Despite being successful in preventing pests from entering stored goods, residual synthetic pesticides have had a negative impact on the environment. However, the prohibitive cost of synthetic pesticides and the risk of target pests developing insecticide resistance have prompted researchers to develop alternative management strategies. Since plant-based pesticides are biodegradable and less dangerous for organisms other than the target species, they are a useful alternative to chemical pesticides. The aim of the present study was to investigate the effectiveness of plant extract in preventing the rice weevil Sitophilus oryzae (Linnaeous) (Coloptera: Curcolinidae) from infesting stored-products. For toxicity and synergism against S. oryzae, aqueous extracts of Cannabis sative L., Dodonaea visicosa L., and Parthenium hysterophorus L., were evaluated at different concentrations. D. viscosa and P. hysterophorus extract concentrations were 0.25, 0.5, 1.0, 2.0, and 3.0%, and C. sativa extract concentrations were 0.62, 1.25, 2.5, 5.0, and 7.5%. A completely random design with three replications was used, with distilled water serving as the control. The experimental setting was kept at 27± 2oC and 65±5% R.H. The findings showed that D. visicosa, P. hysterophorus, and C. sativa caused 97%, 90%, and 83% of mortalities at the highest doses, respectively. At highest concentrations, the mortalities found for binary combinations of D. viscosa and P. hysterophorus, D. viscosa and C. sativa, and P. hysterophorus and C. sativa, respectively, were 80%, 77%, and 70%. When used in combination, the effects of D. visicosa, P. hysterophorus, and C. sative produce 100% mortalities, indicating synergism. In single applications for all treatments, plant extracts were the most toxic. However, when used in combination, S. oryzae is completely killed. Phytochemical screening test all the compounds were detected but saponins and coumarins were higher in D. visicosa and P. hysterophorus. As a result, mixing plant extract greatly increases the effectiveness of reducing S. oryzae in storage facilities. Smallscale farmers may benefit from the study's findings since they may offer them a grain storage approach that is both practical and affordable.

The red flour beetle (Tribolium castaneum Herbst), a major pest of stored grains in tropical and subtropical regions, causes significant economic losses in several agricultural storage items. This research investigates the use of aqueous plant extracts and synthetic insecticide (deltamethrin) for the sustainable and safe management of the red flour beetle. Aqueous extracts from five plant species – Alpinia galanga, Azadirachta indica, Curcuma longa, Nicotiana tabacum, and Nicotiana rustica – were evaluated at six different concentrations (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0%) along with deltamethrin against T. castaneum. Toxicity (both contact and residual) was assessed after 24, 48, 72, and 96 hours using a completely randomized design with four replications. Probit analysis was carried out to determine LC50 and LC90 values. Results revealed that, generally, the mortality of T. castaneum increased as the concentration and exposure time increased. Deltamethrin exhibited the highest contact toxicity overall, with an LC50 of 0.88 ppm and LC90 of 4.74 ppm, and the highest residual toxicity showed the lowest LC50 (0.93 ppm) and LC90 (3.83 mol/L) after a 96 h exposure period. Among the plant species extracts in contact toxicity, N. rustica showed the highest toxicity with an LC50 of 1.00 g/L and LC90 of 5.38 g/L, followed by N. tabacum (LC50 of 1.09 g/L and LC90 of 6.50 g/L). In residual toxicity tests, among the plant species, N. rustica again had the highest toxicity in residual tests with an LC50 of 0.79 g/L and LC90 of 10.37 g/L, followed by N. tabacum (LC50 of 1.18 g/L and LC90 of 9.02 g/L) and A. indica (LC50 of 1.82 g/L and LC90 of 22.36 g/L). The findings suggest that deltamethrin is recommended for managing T. castaneum; however, N. rustica, N. tabacum, and A. indica can effectively control T. castaneum and may be useful in developing novel biopesticides.