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Field Borders Provide Winter Refuge for Beneficial Predators and Parasitoids

Scott Clem, Ph.D., recently completed his doctoral degree at the University of Illinois. Part of his research focused on evaluating the value of semi-natural field borders as winter refuge for beneficial arthropods that like to eat or parasitize crop pests.

Plants are always at risk of untimely damage and death, often due to the weather—a late frost, too much rain, too little rain, excessive wind—but various living organisms can also cause devastation. For gardeners, damaged plants are maddening, but, for farmers, preventing or limiting that damage is necessary for maintaining their livelihood. The weather is beyond the control of farmers and gardeners, but they do have a long list of tools to use against many of their living foes, from crop rotation to pesticides to purchased predators and parasites. For some, a hidden benefit of the predator/parasite route is the morsel of satisfaction felt when some sap-sucking, leaf-chewing, wood-boring, or disease-bearing pest is taken out by a tiny predator or turned into a pantry for a parasite’s offspring.

Natural enemies of pests don’t have to be purchased. Wild predators and parasites can be encouraged to live near agricultural fields, and a new paper published in May in the open-access Journal of Insect Science shows that semi-natural field edges can provide winter refuges for natural enemies of pests so that they can be ready to jump into pest-destruction services early in the season.

Having natural enemies like predaceous beetles, spiders, and wasps spending the winter near crops can provide enormous benefits. Clem and co-author Alexandra Harmon-Threatt, Ph.D., write, “If natural enemies are not present at sufficient levels early in the season, they are less likely to manage pest problems before they breach economic threshold in spring and ensuing warm months.”

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Publication Date: 06/02/2021
Photo credits: L. Brian Stauffer
Editor: Paige Embry, Entomology Today