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International IPM Program Drives Sustainable Management of Tomato Leafminer

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Since 2012, the Centre for Agriculture and Bioscience International’s Plantwise program has guided growers in 10 Latin American countries on managing Tuta absoluta (larva shown here), a devastating lepidopteran pest of tomatoes, and substituting or complementing chemical control with more sustainable strategies. (Photo by Marja van der Straten, NVWA Plant Protection Service, Bugwood.org)

By Yelitza C. Colmenárez, Ph.D., and Donna Smith

The lepidopteran pest Tuta absoluta is one of the world’s most devastating phytophagous species affecting tomato plants and fresh tomatoes, causing high levels of crop production loss, especially when no control strategies are implemented. Tuta absoluta—sometimes known as the tomato leafminer, tomato pinworm, or tomato moth—continues to cause crop losses in the Americas, where it originates, but more recently it has invaded production areas in Europe, Asia, and Africa, owing to the globalization of commerce and trade, which, along with other factors, is considered responsible for the increase in invasive species.

Given T. absoluta‘s economic importance, management strategies have mainly focused on pesticides with a wide range of organic micropollutants that negatively impact the environment, mostly due to biomagnification and bioconcentration. Thus, more sustainable strategies need to be used alongside chemical control, including biological control agents such as parasitoids, predators, and entomopathogenic microorganisms; botanical insecticides; and pheromones and plant resistance.

In an article published in May 2022 in the open-access Journal of Integrated Pest Management (JIPM), researchers at the Centre for Agriculture and Bioscience International and several universities in Latin America detail case studies in sustainable management efforts for T. absoluta through CABI’s Plantwise program. (Co-author of this article Yelitza C. Colmenárez, Ph.D., is lead author of the report in JIPM.)

Tuta absoluta Management From a Plantwise Perspective

Plantwise is a global program led by CABI that helps farmers handle plant health problems through a national network of plant clinics, established in each country through which the program is implemented. The clinics are run by trained plant doctors, from whom farmers can obtain practical advice. During its 10-year implementation, there were more than 3,700 plant clinics in 34 countries around the world, where plant doctors provided diagnoses and management advice for any problem and any crop, benefitting farmers who need help with the plant pests and diseases affecting their crops.

In Latin America and the Caribbean, Plantwise was operational in Barbados, Bolivia, Brazil, Costa Rica, Grenada, Honduras, Jamaica, Nicaragua, Peru, and Trinidad and Tobago.

In Bolivia, plant clinics were considered a standard procedure to enhance the technical abilities of extension officers and farmers, and there is evidence that they have led to increased crop yields and quality. Likewise, in Costa Rica efforts have been made to implement plant clinics in collaboration with key institutions in the country.

All Plantwise countries have developed pest management guides called “Green and Yellow Lists” with the help of experts in entomology, phytopathology, nematology, and acarology, as well as agricultural extension agents from different institutions (e.g., public universities, the Ministry of Agriculture and Livestock, and research institutes) to develop precise advice on dealing with some of the most important pests.

two men, one standing and one squatting, both wearing green hats, look at a large pile of green and red tomatoes on a tarp on the ground
a person wearing a white jacket and a green hat holds a tomato in their left hand and takes a closeup picture of the tomato with a camera in their right hand, while standing in a field of tomato plants
four people stand at an open-air booth with a sign above that reads "Clinica de Plantas"

The plant clinics have allowed researchers to determine the distribution of T. absoluta and identify the tomato cultivars most frequently associated with this pest in Bolivia and Costa Rica; it has been found to be most widespread in the department of Santa Cruz, followed by Cochabamba (five localities), Chuquisaca, Tarija, and Tiraque in Bolivia, while in Costa Rica it has been reported from Alajuela Province, where T. absoluta feeds on eight cultivars.

In Bolivia, T. absoluta management recommendations evolved greatly between 2012 and 2018. When the plant clinics were first established, farmers were predominantly advised to use chemical control; from 2012 onward, however, chemical use diminished and soon stabilized, reaching levels between 35 percent and 49 percent of recommended treatments. Meanwhile, alternative management strategies (e.g., biological, ethological, and cultural controls) began to increase in Bolivia, thanks to the influence and recommendations of the plant clinics.

During Plantwise implementation, the technicians who delivered this advice to the farmers when visiting the plant clinics were also trained in integrated pest management (IPM) and were thus familiarized with more sustainable methods of managing the key pest population. Cultural control-based recommendations, including lower-leaf pruning and elimination of crop residues and infested fruits, among others, have shown a steady increase since 2014. They reached levels of 35 percent and 31.8 percent in 2016 and 2017, respectively, similar to the 2016 chemical control levels. Ethological control recommendations, such as the use of pheromone traps, showed a discrete increase from 2014 to 2016 (12 percent to 15 percent), but in 2017 and 2018 reached a range of 25 percent to 27.1 percent.

two farm workers stand in a field near a table, on which sits a white plastic jug with its sides cut and opened upward as flaps; the jug is a pheromone trap
closeup view of a white plastic jug with its sides cut and opened upward as flaps; the jug is a pheromone trap

As demonstrated in Bolivia and Costa Rica, the Plantwise program has brought substantial change to the ways in which farmers deal with pests, including T. absoluta, based on substituting or complementing chemical control with more sustainable strategies, due partially to the plant doctors’ recommendations.

Positive performance outcomes can impact the extension advisor’s ability to efficiently carry out a given task, giving them the confidence to perform similar tasks in the future. Reducing the overuse of insecticides in tomatoes alongside a higher IPM adoption rate provided a great case study illustrating the importance of field extension professionals in advising growers. It proved the importance of investing in technology transfer to improve food quality and, from a broader perspective, overall quality of life.

The positive results presented through the case studies shared in JIPM should encourage governments to invest more money in these basic principles. It is certainly much more efficient than attempting to mitigate the consequences associated with the misuse of pesticides, such as pollution, public health issues, and pest resurgence, among other problems.

Read More

Sustainable Management of the Invasive Tuta absoluta (Lepidoptera: Gelechiidae): an Overview of Case Studies From Latin American Countries Participating in Plantwise

Journal of Integrated Pest Management

Yelitza C. Colmenárez, Ph.D., is director of the CABI Brazil Centre and regional coordinator of Plantwise in Latin America and the Caribbean, based in Botucatu, São Paulo, Brazil. Email: y.colmenarez@cabi.orgDonna Smith is a communications manager at CABI Switzerland.

This article is adapted from an article originally published on the Plantwise Blog. Republished with permission.

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Remote-sensing models to combat Banana bunchy top virus in Africa

The IITA–CGIAR team has published a method using drones and satellite imager-based remote sensing approaches for mapping banana farms to guide surveillance for the detection and mapping of the banana bunchy top virus spread and support data-informed decision-making on virus containment strategies in sub-Saharan Africa.

The study, Banana Mapping in Heterogenous Smallholder Farming Systems Using High-Resolution Remote Sensing Imagery and Machine Learning Models with Implications for Banana Bunchy Top Disease Surveillance, was published in the peer-reviewed, open access Remote Sensing journal.

BBTV has emerged as a major threat to banana production in sub-Saharan Africa. The virus infection results in severe dwarfing (bunching) of the shoots and cessation of fruit production, denting the food and income security of smallholder farmers.

Source: iita.org

Publication date: Mon 16 Jan 2023

Saturday, 14 January 2023 16:05:11

PestNet

Grahame Jackson posted a new submission ‘Bacterial volatile organic compounds attenuate pathogen virulence via evolutionary trade-offs’

Submission

Bacterial volatile organic compounds attenuate pathogen virulence via evolutionary trade-offs

Nature

Jianing WangWaseem RazaGaofei JiangZhang YiBryden FieldsSamuel GreenrodVille-Petri FrimanAlexandre JoussetQirong Shen & Zhong Wei 

The ISME Journal (2023)

Abstract

Volatile organic compounds (VOCs) produced by soil bacteria have been shown to exert plant pathogen biocontrol potential owing to their strong antimicrobial activity. While the impact of VOCs on soil microbial ecology is well established, their effect on plant pathogen evolution is yet poorly understood. Here we experimentally investigated how plant-pathogenic Ralstonia solanacearum bacterium adapts to VOC-mixture produced by a biocontrol Bacillus amyloliquefaciens T-5 bacterium and how these adaptations might affect its virulence. We found that VOC selection led to a clear increase in VOC-tolerance, which was accompanied with cross-tolerance to several antibiotics commonly produced by soil bacteria. The increasing VOC-tolerance led to trade-offs with R. solanacearum virulence, resulting in almost complete loss of pathogenicity in planta. At the genetic level, these phenotypic changes were associated with parallel mutations in genes encoding lipopolysaccharide O-antigen (wecA) and type-4 pilus biosynthesis (pilM), which both have been linked with outer membrane permeability to antimicrobials and plant pathogen virulence. Reverse genetic engineering revealed that both mutations were important, with pilM having a relatively larger negative effect on the virulence, while wecA having a relatively larger effect on increased antimicrobial tolerance. Together, our results suggest that microbial VOCs are important drivers of bacterial evolution and could potentially be used in biocontrol to select for less virulent pathogens via evolutionary trade-offs.


Science News

from research organizations


Molecular mechanism behind nutrient element-induced plant disease resistance discovered

Date:January 10, 2023Source:American Phytopathological SocietySummary:In one of the few studies to directly investigate the mechanism underlying the effect of essential elements on plant disease resistance, scientists demonstrate that nutrient elements activate immune responses in tomato plants through different defense signaling pathways.Share:

    

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Just like humans can’t subsist on a diet of only French fries and brownies, plants must also consume a balanced diet to maintain optimal health and bolster their immune responses. Nutrient element uptake is necessary for plant growth, development, and reproduction. In some cases, treatment with essential elements has been shown to induce plant disease resistance, but conclusive research on the molecular basis of this remedy has been limited.

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In one of the few studies to directly investigate the mechanism underlying the effect of essential elements on plant disease resistance, Rupali Gupta of Volcani Institute and colleagues demonstrate that nutrient elements activate immune responses in tomato plants through different defense signaling pathways.

Their paper, recently published in Phytopathology, outlines the molecular mode of action that potassium, calcium, magnesium, and sodium take to minimize both fungal and bacterial plant diseases. Using straightforward laboratory methods, the authors demonstrate that essential element spray treatment sufficiently activates immune responses in tomato — including defense gene expression, cellular leakage, reactive oxygen species production, and ethylene production — leading to disease resistance. Their results suggest that different defense signaling pathways are required for induction of immunity in response to different elements.

Understanding the genetic mechanism underlying this process may provide new insights into crop improvement. Corresponding author Maya Bar comments, “We are excited to probe the molecular basis of this phenomenon, define another facet of induced resistance, and provide data that will assist in applying this principle to agricultural systems in a more purposeful, reproducible manner.”

The tenets of mineral nutrient-induced disease resistance discovered in this study can be exploited in agricultural practices — benefiting growers/farmers and protecting valuable crops.

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Materials provided by American Phytopathological SocietyNote: Content may be edited for style and length.


Journal Reference:

  1. Rupali Gupta, Meirav Leibman-Markus, Gautam Anand, Dalia Rav-David, Uri Yermiyahu, Yigal Elad, Maya Bar. Nutrient Elements Promote Disease Resistance in Tomato by Differentially Activating Immune PathwaysPhytopathology®, 2022; 112 (11): 2360 DOI: 10.1094/PHYTO-02-22-0052-R

Cite This Page:

American Phytopathological Society. “Molecular mechanism behind nutrient element-induced plant disease resistance discovered.” ScienceDaily. ScienceDaily, 10 January 2023. <www.sciencedaily.com/releases/2023/01/230110150941.htm>.

  Our favorites this week  
A win for the bees is a win for everyone
The US Department of Agriculture has approved the first-ever vaccine for honeybees! Yes, you read that correctly. The vaccine protects against American foulbrood disease, a fatal bacterial disease that can destroy honeybee colonies — and thus threaten ecosystems that depend on the bees’ myriad ecological benefits. While it’s amusing to imagine a bunch of bee clinics with tiny little syringes and Band-Aids, there’s a much more practical way of administering this type of  vaccine. It’s mixed into “queen feed,” which the worker bees consume. The worker bees incorporate the vaccine into royal jelly, which they feed to the queen bee. Once the queen bee has consumed the vaccine-laden royal jelly, her offspring will all be immune as well. 

JANUARY 12, 2023

Review highlights a century of science in tackling emerging fungal diseases in response to climate change

by CABI

Review highlights a century of science in tackling emerging fungal diseases in response to climate change
Dr David Smith examines CABI’s living culture collection of over 30,000 strains of fungi and bacteria including 5,000 plant pathogens and other microorganisms. Credit: CABI

A new CABI-led review published in the journal Microbiology Australia highlights how CABI has spent over 100 years identifying and combatting emerging fungal diseases of plants in response to the impacts of climate change.

Dr. David Smith, Emeritus Fellow and former Director, Biological Resources at CABI, led a team of scientists who focused on how climate change is influencing disease occurrence and how CABI’s work and resources can help in the battle to help reduce them.

Ultimately, the researchers highlight how CABI and its 49 Member Countries are working collaboratively with a global network of partners to manage emerging and spreading diseases which can affect livelihoods and impact upon food security.

This includes diseases such as Maize Lethal Necrosis Disease (MLND) which has been negatively affecting maize crops and their seeds in eastern and central Africa. Part of CABI’s work to help mitigate this included a project that sought to enhance the knowledge base on MLND viruses and the epidemiology of the disease in the affected countries.

A key component of CABI’s work in the field is its living culture collection. This was born from the establishment of the Imperial Bureau of Mycology in 1920 and laid the foundation of CABI’s expertise in mycology which continues to this day.

Currently there are over 30,000 strains of fungi and bacteria—including 5,000 plant pathogens and other microorganisms—in the collection of which 90% are unique to CABI. It represents one of the world’s largest genetic resource collections and holds the UK’s National Collection of Fungus Cultures.

Another aspect of CABI’s work is its Diagnostic and Advisory Service (DAS) which provides diagnostic advice on pests and diseases on crops from around the world. An example of this was the confirmation of the invasive apple snail (Pomacea canaliculate)—which threatens Kenya’s rice crops—using DNA analysis.

In addition to sequencing, techniques such as MALDI-TOF (matrix-assisted laser desorption ionization—time of flight analysis) are used are used to identify and characterize disease causing microorganisms.

Other recent new country reports of pests and diseases confirmed by the DAS laboratory include Moniliophthora roreri causing frosty pod rot on cocoa in Jamaica and the fall armyworm (Spodoptera frugiperda) which affects more than 100 plant species and is found in Africa and Asia.

Dr. Smith said, “An understanding of microbes and microbial communities is essential for improving crop yields and facilitating interventions, such as biocontrol of pests, diseases, and invasive species.

“In parallel to the scientific work, CABI information resources are supporting the science and fieldwork to increase the reach, application, and understanding of the science worldwide.”

“In carrying out its work, CABI has seen an impact on emerging disease due to climate change and has implemented programs to help farmers adapt to its impact.”

These programs include the global PlantwisePlus program which works closely with national agricultural advisory services to establish a global network of plant clinics, run by trained ‘plant doctors’.

Rural plant clinics, staffed by agricultural advisors trained through PlantwisePlus, receive diseased samples and provide a timely diagnosis and appropriate remedial advice.

The program has been introduced to 34 countries in Africa, Asia and the Americas, presented over 5,000 plant clinics, trained over 13, 200 plant doctors and reached over 54 million smallholder farmers.

Recommendations to farmers have resulted in halving the use of restricted chemicals, increasing yields by more than 20% and over 1.5 million farmers have improved food security.

Another program is the Pest Risk Information Service (PRISE) which, in sub-Saharan Africa, used earth observation environmental data and models on pest life cycles to create early-warning alerts and advice to farmers on the timely application of pest control products.

It has delivered pest alerts in Kenya, Ghana, Zambia and Malawi to over 1.8 million farmers since it began in 2017. SMS information was sent to 6,000 farmers in Kenya, for example, on the fall armyworm which resulted in 60% of the farmers reporting a change in their farming practices as a result.

Dr. Smith added, “It is clear that climate change exacerbates problems and broadens the scope and range of plant pests and invasive species by enabling organisms to grow in environments from which they have normally been excluded.”

“Predictive models and early warning systems are needed if we are to combat such problems, for which CABI’s information resources and dissemination systems can play a critical role.”

A CABI-led review in the Journal of Economic Entomology has already highlighted several management options for the fall armyworm after recent climatic models reveal that the pest is likely to itself in the southern parts of Europe including southern Spain, Italy, Portugal or Greece.

More information: David Smith et al, CABI’s 100 years in identifying and combating emerging fungal diseases in response to climate change, Microbiology Australia (2022). DOI: 10.1071/MA22054

Dirk Babendreier et al, Potential Management Options for the Invasive Moth Spodoptera frugiperda in Europe, Journal of Economic Entomology (2022). DOI: 10.1093/jee/toac089

Journal information: Journal of Economic Entomology 

Provided by CABI

January 4, 2023 

Elizabeth King 

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East Africa’s bean industry adapts to climate change

Climate change is likely to have a severe impact on East Africa’s bean industry. Beans are a vital crop, with over 200 million people in Sub-Saharan Africa depending on them as their most important pulse.

Runner/butter beans growing
Runner beans (Phaseolus coccineus), also known as butter bean

The global challenges of climate change have significant impacts on agriculture, food and nutrition security, and livelihoods. Farmers face environmental degradation, increasingly extreme weather, and reduced access to natural resources. As a result, there is a need for new research to find innovative solutions to ensure a food-secure future.

Research-based solutions

Alliance Bioversity International and the International Center for Tropical Agriculture (CIAT) work with local, national, and multinational partners to deliver extensive programs. These programmes find research-based solutions to create sustainable, prosperous, and nourishing food systems and landscapes.

One example of this is the Pan Africa Bean Research Alliance (PABRA). In collaboration with the Kenya Agricultural and Livestock Research Organisation (KALRO), the University of Nairobi, and Egerton University, PABRA has researched and released over 550 new bean varieties across 31 countries. This includes 33 varieties in Kenya (as of June 2022).

These bean varieties help to address a range of consumer needs. Benefits include increased abiotic resistance to factors like heat, drought, cold, and low soil fertility, and increased biotic resistance to a range of pests and diseases. Some varieties also improve cooking and nutritional quality with higher zinc or iron levels. Others even increase product yield. As a result, they help to increase the competitiveness of bean markets by providing customers with improved products. This, in turn, contributes to economic growth.

Dried beans
A variety of dried legumes

The importance of beans

Beans are a vital crop across sub-Saharan Africa, with over 200 million people depending on beans as their most important pulse. This creates a vast demand for beans of between 750,000 and 1 million MT per year. As a result, beans are economically significant.

Beans are also nutritionally vital, providing protein, fibre, complex carbohydrates, vitamins, and micronutrients. Dry beans (Phaseolus vulgaris L.) are the second most important food crop, after maize, in Kenya.

Development of drought-tolerant bean varieties

For the last 2 years, East Africa has received below-average levels of rainfall during the rainy seasons.  70 million people face severe drought conditions. This is the worst drought on record for the Horn of Africa since 1981.

The impact on the agricultural sector across East Africa is significant. Hit particularly hard are the northern and eastern pastoral areas of Kenya and the southern and eastern parts of Ethiopia.

This has resulted in water shortages, rising fertiliser prices, loss of livestock, and crop failure. Consequently, crop varieties that are more resilient to increasingly frequent extreme weather conditions are vital.

These bean varieties help farmers adapt to these changing conditions. For example, PABRAs development of a drought-tolerant variety, the Nyota bean, has been hugely successful.

Released in 2017, it targeted semi-arid counties (which cover 70% of Kenya) including Machakos, Makueni, Narok, and Baringo in Kenya. This variety also matures quickly with a 70-75-day maturity period, whilst other varieties take 90-120 days. In addition, it cooks quickly and is rich in essential micronutrients, including zinc and iron.

bean industry adapts to climate change
Beans at a market

Beans and integrated crop management (ICM)

The Pan Africa Bean Research Alliance also takes this a step further by promoting integrated crop management (ICM) strategies in combination with planting improved bean varieties. They work closely with farmers through field demonstrations, exchange visits, and printed guidance materials to promote efficient, climate-smart agricultural practices. In this way, PABRA helps farmers to significantly increase yields and be more climate-resilient.

ICM technologies include cropping systems like rotation and intercropping, and the use of organic fertiliser to improve soil fertility. They also include water management practices like infield water harvesting techniques.

PABRA estimates that 6 million farmers (68% of which are women) are aware of, and use, ICM technologies to improve bean production. In addition, PABRA continues to research ICM to find new and improved solutions. One example is assessing the potential for beans to contribute to nitrogen fixation which in turn increases yields of subsequent cereal crops when in a rotation cropping system.

Beans and climate change

Climate change threatens bean production due to more frequent extreme weather events. Drought has particularly affected East Africa, and temperatures are expected to increase by 2.5°C between 2000 and 2050. This is likely to reduce bean-growing regions by 50%.

Meanwhile, some areas are experiencing excessive rain, for example, in Western areas of Kenya. These conditions, alongside other factors, drive the spread of pests and diseases. They affect the geographic distribution of pests and diseases, as well as the survival rate, migratory routes, and population sizes of pests and vectors.

It is therefore vital to continue researching and implementing climate-smart technologies and practices, like creating more tolerant and resilient crop varieties. As well as, by building the capacity of governments to operationalise key related policies, to create a food-secure future.

Further reading

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

Development and delivery of bean varieties in Africa: The Pan-Africa bean research alliance (PABRA) model’.

Integrated crop management’ – CABI.

‘Climate-smart agriculture’ – World Bank.

Pan-Africa Bean Research Alliance (PABRA)’ – Alliance Bioversity International and CIAT.

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Acknowledgements

The CABI-led PlantwisePlus programme is financially supported by the Directorate-General for International Cooperation (DGIS), Netherlands; European Commission Directorate General for International Partnerships (INTPA, EU); the Foreign, Commonwealth & Development Office (FCDO), United Kingdom; the Swiss Agency for Development and Cooperation (SDC); the Australian Centre for International Agricultural Research (ACIAR); the Ministry of Agriculture of the People’s Republic of China (MARA)

Climate smart agricultureEast AfricaKenyabeansclimate change

Agriculture and International DevelopmentClimate change and biodiversityCrop healthFood and nutrition security

Supporting Pollinator Habitats Through Operation Pollinator

By Caydee Savinelli, Ph.D.Editor’s Note: This Entomology Today post is a sponsored article contributed by Syngenta, a Gold Corporate Partner of the Entomological Society of America. The views presented in sponsored posts reflect those of partner organizations and not necessarily those of ESA. Learn more about Syngenta and the ESA Corporate Partner program.Biodiversity is essential for effective crop production and the health of our natural resources. It sustains the ecosystems that underpin fertile soils and plant pollination, helping farmers grow healthy food. Bees alone contribute nearly $20 billion to the value of crop production in the U.S. each year, and more than one-third of all crops depend on pollinators for propagation. Ensuring a sustainable food supply requires each of us to play a role in preserving our land and protecting pollinators and other beneficial insects and animals. Syngenta understands the importance of the interconnectedness of agriculture and nature and is committed to helping biodiversity flourish.Taking strides toward sustainable agriculture helps promote an industry that can successfully feed today’s consumers while also safeguarding pollinators and conserving the environment for generations to come. The Good Growth Plan highlights our ongoing commitments and initiatives to support farmers and the environment through 2025. And, through our Operation Pollinator program, Syngenta is focused on creating essential habitats to restore pollinators in agricultural settings, on golf courses, and within other landscapes.Operation Pollinator provides farmers, golf course managers, and other land managers with the tools and information needed to successfully establish and manage attractive wildflower resources that are crucial for bumble bees and pollinating insects while enhancing the visual appearance of the utilized land. The habitat provides nesting and food resources for bees, other pollinators, beneficial insects, as well as small mammals and farmland birds, enhancing overall biodiversity. It also provides important ecosystems services like pollination and pest control that improve crop yields, thereby securing both sustainable farming and environmental balance.The vast landscapes of golf courses, meanwhile, provide an ideal opportunity to preserve and enhance the essential habitat of pollinators and create pride for golf club members. With guidance from Syngenta, golf course superintendents can extend their environmental stewardship to make a positive impact on the environment. By establishing pollinator habitats in under-utilized land like out of play areas, run-off buffer zones, or roadway green spaces, positive benefits are achieved for multiple stakeholders including pollinators, golf course superintendents, and the environment itself.We can all do our part to protect pollinators and other beneficial insects by promoting more sustainable practices that diversify agricultural land, golf courses, and other landscapes. To learn more about pollinator protection and stewardship best practices, visit www.BeeHealth.org.

Caydee Savinelli, Ph.D., is stewardship team and pollinator lead at Syngenta in Greensboro, North Carolina. Email: caydee.savinelli@syngenta.com.

Sunflowers Linked to Reduced Varroa Mite Infestations in Honey Bees

ENTOMOLOGY TODAY  1 COMMENT

A new study indicates a benefit to honey bees of local sunflower cropland. Even low levels of sunflower acreage nearby correlate with reduced Varroa mite infestation in managed colonies, researchers found, and supplemental sunflower pollen helps ward off the mites, as well. (Photo by Lillian Wong via FlickrCC BY-SA 2.0)

By Paige Embry

Paige Embry

Varroa destructor is aptly named. It is a parasitic mite of Asian honey bees (Apis cerana) that jumped to European honey bees (Apis mellifera) and then romped around most of the world, wreaking havoc.⁠ In 1987 it arrived in the United States,⁠ where it wins the dubious award of being the most problematic of the honey bee’s many pests and diseases.⁠

Scientists long thought that Varroa mites were tick-like—blood-suckers that transmitted diseases—and that the bulk of the harm they caused came from the diseases they spread. Even without spreading diseases, Varroa mites damage bees because they don’t actually eat replaceable hemolymph (a bee’s blood-equivalent); rather, they eat its fat body. It sounds benign because the name is misleading. A bee’s fat body is a bit like a human’s liver. It plays a role in the bee’s immune system and its ability to survive the winter and detox pesticides. Any method of lowering Varroa loads would be a huge boon to honey bees and their keepers.

new study published in December in the Journal of Economic Entomology provides early evidence that the humble sunflower (Helianthus annuus) may provide some relief from those fat body-destroying mites.

Evan Palmer-Young, Ph.D.

The pollen and nectar of sunflowers (and some other members of the Asteraceae family) are protein-poor and generally considered a subpar source of nutrition for bees. From an overall health perspective, however, sunflower pollen and nectar look like great food because they may help reduce parasites. Evan Palmer-Young, Ph.D., a postdoctoral fellow at the U.S. Department of Agriculture’s Bee Research Lab in Beltsville, Maryland, is lead author on the new study. Previous experiments on bumble bees had shown that sunflower pollen strongly reduced infections by a specific parasite, so, Palmer-Young says, “We wanted to see whether honey bees might derive similar, infection-reducing benefits from sunflowers.”

The study covers four different experiments that looked at two parasites and several viruses, but only two experiments showed significant results. The authors sum up their findings: “Although we did not find significant effects of sunflower pollen on endopasrasites [Nosema ceranae] or viruses in laboratory or field settings, sunflower pollen was associated with reduced levels of Varroa mites in honey bee colonies.”

In one experiment the scientists provided supplemental pollen (sunflower pollen, wildflower pollen, or artificial protein patties) to field colonies of honey bees in late summer when Varroa levels often begin to rise. The colonies given supplemental sunflower pollen saw a 2.75-fold diminishment in Varroa infestation levels relative to bees receiving artificial pollen patties. (The group receiving wildflower pollen had more mites than the ones fed sunflower pollen, but the difference was not statistically significant.)

Perhaps the most significant finding was from the experiment that looked at the association of Varroa mite infestation levels and sunflower crop acreage. The scientists found that honey bees located near sunflower cropland had lower mite levels—even when the total land cover by sunflowers was scant (a median of 0.32 percent). Their models predicted that each doubling of sunflower acreage within two miles of an apiary would lead to a 28 percent decrease in mite infestation. The researchers note that this pattern is a correlation, and some other factors related to having sunflowers in the vicinity—different management practices by beekeepers or pesticide exposure, for example—may be the cause for the lower mite loads. Nevertheless, Palmer-Young says a big takeaway from the work is, “that sunflowers appear to be protective against a major threat to honey bees (i.e., mites), whereas the amount of U.S. sunflower cropland is declining—potentially limiting bees’ access to sunflower-associated benefits.”

Total crop area devoted to sunflowers in the U.S. has decreased by 2 percent per year since 1980. The authors note that market and policy shifts that led to changes in agriculture in the Dakotas played a role in that decline. In the 1980s, low-quality farmland was converted to (flower-rich) grasslands as part of the Conservation Reserve Program (CRP)—a change likely beneficial to bees of all sorts. Post-2000, both sunflower crop area and CRP acreage were replaced by corn and soybeans. The authors note, “Between 2006 and 2016, 53 percent of CRP land surrounding existing North and South Dakota apiaries was converted to crop production, but only 8 percent was used for bee-friendly crops.” This area hosts 75 percent of U.S. sunflower acreage as well as 40 percent of U.S. honey bees during the summer.

The authors write that they don’t have enough evidence yet to recommend specific changes in land use, but Palmer-Young says, “If sunflowers are as big of a factor in mite infestation as indicated by our landscape-level correlations … having a few more acres of sunflower within a mile or two of apiaries could bring colonies below the infestation levels that require treatment of hives with acaracides (i.e., mite-controlling chemicals).”

Palmer-Young provided a poetic summary for the paper:

Fields of sunflower blooming in sight
yield for many a bee a delight.
But with bright yellow joy
Displaced by corn and soy,
Honey bees could lose balm for their mites.

In other words, if additional research supports sunflowers as an anti-parasitic for Varroa mites, don’t be surprised if beekeepers start tossing out sunflower seeds everywhere they go.

Read More

Sunflower-Associated Reductions in Varroa Mite Infestation of Honey Bee Colonies

Journal of Economic Entomology

Paige Embry is a freelance science writer based in Seattle and author of Our Native Bees: North America’s Endangered Pollinators and the Fight to Save Them. Website: www.paigeembry.com.

Sunday, 08 January 2023 09:37:18

PestNet

Grahame Jackson posted a new submission ‘Aussie science tackling rusty plant threat’

Submission

Aussie science tackling rusty plant threat

AAP

When eucalypt-destroying myrtle rust was detected on a cut flower farm and in two nurseries north of Sydney 12 years ago, a major containment operation was launched.

Millions of dollars were spent but to no avail. Within months, the invasive fungus, identified by its bright yellow spots, had swept up the coast and been discovered as far north as Cairns.

It has since spread across the Australian landscape and now flourishes in bushland reserves, backyards, commercial operations, nature strips and park lands alike.

With the exception of South Australia, it’s infiltrated every state including Tasmania, as well as the Tiwi Islands in the Northern Territory.

Authorities agree myrtle rust is now endemic and cannot be eradicated.  

In South America, from where it originated, it’s relatively harmless. Not so locally, given that almost 80 per cent of Australian native trees belong to Austropuccinia psidii’s primary victim, the myrtaceae family.

Among 2000 Australian plants in total, the bottle brush, lemon myrtle, tea tree, lilly pilly, blackbutt and broad-leaved paperbark tree melaleuca quinquenervia are among its most vulnerable members.   

According to the Invasive Species Council, myrtle rust could eventually universally “alter the composition and function of forest, woodland, heath and wetland ecosystems”.

It says the incursion “is about as bad as it can get for biosecurity in Australia”.

Federal Environment Minister Tanya Plibersek agrees a co-ordinated response is needed.

Read on: https://www.aap.com.au/news/aussie-science-tackling-rusty-plant-threat/


The scientists tracked Tweets and online news articles (published between 2011 and 2021) about two invasive insects

01-05-2023

Tweets provide insights on how invasive insects spread

ByAndrei Ionescu

Earth.com staff writer

READ MORE

A new study led by North Carolina State University has found that Twitter and online new articles could be used effectively to track the timing and location of invasive insect spread in the United States and globally. These findings suggest that such sources are promising for filling gaps when official data are not widely available.

“The idea was to explore if we could use this data to fill in some of the information gaps about pest spread, and ultimately, to support the development of better predictive models of where pest spread is happening, and when to use costly control measures,” said study lead author Laura Tateosian, an associate professor of Geospatial Analytics at NC State. “Even though these are not formal scientific sources, we found that we could clearly see some of the major events that were occurring about two invasive pests in the news, and on Twitter.”

The scientists tracked Tweets and online news articles (published between 2011 and 2021) about two invasive insects: the spotted lanternfly and the tomato leaf miner (Tuta absoluta). The former – first spotted in the U.S. in 2014 – is an insect native to Asia which can damage or even destroy grapes, cherries, hops, certain lumber trees, and other plants. The latter – often nicknamed the “tomato Ebola” – is native to South America, and was first discovered in Spain in 2006 before spreading to Europe, Asia, Africa, and the Middle East.

“While some invasive insects have reached their global range, in both of these cases, the pests are actively spreading,” said study co-author Ariel Saffer, a graduate student in Geospatial Analytics at NC State. “We launched this as a proof-of-concept study to see if it would be scientifically reasonable to use these sources to track pest spread. We compared information in places where the insects were known to be present to see if these sources accurately captured existing knowledge.”

The analysis revealed that activity on Twitter and in news stories reflected some of the patterns in official surveys, such as the pests’ seasonal cycles, and major outbreaks. In Pennsylvania – where the spotted lanternfly was first found – news articles uncovered one county not listed in the official records.

“News media and social media have the potential to give you more immediate insight into what’s going on, especially if scientific information on insect spread is not immediately published in scientific literature, or not widely available to other scientists. Also, relying on data from scientific publications can sometimes offer a patchwork coverage of space and time, depending on when that study happened. It can be hard to get aggregated information in continuous time, especially at the global scale, as that information can be managed by multiple agencies,” Saffer concluded.

The study is published in the journal Computers, Environment and Urban Systems.

By Andrei Ionescu, Earth.com Staff Writer

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