This study was conducted to compare the repellent effect and contact toxicity of eight essential oils (EOs), including Syzygium aromaticum, Allium sativum, Eucalyptus camaldulensis, Lavandula officinalis, Simmondsia chinensis, Matricaria chamomilla, Citrus limon, and Prunus dulcis, against adults of Tribolium castaneum Herbst. Four concentrations (1, 5, 10, and 15% in acetone solvent) of each EO were tested. The 5, 10, and 15% concentrations of S. aromaticum EO had a high repellency effect against T. castaneum compared with A. sativum, E. camaldulensis, L. officinalis, S. chinensis, M. chamomilla, C. limon, and P. dulcis after 30 min of exposure. The repellency test of the S. aromaticum, E. camaldulensis, L. officinalis, M. chamomilla, C. limon, and P. dulcis EOs on T. castaneum has shown that the mortality percentages enhanced with the increase in the EOs concentration and also with the exposure time. The 15% concentration of P. dulcis and M. chamomilla EOs have a significant impact on the mortality rate of T. castaneum compared with S. aromaticum, A. sativum, E. camaldulensis, L. officinalis, and S. chinensis after the 24 h of contact test. Moreover, the 15% concentration of the C. limon EO caused a greater mortality percentage compared with S. aromaticum, A. sativum, E. camaldulensis, and L. officinalis. It could be concluded that using the S. aromaticum EO as a repellent oil and using P. dulcis, M. chamomilla, and C. limon for contact toxicity to treat the flour infested by T. castaneum can play an important role in protecting stored grains and their products.

The rice weevil, Sitophilus oryzae (L.), is the most destructive insect pest of stored cereals worldwide. The current study was conducted to determine the lethal, reproductive, and histological effects of gamma irradiation on S. oryzae adults. In addition, the impact on germination, chlorophyll, and proline content in wheat seedlings from treated grains was determined. Wheat grains were infested with rice weevil adults and then irradiated by gamma rays. Gamma radiation was applied at a dosage of 0.10, 0.25, 0.50, and 1.00 kGy. Mortality percentage and LD₅₀ were recorded after 48, 72, 96, and 120 h of treatment. The dosage of 1.00 kGy caused 100% mortality after 96 h of irradiation. The required dosage of gamma radiation to kill 50% (LD₅₀) of adults after 48 h was 1.51 kGy. All tested doses caused complete sterility to 24 h old adults. A histological alteration was noticed at a dosage of 1.00 kGy, which showed cytoplasmic vacuolization, tissues exhibiting signs of putrefaction, and necrosis of cells; furthermore, gamma irradiation affected chlorophyll a and b. The highest amounts were detected in wheat seedlings from grains irradiated at 0.10 kGy. There was a significant increase in plant proline content at the higher doses (0.50 and 1.00 kGy) compared with seedlings from nonirradiated grains. It could be concluded that gamma radiation can be used as an eco-friendly trend to control stored-product pests without any residual effects.

The silverleaf whitefly (Bemisia tabaci) is one of the most harmful insects attacking several economic plant crops worldwide, and it has developed a resistance toward several conventional insecticides. This study was conducted to estimate the impact of potassium phosphite (PK), effective microorganisms (EMs), and salicylic acid (SA) as plant inducers, and imidacloprid (IMI) as a synthetic insecticide on the systemic acquired resistance of sweet pepper (Capsicum annuum var. annuum) crop, whitefly population, and crop yield under greenhouse conditions. The treatment plots were sprayed with IMI, PK, EMs, SA, and water (control) on the 27th day after planting, and dinotefuran was applied when the whitefly-infestation ratio reached 3.00%. The enzymes responsible for the internal defence system, whitefly population, and crop yield were determined. Our results confirmed the idea that the PK, EMs, and SA may induce the synthesis of plant enzymes responsible for the internal defence system. The IMI, PK, EMs, and SA significantly suppressed the whitefly population compared with the control. Moreover, the reduction percentages of the whitefly population were significantly higher when using IMI and PK than EMs and SA. The IMI, PK, EMs, and SA improved the crop yield. It could be concluded that PK, EMs, and SA enhanced the systemic acquired resistance in sweet pepper crop causing high defence against the population of whitefly and might be a potent alternative to conventional insecticides and compatible with an integrated pest management program.

The cotton leafworm, Spodoptera littoralis (Bosid.), is a major pest in African and Asian nations that attacks a wide variety of host plants. This study was conducted to assess the effectiveness of effective microorganisms (EMs) on the biological and physiological features of S. littoralis larvae. Five concentrations (100, 200, 300, 400, and 500 ppm) of EMs were tested. Antifeedant activity, food consumption index, the efficiency of converting digested food, the efficiency of converting ingested food, relative growth rate, and approximate body tissue of the fourth larval instar of S. littoralis were determined. Moreover, carbohydrate enzyme activities (amylase, trehalose, and invertase), total protein, and total lipids of S. littoralis larvae were measured to elucidate the mode of action of the tested agent in the S. littoralis’s larval stage. The EMs at 500 ppm had a substantial impact on antifeedant activity, nutritional indices, egg deposit reduction, and hatchability in S. littoralis during the five days. All concentrations interrupted S. littoralis’s life cycle and developmental phases. Furthermore, all concentrations were quite useful in lengthening the developmental stages of S. littoralis. In addition, Ems affected the biochemical activities of larvae, leading to disturbances in carbohydrate, lipid, and protein levels. From this study, EMs can be used as a bioinsecticide alternative to traditional insecticides against S. littoralis and may be compatible with integrated pest management approaches.