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Scientists Warn of Insects Damaging Plants at Unprecedented Levels

TOPICS:FossilsInsectPaleontologyUniversity Of Wyoming

By UNIVERSITY OF WYOMING DECEMBER 11, 2022

Insect-Damaged Leaf Fossil

This fossil leaf from Wyoming’s Hanna Basin, about 54 million years old, shows damage by insects. Credit: Lauren Azevedo-Schmidt

Insects today are causing unprecedented levels of damage to plants, even as insect numbers decline, according to new research led by scientists from the University of Wyoming.

In the first-of-its-kind study, insect herbivore damage of modern-era plants was compared with that of fossilized leaves from as far back as the Late Cretaceous period, nearly 67 million years ago. The findings were recently published in the prestigious journal Proceedings of the National Academy of Sciences.

“Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material,” says the lead researcher, University of Wyoming Ph.D. graduate Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. “The difference in insect damage between the modern era and the fossilized record is striking.”

Azevedo-Schmidt conducted the research along with the University of Wyoming Department of Botany and Department of Geology and Geophysics Professor Ellen Currano, and Assistant Professor Emily Meineke of the University of California-Davis.

Lauren Azevedo-Schmidt Fossilized Plant Search

Lauren Azevedo-Schmidt searches for fossilized plants in Wyoming’s Hanna Basin in a deposit that is about 60 million years old. She and other researchers compared fossil leaves with modern samples and found higher rates of insect damage today. Credit: Lauren Azevedo-Schmidt

In the study, fossilized leaves with insect feeding damage from the Late Cretaceous through the Pleistocene era, a little over 2 million years ago, were examined. They were then compared with leaves collected from three modern forests by Azevedo-Schmidt. The detailed research looked at different types of damage caused by insects, finding marked increases in all recent damage compared to the fossil record.

“Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite widespread insect declines,” wrote the scientists, who suggest that the disparity can be explained by human activity.

Although more research is necessary to determine the precise causes of increased insect damage to plants, the scientists say a warming climate, urbanization, and the introduction of invasive species likely have had a major impact.

“We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution,” the researchers wrote. “Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming.”

But climate change doesn’t fully explain the increase in insect damage, they say.

“This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone but, rather, the way in which humans interact with the terrestrial landscape,” the researchers concluded.

Reference: “Insect herbivory within modern forests is greater than fossil localities” by Lauren Azevedo-Schmidt, Emily K. Meineke and Ellen D. Curran, 10 October 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2202852119

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Now, an international team of experts is providing a convincing overview of the role of climate change and climatic extremes in driving insect decline.

11-07-2022

Insects need urgent help to survive climate change

ByKatherine Bucko

Earth.com staff writer

While the scientific community has previously warned about an alarming decline in insect populations, not much has been done to address this issue on a global scale. Now, an international team of experts is providing a convincing overview of the role of climate change and climatic extremes in driving insect decline. 

“If no action is taken to better understand and reduce the impact of climate change on insects, we will drastically limit our chances of a sustainable future with healthy ecosystems.” This is the warning from a paper composed by 70 scientists from 19 countries around the world as part of the of the Scientists’ Warning series. 

“Climate change aggravates other human-mediated environmental problems,” said lead author Jeffrey Harvey from the Netherlands Institute of Ecology. “Including habitat loss and fragmentation, various forms of pollution, overharvesting and invasive species.”

Insects play critical roles in many ecosystems, making this problem incredibly urgent, as ecosystem loss is on the rise.

“The gradual increase in global surface temperature impacts insects in their physiology, behaviour, phenology, distribution and species interactions. But also, more and longer lasting extreme events leave their traces,” said Harvey.

While fruit flies, butterflies and flour beetles have the capacity to survive heat waves, they can become sterilized and unable to reproduce. Bumblebees, in particular, are very sensitive to heat, and climate change is now considered the main factor in the decline of several North American species.

“Cold-blooded insects are among the groups of organisms most seriously affected by climate change, because their body temperature and metabolism are strongly linked with the temperature of the surrounding air,” said Harvey.

Insects also play a critical role in supporting the global economy through services such as pollination, pest control, nutrient cycling and decomposition of waste. These vitally important services help to sustain humanity and provide billions of dollars annually to the global economy. 

“The late renowned ant ecologist Edward O. Wilson, once argued that ‘it is the little things that run the world’. And they do!’” said Harvey.

The ability for insects to adapt to global warming is further impacted by human threats such as habitat destruction and pesticides. Heatwaves and droughts can drastically harm insect populations in the short term, making insects less able to adapt to more gradual warming.  

The paper includes solutions and management strategies. Individuals can help by caring for different wild plants, providing food and shelter for insects during climate extremes. Reducing the use of pesticides and other chemicals is also recommended. 

“Insects are tough little critters and we should be relieved that there is still room to correct our mistakes,” said Harvey. “We really need to enact policies to stabilise the global climate. In the meantime, at both government and individual levels, we can all pitch in and make urban and rural landscapes more insect-friendly.”

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

By Katherine BuckoEarth.com Staff Writer

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Thrips Show Promise in Controlling the Invasive Brazilian Peppertree in Florida

USDA Agricultural Research Service sent this bulletin at 10/12/2022 09:27 AM EDT

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ServiceBrazilian peppertree thrips larvae and adults feed on a Brazilian peppertreeBrazilian peppertree thrips larvae and adults feed on a Brazilian peppertree. (Photo by Dale Halbritter)Thrips Show Promise in Controlling the Invasive Brazilian Peppertree in FloridaFor media inquiries contact: Jessica Ryan, (301) 892-0085October 12, 2022Brazilian peppertree thrips (Pseudophilothrips ichini) showed promise as biological control agents for invasive Brazilian peppertree populations in Florida according to a recent study published in the Florida Entomologist.Thrips are common insect pests on horticultural plants, but specialized Brazilian peppertree thrips from South America feed exclusively on the Brazilian peppertree’s leaves and stem tips. Their feeding results in reducing the peppertree’s growth rate, plant height, number of leaves, and green stems as well as fruit and flower production.Scientists from the United States Department of Agriculture’s Agricultural Research Service (ARS) collaborated with University of Florida and Florida Department of Food and Consumer Services researchers to mass produce and release thrips throughout 567 sites in Florida between May 2019 and December 2021.The study results show that these thrips persisted in 60 percent of the survey sites for at least one generation as indicated by the recovery of adult thrips at least 60 days after their release. “This is a significant finding, because it indicates the thrips have a self-sustaining population at up to 60 percent,” said Gregory Wheeler, research entomologist at the ARS Invasive Plant Research Laboratory in Fort Lauderdale, Florida.Native to South America, the Brazilian peppertree is a woody and evergreen shrub known for its bright red berries and green foliage. This invasive species grows in dense thickets in invaded ranges and crowds native vegetation. Its fruit is toxic when consumed by wildlife, and many people have allergic reactions to its pollen and sap. In the U.S., the Brazilian peppertree has made its way to California, Florida, Hawaii, and Texas. In Florida alone, the Brazilian peppertree tree has colonized most of the state’s peninsula and covers more than 700,000 acres of land.Use of biological control agents can be a solution for land managers seeking to control invasive populations, according to Wheeler.”Biological control agents like thrips can be a cost-effective and environmentally friendly means of pest control that can be a part of an integrated approach that includes a number of different tactics,” said Wheeler.Thrips are the first biological control agent for this invasive species released in Florida. Researchers will continue field releases and assessments to determine thrips’ effectiveness.The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in U.S. agricultural research results in $20 of economic impact.Interested in reading more about ARS research? Visit our news archiveU.S. DEPARTMENT OF AGRICULTURE
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Fruit and vegetable crops in the Willamette Valley have been affected

USDA ARSWFP-ARS-BMSB.jpg

One promising biological approach is the samurai wasp (Trissolcus japonicus),

The brown marmorated stink bug has increased this year.

Fruit and vegetable crops in the Willamette Valley have been affected.

Kym Pokorny | Nov 11, 2022

Jan 18, 2023 to Jan 20, 2023

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The amount of invasive brown marmorated stink bugs in 2022 tops anything seen in Oregon for at least five years and poses a serious threat to Oregon crops and garden plants, according to Oregon State University Extension Service’s orchard crop specialist.

Nik Wiman, an associate professor in the College of Agricultural Sciences, said fruit and vegetable crops in the Willamette Valley have been affected.

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“It’s unusual for brown marmorated stink bugs to feed on fruit and vegetable crops,” he said. “There has been a lot of damaging populations of BMSB in hazelnuts orchards. Growers use preventative measures so we’re surprised we’ve seen so many.”

It’s unclear why the population exploded this year, Wiman said. Like other insects, the population of the shield-shaped brown marmorated stink bug (BMSB) varies from year to year depending on climatic factors. The extremely wet spring most likely contributed to it, but the increase could also be attributed to a natural cycle.

Native to Asia, BMSB was introduced on the U.S. East Coast in the late 1990s – probably by ship – and has spread to almost every state in the country, including Oregon in 2004. The insect feeds on at least 170 plants, particularly vegetables, pears, apples and hazelnuts, but also ornamentals. Its name describes the odor they emit when they’re crushed.

Oregon’s hazelnut industry, valued at $132 million in 2020, is one of the state’s crops hardest hit by the invasive bug, according to the Oregon Department of Agriculture. The state’s problem echoes the situation in Turkey – the world’s leader in hazelnut production – as well as Italy and the country of Georgia, said Wiman, who researches alternative practices for controlling BMSB, including biological control, habitat manipulation, trap crops and barriers.

Samurai wasp

One promising biological approach is the samurai wasp (Trissolcus japonicus), an insect native to areas of Asia where it keeps the indigenous BMSB population under control. Scientists have discovered the wasp in the United States and Oregon, where it was initially distributed across the state by Wiman and a team of scientists at OSU and elsewhere.  The Oregon Department of Agriculture is now leading the effort.

The parasitic wasp hunts for the egg masses of the stink bug and lays an egg inside each egg in the mass. The wasp develops inside the egg, effectively killing the stink bug, and then chews its way out. OSU Extension has a short publication on the wasp and its effect on the stink bug.

In addition to agricultural crops, the stink bug shows up in homes in autumn when they are looking for a warm, dry place for winter.

“We’ve done analysis of reports we get from people,” Wiman said. “We’ve looked at timing and by far and away we get the most BMSB reports in the fall. Adults are at peak and are trying to get into houses. Warm fall weather gives more opportunity to get into buildings. They can be very annoying when they are coming into homes, and they may fly around inside your house all winter. Then they come out in spring.”

Wiman advises homeowners to seal all cracks where the stink bug can enter and vacuum up inside infestations. On outdoor buildings, washing them off with a strong shot of water will keep some at bay. If they come back, spray them again.

Farmers and homeowners can serve a key role in samurai wasp research by collecting possible brown marmorated stink bug egg masses and reporting them.

[Kym Pokorny is a communication specialist at OSU.]

Source: Oregon State University

TAGS: CROPS

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Scientists warn of ‘insect apocalypse’ amid climate change

insect egg
Credit: CC0 Public Domain

An emerging “insect apocalypse” will have radical effects on the environment and humankind, an Australian scientist has warned.

An international study on the future of insects under climate change scenarios has found the loss of insects will drastically reduce the ability of humankind to build a sustainable future.

Co-author William Laurance, of James Cook University in Australia, said the biosphere had already warmed by about 1.1 degrees Celsius since industrialization. It is projected to warm a further 2–5 degrees Celsius by 2100 unless greenhouse gas emissions are significantly reduced.

An insect’s small body size and inability to regulate their own body temperature made them particularly susceptible to changing temperature and moisture levels, Laurance said in a Tuesday statement.

“A growing body of evidence shows many populations of insects are declining rapidly in many places. These declines are of profound concern, with terms like an emerging ‘insect apocalypse’ being increasingly used by the media and even some scientists to describe this phenomenon,” Laurance said.

“The loss of insects works its way up the food chain, and may already be playing an important role in the widespread decline of their consumers, such as insect-eating birds in temperate environments.”

Insects are important parts of biodiversity and provide services to the wider environment—including pollination, pest control and nutrient recycling—all of which are beneficial to other creatures, including humans, Laurance said.

The study found climate change amplified the effects of other factors threatening insect populations, such as pollution, habitat loss and predation.

“It’s essential to manage and restore habitats that make them as ‘climate-proof’ as possible and enable insects to find refuges in which they can ride out extreme climatic events,” Laurance said.

“The evidence is clear and striking. We need to act now to minimize impacts on insect populations—we know how to do it, but the decision making and requisite funding keep getting pushed down the road,” Laurance added.

2022 dpa GmbH.

Distributed by Tribune Content Agency, LLC.


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Temperate insects as vulnerable to climate change as tropical species

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New Meta-Analysis Examines How Landscape Fire Smoke Affects Insects

ENTOMOLOGY TODAY  LEAVE A COMMENT

Research has found a variety of impacts on insects, both positive and negative, caused by smoke from wildfires and prescribed burns, but a new review of past studies shows we have much to learn. (Photo by Sebastian Werner via FlickrCC BY 2.0)

By Laura Kraft, Ph.D.

Laura Kraft, Ph.D.

During the 2019-2020 bush fire in Australia, some entomologists wanted to calculate the area burned and the total number of insects that may have been killed during the blaze. While those calculations were based solely on the charred acres, a new research review published in September in Environmental Entomology attempts to map previous research on how landscape fire smoke, including smoke from bush fires like the one in Australia, affect insects—and where gaps lie in knowledge that new research could fill.

Yanan Liu, a Ph.D. student in geography at King’s College London, led the study. She and colleagues first searched through more than 9,000 articles that linked to their search terms related to smoke. After carefully parsing through the literature and removing articles on smoke from sources like cigarettes or vehicles, the team ended up with 42 total publications focused only on landscape fire smoke, which includes wildfires, prescribed burns, and agricultural residue burns. The selected studies spanned 15 different countries.

Yanan Liu

The papers represented show an inordinate amount of research that tracks how smoke affects beetles, with fewer papers focusing on effects on flies, bees, and butterflies. And, Liu’s team found, the general consensus is that there is no general consensus. Landscape fire smoke both positively and negatively affects insects in a variety of different ways. Says Liu, “I expected the smoke to repel all the insects or have a negative effect, but it depends on the insect order. For example, beetles are actually attracted [to landscape-based fire].”

For some of those beetles, though, including the red flour beetle (Tribolium castaneum) and the rice weevil (Sitophilus oryzae), smoke produced from burning cow dung and neem leaves caused high mortality. Smoke produced from rice paddy burning with high carbon dioxide levels at 5,000 parts per million may have also caused 50 percent mortality in the rice weevil and the lesser grain borer (Rhyzopertha dominica) in one study.

When it doesn’t cause death, particulate matter in smoke appears to block the antennal receptors in some insects, including bees. While European honey bees (Apis mellifera) famously show signs of decreased aggression in response to smoke (which is why beekeepers have long used smoke to work in hives), other stinging species, like the Sonoran bumble bee (Bombus pensylvanicus sonorous) and the western yellowjacket (Vespula pensylvanica), also show a dramatic reduction in attacks due to smoke. “We normally use smoke to repel bees if you want to get honey from the bees’ home … and when you use a smoker, the bees fly away from their nest. If this smoke influences some insects and changes their behavior, maybe smoke from the landscape fire or from wildfire changes the behavior of other insects,” says Liu.

There are some signs that landscape fire smoke may affect insect flight and migration. Some butterflies initiate flight in response to savanna fires, and painted lady butterflies (Vanessa cardui) show decreased flight performance when subjected to smoke. Other insects have been shown to delay their flights until sky conditions are clear, which may be due to smoke affecting the polarization of light that the insects would typically follow.

Some insects benefit from landscape fire smoke and are attracted to it. This includes wood-burrowing beetles from insect families Cerambycidae and Buprestidae. Some species of these beetles are attracted to smoke and rush back to damaged trees to reproduce at higher rates and colonize the newly damaged trees.

In addition, black army cutworm moths (Actebia fennica) doubled the amount of eggs they laid in response to the volatiles produced from burning vegetation due to increased reproductive hormones. And they weren’t the only butterflies to benefit. During severe forest fires in Borneo in 1997and 1998, most insect species declined, except the butterfly Jamides celeno (family: Lycaenidae) that increased its abundance out of all butterflies in the region from just 5 percent to 50 percent of the assemblage.

Of the 38 studies that examined landscape-fire smoke impacts on insects included in a new research review in Environmental Entomology (and which were associated with individual countries), more than half (20) looked at fire in the United States or Canada. (Number of studies and number of insect species per country noted in parentheses.) (Image originally published in Liu et al 2022, Environmental Entomology)

Despite having publications from five of the seven continents, one of the trends that the researchers found was a clear bias toward papers from the United States and Canada, with a moderate amount from Australia and far fewer stretched out over developing countries in Africa and Asia. While Western readers are familiar with many wildfires in those regions that hit major news outlets, Liu’s team points out that average levels of particulate matter—the small, often toxic particles making up smoke—are often even more highly concentrated in other regions; a study published last year identified central and west Africa and south and southeast Asia as regions most affected by landscape fire smoke globally. Clearly, there is need to increase research studying how landscape fire smoke affects insect populations in these understudied regions.

These few examples of how landscape smoke dramatically affects some insect populations, both positively and negatively, show that more research is needed to expand our understanding of the effects of landscape fire smoke—for a wider diversity of insects, in a broader range of behaviors, and over a larger geographic area.

In the meantime, Liu and her colleagues are now chipping away at some of these questions by studying how smoke affects painted lady butterfly flight behavior.

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Systematic Mapping and Review of Landscape Fire Smoke (LFS) Exposure Impacts on Insects

Environmental Entomology

Laura Kraft, Ph.D., is an entomologist, science communicator, and world traveler currently based in Orlando, Florida. Email: laurajkraft@gmail.com.

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How can flying insects and drones tell up from down?

Date:October 20, 2022Source:CNRSSummary:For proper operation, drones usually use accelerometers to determine the direction of gravity. Scientists have now shown that drones can estimate the direction of gravity by combining visual detection of movement with a model of how they move. These results may explain how flying insects determine the direction of gravity and are a major step toward the creation of tiny autonomous drones.Share:

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While drones typically use accelerometers to estimate the direction of gravity, the way flying insects achieve this has been shrouded in mystery until now, as they have no specific sense of acceleration. In this study, a European team of scientists1 led by the Delft University of Technology in the Netherlands and involving a CNRS researcher has shown that drones can assess gravity using visual motion detection and motion modelling together.

To develop this new principle, scientists have investigated optical flow, that is, how an individual perceives movement relative to their environment. It is the visual movement that sweeps across our retina when we move. For example, when we are on a train, trees next to the tracks pass by faster than distant mountains. The optical flow alone is not enough for an insect to be able to know the direction of gravity.

However, the research team discovered that it was possible for them to find this direction by combining this optical flow with a modelling of their movement, i.e. a prediction of how they will move. The conclusions of the article show that with this principle it was possible to find the direction of gravity in almost all situations, except in a few rare and specific cases such as when the subject was completely immobile.

During such perfect stationary flights, the impossibility of finding the direction of gravity will destabilize the drone for a moment and therefore put it in motion. This means the drone will regain the direction of gravity at the next instant. So these movements generate slight oscillations, reminiscent of insect flight.

Using this new principle in robotics could meet a major challenge that nature has also faced: How to obtain a fully autonomous system while limiting payload. Future drone prototypes would be lightened by not needing accelerometers, which is very promising for the smallest models of the size of an insect.

Though this theory may explain how flying insects determine gravity, we still need confirmation that they actually use this mechanism. Specific new biological experiments are needed to prove the existence of these neural processes that are difficult to observe in flight. This publication shows how the synergy between robotics and biology can lead to technological advances and new biological research avenues.

Notes

1 This research results from a European collaboration between two laboratories: the Micro Air Vehicle Laboratory at the The Faculty of Aerospace Engineering at the Delft University of Technology in the Netherlands and the Institut des Sciences du Mouvement (CNRS/Aix Marseille Université) in France.


Story Source:

Materials provided by CNRSNote: Content may be edited for style and length.


Journal Reference:

  1. Guido C. H. E. de Croon, Julien J. G. Dupeyroux, Christophe De Wagter, Abhishek Chatterjee, Diana A. Olejnik, Franck Ruffier. Accommodating unobservability to control flight attitude with optic flowNature, 2022; 610 (7932): 485 DOI: 10.1038/s41586-022-05182-2

Cite This Page:

CNRS. “How can flying insects and drones tell up from down?.” ScienceDaily. ScienceDaily, 20 October 2022. <www.sciencedaily.com/releases/2022/10/221020130254.htm>.

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UMaine News

A photo of a leaf damage
Photo by Sarah Fanning, courtesy of Lauren Azevedo-Schmidt.

Insects cause more damage to leaves in recent history than millions of years ago, study finds 

October 12, 2022 

Insect herbivores have caused more damage to plant matter from leaves in recent history than millions of years ago, according to a new study led by a University of Maine postdoctoral researcher. 

Despite global insect decline and biodiversity loss fueled by human activity, the frequency of leaf damage by insects among forest plants in recent history, post-1955, is more than twice that of vegetation from the Pleistocene, 2.06 million years ago, and the Late Cretaceous period, 66.8 million years ago. The unprecedented increase in insect damage on leaf matter could pose negative effects on plant productivity and forest health.

To conduct their study, Lauren Azevedo-Schmidt, a postdoctoral researcher with UMaine’s Climate Change Institute, and her colleagues collected leaf samples deposited within sediment across three modern forest ecosystems — Harvard Forest in Massachusetts, the Smithsonian Environmental Research Center in Maryland, and La Selva in Costa Rica — and compared them to previously published leaf litter and fossil data. 

The research team, which also includes Emily Meineke of University of California, Davis and Ellen Currano of the University of Wyoming, used radiocarbon dates to verify the ages of modern leaves along with quantifying the frequency and diversity of insect damage in each sample.  

The causes of this increase in leaf damage due to insect herbivores and the specific consequences of it remain unknown. However, researchers believe widespread change influenced by human activity, such as the rate of global warming, urbanization and the introduction of invasive plants and insects, could be driving the uptick. Human activity may have drastically changed how insect herbivores are interacting with their food source, the researchers say. 

The research team published their findings in Proceedings of the National Academy of Sciences of the United States of America. 

“Humans understand that climate is always changing and that the Earth has previously been hotter, but we often can’t grasp the ‘oddity’ of modern climate change,” Azevedo-Schmidt says. “The geologic record reported here should have supported comparable levels of insect herbivory, but it didn’t because humans weren’t present in our post-industrial revolution capacity. This shows the heartbreaking reality that humans have a much higher impact on forest ecosystems than increased atmospheric CO2 alone. However, we can work to minimize our impacts on forest ecosystems by considering the intersection of these findings.” 

The researchers also found that the damage caused by insects in leaf samples from recent history is slightly more diverse than that in fossilized leaves. The increase in leaf damage diversity, however, is not as drastic as the spike in damage frequency. 

Researchers examined total damage frequency and diversity along with various types of damage including specialized, piercing and sucking, surface feeding, hole feeding, galling, mining, skeletonization, margin feeding and specialized damage. In addition to discovering an overall uptick in total damage frequency, the team also found an increase across all groupings of damage. 

“Increased insect feeding can’t be explained by one group of insects but rather, all groups of feeding damage analyzed here,” Azevedo-Schmidt says. “This suggests that all insect herbivores within these three modern forests are increasing their feeding damage; complicating the story as we can’t simply blame one species or group.” 

No correlation was identified between damage diversity and frequency, according to researchers. The drivers behind the uptick in damage diversity are also unknown. 

“This is interesting because it suggests that insect diversity isn’t influencing insect feeding frequency and that other drivers are responsible for the drastic increase we are seeing,” Azevedo-Schmidt says. 

According to researchers, insects and plants possess the most diverse lineages on the planet, and how they interact has evolved over millennia in response to natural and unnatural causes. 

How plant-insect relationships change over time, including the extent to which the latter feeds on the former, has implications for biodiversity, plant functionality and mortality, and carbon balance in forests — the loss of plant life can decrease the ability for a forest to absorb atmospheric carbon dioxide through photosynthesis.

“This study is the first to compare similar records of plant-insect interactions across modern and fossil datasets,” Azevedo-Schmidt says. “These findings highlight the importance of humans interacting with landscapes and although climate change influences ecosystem processes, it is not the only factor we need to consider. Humans are agents of disturbance and dispersal, greatly influencing the natural world around us.” 

Contact: Marcus Wolf, 207.581.3721; marcus.wolf@maine.edu

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Diversity in Career Paths: A Q&A With Five Entomologists

Entomology Today Oct 24 What jobs can we do as entomologists? More than you might think. For students looking ahead at potential career paths, learn from this Q&A with five entomologists working in a wide range of positions, from biotechnology to tourism and more. Read more of this post

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Study tracks plant pathogens in leafhoppers from natural areas

Diana Yates, University of Illinois News

Sep. 25, 2022

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Illinois State Entomologist Christopher Dietrich (top) joined efforts with ecology and evolutionary biology researcher Valeria Trivellone (right) and Yanghui Cao.
1of5Illinois State Entomologist Christopher Dietrich (top) joined efforts with ecology and evolutionary biology researcher Valeria Trivellone (right) and Yanghui Cao.Fred Zwicky/University of Illinois News
Leafhoppers that are known – or are likely – to transmit phytoplasmas to plants include species of the genera Hishimonoides (clockwise from top left), Macrosteles, Amplicephalus, Osbornellus and Amplicephalus. The leafhopper on the lower right, Osbornellus auronitens, was found for the first time to harbor a phytoplasma strain.

Phytoplasmas are bacteria that can invade the vascular tissues of plants, causing many different crop diseases.

While most studies of phytoplasmas begin by examining plants showing disease symptoms, a new analysis focuses on the tiny insects that carry the infectious bacteria from plant to plant. By extracting and testing DNA from archival leafhopper specimens collected in natural areas, the study identified new phytoplasma strains and found new associations between leafhoppers and phytoplasmas known to harm crop plants.

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Reported in the journal Biology, the study is the first to look for phytoplasmas in insects from natural areas, said Illinois Natural History Survey postdoctoral researcher Valeria Trivellone, who led the research with INHS State Entomologist Christopher Dietrich. It also is the first to use a variety of molecular approaches to detect and identify phytoplasmas in leafhoppers.

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“We compared traditional molecular techniques with next-generation sequencing approaches, and we found that the newer techniques outperformed the traditional ones,” Trivellone said. These methods will allow researchers to target more regions of the phytoplasma genomes to get a clearer picture of the different bacterial strains and how they damage plants, she said.

“One thing that is really novel about this study is that we’ve focused on the vectors of disease, on the leafhoppers, and not on the plants,” Dietrich said. The standard approach of looking for phytoplasmas in plants is much more labor-intensive, requiring that scientists extract the DNA from a plant that appears to be diseased and checking for phytoplasmas, he said.

“But even when you identify the phytoplasma, you don’t know what leafhopper or other vector transmitted it to the plant,” Dietrich said. “So researchers must go back out into the field to collect all potential insect vectors. Then they do transmission experiments, where they let the leafhoppers feed on an infected plant and then put them on an uninfected plant to see if it catches the disease.”

Because this research is laborious and slow, “we still don’t have a good idea of which insects are spreading most phytoplasmas between plants,” Dietrich said. “That really limits your ability to set up an effective management strategy.”

For the new study, the researchers turned to leafhopper specimens in the INHS insect collection. Dietrich had collected many of these insects over a period of 25 years as part of his work classifying their genetic relatedness and evolution. The researchers examined 407 leafhopper species collected around the world in areas less disturbed by human development. The specimens came from North and South America, Africa, Europe, Asia and Australia.

The team extracted total DNA from the specimens and processed each one, using both traditional and newer sequencing approaches. The latter are less costly and more informative than traditional methods, the researchers report. Of the insects sampled, 41 tested positive for phytoplasmas, and the researchers obtained usable phytoplasma sequence data from 23 leafhoppers. The phytoplasmas included those that cause a disease known as aster yellows, which inhibits photosynthesis and reduces the productivity of several different crop plants. These phytoplasmas were found in several new species of leafhoppers never before identified as vectors of the disease.

“These leafhoppers may transmit the phytoplasmas to wild plants in natural areas,” Trivellone said.

The study found phytoplasmas in regions of the world where such diseases had not been reported and identified several new strains of bacteria. It also found previously unreported associations between some phytoplasmas and species of leafhopper.

Scientists have no tools to target the bacteria in asymptomatic plants to prevent disease outbreaks, so controlling phytoplasmas involves the use of pesticides to kill the insect vectors.

“Because the insecticides are only partially specific to the target insects, they kill a variety of beneficial insects as well, which is not sustainable,” Trivellone said.

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“We’re finding that there are lots of new phytoplasmas out there in nature that nobody’s ever seen before,” Dietrich said. “They don’t cause disease symptoms in the native plants they’ve associated with for maybe millions of years. They only start causing disease when they jump to a new host that has not been exposed to the phytoplasma before.”

The new findings parallel those seen in emerging infectious diseases of humans originating in wildlife, Dietrich said. “This is why we need to look more broadly across nature and see what’s out there.”

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Global Agriculture 

New research maps potential global spread of devastating papaya mealybug pest

   Delhi Bureau  1 Comment Biopesticides & BiocontrolsCABI  4 min read

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10 November 2020, UK: CABI scientists have mapped the potential global spread of the devastating papaya mealybug (Paracoccus marginatus), highlighting new areas in Africa, Asia and the Americas into which this pest could potentially invade.

Also Read: BASF commits to targets for boosting sustainable agriculture

The papaya mealybug, which is native to Mexico and Central America, can have severe impacts upon livelihoods and food security. In Ghana, for example, infestations led to a 65% yield loss which reduced export earnings and resulted in the loss of 1,700 jobs.

Using location data received through collaborations with Kerala Agricultural University, India; the National Rice Research Institute, India; the Bangladesh Agricultural UniversityUniversity of Queensland, Australia; the International Institute of Tropical Agriculture (IITA); Fujan Agriculture and Forestry University in China and CSIRO, researchers were able to model the potential distribution of this pest, taking into account environmental conditions, and the distribution of suitable host crops and irrigation patterns.

The researchers, led by CABI’s Dr Elizabeth Finch, believe the polyphagous insect pest, which affects over 200 plants including economically important crops such as papaya, cassava and avocado, could spread to areas such as the south of the Democratic Republic of Congo, northern Cameroon, Zambia, Madagascar and western Ethiopia which are environmentally suitable and have suitable crop hosts.

In the Americas, the research, published in the journal Pest Management Science, suggests papaya mealybug could extend into El Salvador, Honduras, Nicaragua, and Panama – although the scientists believe it could already be in these locations but its presence is yet to be confirmed.

Whilst papaya mealybug is already present in Florida, where it is under successful control as a result of the release of endoparasitoid wasp species – Acerophagus papayaeAnagyrus loeckiAnagyrus californicus – suitable conditions for this pest are also present in the southern tip of Texas.

Conditions are likely to be too cold in the rest of the USA for permanent papaya mealybug populations, however the research showed that seasonal populations could survive in California, along the Pacific coastline and in the central and eastern states of the USA during the warmer summer months.

Also Read: FMC Corporation Recognized at 2020 Crop Science Awards

In Asia, the areas with suitable conditions were more expansive than the areas with known populations of papaya mealybug, suggesting the potential for further expansion of papaya mealybug specifically in India, Southeast Asia and the southern regions of the Guangxi and Guangdong provinces of southern China.

However, in Australasia the risk is low as only a small amount of fragmented land along the north-eastern side of Queensland, from the very northern tip of Queensland to Bundaberg, is climatically suitable. This is due to heat stress from the high temperatures on the continent.

Similarly, in Europe – though due to cold rather than heat stress – widespread distribution of papaya mealybug is not expected, with only a very small area of land surrounding Seville in Spain and around Sicily in Italy having suitable conditions for resident populations.

Dr Finch said, “This pest has been so successful due to its quick development and prolific reproductive capacity. It has the potential to spread to new areas and rapidly reach high numbers unless suitable phytosanitary or control methods are implemented.

“Information about the papaya mealybug’s potential distribution is important as it can highlight key areas susceptible to invasion, giving an early warning to decision makers, allowing them to put into place phytosanitary measures to prevent or slow the invasion of the pest into their jurisdiction.”

Dr Finch added, “In areas where the papaya mealybug has become established and reached a high enough population density, the use of parasitoids – such as Acerophagus papayae and Anagyrus loecki – remains an effective potential control method.

“Further ecological niche modelling of these parasitoid species is recommended to anticipate their survival, fitness and ultimate biological control impact in areas into which papaya mealybug could potentially expand and become established.”

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