Evaluation of benzoylphenyl ureas for controlling the spiny bollworm, Earias insulana (Boisd.), in cotton

Abstract

Three benzoylphenyl ureas (BPUs) were compared for their relative toxicity against different life stages of the spiny bollworm (SBW), Earias insulana (Boisd.). Results showed that the LC 50 values of chlorfluazuron, teflubenzuron and hexaflumuron ingested by neonate larvae of the spiny bollworm, were 0.01, 0.05 and 0.25 p.p.m. (a.i.), respectively. A dipping concentration of 50 p.p.m. (a.i.) hexaflumuron and teflubenzuron resulted in suppression of ∼ 80% and 50% egg hatch, respectively, whereas chlorfluazuron showed no effect. Egg hatch inhibition of 65% and 42% was obtained after 7–10 days' exposure to hexaflumuron and teflubenzuron, respectively. No significant response was found with chlorfluazuron. In addition, a gradual decline in egg viability was observed with the increase of adult exposure to treated cotton plants. Treatments of 50 p.p.m. (a.i.) chlorfluazuron, teflubenzuron and hexaflumuron under experimental field conditions, gave satisfactory control of SBW larvae that had been introduced as neonates on to the treated young cotton bolls. The level of damaged bolls after treatment with the benzoylphenyl ureas ranged from 10% to 12%, compared with 77% in the untreated control. Our results indicate that chlorfluazuron and teflubenzuron, and possibly other BPUs, have potential for controlling SBW larvae under field conditions.