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Abstract Background Biological control of insect pests is an economic, eco-friendly and harmless approach to integrated pest management strategies. Bracon hebetor (Say) (Hymenoptera: Braconidae) considers a polyphagous ectoparasitoid of various pests of the order Lepidoptera. The parasitized host insects' defense mechanisms are triggered as a result of the parasitic wasps' injury and penetration. Thus, induce the host cellular and humoral immune responses through a blend of secretions injected into the host body. The present study was designed to evaluate the efficacy of B. hebetor on the immune response of the parasitized full grown larval instar of the rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) under natural envenomation. Results On cellular level, the ultrastructure examination of the hemocytes displayed a considerable structural deformation in hemocyte morphology of the detected types of the hemocytes. Moreover, the effects of parasitism on both differential hemocyte counts (DHCs) and total hemocyte counts (THCs) were investigated. The number of prohemocytes (PR) (40.33 ± 5.61, 43 ± 8.33 and 26 ± 2.31) was statistically differed after (24, 48 and 72 h) of parasitism, respectively, compared to unparasitized (31.33 ± 6.49) larvae. Similar observations were recorded in plasmatocytes (PL) before and after the parasitism. However, Spherulocytes (SP) and Oenocytoids (OE) were recorded in the hemolymph with little abundance. On the other side, the quantitative analysis of total hemolymph proteins (THP) provoked a significant effect of considering parasitized and non-parasitized larvae. As the Phenoloxidase (PO) cascade plays a critical role in immune defenses, so the substantial activation of PO in the host's hemolymph following successive hours of parasitism compared to unparasitized larvae using L-DOPA as a substrate indicated the induction of larval immune system. The parasitized larvae showed a gradual increase in the PO activity (0.442 ± 0.103) after 24 h reached up to (1.482 ± 0.272) at the end of parasitism (72 h) in comparable to unparasitized larvae (0.177 ± 0.0.044). Conclusion The present investigations clarified the efficacy of B. hebetor parasitism on the host immune mechanism, which will enable the progress of sustainable stored product protection approaches for the control of an important pest rice moth C. cephalonica.

Abstract Laboratory experiments were carried out to evaluate the acceptance of Trichogramma evanescens (Westwood) (Hymenoptera: Trichogrammatidae) to long and short cold storage periods of the host, the Angoumois grain moth, Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae) eggs. The eggs were stored at 5 °C for 5, 10, 15, 20, and 30 days, before exposing to the parasitoid. Fecundity, longevity, percentage of adult emergence, sex ratio, and general productivity (GP) were investigated. Storage period to 5 days showed the highest productivity of (28.16 females), with a parasitism efficiency of 85.64%. Increasing storage periods to 10, 15, and 20 days reduced the general productivity of the females to 22.90, 15.00, and 7.75 females, respectively, accompanied by decreased parasitization efficacy values 69.65, 46.62, and 23.57%, respectively. The 30-day storage period decreased sharply the fitness components of Trichogramma females. Generally, the results indicated that the storage period to 5 days was the most favorable.

Fourth instar larvae of cotton leafworm,Spodoptera littoralis(Boisd.), fed on castor bean leaves treated with sub-lethal concentrations of both alcohol and hexane extracts of Egyptian conyza and Challenger 36% SC insecticide as well to study their effects on mortality, food consumption and utilisation of food. The tested insecticides exhibited relatively high mortality in alcoholic extract of Egyptian conyza (5.0% concentration) followed by Challenger (1.0% concentration). Results showed a slight reduction in the consumption index for larvae treated with both alcoholic extract and Challenger at low concentrations, while hexane extract (5%) recorded significant increase. The approximate digestibility (AD) was reduced in all treatments of alcoholic extract and the relative growth rate insignificantly decreased at 5% concentration, whereas AD increased for larvae fed on Challenger 0.25% concentration. The lower concentration of alcoholic extract of conyza and all treatments of Challenger pesticides induced insignificant decrease in the efficiency of conversion of the ingested food, while hexane extract exhibited insignificant increase. Challenger at all tested concentrations achieved insignificant decrease in the efficiency of the conversion of digested food with respect to the control. [ABSTRACT FROM AUTHOR]