Archive for the ‘Migratory insects’ Category

East Africa gets ready for return of destructive locust swarms

In 2020, East Africa was struck by the worst locust plague in decades. Unfortunately, now, the swarms are returning.

The locusts invading East Africa last year ravaged crops and pastures and drove the levels of hunger and economic hardship higher in parts of the region. One year later, right at the start of 2021, the United Nations has warned that a second and maybe even deadlier return of locusts has already begun.

The first wave of the pests emerged at the end of 2019, numbering in hundreds of billions, multiplying by a factor of 20 per generation, according to the UN Food and Agriculture Organization (FAO). The second generation in March and April numbered in the trillions. A plague that spread like wildfire — up to now.

Image: FAO / DUS

View Post

“It’s a continuation of the 2020 locusts swarm. The adults have flown to various areas and are laying eggs”, Frances Duncan, Professor of Animal, Plant & Environmental Sciences at the University of the Witwatersrand, told DW. “If we have good rains like it is the case at the moment in most areas, the hoppers will hatch, and we get the second wave of the swarm.”

However, Keith Cressman, FAO’s Senior Locust Forecasting Officer, remains optimistic. “I think it’s still a very dangerous situation. But it should not be worse as it was last year.” According to the weather forecast, the months to come should be dry, reducing the locusts’ reproductive rate.

Publication date: Wed 6 Jan 2021

Read Full Post »

The Economist

A plague of insects
Why locusts swarm

A new discovery could offer novel ways of controlling the insectsScience & technologyAug 15th 2020 edition

Aug 15th 2020

  • In some parts of the world, covid-19 is not the only plague that 2020 has brought. In parts of Asia and east Africa, swarms of locusts have stripped fields. The un reckons the swarms in India and Pakistan are the largest for a quarter of a century, and that the numbers in Kenya are the highest for 70 years. One swarm in northern Kenya was estimated to be 25 miles (40km) long and 37 miles wide.

Locusts are usually inoffensive, solitary creatures that do not stray far from the place that they were born. But under the right circumstances—namely heavy rain, and a subsequent boom in plant growth—they can become “gregarious”. When that happens the insects change colour and gather in ravenous swarms which can fly more than 100km in a day.

Read Full Post »

Rising carbon dioxide levels pose a previously

July 10, 2018, University of Michigan
Researcher Leslie Decker with a monarch butterfly in a University of Michigan laboratory. Credit: Austin Thomason/Michigan Photography

A new study conducted at the University of Michigan reveals a previously unrecognized threat to monarch butterflies: Mounting levels of atmospheric carbon dioxide reduce the medicinal properties of milkweed plant that protect the iconic insects from disease.

Milkweed leaves contain bitter toxins that help monarchs ward off predators and parasites, and the plant is the sole food of . In a multi-year experiment at the U-M Biological Station, researchers grew four milkweed species with varying levels of those protective compounds, which are called cardenolides.

Half the were grown under normal carbon dioxide levels, and half of them were bathed, from dawn to dusk, in nearly twice that amount. Then the plants were fed to hundreds of monarch caterpillars.

The study showed that the most protective of the four milkweed species lost its medicinal properties when grown under elevated CO2, resulting in a steep decline in the monarch’s ability to tolerate a common parasite, as well as a lifespan reduction of one week.

The study looked solely at how elevated carbon dioxide levels alter plant chemistry and how those changes, in turn, affect interactions between monarchs and their parasites. It did not examine the climate-altering effects of the heat-trapping gas emitted when fossil fuels are burned.

“We discovered a previously unrecognized, indirect mechanism by which ongoing environmental change—in this case, rising levels of atmospheric CO2—can act on disease in monarch butterflies,” said Leslie Decker, first author of the study, which is scheduled for publication July 10 in the journal Ecology Letters.

“Our results emphasize that global environmental change may influence parasite-host interactions through changes in the medicinal properties of plants,” said Decker, who conducted the research for her doctoral dissertation in the U-M Department of Ecology and Evolutionary Biology. She is now a postdoctoral researcher at Stanford University.

U-M ecologist Mark Hunter, Decker’s dissertation adviser and co-author of the Ecology Letters paper, said findings of the monarch study have broad implications. Many animals, including humans, use chemicals in the environment to help them control parasites and diseases. Aspirin, digitalis, Taxol and many other drugs originally came from plants.

“If elevated carbon dioxide reduces the concentration of medicines in plants that monarchs use, it could be changing the concentration of drugs for all animals that self-medicate, including humans,” said Hunter, who has studied monarchs at the U-M Biological Station, at the northern tip of Michigan’s Lower Peninsula, for more than a decade.

“When we play Russian roulette with the concentration of atmospheric gases, we are playing Russian roulette with our ability to find new medicines in nature,” he said.

Earlier work in Hunter’s lab had shown that some species of milkweed produce lower cardenolide levels when grown under elevated carbon dioxide. That finding caught the attention of Decker, who with Hunter designed a follow-up study to look at the potential impact of rising CO2 on the disease susceptibility of monarchs in the future.

They created an experimental system that allowed them to manipulate and measure all the key links in the chain: carbon dioxide levels, toxin concentrations in milkweed leaves, infection by parasites, and monarch susceptibility to those . The fieldwork was conducted in 2014 and 2015.

Inside 40 growth chambers on a hilltop at the Biological Station, they exposed milkweed plants to two different carbon dioxide levels. Twenty chambers were maintained at current global CO2 concentrations of around 400 parts per million, and 20 chambers received 760 ppm of CO2, a level that could be reached well before the end of the century if the burning of fossil fuels continues unabated.

The four milkweed species differed in their levels of protective cardenolide compounds. The most protective species was Asclepias curassavica, commonly known as tropical milkweed. The chamber-raised plants were fed to monarch caterpillars, and each caterpillar got a steady diet of a single milkweed species with known carbon dioxide exposure.

Three-day-old caterpillars were also infected with carefully controlled doses of a common monarch parasite that is distantly related to the malaria pathogen. Ophryocystis elektroscirrha is a protozoan that shortens adult monarch lifespan, impedes its ability to fly and reduces the number of offspring it produces.

Over about two weeks’ time, the infected caterpillars grew to a length of about 2 inches, with striking yellow, white and black bands. Then they pupated inside a hard-shelled chrysalis for about 10 days before emerging as orange-and-black butterflies.

At their Biological Station lab, Decker and Hunter raised hundreds of adult monarchs. The lifespan of each individual—in Michigan, monarch butterflies typically live for about a month—was recorded, and the number of parasitic spores on each carcass was counted.

Piecing together all this data, the researchers were able to determine how changes in levels altered toxin concentrations in the four milkweed species and, in turn, how exposure to those plants affected the monarch’s lifespan and disease susceptibility.

The largest declines in parasite tolerance and butterfly lifespan occurred in monarchs that fed on A. curassavica, a milkweed species in which cardenolide production declined by nearly 25 percent when grown under elevated CO2.

In caterpillars that fed on A. curassavica milkweed grown under elevated CO2, tolerance to the parasite declined by a whopping 77 percent when compared to caterpillars that fed on A. curassavica grown under ambient-level CO2.

Monarchs that fed on A. curassavica grown under elevated CO2 suffered a reduction in lifespan of seven days due to parasitic infection. Parasites reduced mean lifespan by only two days for monarchs that ate A. curassavica grown under ambient CO2 levels.

“We’ve been able to show that a medicinal species loses its protective abilities under elevated ,” Decker said. “Our results suggest that rising CO2 will reduce the tolerance of to their common parasite and will increase parasite virulence.”

In recent years, monarch populations have been declining rapidly. Most discussions of the monarch butterfly’s plight focus on habitat loss: logging of trees in the Mexican forest where monarchs spend the winter, as well as the loss of wild that sustain them during their annual migration across North America.

“Habitat loss, problems during migration and climate change all contribute to monarch declines,” Hunter said. “Unfortunately, our results add to that list and suggest that parasite-infected monarchs will become steadily sicker if atmospheric concentrations of CO2 continue to rise.”

Explore further: Milkweed plants in CO2 growth chambers provide glimpse of biosphere change

Read more at: https://phys.org/news/2018-07-carbon-dioxide-pose-previously-unrecognized.html#jCp

Read Full Post »

Lund univ logo


WATCH: Insects also migrate using the Earth’s magnetic field

A major international study led by researchers from Lund University in Sweden has proven for the first time that certain nocturnally migrating insects can explore and navigate using the Earth’s magnetic field. Until now, the ability to steer flight using an internal magnetic compass was only known in nocturnally migrating birds.

Lund 1

Bogong moth

Published on 21 June 2018

WATCH: The incredible journey of the bogong moth

“Our findings are the first reliable proof that nocturnally active insects can use the Earth’s magnetic field to guide their flight when migrating over one thousand kilometres. We show that insects probably use the Earth’s magnetic field in a similar way to birds”, says Eric Warrant, professor at Lund University.

Eric Warrant and David Dreyer at Lund University, together with colleagues from Australia, Canada, Germany, and the USA , studied the moth species Agrotis infusa, also known as the Bogong moth, in Australia.

The findings indicate that the insects use both visual landmarks in their flight path and the Earth’s magnetic field, probably making their navigation more reliable.

The researchers believe that moths in northern Europe may use the Earth’s magnetic field in an equivalent manner when flying over the Alps to the Mediterranean.

The moths migrate over a great distance every year, from a large area in southeastern Australia to a specific area of small, cool caves high up in the mountains more than one thousand kilometres away. After a few months in a dormant state, they make the same journey back when summer is over. Besides the Bogong moth, only the North American Monarch butterfly migrates with equivalent precision.

Lund 2

View from a Bogong cave (Photo: Eric Warrant)
The researchers focused on investigating how the Bogong moth knows in which direction to fly. They found answers by capturing the moths in flight and placing them in a flight simulator where the insects were free to fly in any direction they chose. The flight simulator – invented by team members Barrie Frost and Henrik Mouritsen for studying navigation in Monarch butterflies – was in turn placed in a system of magnetic coils which allowed the researchers to turn the magnetic field in any direction. In addition, they were able to show visual landmarks to the moths.

“By turning the magnetic field and the landmarks either together or in conflict with each other, we were able to investigate how the Bogong moths use magnetic and visual information to direct their flight”, says David Dreyer, adding:

“When the magnetic field and the landmarks were turned together, the moths changed their flight path in an equivalent manner. However, if the magnetic field and the landmarks were turned in conflict with each other, the moths lost their sense of direction and became confused.”

Lund 3

Bogong Moths on Cave Wall (Photo: Eric Warrant)

Aestivating Bogong moths (i.e. moths in dormancy) clustered on an alpine cave wall near South Ramshead in the Kosciuszko National Park (New South Wales) during the Australian summer. There are approximately 17,000 moths per square metre of cave wall.

Eric Warrant has many years of experience of researching animal night vision and how animals navigate in the dark. Nevertheless, the findings surprised him.

“I believed the studies would show that Bogong moths only use visual cues such as stars, the moon and landmarks to navigate. But that is not the case. They perceive the Earth’s magnetic field in exactly the same way as birds do – and probably for the same reason.”

The next step will be to find out how the moths, despite never having been to the caves before, know that they have arrived at their destination. The researchers also want to locate and characterise the insects’ elusive magnetic sensor.

Besides Lund University, the following higher education institutions and organisations took part in the research work: Queens University in Canada, University of Oldenburg in Germany, Duke University, USA, New South Wales National Parks and Wildlife Service and the Australian Cotton Research Institute, both in Australia.
For raw video material or more images, please contact the press office.

For journalists interested in covering the team’s upcoming field work in Australia, please contact Eric Warrant directly or the press office.

Link to publication: The study is published in the journal Current Biology

Eric Warrant, professor
Department of Biology, Lund University
+46 70 496 49 27

David Dreyer, researcher
Department of Biology, Lund University
+46 46 222 78 02
+46 72 568 27 06

Read Full Post »

WA research finds to Australia

ABC Rural

It is not just the physical borders that need to be protected to prevent crop diseases making their way to northern Australia — we must also be wary of the wind.

Our best stories in your inbox?

Subscribe to Rural RoundUp: stories from the farm.

Research from the University of Western Australia’s Institute of Agriculture has found foreign insects blown hundreds of kilometres across the ocean may have brought plant disease strains all the way from East Timor and Papua New Guinea to the northern part of the country.

During the three-and-a-half-year project funded by the Cooperative Research centre for Plant Biosecurity, PhD student Solomon Maina identified a disease strain in the Kimberley’s Ord Valley, not found anywhere else in Australia.

His supervisor Adjunct Professor Roger Jones said the unique match between Zucchini Yellow Mosaic Virus (ZYMV) in Kununurra and East Timor, backed up their theory that plant diseases could be pushed into Australia via monsoonal winds.

“What we were looking for was what we call genetic connectivity, where a sequence from one of our northern neighbours such as East Timor matches the sequence found in Australia,” he said.

“We can now say the tropically adapted strain got established in Kununurra and is the one that’s causing the bigger epidemics in the cucurbit crops [such as squash and pumpkin].

“They have a unique problem in that the disease is being caused by a different strain than everywhere else in the country.”

Professor Jones said it was an easier journey for pathogens to cross from South East Asia than you might think.

“It has been recorded before these kinds of aphids; in the US they have been recorded blowing from the south to the north in jet stream winds and settling down and being deposited in crops which are huge distances away from where they originated.”

Increased surveillance needed

Professor Jones said it was a significant research for the northern horticultural industry where severe ZYMV epidemics in melon and pumpkin crops threatened its long-term viability.

The aphid-borne virus, causes major losses in yield and quality of cucurbit crops including cucumber, pumpkin, rockmelon, squash, watermelon and zucchini.

The project also uncovered genetic matches between Papaya Ringspot Virus in cucurbits across northern Australia and Papua New Guinea, and Sweet Potato Feathery Mottle Virus from sweet potato from East Timor and Kununurra.

Professor Jones said the research emphasised the need for increased surveillance of vira-pathogens to reduce the biosecurity threat to crops in the north.

“We can’t really prevent aphids building up on crops in another country, and you can’t influence wind direction and the climate,” he said.

“But what you can do is have surveillance targeting crops to see if any other new things have arrived.

“I think it’s important to keep going with this kind of research, with other crops in mind than just cucurbits and sweet potatoes; it would be good if there was funding available to do that in the future.”

Trapping aphids on the ground

Professor Jones said he had also been working with growers in the Ord Valley on another project funded by Royalties for Regions, which had uncovered more about the aphid species and diseases affecting cucurbit crops.

He said he hoped the three-year project between the Department of Primary Industries and Regional Development, the Kununurra Research Station, UWA and local growers would find a way to manage mosaic viruses in the Ord Valley and limit its impact on crop production.

“It gave a lot of understanding of what was going on and where the aphids and virus was coming from and what kinds of aphids were present, because there was very little information known for the Ord,” he said.

“We got information from five sites where aphids were trapped every week over a three year period, so we knew what the numbers were and when they were building up at different times of year.

“There were six aphid species found up in the Ord, [so] there may be other species blown over from East Timor or Indonesia.”

Local grower Christian Bloecker said one of the biggest challenges for melon farmers in the Ord was controlling aphids and the damage caused by ZYMV on their crops.

He said this new research would go a long way to giving growers the best line of defence against pests and disease.

“What it does mean is that we’ve always got to be on the lookout, which means on the farm in terms of hygiene we need to be mindful of the rotation of crops, making sure there’s no cucurbit weeds near our plantings,” he said.

“It would be great to keep that going because it gives is a little bit of warning on when we need to be on the lookout for aphids and also for the virus.

“There’s also potential to look at varieties that have some kind of resistance to the aphids and ZYMV and the use of barrier crops or alternative cropping systems to delay the arrival of the aphids and virus; that’s where the future research lies.”


Read Full Post »


WEMA Maize Shows Promising Resistance to Fall Armyworm in Mozambique

Early results from the field trials of Water Efficient Maize for Africa (WEMA) show that the genetically modified maize plants are protected against insect pests, even without the use of pesticides. This indicates that the GM maize varieties could help ensure Africa’s food security.

The GM maize varieties under field trials were engineered to withstand drought and stem borer attack. Moreover, results also showed that the GM maize varieties also exhibit promising resistance to fall armyworm, which is one of the major pest problems faced by many farmers in Africa today.

These initial results have positive implications not just for Mozambique, but also for other countries developing WEMA varieties such as Tanzania, Uganda, Kenya, South Africa, and Ethiopia.

Read the article from Biosciences for Farming in Africa and My Joy Online for more information.


Read Full Post »

Science News

Flying insects tell tales of long-distance migrations

Well-timed travel ensures food and breeding opportunities

6:00am, April 5, 2018
hawk moth

MASS MIGRATIONS  This hawk moth (Hyles gallii) is one of millions of insects that migrate through a Swiss Alpine pass each year. Trillions of insects fly vast distances with the seasons to eat and breed. They may teach us something about how insects and other animals move around the planet.

Every autumn, a quiet mountain pass in the Swiss Alps turns into an insect superhighway. For a couple of months, the air thickens as millions of migrating flies, moths and butterflies make their way through a narrow opening in the mountains. For Myles Menz, it’s a front-row seat to one of the greatest movements in the animal kingdom.

Menz, an ecologist at the University of Bern in Switzerland, leads an international team of scientists who descend on the pass for a few months each year. By day, they switch on radar instruments and raise webbed nets to track and capture some of the insects buzzing south. At sunset, they break out drinks and snacks and wait for nocturnal life to arrive. That’s when they lure enormous furry moths from the sky into sampling nets, snagging them like salmon from a stream. “I love it up there,” Menz says.

He loves the scenery and the science. This pass, known as the Col de Bretolet, is an iconic field site among European ecologists. For decades, ornithologists have tracked birds migrating through. Menz is doing the same kind of tracking, but this time, he’s after the insects on which the birds feast.

Migrating insects, like those that zip through the Swiss mountain pass, provide crucial ecosystem services. They pollinate crops and wild plants and gobble agricultural pests.

“Trillions of insects around the world migrate every year, and we’re just beginning to understand their connections to ecosystems and human life,” says Dara Satterfield, an ecologist at the Smithsonian Institution in Washington, D.C.

Scientists like Menz are fanning out across the globe to track butterflies, moths, hoverflies and other insects on their great journeys. Among the new discoveries: Painted lady butterflies time their round trips between Africa and Europe to coincide within days of their favorite flowers’ first blossoms. Hoverflies navigate unerringly across Europe for more than 100 kilometers per day, chowing down on aphids that suck the juice out of greening shoots. What’s more, some agricultural pests that ravage crops in Texas and other U.S. farmlands are now visible using ordinary weather radar, giving farmers a better chance of fighting off the pests.

Until now, most studies of animal migration have focused on large, easy-to-study birds and mammals. But entomologists say that insects can also illuminate the phenomenon of mass movement. “How are these animals finding their way across such large scales? Why do they do it?” asks Menz. “It’s really quite fantastic.”

NOTHING BUT NET Butterflies, hoverflies and other migrating insects poured across the Col de Bretolet pass in the Swiss Alps on this day in September 2016. Researchers based at the University of Bern captured, marked and released red admiral (Vanessa atalanta) butterflies as part of a project, including citizen-science efforts, to track this migrating species.

To warmer worlds

Animals migrate for many reasons, but the aim is usually to eat, breed or otherwise survive year-round. One of the most famous insect migrations, of North America’s monarch butterflies (Danaus plexippus), happens when the animals fly south from eastern North America to overwinter in Mexico’s warmer setting. (A second population from western North America overwinters in California.) In Taiwan, the purple crow butterfly (Euploea tulliolus) migrates south from northern and central parts of the island to the warmer Maolin scenic area every winter, where the butterfly masses draw crowds of lepidopteran-loving tourists. In Australia, the bogong moth (Agrotis infusa) escapes the hot and dry summer of the country’s eastern parts by traveling in the billions to cool mountain caves in the southeast.

The migrations can be arduous. Each spring, the painted lady butterfly (Vanessa cardui) moves out of northern Africa into Europe, crossing the harsh Sahara and then the Mediterranean Sea before retracing the route in the autumn (SN Online: 10/12/16). Because adult life spans are only about a month, the journey is a family affair: Up to six generations are needed to make the round trip. It’s like running a relay race, with successive generations of butterflies passing the baton across thousands of kilometers.

Naturalists track the distinctive painted lady butterfly (Vanessa cardui) during its annual migrations.

 John Serrao/Science Source

Constantí Stefanescu, a butterfly expert at the Museum of Natural Sciences in Granollers, Spain, has been tracking the painted lady migrations. He relies on citizen scientists who alert him when the orange-and-black-winged painted ladies arrive in people’s backyards each year, as well as field studies by groups of scientists. In 2014, 2015 and 2016, Stefanescu led autumn expeditions to Morocco and Algeria to try to catch the return of the painted ladies to their wintering grounds.

By surveying swaths of North Africa, Stefanescu’s team confirmed that the painted ladies virtually disappeared from the area during the hot summer months and returned in huge numbers in October. The fliers arrived back in Africa just in time to feed on the daisylike false yellowhead (Dittrichia viscosa) and other flowers. The findings make clear how well the butterflies are able to time their migrations to take advantage of resources, Stefanescu reported in December in Ecological Entomology.

Flying far

Painted lady butterflies embark on one of the world’s most distinctive migrations, traveling thousands of kilometers from Africa into Europe each spring, and back again in the fall. It can take six generations of butterflies to make the round trip journey.

Gerard Talavera, Based on G. Talavera and R. Vila, Biological Journal of the Linnean Society 2017

Other insect species are less visibly stunning than the painted lady, but just as important to the study of migrations. One emerging model species is the marmalade hoverfly (Episyrphus balteatus), which migrates from northern to southern Europe and back each year.

Marmalade hoverflies have translucent wings and an orange-and-black striped body. As larvae, they eat aphids that would otherwise damage crops. As adults, the traveling hoverflies help pollinate plants. “They’re useful for so many things,” says Karl Wotton, a geneticist at the University of Exeter in England.

Wotton started thinking about the importance of insect migration after 2011, when windblown midges carried an exotic virus into the southern United Kingdom that caused birth defects in cattle on his family’s farm. Intrigued, Wotton set up camp at a spot in the Pyrenees at the border of Spain and France to study migrating hoverflies. Then he heard that Menz was doing almost exactly the same kind of research at the Col de Bretolet and a neighboring pass. The two connected, hit it off and now collaborate in both the Pyrenees and the Alps.

Scientists rigged a moth trap at this Swiss pass so they could capture, identify and release migrating moth species.

Will Hawkes, @Hawkes_Will

Funneled by the high mountain topography, hoverflies whiz through the passes like rush hour commuters through a railway station. “We’re talking about an immense number of insects,” Menz says. Millions of flies traverse the Swiss passes each year. Extrapolating to all of Europe, Wootton estimates that many billions of hoverflies are probably migrating. The insects consume billions of aphids that otherwise would have feasted on agricultural crops.

As astonishing as this migration is, most people never notice it. Only at the passes do the hoverflies become noticeable, a never-ending stream of tiny bodies glinting in the mountain light. They ride high on tailwinds and scoot low when the wind is against them. “They fly fast and low and they don’t stop,” Wotton says. “The butterflies are getting turned around like in a tumble dryer, but the hoverflies just shoot straight over.”

Wotton, Menz and colleagues use specialized upward-looking radar to track signals reflecting off of insects passing overhead. The researchers also use traps to catch individual flies to identify the species passing through.

The marmalade hoverfly (Episyrphus balteatus) eats aphids and pollinates plants as it travels.

 Will Hawkes, @Hawkes_Will

And they study navigation in a sort of hoverfly flight simulator. The researchers glue the backs of flies to the heads of pins and watch how the flies navigate when held between two magnets. The aim is to see if the insects are using cues from Earth’s magnetic field to find their way. Suspended between the magnets, the insects can move freely left or right, choosing their direction of travel. The whole contraption is enclosed in an opaque plastic barrel so the flies cannot see the visual cues of the surrounding mountains. Preliminary findings suggest the flies do indeed find their way using some kind of compass, Wotton reported in Denver in November 2017 at a meeting of the Entomological Society of America.Season after season, the researchers are building up a hoverfly census. By comparing that information with a 1960s survey done at the Col de Bretolet, the team hopes to determine whether species’ numbers have changed over time. Menz says: “I wouldn’t be surprised if they’ve declined.”

Other entomologists have documented sharp drops in the numbers of insects across Europe. In October 2017, a Dutch-German-British research team reported in PLOS ONE that the total insect biomass collected at 63 nature-protection areas in Germany over 27 years had dropped by more than 76 percent.

The paper garnered media headlines around the world as heralding an “insect Armageddon.” That may be overly dramatic. The work covered just one small part of Europe, and the authors could not explain what might be causing the drop, whether climate change, habitat destruction or something else. But if hoverfly numbers are dropping, that would mean fewer are around to eat destructive aphids and to spread beneficial pollen. Hoverflies, which pollinate a wide range of plants, are the second most important group of pollinators in Europe after bees, Wotton says.

Drop in insect biomass collected in protected areas in Germany from 1989 to 2016

Hoverflies also migrate in North America, in ways that are far less understood than in Europe. This month, Menz and Wotton are visiting Montaña de Oro State Park on California’s Central Coast, where last year an entomologist reported spotting a rare hoverfly migration. The researchers hope to see whether the American hoverflies, probably a different species, are moving in the same ways their European cousins do.

Swoop in the destroyers

Not all migrating insects are beneficial. Some are troublemakers that chase ripening crops with the season. Farmers can spray pesticides once insects arrive in the fields, but knowing more about when and where to expect the critters can help growers better prepare for the onslaught.

Weather radar — Doppler data that meteorologists use to follow rain, hail and snow in near real time — is beginning to help. The radar signals reflect off of birds and other animals flying through the air. And although many insect species are too small to be detected in Doppler radar data, researchers are finding new ways to extract the signals of insects and track their migrations as they happen.

John Westbrook, a research meteorologist at the U.S. Department of Agriculture’s Agricultural Research Service in College Station, Texas, has been using weather radar to follow insect flyways in the south-central United States. A 1995 outbreak of two migratory moth species — beet armyworm (Spodoptera exigua) and cabbage looper (Trichoplusia ni) — devastated cotton crops in Texas’ Lower Rio Grande Valley. Westbrook recently dug through the Doppler data from 1995 and was able to pick out the signals of these two species moving during the outbreak, Westbrook and USDA colleague Ritchie Eyster wrote in November 2017 in Remote Sensing Applications: Society and Environment.

Tracking pests

Weather radar data from southern Texas reveal the higher reflectivity of flying crop-eating moths (red). During an outbreak in 1995 that destroyed cotton crops, the moths flew northwest across much of Willacy County (shown) in under an hour. Farmers could use similar radar data to track pests approaching fields.

J.K. Westbrook and R.S. Eyster/Remote Sensing Applications: Society and Environment 2017

“Outbreaks are unpredictable,” Westbrook says. “But the weather radar can show where they are occurring.” Modern weather radar contains even more information than 1995 systems did, he notes — and farmers can use that data to their advantage. They may decide to spray heavily where most of the insects are gathering before they spread. Or farmers might stock up on pesticides if a particularly dangerous outbreak is headed in their direction.

Another way to track destructive insects is to grind them up and test the chemistry of their tissues. As caterpillars grow, they take on a characteristic chemical signature of the environment, with hydrogen, oxygen and other elements fixed in tissues in varying amounts. Analyzing those ratios can reveal the geographic region of a caterpillar’s origin.

Keith Hobson of Western University in London, Canada, and colleagues have been studying the insect pest known as the true armyworm moth (Mythimna unipuncta). It travels between Canada and the southern United States every year, damaging crops along the way. But scientists weren’t sure exactly where the insects originated each year, making it harder to figure out how to manage the problem with pesticides.

In new experiments, Hobson’s team captured true armyworm moths in Ontario throughout the year and analyzed the hydrogen retained within the moths’ wings. Moths captured early in the season had values similar to those seen in Texas waters, while those captured in the summer showed values closer to Canadian waters. The reverse was also true: Adult moths captured in autumn in Texas had Canadian-type values.

It is the first direct evidence that individual moths are making these long-distance round trips, the scientists wrote in January in Ecological Entomology. Further studies could reveal how to better control the pests throughout the growing season, by showing precisely where the insects are coming from and how far they will travel.

Larvae of the migratory cabbage looper (top) destroy cabbage and other crops.

Alton N. Sparks, Jr., Univ. of Georgia, United States/Wikimedia Commons (CC BY 3.0); Univ. of Minnesota.

The migrating masses

For Menz, Wotton, Satterfield and the rest, the ultimate goal is to go from studying individual species to investigating broader questions of how and why animals move around. That includes exploring how insects alter food webs during migrations across the landscape.

For instance, Mexican free-tailed bats (Tadarida brasiliensis) in Texas and Mexico forage for nocturnal moths, which migrate in very narrow layers in the atmosphere based on how the wind is blowing. “These are like food webs in the sky,” says Jason Chapman, an ecologist at the University of Exeter. “Can bats read the weather patterns and predict where the insects are going to be?”

Similarly, many dragonflies attempt to migrate 3,500 kilometers or more across the Indian Ocean from India to east Africa and back each year, breeding in temporary ponds created by monsoon rains. The dragonfly-eating Amur falcon (Falco amurensis) makes a similar journey, in one of the longest-known migrations for any raptor. If the dragonflies are the reason for the falcon migration, then tiny insects are a major player in this important bird movement.

Insects rule the migratory world by virtue of their sheer numbers. Compared with birds, mammals and other migratory animals, insects are by far the most numerous. Roughly 3.5 trillion migrate each year over just the southern United Kingdom, a 2016 radar study suggested (SN: 2/4/17, p. 12). That means that the majority of land migrations are made by insects.

To Aislinn Pearson, an entomologist at Rothamsted Research in Harpenden, England, studying insects will boost scientific understanding of how animals flow around the planet. “In the next 10 years,” she says, “a lot of the key findings of migration are going to come from these tiny little animals.”

This story appears in the April 14, 2018 issue of Science News with the headline, “Mass migrations: Researchers are asking big questions about animal movements by tracking tiny insects in flight.”


K.A. Hobson et al. Inferring origins of migrating insects using isoscapes: a case study using the true armyworm, Mythimna unipuncta, in North America. Ecological Entomology. Published online January 18, 2018. DOI:10.1111/een.12505.

C. Stefanescu et al. Back to Africa: autumn migration of the painted lady butterfly Vanessa cardui is timed to coincide with an increase in resource availability. Ecological Entomology. Vol. 42, December 2017, p. 737.

J.K. Westbrook and R.S. Eyster. Doppler weather radar detects emigratory flights of noctuids during a major pest outbreak. Remote Sensing Applications: Society and Environment. Vol. 8, November 2017, p. 64.

C.A. Hallmann et al. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLOS ONE. Vol. 12, October 18, 2017, p. e0185809.

G. Hu et al. Mass seasonal bioflows of high-flying insect migrants. Science. Vol. 354, December 23, 2016, p. 1584.

Further Reading

Insect Migration and Ecology Lab, University of Bern.

S. Milius. Long-ignored, highly-flying arthropods could make up largest land migrations. Science News. Vol. 191, February 4, 2017, p. 12.

S. Zielinski. Painted lady butterflies’ migration may take them across the Sahara. Science News Online, October 12, 2016.

H. Thompson. Math models predict mysterious monarch navigation. Science News Online, April 15, 2016.

K. Baggaley. Monarch butterflies’ ancestors migrated. Science News. Vol. 186, November 1, 2014, p. 7.

S. Milius. Thoroughly modern migrants. Science News. Vol. 165, June 26, 2004, p. 408.

Read Full Post »

logo-feed-the-future 1Faw RISK aS REPT Cover

Partnering to Combat Fall Armyworm in Africa

The Fall Armyworm is an invasive crop pest that is rapidly spreading across Africa, threatening maize harvests in particular, and food security more broadly.

The good news is, we largely know how to solve this issue. The Americas have successfully controlled the pest and have a lot of know-how and experiences to share. By working together, we can help Africa tackle this challenge and build resilience to manage future agricultural threats.

Governments, businesses, civil society, the research community, and foundations must work together to assist Africans in combatting Fall Armyworm. To effectively manage this food security threat, we need to help African countries and farmers respond rapidly and prevent major damage before it greatly affects the world’s food supply and exacerbates global poverty and hunger.

Learn more about this crop pest, why it’s a problem, and what we’re doing about it in this fact sheet.

Fall Armyworm Facts:

  • In Africa, the Fall Armyworm’s presence is confirmed in 28 countries and suspected in 9 additional countries (FAO, December 2017).
  • The Fall Armyworm feeds on over 80 different crops including maize, rice, sorghum and sugarcane (CABI, September 2017).
  • It could cause losses of 8.3 million to 20.6 million metric tons of maize in 12 African countries annually (CABI, September 2017), which could feed 40.8 million to 101 million people.

Be a Part of the Solution

Fall Armyworm Tech Prize: Feed the Future and its partners will be looking for digital solutions that help identify and provide actionable information on how to treat the Fall Armyworm in Africa, considering countries’ policies and laws, as well as cultural context. We have two ways for you to get involved in supporting solutions that empower smallholder farmers to effectively manage the threat of Fall Armyworm.

  • Have a relevant innovation that could help? Click here to learn more about submitting your solution. We encourage innovators from around the world to apply!
  • Interested in supporting this effort? We are also seeking partners interested in providing financial, technical and other in-kind support. Email fallarmyworm@usaid.gov to connect with us.

Fall Armyworm Guidance and Related Resources

Fall Armyworm in Africa: A Guide for Integrated Pest Management (First Edition)

In collaboration with international and national research and development partners, Feed the Future developed this Fall Armyworm Technical Guide to share the latest protocols related to integrated pest management to control this pest. We intend to revise and release subsequent editions of this Technical Manual as more evidence emerges on effective management of Fall Armyworm.

Fact Sheet: Combatting Fall Armyworm

Feed the Future strengthens the capacity of African communities, institutions and governments to manage the Fall Armyworm through a range of sustainable and effective integrated pest management strategies that protect people and the environment. Learn more in this fact sheet.

Press Release: USAID Administrator Green Announces Call to Action, New Private Sector Partnerships

In a keynote address at the annual World Food Prize in Des Moines, Iowa, United States Agency for International Development Administrator Mark Green announced a call to action to combat the Fall Armyworm. Check out this press release to learn more.

Map of Areas affected by Fall Armyworm

According to the Food and Agriculture Organization of the United Nations, December 2017.

Plant Protection EBA Data in Action Technical Brief

This brief, authored by the Feed the Future Enabling Environment for Food Security project, offers timely considerations for mitigating and addressing Fall Armyworm in Africa in the near and long term.

Read Full Post »

Faw RISK aS REPT Cover

The document, ‘Pest Risk Assessment of the Fall Armyworm in Egypt’ has just been released by the Feed the Future Integrated Pest Management Lab at VA Tech. The document provides information on the following subjects:

FAW identification



Mortality and dispersal

Spread and establishment

Risk to other countries

Economic impact

Development of a management plan for the FAW in Egypt

The document can be accessed on the IPM IL website at:

Click to access Egypt-FAW-Risk-Assessment-12-14-17.pdf

Read Full Post »

The Wisconsin Gazette

March 2, 2018

monarch MX

Within the next two years, more than 60 million acres of monarch habitat will be sprayed with a pesticide that’s extremely harmful to milkweed, the only food for monarch caterpillars, according to a new analysis from the Center for Biological Diversity.

Monarch populations have fallen 80 percent in the past two decades due to escalating pesticide use and other human activities, according to CBD. The center’s new report, A Menace to Monarchs, illustrates how the butterfly faces a new threat from accelerating use of the drift-prone and toxic weed killer dicamba across an area larger than the state of Minnesota.

“America’s monarchs are already in serious trouble, and this will push them into absolute crisis,” said Nathan Donley, a senior scientist at the center. “It’s appalling that the EPA approved this spraying without bothering to consider the permanent damage it will do to these butterflies and their migration routes.”

The report released this week found that by 2019, use of dicamba will increase by nearly 100-fold on cotton and soybean fields in the monarch’s migratory habitat across the heart of the United States.

Other key findings include:

  • In addition to 61 million acres of monarch habitat being directly sprayed with dicamba, an additional 9 million acres could be harmed by drift of the pesticide.
  • The timing and geographical distribution of dicamba use coincides with the presence of monarch eggs and larva on milkweed.
  • Dicamba degrades monarch habitat by harming flowering of plants that provide nectar for adults as they travel south for the winter and by harming milkweed that provides an essential resource for reproduction.
  • Research has shown that just 1 percent of the minimum dicamba application rate is sufficient to reduce the size of milkweed by 50 percent, indicating it may have a greater impact on milkweed growth than the already widely used pesticide glyphosate.

The Environmental Protection Agency in 2016 approved new dicamba products for use on genetically engineered cotton and soybeans.

In 2017, there were reports of at least 3.6 million acres of off-target, dicamba-induced damage to agricultural crops and an unknown amount of damage to native plants and habitats, including forests.

“There’s no question that use of dicamba across tens of millions of acres will deepen risks to our dangerously imperiled monarch populations,” Donley said. “When dicamba’s use on GE cotton and soybeans comes up for reapproval later this year, the only responsible thing for the EPA to do is allow that approval to expire.”

Read Full Post »

Older Posts »