Development and Evaluation of a Plastic Trench Barrier for Protection of Potato from Walking Adult Colorado Potato Beetles (Coleoptera: Chrysomelidae)

Abstract

Laboratory and field experiments conducted in New Brunswick between 1991 and 1992 demonstrated that plastic-lined trenches can act as barriers against walking adult Colorado potato beetles, Leptinotarsa decemlineata (Say), moving into or out of potato fields. Adult beetles can walk on clean plastic mulch but cannot walk on plastic that is coated with fine soil particles. The fine dust prevents the beetle from establishing direct contact with the plastic and coats the adhesive tarsal pads of the adults. Trenches with walls sloping at 46° or more will retain all captured beetles in the laboratory and an average of 84% under field conditions. The reduction in field efficacy is caused primarily by rainfall. Small numbers of beetles may escape from field trenches during periods of rain, but the efficacy of the trench is reinstated as soon as the slopes of the trench become dry. Water accumulated at the bottom of the trench does not reduce the efficacy of the trap. A potato field surrounded by plastic-lined trenches could see its populations of over wintered adult beetles reduced by 47-49% and its population of summer-generation adult beetles reduced by 40-90% compared with fields without trenches. A similar effect was measured on egg masses. Sections of plastic-lined trenches installed along commercial potato fields produced average percentage reductions in the number of adult potato beetles on the plants varying from 0-45%. The latter test indicated that the installation of plastic barriers is feasible under commercial field conditions. Alone, plastic-lined trenches are not sufficient to control Colorado potato beetle populations fully in potatoes but easily can be integrated with other control strategies.