Invasive Species Compendium

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Abstract

Larvicidal efficacy of some chitin synthesis inhibitors against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

Abstract

The nine different concentrations i.e. 0.002, 0.004, 0.006, 0.008, 0.02, 0.04, 0.06, 0.08 and 0.1%, respectively, of two chitin synthesis inhibitors viz., chlorfluazuron and novaluron were tested separately in the laboratory against larvae (five instars) of fall armyworm, Spodoptera frugiperda (J.E. Smith). The percent larval mortality in various treatments of chlorfluazuron ranged from 33.33 to 100.00, 23.33 to 100.00, 23.33 to 100.00, 23.33 to 100.00 and 13.33 to 90.00, respectively in progressive instars. Whereas, for novaluron, the percent larval mortality varied from 36.67 to 100.00, 20.00 to 100.00, 26.67 to 100.00, 20.00 to 100.00 and 16.67 to 93.33, respectively in successive instars. The LC50 values recorded for first, second, third, fourth and fifth instars were 0.003828, 0.005880, 0.007689, 0.006311 and 0.015971%, respectively, for chlorfluazuron and for novaluron these values were 0.003469, 0.007244, 0.005969, 0.008421 and 0.012948%, respectively. Most of the affected larvae failed to shed off their exuviae at the time of moulting, turned black and displayed morphological deformities. Further, both the compounds adversely affected the larval growth and weight. The larval period was also prolonged in treated larvae as compared to that in control.