Mosquito control is the most common health problem facing many poor developing countries especially the transmitted diseases by mosquitoes (Deepak et al. 2019). Mosquitoes transmit many pathogens which cause dangerous diseases like Zika virus, filariasis, Japanese encephalitis, chikungunya, yellow fever, dengue, and malaria; that pose a real danger not only to human health (Santhosh et al. 2015; Vinoth et al. 2019) but also, extend their impact on the economy worldwide (Abutaha et al. 2018). Culex pipiens L. (Diptera: Culicidae) is one of the most common species in Egypt which causes many human diseases (Kady et al. 2008). Cx. pipiens is the vector of Wuchereria bancrofti, Bancroftian filariasis up to 100 million persons every year (Sayed et al. 2018), Rift Valley fever (Abdel-Hamid et al. 2009). Bancroftian filariasis is one of the fastest spreading insect-borne diseases for men in the tropics (Badawy et al. 2015).

The effect of six plant essential oils against three stored grain insects, Sitophilus oryzae, Rhizopertha dominica and Tribolium castaneum were studied under laboratory conditions. The tested oils are namely, fennel oil (Foeniculum vulgare), caraway oil (Carum carvi), cinnamon oil (Cinnamomum verum), citronella oil (Cymbopogon winterianus), nutmeg oil (Myristica fragrans) and black cumin oil (Nigella sativa). The result showed that increasing of the oil concentration and exposure times significantly increased the mortality percentage.Generally, the toxicity of essential oils at all tested concentrations increased with the increasing of exposure time. So, the results indicated that toxicity of all tested essential oil against the three stored grain insects at the high concentration was recorded high mortality faster than low concentration.The tested essential oils significantly decreased the different haemocyte counts in tested insects, cinnamon oil markedly increased the haemocyte surface areas in the tested insects especially the surface area of oenocytoides in T. castaneum.The recorded results indicate that the essential oils of fennel, caraway, cinnamon and citronella could be applicable to the management of S. oryzae, R. dominica and T. castaneum adults.

The present study investigates the effect of AgNPs on some biological parameters and total protein amount, antioxidant potential and catalase activity of silkworm Bombyx mori. Incorporation of AgNPs (100 μg mL-1) in supplementary diets results in significant increases in the larval weight and the antioxidant potential but significantly decreases the catalase activity. The relative growth rate decreases as the high concentration (1000 μg mL-1). Exposure to AgNPs also caused violent results in alteration of haemocyte including an immediate increase in THC, may due to the release of these haemocytes either from an increase in cell divisions or from attached haemocyte populations, and decline in the percentage of prohaemocytes and increase in the percentage of two immune-phagocytes, i.e., granulocytes and plasmatocytes. Also, AgNPs at 100 and 1000 μg mL-1 caused different levels of deformations on almost all haemocyte types and increased the antioxidant enzyme activity (catalase) in the haemolymph of treated larvae as a result of the toxic effects of treatment.

The efficacy of the bio-insecticide, Bacillus thuringiensis var. israelensis (Bti), and four plant-ethanol extracts Cinnamomum osmophloeum, Matricaria chamomilla, Seasamum indicum, and Nigella sativa was tested against larvae of filarial vector, Culex quinquefasciatus, under laboratory conditions. The Bti and extracts of N. sativa and C. osmophloeum showed the highest insecticidal activity, with LC 50 values of 7.18, 14.59, and 28.87 mg/l 24 and 48 h post treatments, respectively. The extracts of M. chamomilla and S. indicum were effective. The tested extracts altered some biological aspects of Cx. quinquefasciatus, i.e., developmental periods, pupation rate, and adult emergence. Pupation rate was suppressed by Bti at 7.5 mg/l and by C. osmophloeum at 75 mg/l. In addition, the tested plant extracts exhibited various morphological abnormalities of larvae, pupae, and adults.

The expanded uses of zinc oxide nanoparticles (ZnO-NPs) have grown rapidly in the field of nanotechnology. Thus, the increased production of nanoparticles (NPs) increases the potential risks to the environment and occupationally exposed humans. Hence, safety and toxicity assessment including genotoxicity of these NPs is indispensable. In the present study, we have evaluated the genotoxic effect of ZnO-NPs on 5th larval instar of Bombyx mori after feeding on mulberry leaves treated with ZnO-NPs at concentrations 50 and 100 μg/ml. Moreover, we evaluated its effects on total and different hemocyte count, antioxidant potential and catalase activity on the hemolymph of treated larvae. Results showed that ZnO-NPs at concentrations of 50 and 100 µg/ml have significantly decreased the total hemocyte count (THC) and different hemocyte count (DHC) except the number of oenocytes as they were significantly increased. Gene expression profile also showed up-regulation of GST, CNDP2 and CE genes suggesting increase in antioxidant activity and alteration in cell viability as well as cell signaling.