Development of a monitoring trap for detecting pepper weevil in the UK

This project will aim to develop a highly sensitive monitoring trap for use by UK growers to detect occurrence of pepper weevil, Anthonomus eugenii, in glasshouses and packhouses. The pest causes yield loss by destroying blossom buds and immature fruits, which turn yellow and drop to the ground. Both adult and larval feeding causes bud drop. Adult A. eugenii also feed on leaves and blossoms and bore into fruits. Females chew a small hole into the fruit and deposit a single egg within the cavity. Larval feeding on seeds and other tissue in the developing fruits is very damaging, causing the core to become brown, and often mouldy. The stem of pods infested by larvae turn yellow and the pod turns yellow or red prematurely. Economic damage is reported to occur with adult populations of only 0.01 adult per plant.

A recent review highlighted that; ‘It is vitally important that UK growers are able to detect and identify A. eugenii when it arrives in the UK’ (Jacobson et al. 2013). In addition, many of the methods of monitoring the pest’s population development were found to have little relevance to glasshouse crops in the UK, but studies clearly demonstrated that prompt action is required to avoid economic damage. Scouting for adults and damage to terminal buds is time-consuming and areas of the crop can be missed. Yellow sticky traps are used, but these are also attractive to parasitoid wasps and bees.
Adult A. eugenii are attracted to male-produced aggregation pheromones, host plant volatiles and feeding damage volatiles. A trap based on the aggregation pheromone is commercially available, but there is scope to optimise this by adjusting the blend of components and dispenser and by including plant volatiles to make the traps more sensitive. These systems could be developed as highly sensitive detection traps that monitor the pest so that pesticides can be timed optimally, and eventually for mass trapping in UK glasshouse crops.

East Malling Research and the University of Greenwich have experience of working on Anthonomus semichemicals and have successfully developed a monitoring trap for strawberry blossom weevil, A. rubi. EMR holds a quarantine licence to work on A. eugenii and NRI has Defra-approved quarantine insectaries.

 

Economic damage by A. eugenii to peppers is reported to occur with adult populations of only 0.01 adult per plant. Current control measures in the Americas are based on broad spectrum insecticides which are extremely disruptive to IPM. This can lead to secondary problems with other pests and associated diseases, which must also be controlled with chemical insecticides. The disruption and termination of the IPM programme means that growers would lose an important marketing advantage over their overseas competitors.
The full economic implications of the arrival of A. eugenii have not yet been determined for UK growers. However, initial observations suggest that losses due to direct damage, secondary pest problems and the loss of goodwill with retail customers could be very substantial.