Louisiana State University student wins Friends of Southern IPM Award for research in ornamentals

Ambrosia beetles perform important nutrient recycling roles in a variety of natural habitats, but when ornamental nurseries border the right type of habitat, the beetles can cause serious economic damage. A Louisiana State University doctoral student is coming up with some possible solutions to help nursery owners battle the pest. His efforts earned him the 2016 Friends of Southern IPM Graduate Student award in the Ph.D. category.

Chris Werle Friends of IPM Award

From L-R: Henry Fadamiro, Chris Werle and Joe LaForest

For the past few years, Chris Werle has been studying the ecology of ambrosia beetles, focusing on a group of exotic invasives that attack a variety of ornamental trees. Werle and his advisor, Jeff Kuehny, have been testing various theories about how the beetles were entering nurseries and why they preferred certain areas of the nursery over others.

As they looked at the beetles’ ecology, they also tested various products that could provide a deterrence to the damaging nursery attacks. The ultimate goal was to develop an integrated pest management program to reduce beetle attacks while limiting pesticide inputs in the nursery.

Since ambrosia beetles disperse from peripheral forested areas into nurseries, Werle hypothesized that the beetles may have a limitation on how far they were willing to fly to attack crops. To test their theory, he needed to find sites that had consistent beetle pressure in the spring, and that were large enough to measure trap captures at a variety of distances from the forest edge. .

After setting up research plots at several large commercial nurseries, he discovered that beetle captures decreased significantly after as little as 25 meters. Larger nurseries would have an advantage because owners could more easily rearrange where they placed susceptible cultivars. The challenge was how to help smaller nurseries ward off beetle attacks.

“I knew that some cultural techniques may result in less beetle pressure,” Werle says.

Werle participated in another trap experiment through a collaboration with researchers at Virginia Tech and Tennessee State University. That experiment, which tested whether bark beetles preferred certain colors, concluded that white traps captured significantly fewer ambrosia beetles compared with other darker-colored traps.

“There is a product called kaolin clay, widely used in tree fruit production, which is a good preventative for insects,” he says. “It leaves a white coating on the foliage and fruit.” So Werle hypothesized that kaolin-coated ornamental trees may be less attractive to ambrosia beetles.

An experiment comparing kaolin applications with standard insecticides had mixed results. Werle found that it washed off in a hard rain, so growers would have to reapply frequently. Despite an initial deterrence in beetle attacks, three days after treatment, kaolin-treated trees were no better than untreated controls.

Werle first developed his love of entomology at the University of Maine, where he took his first entomology class and decided to take a work-study internship with his professor during the summer.

In addition to the ambrosia beetle work, he also designed a trap for strawberry rootworm, a major pest of ornamentals that chews holes in the leaves of azaleas and other plants. The trap is sturdier than a regular sticky trap, and it contains a solar-powered light at the top, which attracts the nocturnal beetles. As the beetles accumulate on the trap, growers would determine whether to spray their crops. The trap proved to be an effective monitoring device, as it caught rootworms before any damage appeared on the leaves.

Werle received his award on March 15 at the Southeastern Branch Entomological Society of America meeting in Raleigh, NC. He plans to graduate from LSU in May 2016, and continue working in horticultural entomology.

The Southern IPM Center is funded by USDA National Institute of Food and Agriculture.

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