Dicofol as a Feeding Inhibitor of the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

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Abstract
Laboratory and field studies demonstrated that the organochlorine miticide dicofol is an antifeedant against the Colorado potato beetle (CPB),Leptinotarsa decemlineata (Say). The activity of dicofol as a CPB antifeedant varied considerably depending on the formulation used: The 18.5% emulsifiable concentrate (EC) formulation suppressed CPB feeding at a concentration of 0.05 g (AI)/Iiter; the 35% wettable powder (WP) formulation suppressed feeding at a concentration of 0.2 g (AI)/liter; and the nonformulated technical grade dicofol suppressed feeding at a concentration of 0.5 g (AI)/Iiter. Although a threshold response was obtained in laboratory studies, a rate response was evident when EC dicofol was applied to potatoes in the field in 1983, with 3.03 kg (AI)/ha providing excellent larval control and preventing defoliation from exceeding 10% at the end of the season, compared with >95% defoliation of untreated potatoes. In 1984, the EC formulation exhibited greater residual effectiveness than the WP formulation. Two properly timed applications of EC dicofol prevented defoliation from exceeding 20% in 1984, whereas weekly applications of WP dicofol were necessary to obtain similar levels of protection.