More Than Wheat to Eat: New Zealand’s Wheat Bug Has a Taste for Brassicas, Too
By Jody Green, Ph.D.
Nysius huttoni, known by many simply as the wheat bug, is an endemic and widely distributed pest in New Zealand. It is a quarantine pest in Australia, Europe, and the United States, and it was accidently introduced into The Netherlands and Belgium. It is an adaptable feeder, found on at least 75 plant species from over 25 families.
In November, Sundar Tiwari, associate professor of entomology at the Agriculture and Forestry University in Nepal and Ph.D. candidate at Lincoln University in New Zealand, and Stephen Wratten, Ph.D., distinguished professor of ecology at Lincoln University, published a comprehensive report of the wheat bug in the open-access Journal of Integrated Pest Management. Because the wheat bug is a significant pest in New Zealand, Tiwari and Wratten say they want to manage it as part of the broader scope of ecological agriculture.
The wheat bug was known to be a key pest of wheat and other cereal crops. Both adults and nymphs puncture the seed, inject saliva, and feed on the grain. Even marginal feeding of wheat results in product deterioration and reduced gluten protein, resulting in reduced market and baking quality. However, aside from wheat, the bug is also a pest of brassicas such as kale, rape, turnip, and swedes. Wheat bugs damage seedlings by sucking fluids from the base of the seedling, which results in punctures, cankerous tissue growth, interference with sap flow, weakness in the stems, and plant death.
Historically, pest management has relied on insecticidal sprays of permethrin and chlorpyrifos, as well as seed treatment with neonicotinoids. “The bad news is that most of the neonicotinoid leaves the seed within 24 hours after application. It is then taken up by other plants, including ones used as a nectar source by pollinators,” says Wratten, concerned over the impact that prophylactic applications have on nontarget species.
The best integrated pest management (IPM) practices for the wheat bug include early scouting and monitoring for bugs in the field, cultural methods like planting less susceptible cultivars of wheat and kale, and employing a non-chemical, strategic planting strategy known as trap cropping. The more we know about the wheat bug, the better equipped we are to face modern challenges in agriculture like feeding a growing population, Tiwari and Wratten say.
Over the last few years, Tiwari has studied the wheat bug and determined that alyssum and wheat are suitable trap plant species to protect brassica crops. Incorporating trap crop plants in strips around a field results in negligible damage by the wheat bug to brassicas. The shift from insecticide reliance to trap cropping not only protects host plants but also supports multiple ecosystem services. Described by Tiwari, “Choosing a plant like flowering alyssum not only attracts the insect pest, but it also provides shelter, nectar, and alternative food and pollen to predators and pollinators that can promote ecosystem services in farming systems.”
Wratten says of his student’s work, “Simple ideas can make a big difference to reducing high-input farming.”
Journal of Integrated Pest Management
Jody Green, Ph.D., is an urban entomology extension educator at the University of Nebraska-Lincoln and a subject editor and communications editor for the Journal of Integrated Pest Management. Twitter: @JodyBugsMeUNL. Email: firstname.lastname@example.org.