Evaluation of an attract and kill strategy for western corn rootworm larvae

Abstract

Western corn rootworm larvae are serious soil dwelling maize pests, and use carbon dioxide (CO2) to locate maize roots. The efficacy of insecticides can be enhanced by a combination with an attractant used in host finding, known as attract and kill. This study tested the use of CO2 emitting capsules as an attractant in combination with the soil insecticide tefluthrin. An observation device was developed to study the temporal and spatial distribution changes of the larvae and to test whether these are influenced by the application of the capsules. Furthermore it was evaluated to what extent larvae are killed by the insecticide in combination with the capsules and whether this could be used for an attract and kill strategy to manage this pest.The observation device enabled recovery of 20–40% of the inserted larvae. The spatial analysis of distance indices revealed a sequence of spatial and temporal distribution patterns of the larvae in the root system. This sequence of spatial distribution was disrupted by an application of the capsules around which the larvae started to aggregate. Up to 40% mortality of the larvae with attract and kill was observed and thus could be increased over the conventional application (11% mortality) at lower application rates of tefluthrin. In conclusion an attract and kill strategy might be valuable to target this soil dwelling pest. Experiments under field conditions are needed to explore its potential as a management option for the western corn rootworm. Moreover, a further development of the capsules with host specific cues is needed to increase the attractiveness and subsequent mortality of the larvae.