A sublethal concentration of chitosan oligosaccharide suppresses the population growth of the wheat aphid, Rhopalosiphum padi (Linnaeus)

The bird cherry-oat aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is a key pest of wheat in China. Chitosan oligosaccharide (COS) has been widely used due to its biocompatibility, antibacterial activity, environmental friendliness and convenient extraction. This study was aimed at determining the acute toxicity of COS on R. padi and transgenerational effects of sublethal concentrations of COS on the biological characteristics of R. padi. The results indicated that COS possessed acute toxicity against R. padi after 48 h of exposure (LC50: 1227.35 mg/L). The sublethal concentration of COS (LC15: 260 mg/L) induced a decrease in adult longevity, adult prereproductive period and fecundity in the first filial generation (F-1). Moreover, in F-1 progeny, nymphal (1st-3rd), preadult and total prereproductive period significantly enhanced due to sublethal dose. Moreover, finite rate of increase (?), the intrinsic rate of increase (r) and net reproductive rate (R-0) of F-1 progeny were significantly decreased, whereas a sublethal COS concentration exposure significantly increased the mean generation time (T) of F-1 progeny. Overall, the study shows that sublethal concentration of COS can significantly suppress population growth of R. padi F-1 generation, showing the potential of COS as a biorational option to manage aphids.