Feeding effects of chitosan on third and fifth instars of the Cotton bollworm, Helicoverpa armigera (Lep.; Noctuidae)

The Cotton bollworm, Helicoverpa armigera (Lep.; Noctuidae) is one of the most important and most economic pests of cotton. The species is a polyphagous pest and, because of high mobility, high viability under adverse conditions, being multivoltine and resistance to insecticides, it is very difficult to manage. In this study, nutritional effects of chitosan صere studied orally suing different doses of chitosan mixed with an artificial diet. The experiments were carried out under laboratory conditions at six dose rates of 0, 2.5, 4.0, 6.0, 8.0 and 10.0 g/kg of artificial diet. Larval mortality, and anti-growth and antifeedant effects were investigated. In this research, mortality of both third and fifth instars did not observe even by two-days feeding from dose rate of 10.0 g/kg of both chitosan. feeding of third and fifth instars of the Cotton bollworm from different dose rates of chitosan stimulated the growth and feeding of some larvae and inhibited the growth and feeding of some others in each replication. This shows that in dependence on dose rate and larval instar, effects of chitosan on third and fifth instars have been either as growth inhibition or stimulation, and either as feeding inhibition or stimulation. Growth and feeding stimulation of larvae of an insect due to feeding from chitosan is reproted for the first time. This would be led to the better understanding of factors affecting on chitosan efficacy and its effects on different aspects of insect biologies.