Corn earworm Corn earworm:  Blake Layton, Mississippi State University

What’s ahead for insects in 2018?

Entomologists offer insight into what growers may be facing, which pests may dominate and suggestions on handling them in 2018.

Patrick R. Shepard | Dec 05, 2017


What’s the expected insect spectrum and intensity for Mid-South corn in 2018?  We asked regional university entomologists to offer insight into what growers may be facing next year, and to mention a few tools that could be of help.

Tennessee: No surprises are expected in Tennessee corn in 2018, says Scott Stewart, University of Tennessee Extension entomologist at Jackson. “Between seed treatments and Bt technology, we just don’t have consistent major problems in corn. Of course, there are always special circumstances where you might want to bump the rate on a seed treatment, or use an additional at-planting treatment.

“We’re seeing more corn earworm larvae and injury to corn tips in Bt corn, but our research indicates it’s not causing a significant economic effect. However, those worms are being pre-selected for tolerance to Bt toxins, and when they migrate to cotton, they can cause an economic effect in that crop.

“Additionally, we still have some conventional corn being grown, and sometimes have issues with either southwestern corn borer or European corn borer on non-Bt acres.  The intensity of those worms depends on the winter, and we’ve had two warm winters in a row.”

Louisiana: Growers planning to plant corn behind corn in 2018 are urged to use a substantial seed treatment, says Louisiana State University Entomologist Sebe Brown at Winnsboro.

“Our below-ground corn pest complex, which includes wireworms and southern corn rootworm, can cause economic damage and crop delay. I don’t recommend anything less than Poncho 500, if it’s corn behind corn, especially if they don’t run anything in-furrow, such as Counter or Force. You just have to be careful with some of the in-furrow insecticides that have organophosphates in them; when you mix them with some herbicides, it can cause antagonism issues that can stunt corn. If you’re planting on rotated ground, you probably can use Poncho 250 for below-ground insect control.

“If you plant corn in a timely window, you might get some tip feeding and ear feeding by worms, but the damage won’t contribute to yield loss.”

Arkansas: Cutworms were especially bad in Arkansas corn this past season, partly due to the previous mild winter, and more stink bugs attacked seedling corn than in the past. Many growers are using cover crops, which can exacerbate cutworm and stink bug problems.

Boris A. Castro, LSU

Southwestern corn borer


“I’m basically recommending that if corn growers plan to plant into a cover crop, they go with at least a 500 rate, and consider using the highest rate, on their seed treatment,” says University of Arkansas Entomologist Glenn Studebaker at Keiser.

The state’s conventional corn acreage has expanded due to a local poultry producer who markets chickens fed on non-GMO grain, and who pays growers a premium on conventional corn. About 35,000-plus acres of conventional corn was planted, mainly in northeast and central Arkansas.

“That means we closely track southwestern corn borer, which is a major pest in non-Bt corn,” Studebaker says. “We saw a pretty good blip on this pest, mainly in three counties, so growers in that area were alerted and they sprayed. We recommend that growers planting conventional corn use a southwestern corn borer pheromone trapping program. Our threshold is 50 per trap per week for the first generation, and over 100 per trap per week for the second generation, which usually are the ones that cause problems. That usually occurs around the end of June or the first of July.”

Mississippi: “The biggest insect problem in 2017 was stink bugs in seedling corn,” says Angus Catchot, Mississippi Extension entomologist at Starkville. “That problem doesn’t always pop up, but we had to treat a lot of acres this past season for stink bugs, which might have had something to do with the mild winter.

“We also think the damage may be occurring much earlier than we once thought, so we recommend scouting for stink bugs at an even earlier stage. A lot of the damage might be occurring around V1 or V2.  Seed treatments have some effect on stink bugs, but it’s not a standalone because they have to feed to ingest the material. So, we need a good scout-and-spray approach, using foliar sprays of bifenthrin, when economic thresholds are reached.”


Mid-South soybean growers learned in 2017 just how costly redbanded stink bugs can be. Area university entomologists offer suggestions on handling this and other insect pests in 2018.

Mississippi: The insect story for the past season was the redbanded stink bug, says Angus Catchot, Mississippi Extension entomologist at Starkville. “Many growers found out how damaging and costly this pest can be. It’s very sensitive to cold winters, so the severity of this winter will dictate the level of the problem in 2018, or if we’ll even have a problem.

Louisiana State University

Redbanded stink bug


“We’ll conduct surveys of ditchbanks and watch the weather to see if the redbanded stinkbug is able to overwinter again in Mississippi and other Mid-South states. We’ll know before the 2018 season starts. The earlier we can plant the bulk of the soybean crop, the fewer sprays we’ll have to make for this pest, and many others. The sweet spot for planting soybeans ranges from end of March to about April 20, depending on weather. This early window results in the best yield potential and minimizes insect sprays.”

Bollworms can be expected again in 2018, Catchot says, but they usually are effectively controlled by foliar insecticides — it’s easier to optimize spray coverage in soybeans than in cotton. Additionally, the kudzu bug is present in some Mississippi soybean fields, but it has not become a major pest. But, high populations left untreated can reduce yields, so they need to be watched.

Louisiana: The time soybeans are planted is the determinant of most soybean insect issues in the state, says Louisiana State University Entomologist Sebe Brown. Regardless of whether planting is early or late, growers are urged to use an insecticide seed treatment.

“We see a yield benefit with a seed treatment when beans are planted very early, with good temperatures and slow growth,” he says. “We also see an economic benefit with a seed treatment on beans planted very late, typically behind wheat, or where you have a dirtier field that has three-cornered alfalfahoppers and other insects that feed on soybeans.

“I recommend using a seed treatment for any soybeans planting date,” Brown says, “because Louisiana weather is so dynamic that nobody can predict what it will do. The temperature might be hot for a week, then turn off cold for two weeks. In fact, I recommend a seed treatment for every agronomic crop that we grow in Louisiana.”

If a frigid winter occurs, redbanded stink bug numbers are expected to be low at the start of the 2018 season. “South Louisiana will have to deal with them, regardless, because it doesn’t get cold enough south of Alexandria,” Brown says. “If we have another mild winter, I recommend to our growers that they budget for at least three to five stink bug applications. If you plant early, you might get away with one or two applications; if you plant late, you might wind up using all five.”

Mississippi State University

Soybean looper


Louisiana growers also can count on having soybean loopers every year, and the later the beans are planted, the more insect pressure that will occur. “The earlier you can plant beans, the more money you will save on insect sprays,” Brown says. “Growers who get in the last week of March and the first week of April can be harvesting in late July, early August. They miss late-season rains, insects, and hurricanes, and they do well on yield.”

Arkansas: In 2017, the state’s soybean growers were still fighting redbanded stink bugs as late as October, says University of Arkansas Entomologist Gus Lorenz at Little Rock. How big a problem they will be in 2018 depends entirely on the winter, he says. “A cold winter, with extended periods below freezing — unlike what we’ve had the previous two years — could eliminate redbanded stinkbug as an economic pest in soybeans.”

Weather also determines the intensity of pressure for the state’s other key insect pests, including soybean loopers, fall armyworms, and southern green stink bug. “They’re usually migratory, but mild winters have caused a lot of overwintering of these pests here in Arkansas,” Lorenz says. “As a result, this past season they started out earlier and in bigger numbers than normal, and were able to build up to extremely high populations that caused problems.”

Bollworms, the No. 1 pest in Arkansas, were able to build in 2017, not only because of the previous mild winter, but also due to pre-selected ones that came through traited Bt corn. “We had a much higher survival than we’ve seen in previous years,” he says. “When you have a higher survival rate coming through corn, then you have more resistant worms getting into the other crops, including soybeans, cotton, and grain sorghum. So, we saw a breakdown of Bt traits in corn, soybeans, and cotton. In 2018, we’ll watch how worms are doing in traited corn hybrids, because their survival rate will bleed over into soybeans and cotton.

“Many insect pests are going into overwintering this year because of the extremely high numbers that we’ve had this season,” Lorenz says. “We need some good overwintering mortality to knock numbers down, and hopefully stunt the increase of migratory pests.”

Tennessee: Two warm winters in a row have complicated the Mid-South soybean insect spectrum, says Scott Stewart, University of Tennessee Extension entomologist at Jackson. “The two biggest problems we have in soybeans are corn earworms and redbanded stink bugs. West Tennessee experienced a little redbanded stink bug problem in 2017, but if we have another mild winter, it could potentially become an issue in our soybeans in 2018. On the other hand, if we have a hard winter, we might not see this pest in the upper Mid-South next year. It is very cold-sensitive — but it’s also very mobile and hard to control.

“The kudzu bug has not materialized into the pest problem we originally thought it might be,” Stewart says. “Part of that is due to some of the biological controls. A naturally-occurring fungus, Beauveria bassiana, has done a remarkable job of holding kudzu bug populations in check, and some areas also have a parasitoid that attacks the eggs. But, it’s still a significant problem in some places, and we’ve had some scenarios in West Tennessee where we had to spray for kudzu bugs. A hard winter would help us with this pest, too.

“Some of the corn earworm problems are driven by larvae escapes in corn; those worms migrate into soybeans and cotton, where they can cause economic damage. We also always keep an eye on soybean loopers and stink bugs.”


Cotton insects are variable — there are good years for some, and bad years for some. That’s what insects do, say Mid-South university entomologists who offer insight into which pests might dominate in 2018, along with tips for what you can do about them.

Tennessee: The three big insect players in the state’s cotton are thrips, tarnished plant bugs, and bollworms, according to Scott Stewart, University of Tennessee Extension entomologist at Jackson. “We’re pretty much status quo on thrips control. We know we have some resistance issues with the neonicotinoids, but we’re managing that problem, and I don’t foresee any big changes in 2018.

“The Mid-South had a lighter than normal plant bug year in 2017, so my guess is that next year we won’t. But, plant bugs are a manageable problem, and we do a good job with the available tools. It would be nice, though, to have some more insecticide options.”

A big issue that concerns everyone is the increasing resistance to Bt in bollworm populations. “We’re not seeing the level of bollworm control that we’ve had in the past with the Bt technologies: Widestrike, Bollgard II, and TwinLink,” says Stewart. “We will still be growing those traited varieties in 2018, so we’ll have to be a little more aggressive in spraying bollworms, and invest a little bit more money in insecticides to control the problem. The other option is to switch over to some of the newer technologies: Widestrike 3, Bollgard III, and TwinLink Plus.”

Some growers spray a high rate of Orthene, or a pyrethroid+Orthene tank mix to kill some of the bollworm moths, possibly reducing egg lay. “However, bollworms are very migratory pests, and are constantly swarming in an area, so spraying just some fields probably has a negligible impact,” he says. “We’re also seeing less control of bollworms than we saw in the past with pyrethroids, so growers are switching over to newer chemistries, which are more expensive, but more effective.”

Tennessee also experienced more problems with spider mites and aphids in 2017 than normal, and Stewart expects issues to continue because of the well-documented aphid resistance to neonicotinoids. “With spider mites, in past years, we grew a lot of Liberty-tolerant cotton and sprayed two applications of Liberty over that cotton.


Corn earworm in cotton


“Liberty is pretty good at controlling spider mites, even though it’s a herbicide. So, those two early season Liberty applications suppressed mites. This past year, the dynamics changed with the big shift to dicamba-tolerant cotton, and we had a lot less Liberty applied. I think that’s one reason we had more consistent spider mite problems in 2017.”

Louisiana: Cotton growers in the state can always count on having thrips, says Louisiana State University Entomologist Sebe Brown at Winnsboro. Fortunately, they have several seed treatment options to control the early season pest.

“For example, Aries seed treatment offers great protection, and Gaucho also performs well in our state,” he says. “Depending on environmental conditions, you might have to come back with a rescue spray. We also can use an in-furrow application of Ag Logic 15G aldicarb, which performs as well as the old Temik. If you have nematodes, I highly recommend running aldicarb.”

Cotton growers can also count on plant bugs. Brown says Transform provided really good control this past season, and all the standards, including acephate and Bidrin, performed well. “We recommend rotating chemistries, and using Diamond insect growth regulator every other application. I especially like the higher rate of Diamond, 8 ounces to 9 ounces.

Escape bollworms were really bad in Louisiana cotton this past season, he says. “I saw escapes in all three technologies:
Widestrike, Bollgard II, and TwinLink. For 2018, I recommend planting Widestrike 3, Bollgard III, and TwinLink Plus — all have the Vip trait. We’re partly seeing worm escapes in older Bt technology because they are pre-selected in Bt corn.

“Prevathon and Besiege are working well for controlling worms. Growers just need to make sure they have good coverage. They may need to use higher gallonage — a minimum of 10 gallons per acre by ground — and higher rates: Prevathon 20 ounces per acre, and Besiege 10 ounces.”

Arkansas: Spider mites continue to be a problem in northeast Arkansas cotton; the pest survives on many hosts and gets an early start. There also may be some association with cover crops and no-till that help to exacerbate the issue.

Mississippi State University

Tarnished plant bug


“Spider mites got an early start this past season,” says University of Arkansas Entomologist Gus Lorenz at Little Rock. “We rely almost entirely on neonicotinoid seed treatments, which don’t help the matter at all. Spider mites also blow up after growers make a couple of applications of organophosphates or pyrethroids for thrips. Sometimes it seems when cotton comes out of the ground, it’s got mites on it.”

Arkansas producers have also been seeing more resistant bollworms; the number of escape bollworms coming through traited corn means they have already been exposed to Bt before they get to cotton. “We sprayed more acreage in 2017 for bollworms in cotton than ever before, and actually sprayed in areas where we haven’t had to spray before — which indicates we’re losing control in Bt cotton,” Lorenz says.

“Additionally, we just had a big year of bollworm numbers; we had a rolling population that just kept coming in — there weren’t distinct generations. Our moth trap numbers weren’t higher than what we had in 2016, though, which indicates to me that there’s more survival of worms coming through the Bt technology in corn.”

Compared to other years, 2017 was a fairly light plant bug year, Lorenz says. Some growers battled populations in cotton next to corn, or CRP fields, or early-planted soybeans. “But overall, we were probably off one or two applications for plant bugs statewide this year. For whatever reason, the colder the winter, the greater the plant bug population. They overwinter in the state on wild hosts.”

Mississippi: Because of resistance to some neonicotinoid seed treatments, Mississippi recommends going to an imidacloprid-based seed treatment, and supplementing it with either an acephate overtreatment, acephate seed treatment, or acephate sprayed in-furrow to minimize foliar thrips sprays.  “We had great success controlling thrips with this program in 2017,” says Angus Catchot, Mississippi Extension entomologist at Starkville.

Mississippi cotton growers made many sprays for bollworms in Bollgard II cotton in 2017. “Going into 2018, we need to take a hard look at the newer trait technologies, such as Bollgard III, WideStrike 3, and TwinLink Plus,” Catchot says. “Review the yield of these new varieties in county trials and state OVTs, and plant the ones best suited to your farm in order to minimize foliar sprays for bollworms.”

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Asian citrus psyllid
Researchers led by a UC Davis scientist discover sex pheromone for the Asian citrus psyllid.

Scientists discover sex pheromone for Asian citrus psyllid

Team led by UC Davis professor discover sex pheromone for the Asian citrus psyllid

Farm Press Staff | Dec 11, 2017

Researchers are closer to a pheromone trap for the Asian citrus psyllid (ACP) pest.

The finding was announced recently in Brazil by Dr. Walter Leal, a chemical ecologist with the University of California. Leal led a team of scientists from UC Davis, University of Sao Paulo, and the Fund for Citrus Protection (FUNDECITRUS) from the state of Sao Paulo.

 The ACP can vector the deadly bacterial disease Huanglongbing which infects citrus trees and there is no cure. The disease has been found around the world and has decimated citrus groves in Florida. The disease has been found about 250 times in California in residential citrus but so far not in commercial citrus.

“Dr. Leal’s discovery of the Asian citrus psyllid pheromone is a significant breakthrough in preventing the spread of this serious citrus insect, and may offer a less toxic method for its control,” said University of California integrated pest management specialist Frank Zalom. He is the past president of the Entomological Society of America and was not involved in the study.

Identifying the sex pheromone proved “complicated and quite a challenge” due to the insect’s complex behavior and biology, said Leal, a UC Davis distinguished professor who has discovered the sex pheromones of moths, beetles, bugs, cockroaches, mites and other arthropods.

A patent was filed Dec. 1, and journal publication is pending.

California officials currently use a yellow card with adhesive. The color is believed to attract the ACP and other insects. However, it’s been called a ‘blunder trap’ by some officials that may offer no significant attractant to the ACP, and at certain times of the year may not attract psyllids.

“Having a lure to dramatically improve captures of this psyllid with the conventional sticky traps is a major progress toward integrated pest management,” said professor Jose Robert Parra of the University of Sao Paulo.



Fall armyworm feeding on sorghum in Niger

 How do we fight the Fall armyworm, the new wound of African agriculture ?

Two years after its first detection in West Africa, this invasive caterpillar is threatening the food security of millions of small farmers in over 30 African countries. To solve the future food needs in sub-Saharan Africa, entomologists must be a critical part of the puzzle. From Nigeria to Ethiopia, South Africa to Chad, African smallholder farmers often face severe crop losses from damaging bugs from locusts to cassava’s whiteflies, cowpea pod borers or maize and sorghum stem borers. According to the Center for Agriculture and Biosciences International (CABI), pests, (some emerging due to climate change or shifts in land use), reduce African crop harvests by 50%. Most smallholder farmers don’t have the ability to diagnose crop problems quickly and often have no means or knowledge to control these pests. With climate change and increased movement of goods and people, emerging pests will worsen an already serious problem.

Now, a foreign caterpillar from the Americas, the fall armyworm (FAW) Spodoptera frugiperda is quickly invading the continent, swallowing entire fields of maize, but also sorghum, millets and many other staple crops.  There were already armyworms in Africa –worldwide – but the fall armyworm is particularly voracious and versatile, and spreads fast. Targeting over 80 crop species, the caterpillar eats day and night. It’s life cycle can be as short as 30 days and the adult moth is able to fly 100km a night. It is no surprise then that it has invaded over 30 African countries since it was first reported in Nigeria in early 2016. The pest poses a serious threat to the food and nutrition security of millions of farming households in sub-Saharan Africa. According to CABI, the FAW could potentially cause maize yield losses in a range from 8.3 to 20.6 million tons annually in Africa, worth between 2.5 and 6.2 billion dollars, in the absence of any means of control, in just 12 maize-producing countries. But FAW attacks concern also many other important food crops including sorghum and millets, where damages were reported for example in Ethiopia, Kenya, Malawi, Mali, Niger and Rwanda. So what could be the response to this pest problem that is here to stay?

Chemical or natural ways to control the FAW 

Looking at what happens in their native lands in Americas, when caterpillars damage over a quarter of the crop field, systemic pesticides are recommended. Some scientists have noted in the past some excesses which have harmed farmers health and the environment without economic sense, alongside building FAW’s pesticide resistance. Pesticide use may be considered against FAW invasion – plant breeders on ICRISAT research stations used it this summer to protect their experiments – but most of the chemicals that control FAW are not tested and registered in most African countries. Therefore, there is a need to evaluate and fast track registration of effective chemicals for the control FAW. This chemical response is however expensive and often out of reach of most smallholders, and will certainly not be used for their staple food like sorghum and millet.

Natural ways to combat FAW can be an efficient and appropriate approach. Biological control, ie the use of natural enemies of a pest, is a successful approach for many devastating insects like pearl millet head borer which can be almost eradicated by parasitic wasps. FAW has several enemies (predators, parasitoids and pathogens) in its native continent but they may be different than the enemies of the local armyworms species. It is advised to list an inventory of possible natural enemies present in Africa, focusing on parasitoid Telenomus wasps, which control quite well the population of FAW in the Americas. About 11 Telenomus species parasitizing many Lepidoptera insects in Africa could be tested for effectiveness against FAW.  If no indigenous biological control is effective, some parasitoids could be introduced from the Americas after careful pre-release studies. After defining the effective biological control methods, local production of parasitoids should be set up. This could however take years.

Biological pesticides such as the spray application of Bacillus thuringiensis or nuclear polyhedrosis virus (NPVSf) have shown good results against FAW and could be tested in the context of African farms. However, this solution could be out of reach for most small farmers.

Plants also have the extraordinary capacity to repel or attract insects by emitting specific volatiles. Some “call” caterpillar enemies, such as wasp parasitoids, when the caterpillar starts feeding on the plant. Other plants repel – like the tropical forage legume Desmodium – or attract FAW. A push-pull strategy using Desmodium as intercrop and Brachiaria another forage crop as border can reduce by more than 80% FAW damage as this recent study from the International Center of Insect Physiology and Ecology (ICIPE) shows. Such habitat management approaches including crop rotations, intercropping with compatible companion crops and conservation agriculture need to be tested as such options are more manageable for smallholder farmers.

Developing and distributing resistant varieties could be central to an Integrated Pest Management strategy against FAW. ICRISAT has already developed sorghum lines resistant to stem borer (Lepidoptera) that will be evaluated for responses to FAW, working closely with EMBRAPA-Brazil who has in the past screened sorghum germplasm for FAW resistance. Two potential sorghum lines have been identified in the ICRISAT Genebank, which could be useful for breeding for FAW resistance.

Yet, this breeding effort will also take several years to achieve results, and then there will be the “seed systems challenge” of disseminating these improved seeds to farmers.

Providing a rapid response to African smallholder farmers

While FAO and other players are debating big plans to combat FAW, African smallholder farmers need fast responses to save their harvests in the months to come, faster than plant breeding, biopesticides or biological control. If we take a closer look at the insect cycle and impact on the plant, may be it is a change of perspective that is needed.

First we need to know the extent of the problem. Mobile technologies could help map in real-time the exact location of the attacks. With the fast adoption of smartphones across the continent (about 300 million users already), African farmers could access mobile plant diagnosis applications such as Plantix to check if their field is affected by FAW – there are 30 different types of armyworms (Spodoptera genus), some other than the fall species, creating havoc in some Indian States this year due to favorable weather conditions – and report it to the online community. FAW Hot spots mapping could help assess the damages, understand and forecast future outbreaks and plan long-term FAW management.

Farmers may also have to accept limited damages to the adult crop up to a certain level, let’s say 20%, and invest on protecting seedlings with affordable seed treatment, coating seeds with an appropriate pesticide and fertilizer blend that would protect the seedlings to avoid total wipe out of the crop if the caterpillar attacks early. When feeding on seedlings, FAW may eat buds and tipping points, killing the plant.

Seed treatment is far more affordable for small farmers than spraying the field when the crop has matured, and worth the investment. In West Africa, ICRISAT scientists have demonstrated that 2$/ha of millet and sorghum seed treatment with Apron Star could protect seedlings from pests and fungi up to 40 days, improve crop density by a quarter and yields by up to 50%. Training of farmer organizations and the distribution of small packs of seed treatment, could be implemented quite quickly with the right public private partnership.

While the presence of the fall armyworm is now irreversible in Africa, as insects know no borders, there is now a collective international effort to control its damage. The scope and speed of fall armyworm destruction show how African smallholder farming is vulnerable to emerging risks. It is important that varied approaches to tackle this emerging pest are explored, from biological control, biopesticides to pest tolerance crop breeding. But because so many farming families have no other livelihoods and safety nets, research should focus also on delivering scalable and affordable solutions for the next season.

About the authors

Jerome Bossuet
Co-Head – Communications and Partnerships
Strategic Marketing & Communication
Dr Malick Niango Ba
Country Representative – Niger
West & Central Africa Program

Article page: Click here


Dear Colleagues

We are now less than 9 months from the start of the XV International Congress of Acarology (XV ICA2018) in Antalya, Turkey from 2-8 September, 2018 (http://www.acarology.org/ica/ica2018/).

As the countdown continues, we are 10 days from the deadline for proposals for symposia and seminars.

If you are interested in convening a symposium or seminar in the subject areas below, please contact the scientific secretary at ica2018turkey@gmail.com by 22 December, 2017 to register the topic and get the process underway.

Agricultural acarology

Alternative pesticides

Aquatic acarology


Biological control

Chemical control and resistance

Dispersal of mites and ticks

Ecology and behavior of mites

Ecology and behavior of ticks

Evolution and phylogeny

Forensic acarology

Integrated pest management

Invasive species and biosecurity

Medical acarology

Population dynamics

Soil acarology

Taxonomy and systematics

Veterinary acarology

The congress website at http://www.acarology.org/ica/ica2018/ has all the up-to date congress details, including registration and accommodation.

Please note the deadlines for abstract submission (1 March 2018) and bids for staging XVI ICA 2022 (1 March 2018) are fast approaching.

For congress related enquiries, please contact kongre@bilkonturizm.com.tr and for scientific matters, ica2018turkey@gmail.com

The Organising Committee would greatly appreciate your forwarding this reminder to colleagues, and also to related institutions and societies, with a request that they kindly post a link to the XV ICA 2018 website.

See you in Antalya next September!

All the best

  On behalf of the Organizing Committee
Prof. Dr. Sebahat K. Ozman-Sullivan
President, XV ICA 2018




VA Tech logo

Invasive plants have surprising ability to pioneer new continents and climates, Virginia Tech researchers discover

December 4, 2017

Velvetleaf plant
Velvetleaf represents one of the many invasive plant species that was tested by Dan Atwater and Jacob Barney.

Virginia Tech scientists have discovered that invasive plant species are essentially able to change in order to thrive on new continents and in different types of climates, challenging the assumption that species occupy the same environment in native and invasive ranges.

It’s no secret that globalization, aided by climate change, is helping invasive species gain a foothold across the planet, but it was something of a surprise to Virginia Tech researchers just how mutable these invaders are.

The study, by Jacob Barney, an associate professor in the College of Agriculture and Life Sciences’ Department of Plant Pathology, Physiology, and Weed Science, and Dan Atwater, a lecturer in the Department of Biological Sciences at North Carolina State University and Barney’s former post-doctoral advisee, was published Dec. 4 in Nature Ecology and Evolution, a new online journal.

Two Virginia Tech researchers
Dan Atwater, left, and Jacob Barney examined 815 terrestrial plant species from every continent, along with millions of occurrence points, and compared models in the largest global invasive species study to date.

“This is important for both changing how we think about species and where they grow,” said Barney, who is also a fellow in the Fralin Life Science Institute and an affiliate of the Global Change Center. “The findings also change our ability to predict where they will grow and how they may respond in a changing climate. This could be a game-changer for invasive species risk assessment and conservation.”

Atwater used data compiled by undergraduate Carissa Ervine, also an author on the paper, to test a long-held assumption in ecology – that the climate limitations of plants do not change, which means we can predict where they will grow. Small studies supported this supposition. However, the Virginia Tech researchers blew this assumption away by testing more than 800 species using new models developed by Atwater and Barney.

“Some people would say that invasive species have different distributions in a new climate. But we found they are occupying a wider range of new climates,” said Atwater. “Species are changing in their ecology when they move from one continent to another. We should expect species to change, possibly permanently, when they cross continents.”

The results have major consequences for applying environmental niche models to assess the risk of invasive species and for predicting species’ responses to climate change. Species capable of changing their ecology and the climates they call home may pose a challenge to researchers using native range data to forecast the distribution of invasive species.

The driver behind the study was a desire to forecast the future distribution of invasive species, which pose a serious threat to human, environmental, and economic health. The researchers began by posing the question: Do invasive species occupy the same climate in invasive range that they do in their native range? To find out, they compared native and invasive species.

Barney and Atwater examined 815 terrestrial plant species from every continent, along with millions of occurrence points, or locations where the plants have been known to occur, and compared models in the largest global invasive species study to date. They found evidence of climatic niche shifts in all of the 815 plant species introduced across five continents. A climatic niche refers to the set of climates in which a species has a stable or growing population.

Generally, their findings suggest that niche shifts reflect changes in climate availability at the continent scale and were the largest in long-lived and cultivated species. If species move to a warmer continent, for instance, they tend to shift toward occupying warmer climates. In short, cultivated plants with long lifespans are particularly adept at making themselves home in new climates.

“There are not only implications for predicting where invasive species will occur, there are management repercussions as well,” said Barney. “As an example, for certain species we use biocontrol, introducing one organism to control another, an approach that may not be effective or safe if the targeted species undergoes ecological change. When we do climate modeling, we assume the climate niche may be the same when it may not be. So, there are a broad range of implications in a broad range of fields.”

Barney raised another concern.

“By cultivating species — bending them for agricultural or ornamental purposes and selecting for traits, such as cold-hardiness, we push them into environments they would not have occupied,” he said. “Those selection pressures in breeding, plus the environments we put them in, may exaggerate this change. Short-lived species, for example, go into dryer climates. So the take home is that different species’ traits influence the direction of a niche shift.”

Once Atwater and Barney understand these drivers more fully, they hope to be able to predict how the geographic range of an invasive species will increase in order to pinpoint areas likely to be invaded.

“The other piece layered onto this is the assumption that the climate is stable, which is not the case,” said Atwater. “We have also relied on the assumption that a species is a species and its ecological tendencies remain constant. This too is not the case. Species vary in space and time. They behave differently on different continents and in different climates. Consequently, the concept of a species climatic niche is less stable and less clearly defined.”

With food production, human health, ecosystem resilience, and biodiversity at stake as global invasions outpace our ability to respond, a greater understanding of climatic niche shifts is critical to future attempts to forecast species dynamics, according to the researchers.


—      Written by Amy Painter



Black Sigatoka management

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Research reveals mechanism making banana fungus less responsive to crop protection

An international team of scientists led by Wageningen University & Research has discovered a new genetic mechanism that makes the notorious Black Sigatoka fungus less sensitive to the main chemical crop protection products used against the disease.
The discovery shines light on this increasingly reduced sensitivity and underlines the importance of developing banana varieties resistant to the fungus which causes Black Sigatoka.
Pseudocerospora fijiensis, the fungus causing the dreaded Black Sigatoka disease in banana cultivation, is tackled with chemicals. In practice, this requires farmers around the world to spray against the disease between 35 and 70 times a year. One specific type of fungicides, the so-called demethylase inhibitors (DMIs), form the backbone for managing the disease. Unfortunately, the fungus is becoming increasingly less sensitive to these products on a global scale.
Dr Pablo Chong conducted his PhD research under the supervision of Gert Kema, professor in tropical phytopathology at Wageningen University & Research. The working hypothesis was that “we thought that the reduced sensitivity of the fungus was caused by changes in the protein, a demethylase enzyme, which is the target of the DMIs” Kema says.
“As a result we only looked at mutations in the segment of the gene that encodes the enzyme. What we found is that the reduced sensitivity is also caused by changes in the promoter, the switch that controls the gene. In the promoter we discovered a segment of DNA that is concatenated up to six times. The larger the number of DNA-repeats in the promoter, the less sensitive the fungus.”
The less sensitive Black Sigatoka strains that were found in banana cultivation and studied by the team all had a combination of mutations in the encoding part of the gene as well as DNA-repeats in the promoter.
Kema: “Mutations in the coding segment of the gene reduces the ‘docking’ of the compound in the enzyme, while the DNA repeats in the promoter make the gene extra active. These two factors together appear to ensure that the fungus has so much well-functioning enzyme in its cells that it is far less affected by the crop protection. As a result, the banana plants develop disease despite the application of these products.”
The findings emphasise the importance of smart crop protection, using not only DMIs but also fungicides that function in a completely differently way. This will slow the pace of reduced sensitivity in the fungus.
“The results of our research also underline the importance of developing Black Sigatoka resistant banana varieties” concludes Kema. “This is the only way to make global banana cultivation more sustainable.”
For more information:
Erik Toussaint
Wageningen University & Research 
Tel: +31 651 56 59 49

Publication date: 11/22/2017