Pea and bean weevil and bruchid beetle are common pests in UK legumes. Damage caused by the weevil adult is visible as notching around the leaf margins and, although this damage doesn’t usually significantly affect yield, the eggs laid during feeding produce larvae which feed in the nitrogen-fixing root nodules of peas and beans, resulting in yield loss. Damage caused by bruchid beetle is visible as holes in the seed, affecting quality and value to the grower.
“Following discussions with growers over recent years, it has become apparent that current control using spray applications have become less effective,” says Becky Ward, Principal Technical Officer at PGRO. “We believe this is either due to increasing pest pressure, or possibly decreased efficacy of pyrethroid insecticides.”
“As a result of this feedback, PGRO, Rothamsted Research, Oecos, Exosect Ltd and BASF plc are undertaking research to design and produce a control system for beetle pests of peas and beans, which does not use blanket sprays of insecticides.
“Instead, the beetles will be lured to simple devices, baited with beetle-specific attractive odours, where they will be coated with spores of an insect fungal disease. When they leave the device they will spread the disease to other beetles like them.
“This will reduce pest beetle numbers and damage to the crops without damage to the environment or other beneficial and non-target insects such as pollinating bees.
“The insect fungal disease occurs naturally in the soil in the UK and does not pose a risk to other animals. The attractants used are either insect-produced (a specific pheromone) or are odours produced by flowering peas and beans.
“The spores and the attractants will be prepared in a novel formulation that is electrostatically charged and sticks to the beetle’s body and is passed on to other beetles when they meet.”
Monitoring systems are already available which detect adults when they begin migrating in the early spring. The systems comprise traps containing pheromone lures or plant semio-chemicals and are used to aid spray application decision-making. The aim of this new project is to provide effective and environmentally-friendly biological control of both pea and bean weevil and bruchid beetle.
The project is partially funded by Innovate UK and the Biotechnology and Biological Sciences Research Council, with additional support from industry partners PGRO, BASF plc, Oecos and Exosect Ltd.
“The partners are starting detailed work on the project in October with research and investigations being carried out over the next four years,” adds Becky Ward.
The picture shows leaf notching caused by pea and bean weevil