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Farm Frenemies

Insects can be a farmer’s best friends or a collection of fierce foes. On one hand, bees and other pollinators play a key role in developing crops. On the other, pests can decimate them.

Inherent in NC State’s land-grant mission is a commitment to supporting farmers in North Carolina and around the world. Research from the College of Agriculture and Life Sciences helps N.C. agriculture to sustain helpful insects and neutralize harmful ones, while also keeping farmers informed about emerging entrants into both categories.

Why Bees Die — And Thrive

Nearly a third of the food eaten in the United States benefits from pollination by bees, according to the US Department of Agriculture. Bees add about $15 billion in value to U.S. crops each year, making the recent widespread collapse of bee colonies a cause of economic and agricultural concern.

Associate entomology professor Dave Tarpy has published a pair of recent papers that offer new insights into why bee colonies survive and fail.

A March 2013 paper Tarpy co-authored with colleagues from the University of Maryland, Pennsylvania State University and the USDA identified “idiopathic brood disease syndrome” (IBDS), a little-known illness, as a major cause of the death of bee colonies. Colonies where IBDS was present were more than three times as likely to die as others, Tarpy and his team found.

In a separate paper, Tarpy and fellow researchers found that genetic diversity is a key to survival for bee colonies. Colonies whose queen had more than seven mates were nearly three times more likely to survive a 10-month growing season.

“This study confirms that genetic diversity is enormously important in honey bee populations,” Tarpy says. “And it also offers some guidance to beekeepers about breeding strategies that will help their colonies survive.”

[brite img=”” title=”Agriculture meets engineering” header=”A Single Challenge, A Suite of Experts” video=”” link=”” color=”613b23″]The global population is growing; the amount of arable land is static. NC State plant biology and engineering researchers are studying how plants can thrive despite harsh climates and disease.[/brite]

Diet Drives Pests’ Spread

NC State researchers have also recently published research that advances our understanding of emerging crop pests.

Since its first American appearance in 2009, the invasive kudzu bug has been a problem for farmers from Georgia to Virginia. According to a paper by Dominic Reisig, associate professor of entomology, and doctoral student Alejandro Del Pozo-Valdivia, the bug’s could affect a larger geographic area. The key to that broader footprint is a new insight into the kudzu bug’s diet: initially, researchers believed immature bugs fed only on kudzu, limiting their viability to southern regions where the fast-growing vine thrives. Del Pozo-Valdivia and Reisig found that young kudzu bugs can also digest soybean plants.

“Researchers began seeing some of this behavior in the wild in 2012 and, while those data aren’t quite ready for publication, our lab work and the field observations indicate that kudzu bugs are potentially capable of spreading into any part of the U.S. where soybeans are grown. And soybeans are grown almost everywhere,” Reisig said.

Spotted-wing vinegar flies meet on a raspberry.
Spotted-wing vinegar flies meet on a raspberry.

Finally, a March 2013 publication by a team of NC State entomology researchers may have uncovered the reason for an invasive fly’s swift sweep of the United States. First sighted in California in 2008, the spotted-wing vinegar fly is now present across the country. Associate professor Hannah Burrack and colleagues identified the fly’s tendency to feast on sweet, soft fruits, whose flesh they spoil by laying eggs after eating. The fly could ruin up to 40 percent of the blackberry and raspberry crops in the eastern United States, researchers estimate.

“Because we know that D. suzukii prefers softer, sweeter fruit, we can focus our research efforts into which wild fruits may serve as reservoirs for this species and help identify new crops that might be at risk,” Burrack said.

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