Effect of New Bio-component of Cytoplasmic Polyhedrosis Virus (Cypovirus1) with Silver Nanoparticles against Four Pests in Stored Food Products

Abstract

This study was conducted to develop an approach for reducing severe damage to grains caused by various insect pests using the biological control agent Cypovirus1 and silver nanoparticles, both alone and in combination. Four types of beetles that infest stored products, including drugstore beetle (Stegobium paniceum), saw-toothed grain beetle (Oryzaephilus surinamensis), warehouse beetle (Trogoderma variabile), and Cowpea weevil (Callosobruchus maculates), were collected from seven different areas in the Kingdom of Saudi Arabia, specifically Mecca regions. We determined the morphological characteristics of the pests in various grains. Corn borer pupae and larvae of corn plants infected with Cypovirus1 were collected from the stems of live and dead maize plants in fields in Mecca regions to isolate Cypovirus1. Infected samples were examined using triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELIZA) and reverse transcription-polymerase chain reaction (RT-PCR). Transmission electron microscopy (TEM) analysis revealed virus-containing occlusion bodies inside infected cells of corn borer larvae with irregular shapes and dimensions of 2.2–4.9 µm. The effects of different concentrations of the virus activated by synthetic spherical silver nanoparticles with an average diameter of 36.32 nm on the larva of grain pests taken were evaluated, and all treatments led to an increased mortality percentage after 72 h compared to at 48 h. The treatment mixture consisting of 10/100 viral and 400 µg/kg AgNPs led to the highest average death rates of the four insect larvae at 72 h after treatment. Protein bands that were present in the virus-infected larvae of the four pests were absent from healthy larvae, indicating viral infection.