Potentiality of Novel Chitosan-O-Arginine as Insecticidal and Growth Inhibitory Compound against Diamondback Moth, Plutella xylostella L. on Cauliflower

摘要

Chitosan (Cs), a natural biodegradable polysaccharide polymer, prepared from sea waste of crustacean origin, has the potential for plant protection application. In the present study, a novel chitosan derivative, called Chitosan-O-Arginine, synthesized from crude chitosan, was evaluated for its chronic toxicity against second instar larvae of Plutella xylostella by leaf dip method. The results revealed the toxic potential of Chitosan-O-Arginine, which could inflict cent per cent mortality after four days of continuous feeding on the 1000 ppm treated leaf, and the larva could accomplish 0.12 mg weight (99.66 reduction) on the day before death. The next lower concentration (700 ppm) resulted in the maximum larval weight of 0.45 mg (93.71 reduction) after nine days of feeding and resulted in cent per cent mortality after the tenth day. While the untreated larva attained a maximum weight of 5.54 mg. All the larvae were pupated in the next lower concentration (500 ppm) and recorded minimum pupal (1.00 mg; 80 reduction) and adult (0.73 mg; 77.45 reduction) weight, whereas the untreated pupa and adult weighed the maximum of 5.00 mg and 3.20 mg. Considering the developmental period, there was no significant difference in the larval duration and adult life span. While there was an extension of the pupal period by one day at 500 ppm compared to untreated larva. The larval, pupal, and adult malformations were noticed in 300 and 100 ppm concentrations. These findings suggest that chitosan was potent in imposing chronic toxicity and growth inhibitory effect on P. xylostella larvae, and hence it can be recommended as an eco-friendly component in the Integrated Pest Management module.