Robotic weed removal eliminates need for expensive hand crews

TAGS: TECHNOLOGYTodd FitchetteFarmWise weederSingle-

Single-line organic cauliflower is weeded with a robot developed and operated by the Salinas-based FarmWise.FarmWise offers a business model that provides weeding services, freeing the grower from having to own and maintain a machine.

Todd Fitchette | Dec 04, 2020

Produce growers in Arizona and California are being introduced to the futuristic world of George Jetson as robots and artificial intelligence replace labor crews used to rogue weeds from lettuce, cauliflower, and other vegetable crops.

Salinas, Calif.-based FarmWise is a service company with a robotic weeding machine capable of rouging weeds at speeds of one-to-two miles per hour. This eliminates the need for expensive hand crews or chemical herbicides.

The FarmWise weeding machine is part of a service FarmWise provides. Unlike some companies that sell the machines, FarmWise offers a business model that provides weeding services, freeing the grower from having to own and maintain a machine.

The Titan FT35 is the third generation of machines developed by FarmWise. Company Chief Executive Officer Sebastien Boyer said testing on previous generations of machine took place over the past several years. The newest generation of machine is being used commercially in California and Arizona. https://c8c1c3523498a4e6800111cf107f6155.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

The machine uses artificial intelligence to learn the various crops by studying the plant structure, according to Sal Espinoza, regional manager with FarmWise. Once the computer successfully learns the stem structure of the produce plant, the ability to cull weeds is simple. This process can take a few months of machine learning to get it right, Boyer said.

The machines can be outfitted with as many as six weeders. These are the rows of internal components that contain the metal knives that cut through the soil and rogue weeds as cameras track the vegetation and the AI of the onboard computer determines whether the plants are the planted produce, or weeds.

Boyer said his long-term goal is to find additional ways to mechanize the manual labor and tedious tasks performed by human hands. Through the machine learning the AI can distinguish cauliflower, celery, broccoli, and cabbage. Other crops including tomatoes and pepper are being perfected.

The company’s current business model is focused on providing services to produce growers in the desert region of southern California and Arizona after an inaugural run in the Salinas Valley. Boyer said he is also looking at European markets to expand his machine weeding technology.

Aphelenchoides besseyi



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EPPO Datasheet: Aphelenchoides besseyi

Last updated: 2020-07-24


Preferred name:Aphelenchoides besseyi
Authority: Christie
Taxonomic position: Animalia: Nematoda: Chromadorea: Rhabditida: Aphelenchoididae
Other scientific names: Aphelenchoides oryzae Yokoo, Asteroaphelenchoides besseyi (Christie) Drozdovski
Common names in English: rice leaf nematode, rice white-tip nematode, strawberry crimp disease nematode, white-tip nematode
view more common names online…
Notes on taxonomy and nomenclature

The taxonomy used in this datasheet reflects developments suggested by several recent publications, summarised in Decraemer & Hunt (2013), which place Aphelenchoides in the Order Rhabditida, Suborder Tylenchina. This contrasts with the taxonomy nomenclature occasionally used by some authors (such as the CABI Invasive Species Compendium CABI, 2019; Wheeler & Crow, 2020), which place Aphelenchoides in the Order Aphelenchida, Suborder Aphelenchina (Hunt, 1993). Whilst this makes no difference to classification from the level of Superfamily (Aphelenchoidea) to species level (Aphelenchoides besseyi), those studying the species might need to be aware of differences in the literature.EPPO Categorization: A2 list
EU Categorization: RNQP (Annex IV)
view more categorizations online…
EPPO Code: APLOBE HOSTS 2020-07-24 GEOGRAPHICAL DISTRIBUTION 2020-07-24 BIOLOGY 2020-07-24 DETECTION AND IDENTIFICATION 2020-07-24 PATHWAYS FOR MOVEMENT 2020-07-24 PEST SIGNIFICANCE 2020-07-24 PHYTOSANITARY MEASURES 2020-07-24 REFERENCES 2020-07-24 ACKNOWLEDGEMENTS 2020-07-24 How to cite this datasheet? Datasheet history 2020-07-24

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Science/ Friday

Nighttime Streetlights Are Stressing Out Urban Insects

12:10 minutes

two large pink and tan moths clinging to someone's fingers
Standardized monitoring has revealed that the total number of moths has declined steadily by one third over the last 50 years (1968–2017). Pictured are two of the 2,500 moth species found in the UK (Left is a Elephant Hawk-moth, and right is a small Elephant Hawk-moth). Credit: Douglas Boyes

As insect populations—including bees, moths, and other pollinators—decline worldwide, researchers have established a variety of potential causes, including climate change, pesticides, and habitat loss. But now, new findings suggest yet another culprit may be part of the equation: night-time lighting, like street lights in populated areas.

A team of entomologists in the United Kingdom looked at populations of moth caterpillars under street lights, compared to populations that lived in darkness all night. In conditions with night-time lighting, they found nearly half as many caterpillars, in some cases. In addition, caterpillars that grew up under street lights were bigger, suggesting that they might be stressed and attempting to rush into metamorphosis earlier than they should. Furthermore, the greatest threat seems to be coming from energy-efficient LED lights, whose bluer wavelengths may be more stressful than the warmer, redder light of older sodium bulbs.

a round-about intersection that is brightly illuminated by led streetlights
LED streetlights at a rural junction in Curbridge, Oxfordshire. Credit: Douglas Boyes
a person in a bright yellow jacket and orange pants swings a bug net along the side of a brightly lit road in the middle of the night
Sampling nocturnal caterpillars in grass margins using a sweep net under white LED street lights in Golden Balls Roundabout, Oxfordshire. Credit: Jacob Jaffe

The team published their work in the journal Science Advanceslate last month. Guest host Umair Irfan talks to co-author Douglas Boyes about why nighttime lighting might be so bad for insects, and why ditching LED lights isn’t actually the best solution.

a collection of live caterpillars and moths in a cloth net, lit under LED lights
A selection of moth caterpillars caught by sweep netting under streetlights (mix of several species, family: Noctuidae) during fieldwork at night. Credit: Douglas Boyes

Further Reading

The Chilean cherry sector is worried about the necrotic spot virus

The Federation of Fruit Producers expressed its concern about the threat that the Prunus necrotic spot virus poses for the Chilean cherry industry, as it could cause them to lose plantations and part of the international market that buys this product.

In an interview with the newspaper La Tribuna, the president of Fedefruta, Jorge Valenzuela, said that, even though the virus’ incidence in the country is still being studied, they were already studying the cherries that have the virus to contain and control it. “This virus is constantly found in fruits, but it doesn’t always present symptoms,” Valenzuela stated.

“Fedefruta is working with the association of exporters and the Agricultural and Livestock Service (SAG) to teach producers what the symptoms of this virus are so they can identify it and know how to treat it,” he stressed. This will allow producers to carry out tests to detect the virus in time and stop its spread in the different agricultural properties that could face this problem.

However, one of the great difficulties that Fedefruta faces is that there still is no method to treat the virus. Thus, producers should remove the trees that show any symptoms from the orchards.

The Federation has proposed certain guidelines to face this agricultural disease in crops: “Healthy trees can defend themselves better against the virus if they have good agronomic management.” Thus, they recommend keeping the orchards in good sanitary conditions, as the first measure to combat the virus.

The union leader also asked agricultural producers not to panic: “We have restrictions in China, but we must make good selections so that there are no problems with the country later on.”

Valenzuela highlighted the joint work being developed between the Chilean Fruit Exporters Association AG (Asoex), Fedefruta (National Trade Union Federation of Fruit Producers), and the Chinese Government to eradicate the disease as soon as possible.

Source: latribuna.cl 

Publication date: Mon 13 Sep 2021

Red rot disease: Punjab minister asks for survey to assess damage to sugarcane crop

PTI | Chandigarh | Updated: 08-09-2021 21:10 IST | Created: 08-09-2021 21:08 IST

Red rot disease: Punjab minister asks for survey to assess damage to sugarcane crop
Representative Image Image Credit: ANI

Punjab Cooperation Minister Sukhjinder Singh Randhawa on Wednesday asked district administrations of Gurdaspur and Jalandhar to conduct a survey to assess the damage caused to the sugarcane crop by red rot fungus disease.

Randhawa also asked the cooperation department to prepare a compressive report for the perusal of Chief Minister Amarinder Singh, who also holds the portfolio of agriculture, to work out an effective action plan in this matter.

Chairing a meeting to review the current situation that emerged after the outbreak of this disease, the minister directed the deputy commissioners to work in tandem with the Punjab Agricultural University, cane commissioner and others, to find ways and means to combat the disease to save the crop, according to an official statement.

Randhawa stressed the need to intensify research for exploring the factors that led to a sudden attack by fungus on sugarcane.

He appealed to the cane growers not to panic in the wake of disease rather he asked the authorities to identify the hotspot areas to effectively tackle the fungus.

Joining the deliberations through video conferencing, S K Pandey, principal scientist and head of sugarcane, Breading Institute, Regional Centre, Karnal, said this disease had already affected the sugarcane crop in Uttar Pradesh and Haryana in the past due to the problem of waterlogging.

He, however, said that intensive research in this regard revealed that ‘Co 0238’ variety of sugarcane was mainly prone to this fungus and the farmers in these states who had suffered substantial losses were told not to grow this variety in future.

(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)

Hans News Service

Amalapuram: Coconut growers fear spread of Black Scorch disease to plantation Hans News Service   |  2 Sep 2021 1:23 AM IST

Coconut growers fear spread of Black Scorch disease to plantation  In Konaseema region, coconut plantation in 15 acres, around 880 trees affected and due to Black Scorch disease The Chief Minister instructs the officials to form a scientific committee to investigate the issue Amalapuram: ‘Kerala’ of Andhra Pradesh, as Konaseema is known for its abundant coconut plantation in the region, grip of fear as the money fetching coconut trees are adversely affected by a strange and peculiar disease called ‘Black Scorch’ disease in Nellivaripeta, Billakuduru village, Kothapeta mandal of East Godavari district Around 880 coconut trees were destroyed in 15 acres due to the disease. Worried of the spread of disease to other trees, many coconut farmers requested the scientists concerned to find a solution to eradicate the disease.

The people of this region solely dependent on the sale of coconuts livelihood and coconuts are exported to various places in the state as well as other states. The farmers allege that the salt water released by the borewells which were dug by ONGC lead to the cause of the disease to the plantation. The experts from YSR Horticulture University visited the area and studied about the nature and cause of the disease. With their expertise they could successfully prevent the spread of the disease to the surrounding trees.

The experts also conducted the water analysis and soil tests, but they couldn’t exactly diagnose the nature of the disease. The MLAs of Konaseema and officials brought the issue to the notice of the Chief Minister YS Jagan Mohan Reddy. The Chief Minister instructed the officials to appoint an expert committee to find cause of the disease and sort out the issue. The farmers appealed the Chief Minister not only curb the spread of the disease including the steps to root out its horizon, but to come to their rescue.

Horticulture officer PBS Amarnath told “The Hans India” that The coconut trees in Konaseema area attracted Black scorch disease in Nellivaripeta, Billakuduru village, Kothapeta mandal of East Godavari district and 880 coconut trees in 15 acres were already died due to the disease. He said that they spent nearly Rs 80,000 to 1 lakh to conduct the tests. He advised the government to invest few lakhs to conducts these types of tests in the future. He added that they could not conduct certain other tests due to lack of funds.


Fires may have affected up to 85 percent of threatened Amazon species


Since 2001, an area up to the size of Washington state has burned

flames and smoke billow from trees in the Amazon
A fire burns trees in the Amazon basin in Brazil’s Maranhão state in 2014. Fires like these are searing the geographic ranges of thousands of Amazonian species, an analysis of nearly 15,000 plant and vertebrate species finds.MARIO TAMA/GETTY IMAGES

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By Jake Buehler

SEPTEMBER 1, 2021 AT 11:38 AM

Much of the Amazon’s biodiversity is under fire — literally.

In the last two decades, deforestation and forest fires have encroached on the ranges of thousands of plant and animal species in the Amazon rainforest, including up to 85 percent of threatened species in the region, researchers report September 1 in Nature.

The extent of the damage is closely tied to the enforcement, or lack thereof, of regulations in Brazil aimed at protecting the forest from widespread logging as well as the fires often used to clear open space in the forest and other encroachments. The findings illustrate the key role that forest use regulations have in the fate of the Amazon rainforest, the researchers argue.

Threats to the survival of this biodiversity could have long-term effects. Biodiversity boosts a forest’s resilience to drought, says Arie Staal, an ecologist at Utrecht University in the Netherlands who was not involved with this research. A deep bench of tree species allows the plants to replace those that may not survive drought conditions, he says. “If fire-impacted area continues to rise, not only does the Amazon lose forest cover, but also some of its capacity to cope with the changing climate.”

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And as fires advance deeper into the rainforest, more species will experience fire for the first time, Staal says. “These species, including many threatened ones, have not evolved under circumstances with regular fires, so the consequences for those species can be severe.” Such consequences may include increased risk of population declines or extinction, similar to the fears following the major outbreak of fires in Australia in 2019 and 2020 (SN: 3/9/21).

In recent decades, ongoing deforestation and periodic drought in the Amazon basin have been associated with intensifying fires there (SN: 11/20/15). In 2019, a particularly severe series of fires scorched the region (SN: 8/23/19). 

“But we do not know how fires are impacting the biodiversity across the Amazon basin,” says Xiao Feng, a biogeographer at Florida State University in Tallahassee. The Amazon “is a huge area, and it is generally impossible for people to go there and count the number of species before the fire and after the fire,” he says. “That’s an incredible amount of work.”

So Feng and a team of collaborators from Brazil, China, the Netherlands and the United States instead investigated how Amazonian plant and animal species’ geographic ranges have been exposed to recent fires. The team compiled range maps of 11,514 plant and 3,079 vertebrate species, creating what may be the most comprehensive dataset of range maps for the Amazon. The team compared these maps with satellite images of Amazon forest cover from 2001 to 2019. Those images let the team track how logging and fires have led to the degradation of rainforest habitat.

Fire impacted up to about 190,000 square kilometers — an area roughly the size of Washington state, the team found. Up to about 95 percent of the species featured in the study had ranges that overlapped with fires during this period, though for many species, burned areas made up less than 15 percent of their overall range.

Affected species include up to 85 percent of the 610 considered threatened — so vulnerable to extinction or already endangered or critically endangered — by the International Union for Conservation of Nature. This category includes as many as 264 kinds of plants, 107 amphibians and 55 mammals. In 2019 alone, over 12,000 species experienced fire somewhere in their geographic range. 

two white-cheeked spider monkeys swing from trees
From 2001 to 2019, the endangered white-cheeked spider monkey (Ateles marginatus) has had up to about 6 percent of its Amazon forest range affected by fire, researchers say.IGNACIO PALACIOS/GETTY IMAGES PLUS

Starting in 2009, when a series of regulations aimed at reducing deforestation started being enforced, the extent of fires generally decreased, except in drought years, the team found. Then in 2019, fires ticked back up again, coinciding with a relaxation of regulations. Much of the fire-driven forest loss was congregated along the more intensely logged southern reaches of the rainforest.

The shift suggests that effective forest preservation policies can slow this trend of destruction, and may be crucial for preventing the region from reaching a tipping point. That point would occur when the cycle of deforestation, drying and fire triggers widespread transformation of the Amazon basin into a savanna-like habitat.

While this study couldn’t track the fate of specific plants or animals, Feng now plans to look at fire’s impact on certain groups of species that may have very different vulnerabilities to an increasingly flammable Amazon. “We know some trees may be more resistant to burns, but some may not. So it may also be really important to distinguish differences,” he says.

Questions or comments on this article? E-mail us at feedback@sciencenews.org


X. Feng et alHow deregulation, drought and increasing fire impact Amazonian biodiversityNature. Published online September 1, 2021. doi: 10.1038/s41586-021-03876-7.

About Jake Buehler

Jake Buehler is a freelance science writer, covering natural history, wildlife conservation and Earth’s splendid biodiversity, from salamanders to sequoias. He has a master’s degree in zoology from the University of Hawaii at Manoa.

Science News

Body parts reinforced with zinc and manganese make impossible cuts possible, a study suggests

a leaf-cutting ant, with sharp mandibles visible
Leaf-cutting ants (Atta cephalotes) have jaws lined with “teeth” kept razor sharp by interspersing zinc atoms among proteins.RYAN GARRETT

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By Jake Buehler

SEPTEMBER 8, 2021 AT 9:00 AM

If you’ve ever felt the wrath of a biting or stinging insect, it may seem incredible that something so small can so easily slice or puncture human skin. 

Scientists already knew that some small animals’ piercing and slashing body parts are infused with metals such as zinc and manganese, making the parts tough and durable. Now, a study published September 1 in Scientific Reports shows how these toollike appendages form hard and extremely sharp cutting edges.

Robert Schofield, a physicist at the University of Oregon in Eugene, and colleagues used a special microscope to examine the sharp “teeth” that line the jaws of leaf-cutting ants called Atta cephalotes, revealing the teeth’s atomic structure (SN: 11/24/20). The team found that zinc atoms were dispersed homogeneously, rather than in chunks, throughout a single tooth. This uniformity allows the ants to grow much thinner, sharper blades, since “chunks of mineral limit how sharp the tool can be,” Schofield says.

The team also tested a suite of properties of these metal-infused materials, known as heavy element biomaterials, in ant teeth, spider fangs, scorpion stingers and marine worm jaws, among others. These structures are stiffer and more damage resistant than biomineralized materials, like the calcium phosphate typically found in teeth or the combination of calcium carbonate and the protein chitin in many arthropod shells, the team found. The metal-fortified body parts have “the kinds of properties that you want in a knife or needle,” Schofield says.

The team estimates that the zinc-infused teeth of A. cephalotes allow it to puncture and cut using only about 60 percent of the energy and muscle mass it would otherwise. 

By making these sharp, precisely sculpted tools, ants and other small animals can make up for their tiny muscles, allowing them to acquire and process foods that would normally be beyond their reach.

Questions or comments on this article? E-mail us at feedback@sciencenews.org


R.M.S. Schofield et alThe homogenous alternative to biomineralization: Zn- and Mn-rich materials enable sharp organismal “tools” that reduce force requirementsScientific Reports. Published September 1, 2021. doi: 10.1038/s41598-021-91795-y.

About Jake Buehler

Jake Buehler is a freelance science writer, covering natural history, wildlife conservation and Earth’s splendid biodiversity, from salamanders to sequoias. He has a master’s degree in zoology from the University of Hawaii at Manoa.

How Insect Saliva is Helping Crops Protect Against Pest Damage

Cowpea is one of Africa’s most important cash crop, and has been found to detect larvae and reduce feeding damage (Image by Toby Hudson)

A new study has unlocked the hidden ways in which important cash crops such as cowpea (Vigna unguiculata) tackle localised pest invasion and damage using natural defence mechanisms. Insights such as these are key for the future protection of our global agricultural production in the light of increasing pest outbreaks and crop damage.

Scientists have published research in which they have found an immune receptor in cowpea cells that can detect the saliva of caterpillars feeding on their leaves, causing a series of natural defence responses such as the release of chemicals that limit the rapid growth capabilities of the larvae. An example of such a defence mechanism is found when the bean pod borer (Maruca vitrata) larvae feed on cowpea, causing the release of a pheromone which attracts parasites to then feed on the larvae.

“Despite chemical controls, crop yield losses to pests and diseases generally range from 20 to 30 percent worldwide. Yet many varieties are naturally resistant or immune to specific pests,” explains biologist Adam Steinbrenner from the University of Washington. “Our findings are the first to identify an immune recognition mechanism that sounds the alarm against chewing insects.”

As of yet, very little is known about how plants are able to identify and combat pest threats, however this new study which is built on previous research by the same team has found that certain peptides known as inceptins are found in the saliva of the larval pests such as the beet armyworm (Spodoptera exigua) larvae – which is one of greatest threats to cowpea crops across Asia and North America. The beet armyworm is native to Southeast Asia and has colonised parts of America since the late 1800s. This pest is extremely damaging to crop foliage, with larvae being found to consume more than other major crop pests such as the diamondback moth (Plutella xylostella).  

Beet armyworm larvae (Image by Russ Ottens, University of Georgia)

The inceptins are the spark that causes the cowpea defence mechanisms against feeding pests, ultimately resulting in larval damage or death. The research found inceptin receptors (INRs) on cowpea plant calls specifically. Unfortunately, there are limited ways to study cowpea crops, resulting in the team having to use tobacco plants to test how the INRs work in practice.

By inserting the gene for INR production into tobacco crops, the team were able to test what would happen in the presence of armyworm larvae. It was found that the INRs were triggered in response to the presence of certain protein fragments in the saliva of feeding caterpillars, as well as in response to direct feeding damage on leaves. The fragments of saliva protein that caused the defence response was found to be pieces of cowpea proteins that were broken down by the caterpillar during feeding. In the tobacco test crops, the presence of these proteins triggered the release of a plant hormone that is known to occur when under threat, resulting in the suppression of insect growth.

“Like many plant immune receptors, this receptor is encoded only by certain plant species but can be transferred across families to confer new signalling and defence functions,” the author wrote.

With the genomic techniques used in this study, the team were able to discover hidden information about plants natural defence mechanisms against pest damage. With the increasing global demand for food as well as more prevalent agricultural pest outbreaks, such studies must be conducted on numerous important food crops and a variety of environmental climates so we can better prepare for and mitigate future threats.

If you would like to read more on this subject, please see the links below:

armywormbeet armywormcowpeaAgriculture and International DevelopmentCrop healthFood and nutrition securityPlant Sciences

From PestNet

Palm tree disease in Florida transmitted by traveling bug from Jamaica


by American Phytopathological Society

What began as a curious survey of an insect in Florida revealed a much larger network of movement across the Caribbean basin. Haplaxius crudus, commonly known as the American palm cixiid, transmits phytoplasmas (bacteria that cause plant diseases) in palm. The American palm cixiid is known to transmit lethal yellowing disease and lethal bronzing disease, both of which are lethal to a variety of palm species, especially coconut and date palms.

While many scientists have assumed these pathogens migrated to Florida in infected plants, Brian Bahder at the University of Florida wondered if the real culprits were the insects themselves. To test this suspicion, Bahder and his colleagues began by categorizing the insect’s DNA in Florida, where they found four distinct groups.

Next they looked beyond the United States and tested populations in Costa Rica, Colombia, and Jamaica, three places that were distinct and relatively isolated. They found different insect DNA in Costa Rica and Colombia. In Jamaica, however, they found an exact match to one of the groups in Florida.

Read on: https://phys.org/news/2021-09-palm-tree-disease-florida-transmitted.html Haplaxius_crudus

What a warmer, wetter world means for insects, and for what they eat

August 30, 2021 11.28am EDT


  1. Esther Ndumi NgumbiAssistant Professor, Department of Entomology; African-American Studies, University of Illinois at Urbana-Champaign

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Esther Ndumi Ngumbi is a senior Food Security Fellow with the Aspen Institute New Voices.


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new report has been released by the Intergovernmental Panel on Climate Change (IPCC) – the UN’s authority on climate change – which revealed the latest research on how the Earth is changing and what those changes will mean for the future.

The report shows there’s been a dramatic increase in carbon dioxide (CO2) levels and temperatures, stating that Earth is likely to reach the crucial 1.5℃ warming limit in the early 2030s. There are also dramatic changes in precipitation – water that’s released from clouds, such as rain, snow, or hail.

As an entomologist, I study insects and how climate change stressors – such as flooding and drought – affect what insects eat. I’m also a food security advocate.

The report’s projections caused me to reflect on the many direct and indirect impacts that a warmer and wetter world will have on insects, their natural enemies, plants and African food security.

Read more: How changes in weather patterns could lead to more insect invasions

Across the African continent, recent years brought out some of these extremes, showing what a serious issue this is.

For instance, in southern Africa, the 2016 outbreak of the fall armyworm has continued to spread because of increased rainfall and elevated temperatures – perfect conditions for them to breed and grow quickly. These conditions also supported the growth of over 70 host plants that are fed upon by the fall armyworm.

There’s also a major desert locust outbreak in eastern Africa which started in 2019. It spread due to unusually heavy rainfall that created the perfect environment for locusts to breed and increase in numbers and size. The rains also support the growth of vegetation to feed them.

Here I present a closer look at some of the report’s key findings and show how changes could affect insects and, indirectly, us.

Elevated carbon dioxide levels

Global levels of CO₂ are already high, and they’re expected to continue rising. While elevation in CO₂ does not directly impact insects, it can alter plants’ nutritional quality and chemistry. This will indirectly affect insect herbivores.

For instance, according to recent research, elevated CO₂ reduces the nutritional quality of plant tissues by reducing protein concentrations and certain amino acids in the leaves. To compensate, insect herbivores eat more.

Elevated CO₂ levels can also affect an insect’s development, driving down their numbers – as seen in this study of dung beetles.

Rising temperatures

The report says that global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO₂ and other greenhouse gas emissions occur in the coming decades.

Temperature regulates insects’ physiology and metabolism. An increase in temperature increases physiological activity and, therefore, metabolic rates. Insects must eat more to survive and it’s expected that insect herbivores will consume more and grow faster.

This will lead to increases in the population growth rate of certain insects. Because they grow fast they’ll reproduce more. Their numbers will multiply and this will ultimately lead to more crop damage.

Read more: What changes in temperature mean for Africa’s tsetse fly

Previous research projected that with every increase in one degree of global warming, losses of crops to insects will increase from 10% to 25%.

Drought and flooding

The changing climate is expected to change precipitation patterns – such as rainfall. The report anticipates increased and frequent drought and flooding incidences across the world. These environmental stressors will have an impact on plant productivity, plant chemistry, defences, nutritional quality, palatability, and digestibility.

Consequently, insects eat more plants and this can result in more crop damage.

On the other hand, increased precipitation can support fresh vegetation (food for insects) and can facilitate population buildup of insects. As seen with the desert locust, for example, prolonged rain allowed them to have food, multiply in numbers and spread. This was also the case for the fall armyworm; plentiful rains supported the growth of their host plants. When food for the insects is no longer a limiting factor, their populations continue to build up.

Read more: A new model shows where desert locusts will breed next in East Africa

Reducing effectiveness of natural enemies

All insects have natural enemies or predators. For example, the maize stem borer – a significant insect pest of maize across Africa – has several natural enemies, such as Cotesia flavipes. These predators reduce the populations on insects and further reduce the need to use pesticides to control insect pests.

Predators can be affected by climate changes in many ways. For instance, they can be sensitive to increases in temperature and precipitation, ultimately reducing their numbers. Fewer natural enemies could result in more insect pests. One study, which modelled temperature changes on stem borers in East Africa, showed an increase in their numbers and a decrease in impact by natural enemies.

In addition, because of climate change, both crop distribution ranges and insects will shift. As they seek out conditions that suit them, insects move to new areas that lack their natural enemies. This will cause their populations to grow, resulting in more crop damage.

More palatable food

Because of climate change, weather extremes are likely to happen together.

According to researchplants exposed to double stresses may become even more palatable to insects. This is because when two stressors (say drought and insect herbivory, flooding and insect herbivory, or elevated carbon dioxide and elevated heat) happen together, their impact on crops can be additive or synergistic. This would lead to increased crop damage and reduced crop yields.

What can be done?

Climate change will affect agricultural plants and the insects associated with them. These effects are complex, but it is certain pest pressures will increase. There is a need for more insect monitoring and forecasting and modelling so that we can develop adaptation strategies.

In addition, countries should continue to monitor, share information, and use historical data and modelling to predict and prepare for an uncertain future that is expected to have hungrier insect pests, with impacts on crop productivity and food security.

How The Conversation is different

Every article you read here is written by university scholars and researchers with deep expertise in their subjects, sharing their knowledge in their own words. We don’t oversimplify complicated issues, but we do explain and clarify. We believe bringing the voices of experts into the public discourse is good for democracy.

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Editor and General Manager

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From PestNet

Saturday, 04 September 2021 10:28:00

Grahame Jackson posted a new submission ‘High altitudes no longer protect pine trees from disease’


High altitudes no longer protect pine trees from disease


ByAlison Bosman

Earth.com staff writer

Researchers from UC Davis have gathered some of the first scientific evidence that climate change can affect the distribution of pathogens. The team studied the incidence of white pine blister rust in the forests of the Sequoia and Kings Canyon National Parks. White pine blister rust is caused by a fungus Cronartium ribicola that infects several types of pine trees, including whitebark pine, and has caused serious damage to white pine populations in the United States. 

The pathogen was introduced by accident in 1900 and is an invasive species that inevitably causes tree mortality. Part of the life cycle of C. ribicola is completed in secondary hosts, namely currant and gooseberry plants.

In the past, blister rust infections did not occur in high-altitude forests because the pathogen prefers warmer, milder conditions. Consequently, the forests above the Sequoia and Kings Canyon National Parks acted as a refuge from this disease. However, with changing climatic conditions, the pathogen has begun to infect trees that are higher up the slopes. 

“Because pathogens have thermal tolerances, we are seeing expansions and contractions in this disease’s range,” said study lead author Joan Dudney, a postdoctoral researcher at UC Davis in the lab of Professor Andrew Latimer. “Climate change isn’t so much leading to widespread increases in this disease but rather shifting where it is emerging.”

The researchers used data from long-term monitoring plots in the National Park forests in the southern Sierra Nevada mountains. Data spanned the period between 1996 and 2016, which is considered to be a warmer, drier period than normal. Observations from over 7,800 potential host trees were included and, in addition, the scientists measured stable isotope ratios in pine needles. 

They found that the optimal climatic conditions for blister rust moved, during the 20-year study period, from lower to higher elevations. The incidence of blister rust decreased by 5.5 percent in the more arid, lower-elevation forests and increased by 7 percent in forests at cooler, higher elevations.

“Our study clearly demonstrates that infectious plant diseases are moving upslope, and they’re moving fast,” said Dudney. “Few pines are resistant to what is basically a Northern Hemisphere white pine pandemic.”

The high-elevation refuges where pine trees were protected from pathogens by the inhospitable conditions, are now under threat because of climate warming; conditions there are becoming tolerable to the diseases and pests. Pathogens are expanding their ranges into these higher elevation areas while contracting in the lower areas where the climate is now too warm and dry for their survival.

“It’s kind of a race between evolution and climate change,” said Professor Latimer. “So far, climate change is winning.”

Although it seems inevitable that blister rust will impact severely on white pine populations as the climate becomes warmer, Dudney stated that employing disease prevention methods could help to slow the spread of the disease. 

The study is published recently in the journal Nature Communications.

Saturday, 04 September 2021 10:28:00