility and susceptibility towards degradation. Nanoencapsulation/nanoemulsion of EOs is currently considered as a promising tool that improved water solubility, enhanced bio-efficacy, stability and controlled release, thereby expanding their applicability.

Pest insects causing damage to cultivable crops and food products by feeding, fecundity, and parasitizing livestock, also being a nuisance to human health. In consideration with human health, the World Health Organization reports that more than 50% of the world’s population is presently at risk from mosquito-borne diseases. Mosquitoes are primary vectors for major dreadful diseases such as yellow fever, malaria, and dengue fever, which infect millions of human beings all over the world and kill millions of peoples every year. The present research work was carried out to evaluate the antifeedant, larvicidal, pupicidal, larval, and pupal duration activity of Leonotis nepetifolia–mediated silver nanoparticles (AgNPs) against Spodoptera litura, Helicoverpa armigera, Aedes aegypti, and Culex quinquefasciatus. Biosynthesized AgNPs were characterized through various techniques such as UV–Vis spectrometer, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. The AgNPs showed potential antifeedant activity of 78.77% and 82.16% against the larvae of S. litura and H. armigera, respectively. The maximum larval mortality rate (78.49% and 72.70%) and maximum pupal mortality rate (84.66% and 77.44%) were observed against S. litura and H. armigera. Mosquito larvae were tested with biosynthesized AgNPs, and recorded LC₅₀ values were 47.44 ppm and 35.48 ppm on A. aegypti and C. quinquefasciatus, respectively. The histological examinations showed that the acceleration of the nanomaterial caused severe tissue damage in the epithelial and goblet cells in the larval midgut region of S. litura, H. armigera, A. aegypti, and C. quinquefasciatus. Biosynthesis of silver nanoparticles using L. nepetifolia is an ideal eco-friendly approach for the management of insect pests. Graphical abstract

Many commercially available agro and household chemicals are used as pesticides, repellents, and growth inhibitors against insect pests. The repeated uses of these chemicals against insect pests have caused the development of resistance in them; they also cause ill effects on nontarget organisms. The present study was aimed to evaluate the antifeedant, larvicidal, pupicidal, and biochemical effects of the solvent extracts of Solanum xanthocarpum against third instar larvae of Helicoverpa armigera. Hexane, chloroform and ethyl acetate extracts were subjected to phytochemical analysis. The results revealed the presence of terpenoids, flavonoid, and quinone. Maximum antifeedant activity of 72.30% was recorded in chloroform extract followed by hexane (69.02%) and ethyl acetate (57.40%) extracts against H. armigera. Chloroform extracts of S. xanthocarpum showed more than 60% larvicidal and pupicidal activity against H. armigera. The effective chloroform extract was fractionated with increasing polarity of solvent system (hexane, chloroform, and ethyl acetate extracts). Based on the TLC profile, nine major fractions were isolated. The fourth fraction showed higher antifeedant, larvicidal, and pupicidal activity against H. armigera. The effective fraction reduced the hemolymph and gut protein concentration in a concentration-dependent manner (r ² 0.99). The effective fraction 4 showed 100% larvicidal activity at 500 ppm concentration with LC₅₀ value of 227.95 ppm. The fourth fraction did not show any toxic symptom or mortality of earthworm. Based on these results, this effective fraction could be used in the development of a pesticide formulation to control insect.