Comparison of insecticidal activities of viral and bacterial chitinases; effect of chitinase on viral infectivity

The negative impact of the massive use of synthetic pesticides on the environment and on human health has stimulated the search for environment-friendly practices for controlling plant diseases and pests. Among them, microorganisms and their products come to the fore. Chitinases are important microbial products that can be used to control of harmful organisms.. Invertebrate iridescent virus 6 (IIV-6) is an insect virus that causes infection in some important pests. However, IIV6 is lowly infectious by oral ingestion. In this study, the insecticidal activities of viral and bacterial chitinases were compared and the contribution of chitinase protein to the oral infectivity of IIV6 was investigated. For this study, the chitinase encoding genes of Autographa californica nuleopolyhedrovirus (AcNPV) and Cydia pomonella granulovirus (CpGV) were expressed in pET-28a expression vector. The insecticidal effects of chitinase proteins of these two viruses and Serratia marcescens chitinase C protein, which was previously cloned, were evaluated on test insects Galleria mellonella. The next step whether the chitinase protein increased the oral infectivity of IIV6 was also investigated on Galleria mellonella. Results showed that CpGV chitinase protein caused the highest mortality effect on G. mellonella larvae. The chitinase from S. marcescens has relatively higher mortality effect than AcNPV chitinase. As well as, IIV6 implemented with chitinase, produced more insecticidal effect than the IIV6 tested alone. Key Words: Chitinase, İnvertebrate İridescent Virus 6 (IIV-6), İnsecticidal activite, Biological control