Repellency and antifeedant effects of selected chitin synthesis inhibitor insecticides on the termite Microcerotermes diversus under laboratory conditions

This study evaluated the repellency and antifeedant effects of four chitin synthesis inhibitor (CSI) insecticides—chlorfluazuron, diflubenzuron, cyromazine, and etoxazole—against Microcerotermes diversus , a destructive termite species in tropical Iran. Laboratory free-choice and no-choice feeding tests were conducted using bait disks treated with varying concentrations (0.001, 0.002, 0.01) of each insecticide. Results showed that chlorfluazuron and diflubenzuron exhibited significant repellent properties, reducing termite settlement on treated baits by 44.15–72.34% compared to controls. Conversely, cyromazine at low concentrations (0.001 and 0.002) increased bait attractiveness by 41.15% and 23.52%, respectively, though it became repellent at 0.01 concentration. Etoxazole demonstrated attractant properties at all tested concentrations, increasing termite settlement by up to 55.42%. Feeding tests confirmed that chlorfluazuron and diflubenzuron negatively impacted feeding behavior, while cyromazine and etoxazole stimulated significant consumption at lower concentrations. These findings suggest that etoxazole and low concentrations of cyromazine may be promising candidates for termite bait formulations due to their non-repellent and potentially attractant properties.