Alexandra Ahmed

BackgroundMass rearing cost of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is one of the critical methods for the successful utilization of Baculovirus pathogenicity and sterile insect technique (SIT). Effectiveness of both SIT and S. littoralis Nucleopolyhedrosis Virus ( Spli NPV) was assessed in response to plant-based diet and substitution of agar with commercial sources of gelling components as feed.
Results
Pupal and adult recoveries produced by castor bean leaves were significantly high, followed by the agar-based diet. Moreover, larval durations were significantly prolonged for (starch + gelatin)-based diet than the other dietary diets. Obviously, Spli NPV pathogenicity against the larvae reared on (starch + gelatin)-based diet was 2.5 and 2 times higher than those reared on castor leaves and agar-based diet, respectively. Contrary to expectation, the sterility doses of male moths produced by castor leaves and agar-based diet were relatively similar.
Conclusion
The findings suggest that the lowest cost diets (starch + gelatin)-based diet could be used effectively for increasing the Spli NPV pathogenicity, while either castor leaves or agar-based diet could be considered as a promising choice for SIT program.

A Green nanomaterial synthesis could be considered as an alternative bio-controller source of insect pest management as well as saving the environment. Gamma irradiation-induced silver nanoparticles (AgNPs) synthesis in an aqueous solution of irradiated polyvinyl pyrrolidone, (PVP) at ambient conditions was performed. A homogenous mixture solution consisting of (1 mmol Ag+) ions and irradiated (1% PVP) was subject to gamma rays of Co-60 at dose of 20 kGy. Concurrently, the radiolysis of water by γ-rays produced (H2, ehy and H·,OH·) that act as reducing agents and initiators for Ag0 production and PVP polymerization, respectively. The new absorption band observed at 420 nm is confirmed the formation (Ag/PVP) nanoparticles. The color of (AgNO3/PVP) solution converts from colorless to yellowish emphasizing the formation of (Ag/PVP) nanoparticles. The obtained results from X-ray diffraction (XRD) confirmed the coexistence of Ag nanoparticles and PVP matrix. The presence of PVP influenced the shape and distribution of the uniformly dispersed Ag/PVP nanoparticles with diameter 30 ± 5 nm. Bioassay of Ag/PVP nanoparticle on Spodoptera littoralis larvae indicated that the high concentration (600 ppm) of Ag/PVP nanoparticle gave only 11.5% mortality. The interaction between S. littoralis Nucleopolyhedrosis (SpliMNPV) and Ag/PVP nanoparticle had negative correlation to be considered as antagonism. Our finding indicated that the larvicidal activity of Ag/PVP nanoparticle was too low to consider as insecticide against S. littoralis. In the present study, the novelty is reduction of SpliMNPV pathogenicity as well as increased the virus degradation in response to UV irradiation is assisted by Ag/PVP nanoparticle.

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