Pests
Protecting fruit crops from birds and other predators has never been easy. Scarecrows, reflective tape, netting, shotguns, propane-powered bangers and other audible bird scare devices, as well as traps and falcons, number among the most popular tools at growers’ disposal.
Published in Research
Songbirds and coffee farms in Central America. Ladybugs and soybean fields in the Midwest. These are well-known, win-win stories that demonstrate how conserving natural habitat can benefit farmers.

But an international team of authors, including Megan O’Rourke, assistant professor in the Virginia Tech School of Plant and Environmental Sciences, found that natural habitat surrounding farm fields is not always an effective pest-control tool for farmers worldwide. The team’s analysis was published Aug. 2 in the journal PNAS.

“For the last 20 years, many scientists have suggested that you will have fewer insect pests on your farm if the farm is surrounded by natural habitats, such as forests,” O’Rourke said.

To test that assumption, lead authors Daniel Karp, an assistant professor in the UC Davis Department of Wildlife, Fish and Conservation Biology, and Rebecca Chaplin-Kramer, of the Natural Capital Project at Stanford University, organized an international team of ecologists, economists, and practitioners at the National Socio-Environmental Synthesis Center.

Together, they compiled the largest pest-control dataset of its kind, encompassing 132 studies from more than 6,700 sites in 31 countries worldwide — from California farmlands to tropical cacao plantations and European wheat fields.

Surprisingly, the results were highly variable across the globe. While many of the studies showed surrounding natural habitat does indeed help farmers control pests, just as many showed negative effects on crop yields. The analysis indicates that there are no one-size-fits-all recommendations for growers about natural habitat and pests.

“Natural habitats support many services that can help farmers and society, such as pollination and wildlife conservation, but we want to be clear about when farmers should or should not expect the land around their farms to affect pest management,” said O’Rourke, who works within the College of Agriculture and Life Sciences and the Fralin Life Science Institute. “Diverse landscapes are not a silver bullet for pest control but should be considered as part of a holistic and sustainable pest management plan.”

Critically, Karp and his team of 153 co-authors have made their pest-control database publicly available, opening the door for further scientific insights. Karp hopes the database will grow over time and help inform predictive models about when surrounding habitat helps control pests and when it does not.

The research was supported by the National Socio-Environmental Synthesis Center and the National Science Foundation.
Published in Research
The use of biocontrol pest methods in horticulture is growing, whether it’s trap crops, pheromone traps, predatory insects or biopesticides.
Published in Insects
A Purdue University entomologist suggests that high-tunnel fruit and vegetable growers carefully consider species and tunnel construction when using natural enemies to control pest insect species.

Laura Ingwell, a postdoctoral researcher in the department of entomology, studies pest-control methods in protected agricultural systems. She’s interested in determining best practices for fruit and vegetable growers using high tunnels, which can extend the growing season. Her previous research has shown that high tunnels can increase not only crop yield, but also damaging pests.

In research published in the journal Biological Control, Ingwell tested augmentative biological control, which employs predatory insects that prey on crop pests. Producers supplement natural enemies in the environment with commercially available predators. The study sought to determine the best way to retain the beneficial insects in the high tunnels, reducing their dispersal to neighboring habitats.

Ingwell used small-opening, 0.18 mm2 screens on a subset of tunnels to test a variety of predatory insects, including lady beetles, minute pirate bugs, spined soldier bugs and green lacewings on tomatoes and cucumbers. Three times in the space of a week, researchers collected and counted the predators, but few had survived. Meanwhile, crop pests thrived.

“We had a really low recapture rate of all the predators that we used — less than 10 per cent,” Ingwell said. “The screens did not work, which really surprised us.”

Ingwell said the heat created by the screens was the likely culprit. It might have driven some to escape through cracks and holes in screens that are inevitable with high tunnels. The heat, which reached average maximum temperatures of 98°F, might have also killed many of the predators. The physical barrier prevented other predators from naturally colonizing in these tunnels.

“Airflow was significantly reduced by the screens, which trapped so much heat that it changed the environment inside the tunnels making it inhospitable for the predators we released,” Ingwell said. “The mites and aphids, which damage crops, seem to be less affected by the heat stress. They may be able to better handle those temperatures, or they may reproduce so quickly that their populations were better able to survive.”

In another set of tunnels, flowers and chemicals meant to attract predatory insects were used. The flowers provide alternative food for the predators when prey populations are low and the chemicals, called herbivore-induced plant volatiles, attract predators because they mimic the scents created when pest insects damage crops, signaling to predators that a meal is nearby. In those tunnels, twice as many minute pirate bugs were retained.

Ingwell suggests growers consider using flower varieties that can be sold commercially so as not to waste space that might be used for crops. For this study, Benary’s giant golden yellow zinnia and fireworks gomphrena were effective.

The take-away message from Ingwell is that using beneficial insects can work in some scenarios, but getting the right balance is tricky.

“In general, augmentative biocontrol may not be worth the investment because in most cases, those insects aren’t staying or surviving long enough to have an effect,” Ingwell said. “Unless you alter those environments to keep the predators there, this may not be a cost-effective method for controlling crop pests.”

Ingwell is continuing to test screen sizes and different predator pests to improve pest control in high tunnels. The U.S. Department of Agriculture National Institute of Food and Agriculture funded this study.
Published in Research
Five new fertilizer-compatible products are expected to be available from Vive Crop Protection for U.S. corn, sugarbeet and potato growers in 2019. Each product includes a trusted active ingredient that has been improved with the patented Vive Allosperse Delivery System.

AZteroid FC 3.3 is a high-concentration, fertilizer-compatible fungicide that improves plant health, yield and quality of key field crops, including potatoes, sugarbeets and corn. AZteroid FC 3.3 controls seed and seedling diseases caused by Rhizoctonia solani and certain Pythium spp. It contains azoxystrobin, the same active ingredient as Quadris.

Bifender FC 3.1 controls corn rootworm, wireworm and other soil-borne pests in corn, potatoes and other rotational crops. Bifender FC 3.1 has a new high-concentration, fertilizer-compatible formulation and contains bifenthrin (same as Capture LFR).

TalaxTM FC fungicide provides systemic control of pythium and phytophthora, similar to Ridomil Gold SL but in a fertilizer-compatible formulation. Talax FC contains metalaxyl and helps potatoes and other crops thrive right from the start, resulting in improved yield and quality.

MidacTM FC systemic insecticide is a fertilizer-compatible imidacloprid formulation that controls below-ground and above-ground pests in potatoes and sugarbeets. It provides the same long-lasting protection of Admire PRO but with the convenience of being tank-mix compatible with fertilizers, micronutrients and other crop inputs.

AverlandTM FC insecticide is a fertilizer-compatible abamectin formulation that controls nematodes in corn. It also controls potato psyllid, spider mites, Colorado potato beetle and leaf miners in potatoes. In-furrow application trials for nematode control in a wide range of crops are under way.

All of these fertilizer-compatible products use the Vive Allosperse Delivery System - the first nanotechnology registered for U.S. crop protection. Products containing Allosperse are the best mixing products on the market, whether they are used with each other, liquid fertilizer, other crop protection products, micronutrients or just water.

Brent Petersen, president of Cropwise Research LLC, performed trials on behalf of Vive Crop Protection to test mixability of the company’s products. During spring 2018, he mixed all five of the new products together with liquid fertilizer and observed, “We didn’t see any separation or settling out. It was nice to see because we often see products that aren’t compatible with other products, and especially with liquid fertilizer.”

EPA registration is pending for Talax FC, Midac FC and Averland FC and the new formulations of AZteroid and Bifender.
Published in Weeds
Nematodes are pests that you need to keep an eye on in order to ensure the productivity of market garden crops. Several species are considered parasites of fruits and vegetables. Various types of nematicides have been used in the past to eliminate and/or control the spread of nematodes. Since the 1970s, these nematicides have been phased out of commercial use. The last fumigant nematicide was withdrawn over the last five years. Over time, it became apparent that they were not safe for users or for the environment.
Published in Vegetables
Perennia in association with Nova Scotia Department of Agriculture and Agriculture and Agri-Food Canada has been monitoring for leek moth across Nova Scotia since early May this year.

Leek moth is an invasive insect pest from Europe that feeds on Allium species (onions, garlic, leeks,etc), and can cause significant damage to these crops.

Previous to 2018, leek moth had been identified in Kings County twice, once in 2016 and again in 2017. In response to this a provincial leek moth monitoring project was established, to determine how widespread the pest is in Nova Scotia.

As of July 3, 2018, leek moth has been confirmed in both Kings and Annapolis County. Currently the pest has not been found in large scale commercial fields, and all the leek moth samples have been from garlic. Leek moth favours garlic and leeks primarily; researchers are currently unsure of its effects in onion production.

Leek moth can be monitored using commercially available pheromone traps, which attract adult males. The adult leek moth is a small (five to seven mm in length) brown moth with a distinctive white triangle in the middle of its wings when they are folded at rest.

Additionally allium crops can be scouted for feeding damage from leek moth larvae. On alliums with flat leaves (garlics, leeks) the larvae feeds on the tops and inside of the leaves, as well as bores into the center of the plant leaving noticeable frass. In alliums with hollow leaves (onions, chives) the larvae will feed internally producing translucent areas on the leaf known as "windowing". The larvae will also occasionally bore into bulbs.

There are several chemical controls registered for leek moth in garlic, leeks, and onions that can be found in the Perennia's Garlic Management Schedule, Leek Management Schedule, and Onion Management Schedule.

These pesticides are most effective when eggs are present and leek moth larvae are small, so monitoring is crucial to ensure proper timing of applications. Row cover is also an effective means of protecting allium crops against leek moth, without using chemical controls.

For additional information on leek moth identification and management please consult AAFC's An Integrated Approach to Management of Leek Moth. If you think you have leek moth please contact Matt Peill, horticultural specialist with Perennia (email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it , cellphone: 902-300-4710).

RELATED: Monitoring for Leek Moth
Published in Vegetables
The Pest Management Regulatory Agency (PMRA) recently announced the approval of minor use label expansion registrations for Entrust and Success insecticides for control of cabbage maggot on Brassica leafy greens crop subgroup 4-13B and Brassica head and stem vegetables, crop group 5-13 in Canada.

Entrust and Success insecticides were already labeled for use on a wide variety of crops in Canada for control of several insects.

These minor use projects were submitted by Quebec as a result of minor use priorities established by growers and extension personnel. | READ MORE
Published in Insects
If you were going to tank mix chemical pesticides, you would of course read the label to check for compatibility before mixing products.

The same concept applies when using living organisms for pest control. Whether you are using parasitoid wasps, predatory mites, microorganisms, or nematodes, you need to know whether your biocontrols are compatible with each other and any other pest management products you plan to use.

For example, a biocontrol fungus might be killed if you tank mix it with (or apply it just before) a chemical fungicide. Insecticides (whether or not they are biological) could be harmful to natural enemy insects and mites. Even some beneficial insects are not compatible with each other because they may eat each other instead of (or in addition to) the pest. | READ MORE 
Published in Insects
An invasive pest that was initially contained within Pennsylvania has spread to Delaware and Virginia, and insect experts worry the next stop will be Ohio.

Spotted lanternflies suck sap from fruit crops and trees, which can weaken them and contribute to their death. Native to China, the insect was first found in the United States in 2014 in Pennsylvania.

At this time, spotted lanternflies are still relatively far from the Ohio border. They have been found in the southeastern part of Pennsylvania, near Philadelphia. However, they can be spread long distances by people who move infested material or items containing egg masses.

“The natural spread would take a long time, but it would be very easy to be moved through firewood or trees that are being relocated,” said Amy Stone, an educator with Ohio State University Extension. OSU Extension is the outreach arm of the College of Food, Agricultural, and Environmental Sciences (CFAES) at The Ohio State University.

If it arrives in Ohio, the spotted lanternfly has the potential to do serious damage to the grape, apple, hops and logging industries, Stone said.

The lanternfly’s preferred meal is from the bark of Ailanthus or tree of heaven, which is typically not intentionally planted but instead grows on abandoned property and along rivers and highways.

Compared to the spotted wing drosophila or the brown marmorated stink bug, which seize on fruit and vegetable crops, the spotted lanternfly has a more limited palate so it likely would not do as much damage, said Celeste Welty an OSU Extension entomologist.

“Everybody’s fear is any new invasive pest will be like those two. But it seems to me, it’s not as much of a threat,” Welty said.

And unlike the spotted wing drosophila and the brown marmorated stink bug, the lanternfly is easy to spot because the adult bug is about 1 inch long and, with its wings extended, about 2 inches wide, Welty said.

For now, all that can be done to stem the spread of lanterflies is to stay watchful for their presence and any damage they may inflict. On trees, they zero in on the bark, particularly at the base of the tree. Lanternflies can cause a plant to ooze or weep and have a fermented odor. They can also cause sooty mold or a buildup of sticky fluid on plants as well as on the ground beneath infested plants.

An app developed by the CFAES School of Environment and Natural Resources allows users to report invasive species if they suspect that they have come across them. The app, which is called the Great Lakes Early Detection Network, features details about invasive species that people should be on the lookout for.

If someone sees a lanternfly, he or she should contact the Ohio Department of Agriculture at 614-728-6201.
Published in Fruit
Corteva Agriscience, Agriculture Division of DowDuPont, recently announced that the Pest Management Regulatory Agency (PMRA) in Canada has granted Dow AgroSciences upgraded approval for Closer Insecticide use to actively control Woolly apple aphid in pome fruit crops.

“Canadian apple growers who have used Closer in the past know of its exceptional speed and ability to knockdown aphids. This upgraded designation reinforces the quality and efficacy of Closer and we are pleased that the PMRA has responded to the ongoing need to control insect infestation,” explains Tyler Groeneveld, category leader, Horticulture with Corteva Agriscience.

This approval is significant as it gives growers greater access to a highly effective product that combats sap feeding insects at various stages of growth and outbreak. Insects such as Woolly apple aphid can cause extensive crop damage, ultimately impacting the quality and value of orchard crops.

Closer Insecticide, powered by Isoclast active, is a revolutionary product ideal for control of both resistant and non-resistant pests, delivering the active ingredient sulfoxaflor, which is classified by the Insecticide Resistance Action Committee as the sole member of IRAC Subgroup 4C Sulfoximines. The active ingredient moves quickly through the plant and has excellent systemic and translaminar activity that controls insect pests both on contact and by ingestion. The results are fast knockdown and residual control of aphids and other sap feeding insects.

Closer is highly selective and has minimal impact on beneficial insects. The properties and overall spectrum of activity of Closer Insecticide makes it an excellent fit for treatment when outbreaks occur as well as part of Integrated Pest Management Programs (IPM) to minimize flare-ups.
Published in Insects
Heads up veggie growers: New pest threats!

We have a couple of new pests threatening to descend on Nova Scotian vegetable fields. Perennia, in conjunction with AAFC and the NSDA is setting out some pheromone traps for Leek Moth and Swede Midge.

Check out our YouTube videos on how to set out a pheromone trap.
Published in Vegetables
Heads up veggie growers: New pest threats!

We have a couple of new pests threatening to descend on Nova Scotian vegetable fields.

Perennia, in conjunction with AAFC and the NSDA is setting out some pheromone traps for Leek Moth and Swede Midge. Check out our YouTube videos on how to set out a pheromone trap.
Published in Vegetables
When plants are growing outdoors, it’s no surprise that they are at risk for pest activity. But even once produce is harvested and brought inside for storage and packaging, it can fall victim to pests’ appetites. In fact, pest infestations that are established during storage can put your produce at increased risk, as it is easy for pests to move and spread quickly in the closed environment.

While a pest infestation in the field might be obvious as plants show signs of fatigue, develop deformations or die, an infestation in the warehouse can pass under the radar if it is not monitored.

So, it’s important for your Integrated Pest Management (IPM) plan to include strategies for protecting your fruits and vegetables as you prepare them for storage and shipment. IPM strategies focus on preventive techniques, like exclusion, maintenance and sanitation and use sustainable, environmentally-friendly practices to manage and control pests.

Fresh fruits and vegetables are vulnerable to pest infestations because of their succulence and the aroma they produce. Pests can infest produce items at any point in the supply chain, and improper packaging can make it easier for them to access your produce. Here are some of the most common pests that attack harvested fruits and vegetables:

Spiders
Spiders prey on insects and are naturally inclined to be found on foliage and vegetation. Therefore, harvested produce will harbour spiders. While in the field, spiders do help keep insect populations in check, but you don’t want them on your produce when it gets packaged and shipped.

Springtails
Springtails are tiny insects that jump around when disturbed. They are attracted to moisture, dampness and humidity. They normally live in damp soil and feed on mold and fungi. So, naturally they will be found concealed in foliage and on plant stems, especially on vegetables that grow at soil level. As a result, they can easily make their way into packaged produce once harvested.

Fruit Flies
As their name suggests, fruit flies are attracted to ripening and fermenting fruits and vegetables. Female fruit flies lay their eggs under the surface of fruits and vegetables. Therefore, a detailed inspection of random samples of fruits and vegetables to detect eggs and larvae is crucial to preventing a pest infestation in your processing and storage facilities. Sampled fruits should be cut through and examined for eggs and larvae, which are visible to the eyes.

Indian Meal Moths
While they only feed on dried fruits and vegetables, Indian meal moths are the most common stored product pest in food-handling facilities, homes and grocery stores. They are primarily attracted to dry foods and can damage products as their larvae spin silk webbing that accumulates fecal pellets and cast skins in the food. Common signs of an Indian meal moth infestation include the silk webbing, buildup of droppings in the food product and pupal cocoons along walls, shelving and ceilings.

Prevention
Once harvested and packed, fruits and vegetables must continue to breath to maintain their freshness. So, packaging often has aeration pores that can make produce vulnerable to pest attacks, and it is difficult to find packaging that is impervious to all pest activity. However, there are some packaging materials that should be avoided for produce.

Wooden containers can harbour wood boring insects. When exposed to moisture, they also can rot or cause mold and fungal growth that attracts insects which can spread and infect the packed produce.

Rough, wooden boxes or bamboo like packaging can cause bruising and damage produce, which attracts insects. Materials less capable of withstanding stress also can damage produce, as they are vulnerable to tears, which can expose or damage the fruits and vegetables. Therefore, it’s important to choose the right type of packaging for your produce.

In addition to avoiding these materials, keep an eye out for packaging that doesn’t seal properly. Even the best packaging doesn’t stand a chance if it’s not closed all the way or has a hole. At the end of the day, your goal should be to make it as difficult as possible for pests to reach your fruit and vegetable products.

Fruit and vegetables are susceptible to pest infestations while they are growing. And once in storage, it’s easy for a pest infestation to spread quickly – especially with such an abundance of food for the pests to thrive on. So, it’s important to take steps to manage infestations in the field and to establish controls to help prevent infestations from being brought inside and spreading once in storage.

In the field:
  • Pest prevention starts with Good Agriculture Practices (GAP) in the field that reduce conditions conducive to pest infestations.
  • Extensively monitor for pest activity by inspecting or scouting plants regularly during growing season to catch infestations early.
  • Reduce pest attractants by practicing good sanitation (phytosanitation) and eliminating onsite harbourage sites such as weeds, piles of compose, standing water and idle unused equipment.
  • Remove fallen, overripe or rotting fruits from the fields, as this could attract fruit flies and other pests.
  • At time of harvest, inspect extensively for insects and spiders on produce.
  • Harvest produce when they are dry. This prevents pest and diseases from clinging on them.
  • Clean and sanitize harvest equipment, bins and tools before and after harvesting.
  • Avoid or prevent bruising of produce. The bruising attracts insect pests, especially fruit flies.
In processing and storage:
As a first step, implement these post-harvest handling practices:

Sanitation
  • Have written cleaning and sanitation operating procedures for equipment and the facility.
  • Clean and sanitize packaging, handing bins and equipment regularly to prevent build-ups and habourages.
  • Regularly clean spills or trapped produce, especially in hard to reach areas and dead voids in packaging conveyer machines and equipment footing, as well as under and inside pallets.
  • Ensure floor drains have undamaged cover grids or traps to prevent trapping fruits and vegetables in the drain. This creates a breeding ground for fruit flies, drain flies and phorid flies.
  • Using drain brushes, mechanically clean floor drains at least every two weeks or so.
  • Ensure the floor is void of cracks and tile gaps. The floor should be smooth and level for effective cleaning.
  • Practice good fruit and vegetable waste management to avoiding attracting pests and creating harbourage sites.
Exclusion
  • Air curtains, sensor doors and roll-up doors keep flies from entering into processing or storage areas.
  • Install pest monitors like insect light traps and pheromone traps.
  • Repair screens and weather stripping around doors and windows.
Storage and Shipping
  • Use the first-in, first-out rule for storing and distributing products to avoid fermentation. Keep products off the floor on racked shelves.
  • Keep products refrigerated when you can. Temperature regulation and maintaining your cold storage system keeps the produce fresh and keeps pests away.
  • Allow proper illumination and ventilation to keep moisture down and discourage pest activity.
  • Avoid crisscross movement of packed produce to prevent pest contamination.
  • Ensure transportation vehicles are clean and temperatures are regulated.
  • Inspect packaging for pest activity prior to loading and shipping.
In addition to these preventive steps, be sure to monitor pest activity closely – indoors and outdoors. This will help you identify trends and adjust your pest management program to meet the unique needs of your property. You should also talk with your pest management provider about your process for storing and packaging food. They can offer recommendations specific to the types of produce you grow and help adjust your pest control program accordingly.

Alice Sinia, Ph.D. is a quality assurance manager with regulatory and lab services with Orkin Canada.
Published in Food Safety
Corteva Agriscience, Agriculture Division of DowDuPont, recently announced that the Pest Management Regulatory Agency (PMRA) in Canada has granted Dow AgroSciences new label registration for Closer Insecticide for the control of Campylomma verbasci (mullein bug) effective immediately.

This announcement is significant as it means Canadian apple growers now have full access to a highly effective product for pest control.

“Closer has always been known for its targeted and quick control of aphids and other orchard pests. With this registration, growers can have even greater confidence in the quality and efficacy of Closer on apples when outbreaks occur as well as for resistance management,” explains Tyler Groeneveld, category leader, Horticulture with Corteva Agriscience.

Closer Insecticide, powered by Isoclast active, is a revolutionary product ideal for control of both resistant and non-resistant pests, delivering the active ingredient sulfoxaflor, which is classified by the Insecticide Resistance Action Committee as the sole member of IRAC Subgroup 4C Sulfoximines.

The active ingredient moves quickly through the plant to deliver excellent systemic and translaminar activity. Pests are controlled both through contact and by ingestion, resulting in fast knockdown and residual control.

Closer is highly selective and has minimal impact on beneficial insects. The properties and overall spectrum of activity of Closer Insecticide makes it an excellent fit for treatment when outbreaks occur as well as part of Integrated Pest Management Programs (IPM) to minimize flare-ups. Further information can be found at: www.corteva.com.
Published in Insects
Health Canada’s Pest Management Regulatory Agency (PMRA) recently released its final decision on the future use of chlorothalonil, a fungicide used in agriculture including fruit and vegetable production.

“Under the authority of the Pest Control Products Act, the PMRA has determined that continued registration of products containing chlorothalonil is acceptable,” the report states.

“An evaluation of available scientific information found that most uses of chlorothalonil products meet current standards for protection of human health or the environment when used according to the conditions of registration, which include required amendments to label directions.”

Even so, some changes have been made to the chlorothalonil label, including cancellation of its use on greenhouse cut flowers, greenhouse pachysandra, and field grown roses (for cut flowers). As well, all chlorothalonil products currently registered as dry flowable or water dispersible granules must be packaged in water-soluble packaging. Buffer zones have also been revised and a vegetative filter strip is required.

You can review the decision and new label requirements by clicking here.
Published in Insects
Allium leaf miner (Phytomyza gymnostoma) an invasive pest of European origin, has recently been identified in several U.S. states, including: Pennsylvania (2015), New Jersey (2016), New York (2017), and Maryland (2017), representing the first records in the Western Hemisphere.

Allium leaf miner is an insect pest similar to leek moth, as it causes a substantial amount of damage to Allium crops at the larval stage. Larvae mine into the leaves, stalks, and/or bulbs of leeks, onions (dry bulb, green), garlic, shallots and chives. As they grow, larvae move towards the bulb and sheath leaves, where they often pupate. The galleries in the tissue leave the plant susceptible to infection by fungi and bacteria. Symptoms of feeding injury vary depending on the host plant and its stage of development. Very high rates of injury, including up to 100 per cent crop loss, have been reported. | For the full story, CLICK HERE.
Published in Vegetables
In the past 10 years, the invasive fruit fly known as the spotted-wing drosophila has caused millions of dollars of damage to berry and other fruit crops.

Biologists at the University of California San Diego have developed a method of manipulating the genes of an agricultural pest that has invaded much of the United States and caused millions of dollars in damage to high-value berry and other fruit crops.

Research led by Anna Buchman in the lab of Omar Akbari, a new UC San Diego insect genetics professor, describes the world’s first “gene drive” system—a mechanism for manipulating genetic inheritance—in Drosophila suzukii, a fruit fly commonly known as the spotted-wing drosophila.

As reported in the Proceedings of the National Academy of Sciences, Buchman and her colleagues developed a gene drive system termed Medea (named after the mythological Greek enchantress who killed her offspring) in which a synthetic “toxin” and a corresponding “antidote” function to dramatically influence inheritance rates with nearly perfect efficiency.

“We’ve designed a gene drive system that dramatically biases inheritance in these flies and can spread through their populations,” said Buchman. “It bypasses normal inheritance rules. It’s a new method for manipulating populations of these invasive pests, which don’t belong here in the first place.”

Native to Japan, the highly invasive fly was first found on the West Coast in 2008 and has now been reported in more than 40 states.

The spotted wing drosophila uses a sharp organ known as an ovipositor to pierce ripening fruit and deposit eggs directly inside the crop, making it much more damaging than other drosophila flies that lay eggs only on top of decaying fruit. Drosophila suzukii has reportedly caused more than $39 million in revenue losses for the California raspberry industry alone and an estimated $700 million overall per year in the U.S.

In contained cage experiments of spotted wing drosophila using the synthetic Medea system, the researchers reported up to 100 percent effective inheritance bias in populations descending 19 generations.

“We envision, for example, replacing wild flies with flies that are alive but can’t lay eggs directly in blueberries,” said Buchman.

Applications for the new synthetic gene drive system could include spreading genetic elements that confer susceptibility to certain environmental factors, such as temperature.

If a certain temperature is reached, for example, the genes within the modified spotted wing flies would trigger its death. Other species of fruit flies would not be impacted by this system.

“This is the first gene drive system in a major worldwide crop pest,” said Akbari, who recently moved his lab to UC San Diego from UC Riverside, where the research began. “Given that some strains demonstrated 100 per cent non-Mendelian transmission ratios, far greater than the 50 percent expected for normal Mendelian transmission, this system could in the future be used to control populations of D. suzukii.”

Another possibility for the new gene drive system would be to enhance susceptibility to environmentally friendly insecticides already used in the agricultural industry.

“I think everybody wants access to quality fresh produce that’s not contaminated with anything and not treated with toxic pesticides, and so if we don’t deal with Drosophila suzukii, crop losses will continue and might lead to higher prices,” said Buchman. “So this gene drive system is a biologically friendly, environmentally friendly way to protect an important part of our food supply.”

Co-authors of the paper include: John Marshall of UC Berkeley, Dennis Ostrovski of UC Riverside and Ting Yang of UC Riverside and now UC San Diego. The California Cherry Board supported the research through a grant.
Published in Research
A University of Maryland researcher has traced the origin of pest populations of the Colorado potato beetle back to the Plains states, dispelling theories that the beetle came from Mexican or other divergent populations.

Little was previously known about the beetle's origin as a pest, particularly how it developed the ability to consume potatoes and decimate entire fields so quickly. With its unique ability to adapt to pesticides almost faster than the industry can keep up, this beetle is consistently an issue for potato farmers. Using investigative evolutionary biology to determine the origins of this beetle and understand the pest's genetic makeup better, industry can better target pest management strategies to combat pesticide resistance and ultimately improve the potato industry.

The United States is the fourth largest producer of potatoes worldwide, producing over 20 million tons of potatoes each year. By comparing the genetics of pre-agriculture potato beetles, before the pest began to consume potatoes, to post-agriculture potato beetles, Dr. David Hawthorne of the Entomology Department and his team hope to understand why and how the beetle is developing resistance so quickly, and what can be done to slow resistance.

"The Colorado potato beetle is almost always one of the first insects to develop resistance to any pesticide. In fact, many contribute the entire pesticide arms race and development of pesticides to this particular beetle, which can destroy entire fields very easily," says Hawthorne.

"With this study," explains Hawthorne, "we were trying to gain insight into two major questions: Where did the potato beetle come from? And why do they evolve resistance so quickly? This would have major implications in controlling the pest, since the more growers have to spray, the greater their costs and risk to the surrounding environment. We need a strategy to weigh our options and determine the best way to control these pests without overspraying or even torching entire fields overrun with beetles, which has happened in the past when there has been no effective pesticide options."

Hawthorne and his team found that populations of beetles eating potatoes are most closely related to nightshade eaters in the Plains states. Beetles from Mexico, a possible source of the pest populations, were far too distantly related to have been the source of this beetles.

"Before they became pests, the plains beetles first evolved a taste for potatoes," says Hawthorne. "Some non-pest populations still don't eat them and will prefer the weeds surrounding the potatoes, but not the potatoes themselves. This is just one way that populations may differ."

By understanding the distinctions between these populations and which beetles are the source of current pest populations, more targeted pest management strategies can be developed based on the specific genetic makeup of the beetles, leading to more effective and less spraying.

Hawthorne describes this work as almost forensic biology, tracking the evolution and movement of this beetle across time and geography.

"I like that this work is very interdisciplinary," says Dr. Hawthorne. "It is about taking all the puzzle pieces and trying to put the whole story together to have the biggest impact on the field. Ultimately, this work is a major step towards understanding one of the most harmful pests, and has significant implications in controlling the population, keeping the potato industry stable, and fighting pesticide resistance and overspraying."

Dr. Hawthorne's study was published in The Journal of Economic Entomology.
Published in Vegetables
February 20, 2018, East Lansing, MI – This article provides a brief summary of some of the research being produced by some of the institutions participating in a project titled “Management of Brown Marmorated Stink Bug in U.S. Specialty Crops” funded by the United States Department of Agriculture (USDA) and National Institute of Food and Agriculture (NIFA). It is not a detailed summary of all the work being conducted within this project, but provides highlights from areas of the project that may be of interest to growers.

Researchers continue to track the movement and abundance of brown marmorated stink bugs. The largest populations and the most widespread damage to tree fruits is in the Mid-Atlantic region. In Michigan, we have seen brown marmorated stink bug numbers slowly build and currently the majority of the population is found in the southern third of the state with the highest numbers in the southern two tiers of counties. Damaging levels of brown marmorated stink bug do occur in localized areas north of this area and have produced fruit injury on individual farms north of Grand Rapids, Michigan, in the Ridge area.

The information required to detect the movement and relative numbers comes from trapping. A great deal of effort has gone into finding the most effective trap and lure. A variety of trap styles exist, but the pyramid trap baited with an attractant lure has been the standard way to detect brown marmorated stink bugs. Lures continue to be improved and the current standard is a two-part lure comprised of an aggregation pheromone and an attractant from a related stink bug.

A side-by-side comparison of the pyramid trap with an easier to use clear sticky trap on a 4-foot wooden stake using the same two lures has shown that the pyramid trap catches more stink bug adults than the clear sticky trap early in the season, and more adults and nymphs late in the season, but similar numbers mid-season. Importantly, the number of captured stink bugs on the clear sticky traps is positively correlated with the catch from the pyramid traps, which means the clear sticky traps could replace the pyramid traps and be used to determine presence, relative numbers and seasonal movement.

The pyramid trap was improved by replacing the dichlorvos strip killing agent with a piece of pyrethroid-impregnated netting. The pyrethroid in this case is deltamethrin. The netting is similar to mosquito netting used in malaria prevention programs and is commonly referred to as long-lasting insecticide netting. The benefits are that it lasts for the entire trapping season and is much safer to handle due to its low mammalian toxicity. Long-lasting insecticide netting also shows promise as a means of trapping brown marmorated stink bugs.

The most promising biological control agent continues to be a wasp parasitoid (parasites do not kill their host, but parasitoids do kill them) known as the samurai wasp, Trissolcus japonicas. This tiny wasp puts its own eggs into the stink bug’s eggs, and the developing wasp larvae use the stink bug egg for food until they emerge. In Asia, where brown marmorated stink bug originally came from, 60 to 90 percent of the eggs are parasitized by this wasp. Researchers in the U.S. have determined that the wasp highly prefers brown marmorated stink bug eggs over one of our native stink bugs eggs, spined soldier bug, so they should have little-to-no impact on them.

The USDA has yet to approve the general release of these wasps, but it is under review and could potentially happen at any time. Interestingly, like brown marmorated stink bugs, this wasp has been transported across the ocean. To date, populations have been detected in some Mid-Atlantic states and the Pacific Northwest and are slowly spreading on their own. However, if permission would be given by the USDA, they could be mass-reared and released where they would produce the greatest benefit.

Additionally, other brown marmorated stink bug predators and parasites, ones native to the U.S., have been identified and are being evaluated for their effectiveness. The particular insects attacking brown marmorated stink bugs vary according to habitat in each area. So far, the incidence of attack for these homegrown natural enemies of brown marmorated stink bugs is low.

Another area of interest is looking for ways to protect natural enemies from the negative effects of control procedures used against brown marmorated stink bugs. By carefully managing insecticide use, natural enemies may be preserved. One way to manage insecticide use is by establishing threshold levels for the pest. Determining an accurate threshold level requires testing over several years and in many orchard environments.

Research in West Virginia apple orchards has shown that a threshold of 10 brown marmorated stink bugs per trap can lower insecticide use by 40 percent compared to a grower standard program. A different trapping study compared brown marmorated stink bug captures in traps placed adjacent to wooded areas next to orchards to traps placed within orchards. The interior placement resulted in fewer nymphs captured, but adult catch was similar. However, there is still no clear relationship between the number of brown marmorated stink bugs captured in a trap and the amount of injury this level will cause in the orchard.

Insecticide assays in North Carolina showed that out of four Organic Materials Review Institute (OMRI)-approved materials – Entrust, Neemix, Pyganic, Azera – Entrust was the most harmful to two native parasitoid wasp species, even when exposed to 0.1-times the field rate. However, when exposed to residues of sugar-laced pesticides, only the lowest rate of Neemix had no impact.

In an Oregon study, more than half of the wasps exposed to dry residues of Actara, Asana or Admire Pro died within an hour of exposure. After 24 hours, mortality was greater than 75 per cent for those materials and for Entrust and Exirel, but not for Altacor.

A promising management tactic is attract-and-kill using pheromone-baited perimeter trees that receive either a regular insecticide application or have long-lasting insecticide netting within the canopy. Seven- and 14-day spray intervals using attract-and-kill or perimeter sprays were compared to 10 adults per trap (cumulative) threshold sprays of two alternate row middle applications and to a control. If the cumulative threshold level was met in the attract-and-kill or in the threshold spray plots, it also triggered two consecutive alternate row middle sprays.

Fruit injury was significantly reduced in the apple blocks using the perimeter sprays on seven- or 14-day intervals in the blocks using attract-and-kill with sprays at seven- and 14-day intervals or with long-lasting insecticide netting, and in blocks treated after reaching threshold levels of brown marmorated stink bugs, compared to the grower standard. This suggests perimeter sprays are an effective management tactic to employ against brown marmorated stink bugs.

Long-lasting insecticide netting placed in attract-and-kill trees in a vertical orientation killed more brown marmorated stink bugs than when the fabric was oriented horizontally. The level of injury to peaches and apples under grower standard programs was similar to the injury found when just orchard perimeters consisting of the exterior row plus one row toward the interior were sprayed. This did not hold for peaches if the orchard was 10 acres or more in size.

Another use of long-lasting insecticide netting is to drape a 5-foot by 5-foot section of it over a pole or fence and attach an attractant to the netting. Several of these are placed on the orchard perimeter between woods and the orchard. Brown marmorated stink bugs attracted to the lure come into contact with the pesticide in the netting and die. This may allow for interception of the adults before they enter the orchard resulting in less fruit damage.

Multi-state research efforts allow researchers to quickly acquire information that would take individual states or regions many years by themselves. Most of these experiments will be repeated in 2018 and new ones will be added as we continue to grow the knowledge base that allows us to successfully meet the challenges that brown marmorated stink bugs bring to the tree fruit industry.
Published in Research
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