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How Moths Find Their Flame – Genetics of Mate Attraction Discovered

Biologists have discovered the gene controlling the mating preference of male European corn borer moths for the female sex pheromone
Tufts University

14-May-2021 5:00 AM EDT, by Tufts Universityfavorite_border

Newswise: How Moths Find Their Flame - Genetics of Mate Attraction Discovered

Callie Musto, Charles Linn

A male European corn borer moth (Ostrinia nubilalis) sexually courts a rubber septum doused with the sex pheromone of a female European corn borer moth

Newswise — The mysteries of sexual attraction just became a little less mysterious – at least for moths. A team of six American and European research groups including Tufts University has discovered which gene expressed in the brain of the male European corn borer moth controls his preference for the sex pheromone produced by females.  This complements a previous study on the gene expressed in the female pheromone gland that dictates the type of blend she emits to attract males. The study was reported today in Nature Communications.

The implications go beyond making a better dating app for bugs. Now scientists can begin to ask why mating signals and mating preferences change in the first place, which is a long-standing paradox since any change could reduce the ability of an organism to successfully mate. Knowledge of these two genes will provide a better understanding of how the pheromones of the 160,000 moth species have evolved.

Of course, one important role for mating preferences is to make sure you are not matching up with a completely different species. The signal sent by females must be preferred by males of the same species to ensure that like mates with like–a mechanism called assortative mating.  The European corn borer is interesting because there are two types, called E and Z, with assortative mating within each type.  Even though the two types can be mated to each other in captivity, E mostly mates with E, and Z with Z in the field.  For this reason, the European corn borer has been used as a model for how one species can split into two, ever since the two pheromone types were first discovered 50 years ago. 

 “That means we now know – at the molecular level – how chemical matchmaking aids in the formation of new species. Similar genetic changes to pheromone preference could help explain how tens of thousands of other moth species remain separate,” said Erik Dopman, professor of biology in the School of Arts and Sciences at Tufts and corresponding author of the study.

Different aspects of the research were conducted by the three co-first authors Fotini Koutroumpa of University of Amsterdam, Melanie Unbehend of the Max Planck Institute for Chemical Ecology, and Genevieve Kozak, a former post-doctoral scholar at Tufts University and now assistant professor at University of Massachusetts, Dartmouth.  “Our study’s success can be attributed to a team with a common vision and strong sense of humor that helped make the science worthwhile and fun,” said Dopman.

One of the surprise discoveries made by the team was that while females may vary their signals in the blend of pheromones they produce, preference in the male is driven by a protein that changes their brain’s neuronal circuitry underlying detection rather than affecting the receptors responsible for picking up the pheromones.

Preference for a particular cocktail of pheromones is determined by any of hundreds of variants found within the bab gene of the male. The relevant variants of bab are not in parts of the gene that code for a protein, but in parts that likely determine how much of the protein is produced, which in turn affects the neuronal circuits running from the antennae to the brain. The researchers were able to determine anatomical differences in the male, including the reach of olfactory sensory neurons into different parts of the moth brain, and link them to their attraction to E or Z females.

“This is the first moth species out of 160,000 in which female signalling and male preference genes have both been identified,” said Astrid Groot of the University of Amsterdam, who also helped identify the gene controlling the pheromone difference in E and Z females. “That provides us with complete information on the evolution of mate choice and a way to measure how closely these choices are linked to evolving traits and populations.”

The ability to predict mating could also help control reproduction in pest insects. The European corn borer is a significant pest for many agricultural crops in addition to corn. In the U.S., it costs nearly $2 billion each year to monitor and control. It is also the primary pest target for genetically modified “Bt corn” which expresses insecticidal proteins derived from the bacterium, Bacillus thuringiensis. While Bt corn remains an effective control of the corn borer moth in the U.S., corn borers in Nova Scotia are now evolving resistance to another variety of Bt corn.

“Our results can help to predict whether Bt resistance could spread from Nova Scotia to the Corn Belt of the U.S., or whether assortative mating could prevent or delay it”, said co-author David Heckel at the Max Planck Institute for Chemical Ecology, who also studies how insects evolve resistance to Bt.  “Bt corn has enabled a huge reduction in the use of chemical insecticides, and it should be a high priority to preserve its ecological benefits as long as possible.”REQUEST AN EXPERT

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Soil Biodiversity Under Grave Threat from Pesticides – Most Comprehensive Review Ever

Posted on May 7 2021 – 3:00pm by Sustainable Pulse« PREVIOUSNEXT »Categorized as

new study published Tuesday by the academic journal Frontiers in Environmental Science finds that pesticides widely used in American agriculture pose a grave threat to organisms that are critical to healthy soil, biodiversity and soil carbon sequestration to fight climate change. Yet those harms are not considered by U.S. regulators.

The study, by researchers at the Center for Biological Diversity, Friends of the Earth U.S. and the University of Maryland, is the largest, most comprehensive review of the impacts of agricultural pesticides on soil organisms ever conducted.

The researchers compiled data from nearly 400 studies, finding that pesticides harmed beneficial, soil-dwelling invertebrates including earthworms, ants, beetles and ground nesting bees in 71% of cases reviewed.

“It’s extremely concerning that 71% of cases show pesticides significantly harm soil invertebrates,” said Dr. Tara Cornelisse, an entomologist at the Center and co-author of the study. “Our results add to the evidence that pesticides are contributing to widespread declines of insects, like beneficial predaceous beetles and pollinating solitary bees. These troubling findings add to the urgency of reining in pesticide use.”

The findings come on the heels of a recent study published in the journal Science showing pesticide toxicity has more than doubled for many invertebrates since 2005. Despite reduced overall use of insecticides, the chemicals most commonly used today, including neonicotinoids, are increasingly toxic to beneficial insects and other invertebrates. Pesticides can linger in the soil for years or decades after they are applied, continuing to harm soil health.

The reviewed studies showed impacts on soil organisms that ranged from increased mortality to reduced reproduction, growth, cellular functions and even reduced overall species diversity. Despite these known harms, the Environmental Protection Agency does not require soil organisms to be considered in any risk analysis of pesticides. What’s more, the EPA gravely underestimates the risk of pesticides to soil health by using a species that spends its entire life aboveground — the European honeybee — to estimate harm to all soil invertebrates.

“Below the surface of fields covered with monoculture crops of corn and soybeans, pesticides are destroying the very foundations of the web of life,” said Dr. Nathan Donley, another co-author and scientist at the Center. “Study after study indicates the unchecked use of pesticides across hundreds of millions of acres each year is poisoning the organisms critical to maintaining healthy soils. But our regulators have been ignoring the harm to these important ecosystems for decades.”

Soil invertebrates provide a variety of essential ecosystem benefits such as cycling nutrients that plants need to grow, decomposing dead plants and animals so that they can nourish new life, and regulating pests and diseases. They’re also critical for the process of carbon conversion. As the idea of “regenerative agriculture” and using soil as a carbon sponge to help fight climate change gains momentum around the world, the findings of this study confirm that reducing pesticide use is a key factor in protecting the invertebrate ecosystem engineers that play a critical role in carbon sequestration in the soil.

“Pesticide companies are continually trying to greenwash their products, arguing for the use of pesticides in ‘regenerative’ or ‘climate-smart’ agriculture,” said Dr. Kendra Klein, a co-author who’s also a senior scientist at Friends of the Earth. “This research shatters that notion and demonstrates that pesticide reduction must be a key part of combatting climate change in agriculture.”

“We know that farming practices such as cover cropping and composting build healthy soil ecosystems and reduce the need for pesticides in the first place,” said co-author Dr. Aditi Dubey of the University of Maryland. “However, our farm policies continue to prop up a pesticide-intensive food system. Our results highlight the need for policies that support farmers to adopt ecological farming methods that help biodiversity flourish both in the soil and above ground.”

Background

The review paper looked at 394 published papers on the effects of pesticides on non-target invertebrates that have egg, larval or immature development in the soil. That review encompassed 275 unique species or groups of soil organisms and 284 different pesticide active ingredients or unique mixtures of pesticides.

The assessment analyzed how pesticides affected the following endpoints: mortality, abundance, richness and diversity, behavior, biochemical markers, impairment of reproduction and growth, and structural changes to the organism. This resulted in an analysis of more than 2,800 separate “cases” for analysis, measured as a change in a specific endpoint following exposure of a specific organism to a specific pesticide. It found that 71% of cases showed negative effects.

Negative effects were evident in both lab and field studies, across all studied pesticide classes, and in a wide variety of soil organisms and endpoints. Organophosphate, neonicotinoid, pyrethroid and carbamate insecticides, amide/anilide herbicides and benzimidazole and inorganic fungicides harmed soil organisms in more than 70% of cases reviewed.

Insecticides caused the most harm to nontarget invertebrates, with studies showing around 80% of tested endpoints negatively affected in ground beetles, ground nesting solitary bees, parasitic wasps, millipedes, centipedes, earthworms and springtails.

Herbicides and fungicides were especially detrimental to earthworms, nematodes and springtails.

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Septoria warning as high levels of latent disease found

11 May 2021 | by FarmingUK Team | ArableFarm ProductsNewsA robust T2 fungicide programme is advised to tackle the hidden threat, Corteva Agriscience saysA robust T2 fungicide programme is advised to tackle the hidden threat, Corteva Agriscience says    

A septoria warning has been issued to UK growers as high levels of latent disease has been found in plant samples.

Septoria pressure in wheat crops is expected to build in the coming weeks as warmer temperatures are set to follow early May rainfall.

Laboratory analysis of plant samples has shown high levels of latent septoria, which indicates disease pressure could be greater than expected following a cold dry April.

Corteva Agriscience warns that the conditions could be favourable for septoria to spread through crops ahead of key flag-leaf fungicide applications which take place from mid-May.

Sally Egerton, technical manager said: “In general cereal crops have looked reasonably clean and free from disease which led to T0 fungicides either being skipped, or rates being cut back.

“T1 fungicides are going on following very little rain so, again, programmes will have been adjusted according to the perceived level of disease prevalence.

“Now we are seeing reports of high levels of latent septoria infection which will spread with further rain events and the warmer temperature expected in the next 10-12 days.”

Microgenetics’ rapid test for septoria, SwiftDetect, indicates the level of infection using a traffic light system and log genome equivalents.

This helps farmers to understand their position before making a decision on the appropriate product and rate for a T2 fungicide spray.

Microgenetics said it had not been surprised by the number of positive samples sent in from fields across England and Wales, highlighting the importance of testing.

Chris Steele, the firm’s product manager, said they had detected latent septoria in over 400 samples sent to their laboratory since T1 applications took place.

“Many of the positive samples come from varieties which do not have a strong disease profile, and where growers might expect to find septoria present, even if it was not visible,” he said.

“We have also had positive samples from varieties which have excellent septoria ratings, which demonstrates the importance of testing before deciding on product choice and dose rate.

“Once temperatures get to 15 degrees and above, septoria can really get going,” Mr Steele said.

Corteva Agriscience has advised growers to use a robust product which will deliver lasting protection during a key growth stage of the crop.

Univoq fungicide, containing Inatreq active, was approved for sale and use in the UK last month and offers protectant control on all septoria strains.

The product is the first new target site for septoria control registered in the UK for 15 years.

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Is genetically modified corn the answer to fall armyworm? 

ABC Rural / By Megan HughesPosted 3ddays ago

A close up of a caterpillar on a stalk of corn. It's clear the grub has done a lot of damage
Fall armyworm has been detected across the country from North Queensland to Western Australia and even Tasmania.(Supplied: DPIRD)

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  • It’s a tiny caterpillar that’s difficult to detect, but for more than a year it’s been having a massive impact on crops in Australia, especially corn. 

Key points:

  • Fall armyworm is causing damage to corn crops around Australia 
  • Farmers are asking whether genetically modified corn could help
  • The Maize Association says it will need whole-of-industry support before GM corn can be introduced  

Fall armyworm (FAW) has infiltrated six states and territories and is so hard to control farmers are whispering about a method that’s been off the table for almost two decades — genetically modified (GM) corn.

Maize Association of Australia chairman Stephen Wilson said questions were being raised about whether GM corn could manage the armyworm incursion.

“Anecdotally, I am hearing from the field farmers saying we need GM to help us control the insect,” he said. 

“It’s a major discussion point for the industry as a whole because for the last three decades we, as an industry, as the Maize Association, have been working uniformly to say we do not need GM in Australia.” 

Lessons from the US 

Since arriving in Australia in February 2020, fall armyworm has been detected in Queensland, the Northern Territory, Western Australia, New South Wales, Victoria and, most recently, in Tasmania. 

Fall armyworm is native to the United States, where it has devastated multiple agricultural crops, but growers there have different tools to fight it. 

Fall armyworm on corn plants
Fall armyworm outbreaks are contained by insecticide use and GM crops in the United States.(Supplied: Queensland Department of Agriculture and Fisheries)

North Carolina State University professor and extension specialist Dr Dominic Reisig said in their industry, corn was genetically modified to produce insecticidal proteins that naturally occurred in a bacteria found in soil. It is known as BT corn.

Dr Reisig said while it was not specifically designed to treat FAW it had had an impact. 

“It was first commercially planted in 1996 but that particular crop that was planted did not control fall armyworm,” he said.

“So it wasn’t until different BT toxins were introduced that we really started to see fall armyworm control. 

“But because it’s a sporadic outbreak pest throughout the US it wasn’t like a huge, earth-shattering moment when we were able to control fall armyworm.” 

Are GMO crops the silver bullet? 

According to Dr Reisig, treating FAW across ag industries was a multi-pronged approach with insecticides and a GM crop. 

He said in corn the pest could infest a crop in different stages of its development. 

“Once it gets into the whirl it’s very difficult to control,” he said. 

“But the good thing is when it attacks in those (earlier) stages it’s not that damaging to yield — so the corn looks really bad but it usually pops out of it and it’s not a problem. 

“If fall armyworm attacks later in the season when maize has an ear, then it’s a problem. 

“Once it’s inside that ear you can’t control it and then it’s a really damaging pest in terms of yield and it’s really difficult to control with insecticides so BT (corn) is the way to go.”

He said insecticides were able to control the pest in other crops like soya beans or vegetables because the plants were structured differently.

Weighing up the losses 

Australia only grows three GM crops — cotton, safflower and canola. 

A sea of yellow flowers under a blue sky as the canola crop is in full bloom.
Canola is one of thee genetically modified crops in Australia.(Supplied: Riverine Plains Inc)

Corn has remained GM-free and, as a consequence, the industry has been able to access different markets including Japan and Korea. 

“End users such as snack food and cornflake breakfast cereal manufacturers have told us the whole time they do not want GM in their raw materials,” Mr Wilson said. 

“It would impact on both the export market and also on all the domestic markets — everything from dairy cows utilising the maize as grain or silage right through to beef cattle and right through to human consumption. 

“It’s a major, major, major impact that would need to be agreed to by all sectors of the industry.” 

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A person opens a corn's covering to check if it's ripe.
Australia has been able to access multiple international markets as the corn grown here is GM free.(Pexels: Frank Meriño)

He said any trial would be complicated.

“You have all the regulatory issues of actually bringing germplasm into the country, you have the quarantine issues of having the facilities that could handle the GM product, then you’ve got the issues of field testing,” he said. 

“It would be a long, drawn-out process and we’d have to consider the impact on the industry as a whole because it’s very hard, if not impossible, to have part-GM, part-non-GM. 

“It’s a very expensive process and it makes the non-GM corn being in the minority a very expensive product that people have to pay a premium for.” 

In a statement, a spokesperson from the Federal Department of Agriculture, Water and the Environment said genetically modified maize seeds may only be imported into Australia under an import permit issued by the department, but that no applications had been made. 

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NEWS RELEASE 12-MAY-2021

EurekAlert

Scientists uncover how resistance proteins protect plants from pathogens

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

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IMAGE: THE ZAR1 RESISTOSOME ACTS AS AN ION CHANNEL IN THE PLASMA MEMBRANE TO TRIGGER CA2+ ION FLUX AND IMMUNE RESPONSES view more CREDIT: BI ET AL., CELL

In plants, disease resistance proteins serve as major immune receptors that sense pathogens and pests and trigger robust defense responses. Scientists previously found that one such disease resistance protein, ZAR1, is transformed into a highly ordered protein complex called a resistosome upon detection of invading pathogens, providing the first clue as to how plant disease resistance proteins work. Precisely how a resistosome activates plant defenses, however, has been unclear.

A joint team led by Profs. ZHOU Jianmin, CHEN Yuhang and HE Kangmin at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences and Prof. CHAI Jijie at Tsinghua University recently employed state-of-the-art electrophysiology and single-molecule imaging to investigate the molecular mechanism by which the ZAR1 resistosome activates plant immunity.

By using Xenopus oocyte- and planar lipid bilayer-based electrophysiology studies, the researchers first showed that the ZAR1 resistosome is a cation-selective, calcium-permeable ion channel. They then applied single-molecule imaging to show that the activated ZAR1 resistosome forms pentameric oligomers in the plasma membrane of the plant cell, confirming previous structural data.

The formation of ZAR1 resistosome in the plant cell triggers sustained calcium ion influx and subsequent immune signaling events leading to cell death, and these processes are all dependent on the activity of the ion channel.

Together, these results support the conclusion that the calcium signal triggered by the ZAR1 channel initiates immune activation, thus providing crucial insights into the working of plant immune systems.

Disease resistance proteins are the largest family of plant immune receptors and are of major agricultural importance in protecting crop plants from assault by diverse pathogens and pests including viruses, bacteria, fungi, oomycetes, nematodes, insects, and parasitic weeds.

The findings of this study shed light on the precise biochemical function of many disease resistance proteins, and suggest new methods for controlling diseases and pest damage in crop plants.

This work “presents important findings that will change our view of ETI-triggered cell death,” said a reviewer from Cell. “The use of TIRF to visualize and monitor in real-time membrane-associated resistosomes is very exciting and many researchers will strive to emulate this method.”

###

This study, entitled “The ZAR1 resistosome is a calcium-permeable channel triggering plant immune signaling,” was published online in Cell on May 12.

The research was supported by the National Natural Science Foundation of China and the National Key Research and Development Program of China.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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A race against time: The giant weeds taking over Lake Ossa in Cameroon

Lake Ossa, Cameroon

Lake Ossa, Cameroon   –   Copyright  AMMCOBy Nalova Akua  •  Updated: 12/05/2021

Cameroon’s coastal waters have been invaded by three of the world’s most dangerous water weeds, proving an existential threat to aquatic ecosystems and livelihoods of riparian communities.

The latest of these weeds, Salvinia molesta, is a free-floating, green-brown freshwater fern with branching horizontal stems. It has already invaded more than 40 per cent of Lake Ossa (4,000 hectares), the largest natural lake found on Cameroon’s coast, since 2016.

The weed doubles in size every 10 days.ADVERTISING

The other two, water lettuce and water hyacinth, appeared much earlier – in 1949 and 1970 respectively, according to the Cameroon National Herbarium, a collection centre for plant specimens.

As a flowering invasive aquatic plant, water hyacinth now covers 85 per cent of River Fiko and half of the Wouri River Basin – all water bodies found in Cameroon’s Littoral Region. Mats of this invasive weed double in size in five days.about:blank

The perennial evergreen floating plant known as water lettuce.htm) is found in patches on the surfaces of the Wouri River Basin and the lower reaches of the Sanaga River.

“Water lettuce doubles its biomass in just over five days; triples it in 10 days, quadruples in 20 days and has its original biomass multiplied by a factor of 9 in less than one month,” says Dr. Kenfack Voukeng Sonia Nadège, a Cameroonian weed scientist working with Green Connection, a local environmental conservation non-governmental organisation.

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“As floating weeds, they form dense mats on the surface of water bodies, disrupting aquatic flora and fauna underneath and thus adversely affecting the water ecosystem,” Dr. Kenfack adds.

“This hinders water flow, fishing, swimming, boating, water sports and navigation.”

All these invasive species are native to southeastern Brazil and northern Argentina but can be dispersed within an aquatic system by wind in the dissemination of spores; water currents, floods, and animals; as well as through human activities such as transportation by boat or canoe.

Uncontrolled industrial activities also favour the spread of invasive weeds in Cameroon’s coastal waters.

Pollution due to human activities favours the development of these plants.

Dr Kenfack 

“Being the economic capital, the Littoral Region and especially Douala is the most industrialised municipality in Cameroon with about 60 per cent of the country’s industries’ discharges often released in the open spaces,” says Kenfack.

“Besides, houses built without proper flushing systems contribute to the increase of the nutrients in the environment. Pollution due to human activities favours the development of these plants,” she says.

Canva
Salvinia molesta infests lakes and riversCanva

Dr. Kamla Takoukam Kamla, founder of the African Marine Mammal Conservation Organisation (AMMCO), agrees that poor land use triggers the proliferation of invasive aquatic weeds in Cameroon’s coastal regions given that the water columns are enriched with nutrients.

“Two main nutrients needed for invasive weeds to grow are nitrogen and phosphorous coming from upstream. Lake Ossa and the Sanaga River (the largest River in Cameroon) are connected by a 3km channel. Once this river gets polluted, the lake also gets polluted,” explains Kamla.

“It is possible that the nutrients are coming from the industries, plantations and hydroelectric dam reservoirs that are constructed upstream.”

A threat to the livelihood of humans and protected species

The Lake Ossa complex which contains three main lakes and over twenty islands is located in Dizangue, Littoral Region of Cameroon. In 1974, the complex was designated a faunal reserve and since 2018, has been serving as a National Park.

Before the Salvinia invasion, fishing was the major source of livelihood for over 80 per cent of the local population according to Global Water Partnership.

The lake was also an important habitat for many wildlife species including manatees, freshwater turtles, crocodiles, monitor lizards, snakes, aquatic birds and over 18 families of fish.

Before the Salvinia invasion, fishing was the major source of livelihood for over 80 per cent of the local population.

“The mats [of aquatic weeds] indirectly deplete dissolved oxygen, thereby asphyxiating and killing native fish and phytoplankton. With reduced fish supply, human nutrition in riverine communities where fish are the primary source of protein is jeopardized, leading to poor health,” explains Kenfack.

These invasive species “can rapidly out-compete native species and dominate the ecosystem, consequently reducing biodiversity by their exponential proliferation, depriving in return the native species of space, nutrients and moisture,” she adds.

AMMCO
Lake Ossa over the years, as the infestation has become worse.AMMCO

This results in a modification of the entire structure and functioning of the ecosystems.

The International Union for the Conservation of Nature (IUCN) has described the threat posed by Salvinia molesta to Lake Ossa and its ecosystem as “a conservation emergency.” At least 400 fishermen used to fish in Lake Ossa – fish being the main protein source for a couple of thousand people who live around the lake.

“In the past, I was able to make between 15 and 21 Euros daily as profit from selling fish. But today, I can barely make 6 Euros a day as profit,” says Dina Marie-Louise, a 51-year-old who has been selling fish caught in the lake for the past 22 years.

The lake was also an important habitat for wildlife species including manatees, freshwater turtles, crocodiles, monitor lizards, snakes, aquatic birds and over 18 families of fish.

The mother of 12 said the Salvinia attack on Lake Ossa – their main source of livelihood for generations – has shattered her plans of building a house for her family. Seven of her children have dropped out of school for want of means.

Kouoh Elinga Charles, 56, who has spent 30 years fishing in the lake, expressed the same concern adding that he has resorted to odd jobs to feed his polygamous home.

“The salvinia plant has disrupted fishing considerably,” he says.

Canva
Manatees used to live in Lake OssaCanva

“Initially I was able to save 15.32 euros from fishing daily. But today, it is difficult to fetch 1.53 euros from the activity which can hardly satisfy our household needs,” the father of eight said.

Water hyacinth and Salvinia invasions have also disrupted fishing and sand extraction in the Wouri River Basin and in the River Fiko – other main sources of income to the riparian communities.

Lake Ossa used to harbour a minimum of 50 individual African manatees, the least-studied of the three manatee species in genus Trichechidae. But their number is on the decline owing to the Salvinia attack on the lake. Manatees are large, slow-moving mammals that frequent coastal waters and rivers. They never leave the water but, like all marine mammals, manatees must surface about every five minutes to breathe.

When carpets of invasive weeds lock the surface of the lake, they prevent the African manatee from surfacing and breathing.

Dr Kamla 

“When carpets of invasive weeds lock the surface of the lake, they prevent the African manatee from surfacing and breathing. Consequently, they will likely leave Lake Ossa or move to another part of the lake not yet invaded by aquatic weeds,” Kamla said.

“If nothing is done, the lake will be completely invaded and there will be no fish, no manatees and no freshwater turtles which the lake is endowed with.”

Invasive species are considered the third most dangerous factor threatening world biodiversity, after habitat loss and over-exploitation, according to the International Union for the Conservation of Nature.

Can insects solve the problem?

To counter the spread of aquatic weeds in Cameroon’s coastal waters, the African Marine Mammal Conservation Organisation has partnered with similar international organisations and are considering the three existing approaches: manual removal, biological control and the integrated weed management control method.

The Integrated Weed Management (IWM) method entails combining multiple weed control systems into a single weed management programme, to contain the spread of a particular water weed according to Kenfack.

“Up to now, biological control offers a better opportunity to control the spread of these weeds, as compared to the other methods of control such as the chemical that could be dangerous to human and environment and the manual removal which is a very tedious process.

“Biological control uses host specific insects [Salvinia weevil in case of Salvinia molesta attack] which can only complete their life cycles on the target species to reduce the target plant populations. The insects are the plant’s natural enemies,” Kenfack said.

Salvinia weevils are small beetles which can eat the invasive weeds.

The first releases of the Salvinia weevil as a biological agent were at Lake Moondarra, Mount Isa, Australia in 1980.

AMMCO
The Salvinia weevil is a small beetle which can eat the invasive weeds.AMMCO

“Adults and larvae both feed on these floating ferns,” says Matthew Purcell, Director, USDA ARS Australian Biological Control Laboratory – a structure jointly operated by the Agriculture Research Service of the U.S. Department of Agriculture and the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

“The effectiveness varies from site to site depending on environmental parameters, temperature, nutrient availability and water flow, shade, etc.

“The larvae initially feed on roots, then move to the buds, finally tunneling into the Rhizome which can kill the plant; adults feed on all plant parts externally,” adds Purcell.

Scientists say biological control is globally considered as one of the most cost-effective, environmentally friendly and sustainable ways of reducing the impacts of invasive species.

Nearly 6,000 individual Salvinia weevils are being mass-reared in a facility in Lake Ossa by AMMCO.

“They were brought in from the Louisiana State University in the United States with the authorization of the Cameroon government,” says Kamla.

Scientists say biological control is globally considered as one of the most cost-effective, environmentally friendly and sustainable ways of reducing the impacts of invasive species.

“We keep mass-rearing them until we receive authorisation from the government to release them into the areas affected by water weeds. We are now conducting an experiment to know how long it will take for the weevils to get rid of these aquatic weeds in lake Ossa.”

An effective biological control of Salvinia molesta by using the Salvinia weevil was also applied in the Senegal River in the early 2000s. Similarly, the release of the weevil into South Africa’s fresh water systems in 1985 successfully brought Salvinia molesta under control.

“For water hyacinth, biological control entails the deployment of the weevils Neochetina eichhorniae and N. bruchi which are among the first to be used worldwide in more than 32 countries to control the weed,’’ explains Kenfack.

“They were found in some sites in the Wouri Basin causing damage on the mats of water hyacinth. However, their population is still small and must be mass-reared to obtain effective control of this plant (no need of an import permit).” The biological control agent of water lettuce is different though, she stresses.

Nalova Akua
Locals want Lake Ossa to be clear once again, so that their livelihoods can resume and wildlife can be saved.Nalova Akua

Neohydronomus affinis was used successfully in countries such as Senegal, Benin, Congo, Cote d’Ivoire and South Africa.”

Scientists have expressed hope that Cameroon may just be the next country for the successful implementation of biological control to weed out invasive water weeds.

“Because Cameroon is tropical, the prospects for successful biological control are high. I would predict that there will be a significant reduction in cover within 18 months, if not less,” says Julie Coetzee, Deputy Director and Manager of the Aquatic Weed Biocontrol Programme at Rhodes University, South Africa.

“While the process is not perceived as quick, in comparison to herbicide, it is sustainable in the long term. Patience is key,” she adds.

But Dr. Kenfack is concerned Cameroon may be racing against time.

“Limited progress [to mass-rear and authorise release of weevils] means the watercourses (Lake Ossa, Wouri Basin and Fiko just to name those) and all their biodiversity will be negatively affected.

“This calls for an urgent action in order to reap the benefits from these watercourses not only for us, but for the future generation,” she concludes.

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Sustainable IPM efforts target insect pheromone use

TAGS: CROPSTodd Fitchettewfp-todd-fitchette-desert-broccoli-71.jpg

A biologically safe attractant using pheromones to entice honeybee visits to broccoli for seed is one of several new ag tech ideas promoting sustainable agriculture practices.A company is using a transgenic plant to create low-cost pheromones that could revolutionize pest control.

Todd Fitchette | Apr 21, 2021

Attracting bees to broccoli is just one of many ways a California ag tech company has its mind set on sustainable agriculture with global implications.

Scientists at the Riverside-based ISCA are using a transgenic plant to create low-cost pheromones that could revolutionize pest control and integrated pest management (IPM) efforts in agriculture and beyond.https://7456b58e549c0abcddebe4cfdc5b0937.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

The example of bees and broccoli was demonstrated earlier this year near Yuma, Ariz. By placing a safe pheromone attractant on broccoli grown for seed production, colonies of managed honeybees were attracted to the plants, even during high wind events common during the winter months in the desert region of southwest Arizona.

The use of an attractant to entice honeybees to visit plants needing pollination is just one of several projects, according to ICSA Chief Executive Officer Agenor Mafra-Neto. Moreover, the bee attractant, which looks like a dollop of toothpaste applied to the top of the broccoli plants, could have implications other crops needing pollination by honeybee colonies. Studies in almonds suggest a 5-15% boost in fruit set. Those studies are ongoing.

Mating disruption – the art of fooling male insects into thinking female insects are in an area they are not by means of filling the air with the sex pheromone scent they emit – is yet another sustainable way to improve IPM efforts in agricultural systems. In this case ISCA scientists are using genetically modified strains of camelina plants to create the insect sex pheromones.

These efforts have shown themselves successful in protecting vineyards in Argentina against the European grapevine moth.

USDA funding

According to a company statement, the camelina plant efforts received U.S. Department of Agriculture funding to develop pheromones from natural resources over the use of standard chemical synthesis techniques. A $650,000 grant from the USDA’s National Institute of Food and Agriculture (NIFA) came after a $100,000 NIFA grant that kickstarted the project.

“Pheromone and other semiochemical controls are the future of crop protection, and ISCA’s breakthrough biological pheromone synthesis will propel agriculture into a more lucrative and sustainable enterprise,” Mafra-Neto said in a prepared statement.

Pheromone use is growing in popularity, particularly for mating disruption efforts that are proving themselves successful in agricultural systems. Almond growers are using pheromone attractants in mating disruption efforts against the Navel orangeworm. Unlike with pesticides, insects do not develop resistance against pheromone products.

Mafra-Neto points to the use of the camelina plant, a cousin of broccoli and canola, as a lower-cost method to create pheromones. Biosynthesis in plants eliminates the need to use petroleum-based chemicals as feedstock and bypasses most of the complex organic chemistry steps now required in pheromone production, he said.

Attract-and-kill

Moreover, ISCA studies are also looking at attract-and-kill products that entice targeted insects to a specific location that includes an insecticide capable of killing that insect. Rather than broadcast a chemical insecticide across large swaths of land or to rows of trees, the attract-and-kill method draws insects to a specific location through pheromones. The inclusion of pesticide materials capable of killing the pest when it feeds on or touches the formulation, allows this method to be targeted and safer for the environment.

The attract-and-kill method can greatly reduce the number of chemical pesticides applied on crops for insect control. It also protects non-targeted pests, including pollinators and beneficial insects, because the pheromones used to attract target pests are specific to those species.

Current attract-and-kill studies are ongoing in cotton, corn, and soybeans.

Another topic of study includes the idea of repellants, or semiochemicals that can cause insects to avoid specific plants. As studies in California avocados are ongoing on this front, Mafra-Neto believes forestry systems can use such technology to repel the bark beetle, which is responsible for widespread forest damage and explosive forest fires because of all the dead trees.

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China develops GM corn variety to combat yield-cutting fall armyworm

Dong Xue | CGTN | April 12, 2021

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Credit: Miaoli County Agriculture Office
Credit: Miaoli County Agriculture Office

This article or excerpt is included in the GLP’s daily curated selection of ideologically diverse news, opinion and analysis of biotechnology innovation.

Food security is a major policy issue in China. To strengthen the nation’s seed industry, the country has approved a series of supporting policies, including in South China’s Hainan Province.

Like James Bond once said, “Nothing is impossible.” Lyu Yuping, a veteran plant breeder, had a similar belief and so [he] named his genetically modified corn seed “the 007”.

Lyu has devoted himself to agricultural technology and the seed breeding industry for more than two decades. He believes the corn seeds he’s developed are the real deal.

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LSU student identifies fungus causing soybean taproot decline

This image has an empty alt attribute; its file name is delta-f-perss.png

TAGS: CROP DISEASELSUGarciaArocajpg.jpgTeddy Garcia-Aroca, an LSU Ph.D. student, holds a sample of a fungus he found and named that causes the disease soybean taproot decline.Discovery just “tip of the iceberg” as scientists strive to learn more about this devastating soybean disease.

Bruce Shultz, Louisiana State University | Apr 13, 2021

An LSU graduate student has identified and named a new species of fungus that causes a devastating soybean disease. 

LSU doctoral student Teddy Garcia-Aroca identified and named the fungus Xylaria necrophora, the pathogen that causes soybean taproot decline. He chose the species name necrophora after the Latin form of the Greek word “nekros,” meaning “dead tissue,” and “-phorum,” a Greek suffix referring to a plant’s stalk. 

“It’s certainly a great opportunity for a graduate student to work on describing a new species,” said Vinson Doyle, LSU AgCenter plant pathologist and co-advisor on the research project. “It opens up a ton of questions for us. This is just the tip of the iceberg.” 

Taproot decline

The fungus infects soybean roots, causing them to become blackened while causing leaves to turn yellow or orange with chlorosis. The disease has the potential to kill the plant. 

“It’s a big problem in the northeast part of the state,” said Trey Price, LSU AgCenter plant pathologist who is Garcia-Aroca’s major professor and co-advisor with Doyle. 

“I’ve seen fields that suffered a 25% yield loss, and that’s a conservative estimate,” Price said. Heather Kellytaproot decline in soybeans

Yellowing leaves are early symptoms of taproot decline in soybeans.

Louisiana soybean losses from the disease total more than one million bushels per year. 

Price said the disease has been a problem for many years as pathologists struggled to identify it. Some incorrectly attributed it to related soybean diseases such as black-root rot. 

“People called it the mystery disease because we didn’t know what caused it.” 

Price said while Garcia-Aroca was working on the cause of taproot decline, so were labs at the University of Arkansas and Mississippi State University. 

Price said the project is significant. “It’s exciting to work on something that is new. Not many have the opportunity to work on something unique.” 

Research 

Garcia-Aroca compared samples of the fungus that he collected from infected soybeans in Louisiana, Arkansas, Tennessee, Mississippi and Alabama with samples from the LSU Herbarium and 28 samples from the U.S. National Fungus Collections that were collected as far back as the 1920s. 

Some of these historical samples were collected in Louisiana sugarcane fields, but were not documented as pathogenic to sugarcane. In addition, non-pathogenic samples from Martinique and Hawaii were also used in the comparison, along with the genetic sequence of a sample from China. 

Garcia-Aroca said these historical specimens were selected because scientists who made the earlier collections had classified many of the samples as the fungus Xylaria arbuscula that causes diseases on macadamia and apple trees, along with sugarcane in Indonesia. But could genetic testing of samples almost 100 years old be conducted? “It turns out it was quite possible,” he said. 

DNA sequencing showed a match for Xylaria necrophora for five of these historical, non-pathogenic samples — two from Louisiana, two from Florida, and one from the island of Martinique in the Caribbean — as well as DNA sequences from the non-pathogenic specimen from China. All of these were consistently placed within the same group as the specimens causing taproot decline on soybeans. 

Why now? 

Garcia-Aroca said a hypothesis that could explain the appearance of the pathogen in the region is that the fungus could have been in the soil before soybeans were grown, feeding on decaying wild plant material, and it eventually made the jump to live soybeans. 

Arcoa’s study poses the question of why the fungus, after living off dead woody plant tissue, started infecting live soybeans in recent years. “Events underlying the emergence of X. necrophora as a soybean pathogen remain a mystery,” the study concludes. 

But he suggests that changes in the environment, new soybean genetics and changes in the fungal population may have resulted in the shift. 

The lifespan of the fungus is not known, Garcia-Aroca said, but it thrives in warmer weather of at least 80 degrees. Freezing weather may kill off some of the population, he said, but the fungus survives during the winter by living on buried soybean plant debris left over from harvest. It is likely that soybean seeds become infected with the fungus after coming in contact with infected soybean debris from previous crops. These hypotheses remain to be tested. 

Many of the fungal samples were collected long before soybeans were a major U.S. crop, Doyle said. “The people who collected them probably thought they weren’t of much importance.” 

Garcia-Aroca said this illustrates the importance of conducting scientific exploration and research as well as collecting samples from the wild. “You never know what effect these wild species have on the environment later on.” 

What’s next? Now that the pathogen has been identified, Price said, management strategies need to be refined. Crop rotation and tillage can be used to reduce incidence as well as tolerant varieties. 

“We’ve installed an annual field screening location at the Macon Ridge Research Station where we provide taproot decline rating information for soybean varieties,” Price said. “In-furrow and fungicide seed treatments may be a management option, and we have some promising data on some materials. However, some of the fungicides aren’t labeled, and we need more field data before we can recommend any.” 

He said LSU, Mississippi State and University of Arkansas researchers are collaborating on this front. 

Doyle said Garcia-Aroca proved his work ethic on this project. “It’s tedious work and just takes time. Teddy has turned out to be very meticulous and detailed.” 

The final chapter in Garcia-Aroca’s study, Doyle said, will be further research into the origins of this fungus and how it got to Louisiana. Source: Louisiana State University, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.  

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Combine old with new for resistant weed management

TAGS: HERBICIDEHERBICIDE RESISTANT WEEDSAdam Hixon, BASFadam-hixson-pigweed-glyphosate.jpgSignificant pigweed infestation remains in this field after two applications of glyphosate.Getting back to the basics is critical to managing herbicide resistant weeds.

Ron Smith | Apr 19, 2021

Weeds resistant to herbicides are a way of life for farmers, one more concern to complicate an already complex production system.

But options exist not only to manage resistance but also to reduce the size of the weed seed bank.https://82ae8ac4f4c5904dfe4704d0077ebf4f.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

“Resistance is here to stay,” said Adam Hixson, BASF technical service representative for Texas, Oklahoma, and New Mexico, during a recent media update on managing herbicide resistant weeds in the Southwest.

swfp-shelley-huguley-adam-hixon-profile.jpgAdam Hixson, BASF technical service representative for Texas, Oklahoma, and New Mexico. (Photo by Shelley E. Huguley)

“We’ve heard the expression, ‘out with the old and in with the new,’” Hixson said. “I want to change that to ‘in with the old and in with the new.’”

Back to basics

Getting back to basics, he said, is crucial to managing herbicide resistant weeds. He called on Texas A&M AgriLife Professor and Extension Weed Specialist Pete Dotray to put the problem in perspective.

“According to the International Survey of Herbicide Resistant Weeds, we have eight resistant weed species in Texas,” Dotray said. “The first case of resistance in the state was noted 30 years ago, but in the last 10 years, glyphosate resistance has created a lot of concern.”

Dotray said Roundup resistant Palmer amaranth, also known as pigweed and carelessweed, was first identified on the Texas High Plains about 10 years ago, later than in some Mid-South and Southeastern states. He believes a key to that late arrival was that High Plains farmers never abandoned residual herbicides, especially the yellow herbicides like Treflan and Prowl.

shelley-huguley-dotray-profile.jpgTexas A&M AgriLife Professor and Extension Weed Specialist Pete Dotray (Photo by Shelley E.Huguley)

Overuse of Roundup, using the same chemistry over and over, and use of fewer herbicide and tillage inputs provided an open door for the increase in resistant weed populations, Dotray said. “Resistant weeds were likely already out there in extremely low numbers.”

Palmer amaranth resistance has complicated weed management, Hixson added. “We’ve seen multiple applications of glyphosate at labeled rates fail to control Palmer amaranth.”

He said remedies include manual control, such as hoeing, which is expensive and time-consuming. “Also, we’re always looking for that next ‘shiny object’ that will solve the problem.”

Shiny things have been scarce in recent years, however, so Hixson offers a different option. “We need to use what we have today, but use it in a more calculated, knowledge-based approach. We have to get back to the fundamentals of weed control.”

Year-round effort

He and Dotray agree that successful weed control strategies do not focus solely on in-season herbicide applications. “Good weed management has to be a well-planned, year-round venture,” Hixson said.

Weed identification is a priority. “It’s important to identify the weeds and to understand fully the biology. Know when specific weed species are most vulnerable.”

He explained that Kochia, sometimes “a huge problem and resistant to several herbicides,” emerges early in the spring and typically has only one flush. An effective residual herbicide, applied at the right time, will take care of most Kochia issues.

Palmer amaranth, however, emerges from early in the season well into fall and requires a season-long management program.

Dotray said Palmer seed that emerge late in the season remain a threat to replenish the seed bank and create problems for the next crop year.

“We’ve looked at the abundance of seed one plant can produce,” he said. “Palmer that emerges early produces as many as 500,000 to 600,000 seed, maybe more, per plant. That’s a lot of seed. But a Palmer plant that emerges in August will still produce as many as 20,000 seed, also a lot. As late as September, emerging plants will produce 2,000 seed, and still hundreds by October. Even plants that emerge as late as November can produce some viable seeds.”

“Leaving just one plant,” Hixson said, “may add to the weed seed bank, a key factor for the next season. One seed per square inch represents more than 6 million seeds per acre.” So, next season’s weed control should start before this season ends.

Good news

Dotray said recent research shows a bit of good news about the longevity of Palmer seed. Studies have shown that some weed seed will retain viability for as long as 120 years.

“We had no good answer for how long Palmer seed remain viable, so five years ago we set up a test to see. We buried Palmer seed at various depths across the state.”

They uncover them at intervals, beginning at six months, again at 12 months, and yearly after that. Based on data from the first 48 months of the research, “Palmer seed viability begins to decline significantly after 12 months. Those findings were the same across all locations and at all depths. A second study initiated in 2018 has shown the same results so far,” Dotray said.

“The good news is that a farmer who does a good job of managing Palmer amaranth effectively with a systematic program can get them down to a manageable level in a short time.”

That system should include late applications to prevent escapes, he said.

Knowledge is key

Hixson said an effective weed management program also depends on knowing not only the weed species vulnerabilities but also the interactions of soils and chemistry.

He said using herbicides with multiple, effective modes of action should be a critical part of weed management

“But also understand the properties of the herbicides and how they respond to different conditions, including soil types and moisture. Soil leaching properties will affect herbicide efficacy,” he said. “Also, the more water soluble a product is, the deeper it will move into the soil profile. Less soluble usually means more soil binding.”

He said different soil types — changes in clay content, sand, organic matter level — all may affect herbicide activity.

He said in situations with good moisture, a product like Zidua could be the best option. “In dryland or subsurface drip irrigation conditions, Outlook would be ideal.”Adam Hixon, BASFadam-hixson-timely-applications.jpg

Timely applications, with overlapping residuals (Prowl H2O herbicide followed by Outlook herbicide), along with an effective postemergence herbicide (Engenia herbicide), provide exceptional control of Palmer amaranth.

They key is understanding the weed, the environment, and the herbicide properties, then using the proper material for the target weed under those specific conditions.

Timing and coverage

He added that application timing and coverage also matter.

“Also remember, the cottonseed trait package you plant determines the herbicides you can use.”

“Using residual herbicides, identifying weeds and understanding the difference in solubility and where a product fits best based on soil and moisture are critical to a systems approach to weed management,” Dotray added.

In response to a question about new dicamba labels, Hixson said BASF would not veer from the requirements established by the federal label in Texas, Oklahoma, and New Mexico

Dotray noted that the new registrations come with some significant changes, including bigger buffers, volatility reduction adjuvant requirements and application timing.

“Also, last year some states used 24-C exemptions to alter some regulations. So far this year, states that have applied for a 24-C have been denied.”

Hixson announced that BASF does have one “shiny object” in the pipeline, a new seed trait with tolerance to four herbicides –GLIXTP, pending regulatory approval. He anticipates introduction in 2023, with potentially more availability in 2024.

In the meantime, he said, “Old chemistry still has value.”

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