Preparation and performance of insect virus microcapsules

Abstract

Background: Biological pesticides, especially baculovirus, often lose their activity under the influence of external light, temperature, and other changes. This limited the application of them. The present study was aimed to prolong the biological activity and ensure the efficacy of a biological pesticide using microencapsulation technology. Results: In this study, gelatin/carboxymethylcellulose (CMC)-Spodoptera litura nucleopolyhedrovirus microcapsules were prepared. The morphological characteristics, apparent morphology, embedding rate, virus loading, particle size, laboratory virulence, and UV resistance of the microencapsulated virus, were tested. The best conditions for preparing gelatin /CMC-S. litura nucleopolyhedrovirus microcapsules include the gelatin/CMC ratio of 9:1, wall material concentration of 1%, core material/wall ration ratio of 1:2, re-condensation pH of 4.67, and curing time of 1 h. The prepared microcapsules of S. litura nucleopolyhedrovirus exhibited a good external appearance and spherical shapes with an average particle size of 13 μm, an embedding rate of 62.53%, and a drug loading of 43.87%. The virulence test showed that the microencapsulated virus lost by 2.21 times of its initial activity than the untreated virus. After being treated with field exposure, the gelatin/CMC shell of the microcapsule can better protect the virus in the wild environment. Conclusion: Microencapsulation improves the tolerance of S. litura nuclear polyhedrosis virus to ultraviolet radiation. These results will provide ideas for the research of stable and efficient baculovirus preparations and further promote the application and promotion of environmental friendly biological pesticides.