Mar 11, 2016
Researchers study pest management solutions

Researchers from Michigan State University (MSU) are intensifying their efforts, after receiving a $173,151 grant from USDA’s National Institute of Food and Agriculture, to study novel, non-spray control methods for invasive fruit pests.

The two-year project will examine the use of small nylon pouches that hang from trees and/or bushes. The pouches are treated with insecticides and filled with attractants such as pheromones or food to lure and kill the insects on contact.

Organic pest management expert Matthew Grieshop, tree fruit entomologist Larry Gut and post- doctoral research associate Juan Huang will examine the use of these pouches on three pests, spotted wing drosophila (SWD), brown marmorated stink bug (BMSB) and codling moth.

In a presentation at the recent Northwest Michigan Orchard and Vineyard Show in Acme, Michigan, Grieshop said the project will allow researchers to determine which attractants work best and how long each pest must be in contact with the insecticide to receive a lethal dose. Grieshop indicated that the project model was taken from research conducted with mosquito netting.

“We’ve been working on the attract- and-kill project for three seasons,” Grieshop said. “The first season was really the development and testing of the technique. The second was working with various pests such as Japanese beetle and Oriental fruit moth. It has worked well, and we’ve gotten great data. We hope to have the same type of success with these other pests.”

Michigan State University tree fruit entomologist Larry Gut displays a puch treated with insecticides and filled with attractants such as pheromones or food to lure and kill the insects on contact. Photo: Gary Pullano
Michigan State University tree fruit entomologist Larry Gut displays a puch treated with insecticides and filled with attractants such as pheromones or food to lure and kill the insects on contact. Photo: Gary Pullano

Laboratory testing and field work will be conducted. Researchers must determine in the lab how long each species needs to be exposed to the insecticide to suffer 100 percent mortality. Then, in the field, cameras will monitor wild insects’ interactions with the nylon bags.

The initial work isn’t compatible with organic farming, because the test insecticide is not National Organic Program (NOP)- compliant. However, eventually the researchers want to determine if NOP-compliant insecticides could be substituted.

“My hope is that by expanding our attract-and-kill technique to more pests, we can identify some key insect behavioral characteristics that can predict whether this type of approach is likely to succeed for many pests,” Grieshop said. “The most exciting aspect of this pest management technique is that by bringing the pest to the insecticide rather than broadcasting the insecticide and hoping that the insect will contact it, we are developing pest management tactics that are both economically and environmentally conscious.

“We were inspired by deltamethrin- treated insecticide nets that are used in the tropics to help mitigate effects like malaria and dengue fever,” Grieshop said. “So in those systems the human is the attractant. You’ve got this attractive warm body inside a mosquito net. The mosquito net is treated with deltamethrin, so when the mosquitoes land on the mosquito net, instead of finding that warm body to feed on they find a toxic load and they die.

“So we thought we could maybe do this for some of the fruit pests because we have good understanding of sex pheromones and some plant semiochemicals that are attractive to fruit pests,” he said. “We don’t want to put a cage over the entire tree, though, so instead we got some nylon fabric. We sew up little pouches that are about 5 inches by 5 inches and we treat them with a heavy load of deltamethrin insecticide, and then we put a semiochemical lure of some kind on the inside. So that might be a codling moth pheromone lure like you’d use in
a trap, or it could be a Japanese beetle lure, a semiochemical lure that you put in a trap. It might be apple cider vinegar and brewer’s yeast that you might use for spotted wing drosophila.

“So the (intent) of this is the target insect is attracted to the surface, they touch it and then the contact-active insecticide kills them,” he said. “So we’ve had pretty good success with this system so far.

“This project is allowing us to expand into some other areas. We have done some preliminary work in advance of that grant for spotted wing drosophila, and we’re ready with a prototype device to test this summer. We’re not quite as far along with brown marmorated stink bug, but we do plan on doing some field work this summer.”

Grieshop said the research team “did run a small experiment last summer with codling moth, and we faced our first real sort of research challenge where our attract-and-kill device did not perform as well as a mating disruption solution. This next year, we’re really going to be focusing on the behavioral aspects of codling moth in relation to this, probably using a lot of field videography to see,
do moths actually touch our device? If they do touch it, how long do they stay in contact with it? That’s likely what we’ll do with brown marmorated stink bug, as well.

“So the benefits of an attract-and-kill device I think are somewhat obvious, but really what it comes down to, rather than put a toxic across a broad swath of crop, we’re putting it on a small device that never comes in contact with the crop, and insects are drawn to that and touch that and die.”

He said there hasn’t been a “lot of non- target insects touching our devices in field videography, but that’s probably likely going to be very dependent on the type of semiochemical used and the timing of when they’re put out.

“I see this attract-and-kill as a natural evolution of the mating disruption concept, and as such I’m not going to tell people that I think that this is going to be a silver bullet that’s going to solve a particular pest management issue. However, I felt that much like mating disruption, I think it could make managing some of our key pests much easier, and codling moth is a great example of that. That’s really the best success story of mating disruption.

“Growers that use codling moth mating disruption don’t spray nearly as much as growers who don’t,” Grieshop  said. “They don’t have to because they can maintain the populations at a very low, controllable level. Our hope is that attract-and-kill will do the same thing for these new pernicious pests like spotted wing drosophila and brown marmorated stink bug.”

Grieshop said many attract-and-kill formulations developed to date have provided less or equivalent control compared to reservoir dispensers. Also, many operate via disruption, not insecticide poisoning.

Some of the objectives met by MSU’s work thus far include determining that certain colors promote SWD alignment, while others do not. In a test of colored disks, significantly more flies landed on red, purple and checkered disks than white disks. In a no-choice test, significantly more flies landed on red, orange, green, purple and black than white.

SWD also respond differently to visual targets varying in color (red and yellow), and not just the brightness of a black and white image.

“Significantly more flies landed on fluorescent red than any other fluorescent color,” Grieshop said. “Red, purple and black are the best colors. Color and not just brightness matter. Flourescent red may outperform natural red. Attract and kill devices should be red or fluorescent red.”

He said two seconds of deltamethrin exposure leads to 100 percent mortality
in less than one hour, bringing 40 percent and 20 percent mortality at 10 minutes for males and females, respectively.

For more, watch the “Attract and Kill Pest Managment” video featuring Michigan State University’s Matthew Grieshop.

Gary Pullano, associate editor

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