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Africa Science News

New menacing Cassava pest identified in West and Central Africa

A new pest—southern armyworm, Spodoptera eridania (Stoll)—has been discovered in West and Central Africa!

Originating from the tropical regions of the Americas the fall armyworm (FAW) adult has a remarkable capacity for long distance migration and high female fertility. Its crop-destroying caterpillars can cause serious damage to maize but also to other important crops such as sorghum, rice, and vegetables.

According to Dr Georg Goergen, Entomologist/Biocontrol Specialist and Head of IITA’s Biodiversity Center in Bénin, the FAW was first found in the cassava fields of south-eastern Nigeria in December 2016. Its presence was confirmed by DNA barcode analysis at IITA headquarters in Ibadan.

The recent introduction of the FAW into the African continent and its growing threat to agriculture and food security have caused great concern in many of the 44 countries of tropical Africa invaded by this pest.

Farmers had first observed an outbreak of caterpillars that caused severe defoliation on cassava in a 450-hectare field near Ubiaja in southeastern Nigeria in late 2016.

Alcohol-preserved samples of the larvae were sent for diagnosis to the Biodiversity Center at the IITA station in Bénin, which did not match the morphological characteristics of FAW caterpillars.

The species, however, appeared to have related origins and resembled closely the African cotton leafworm (S. littoralis [Boisduval]). In the absence of adult moths, it was concluded that the latter species, widespread in tropical Africa and known to feed on various kinds of food, must have attacked some sweet varieties of cassava that are less toxic to potential insect pests.

These attributes have made the control of FAW a challenging task. The development of management options adapted to Africa has mobilized international experts and the national capacities of affected countries and raised general attention to caterpillar attacks on various crops.

Similar observations were made in early 2017, when farmers submitted alcohol-stored samples of immatures for identification following complaints about dense caterpillar colonies in their cassava fields in the areas surrounding Dasso, southern Bénin.

Moths were finally obtained from tomato fields attacked in Yaoundé, Cameroon, and samples of adults were made available from a scientist-colleague based at the University of Masuku, in Franceville, Gabon. The examination of the outer features of the moths together with the genitalia of both sexes clearly identified the pest as SAW.

As a further means of control, larval and adult samples were collected and sent to IITA headquarters in Ibadan to the germplasm health, virology, and diagnostics unit for DNA barcode analysis. Results confirmed these findings.

According to Goergen, SAW belongs to the cosmopolitan genus Spodoptera that encompasses 31 species worldwide including many of the most important agricultural armyworm caterpillars such as FAW. The detection of the new pest adds to the eight species already known to occur on the African continent. Caterpillars, particularly mature instars of the SAW, are extremely variable in their general appearance and can hardly be identified based on physical characters alone.

Accurate identification of adults is not easy since S. eridania belongs to the category of Spodoptera moths lacking strong contrasting patterns on the forewings. They measure 33-38 mm in length, are commonly cream or gray, bear a faint kidney-shaped spot, and look identical in both sexes.

The only constant feature is a dark brown streak at the inner margin of the forewing. Some forms exhibit a large bar extending from the center to the margin of the forewing (see photo). The high variability and difficult identification of the species are evidenced by its 20 Latin synonyms.

The southern armyworm is native to the Americas, occurring widely from southern USA to Argentina. With records of more than 200 host plants belonging to 58 plant families including many important crops, the species is probably the most polyphagous species within the genus Spodoptera. Depending on the host plant and temperature, the southern armyworm can complete its life cycle within 30-40 days and is able to produce 1500-3000 eggs over its lifetime.

Although the species has been known only sporadically until now as a serious pest in southern USA, in recent years it has emerged as an important pest of soybean in the cotton growing areas of South America.

In addition, recurrent interceptions on internationally traded goods by quarantine authorities at entry points in Europe have led to a new risk assessment for the species. In 2015, S. eridania was newly ranked as an A1 quarantine pest recommended for regulation on the list of the European and Mediterranean Plant Protection Organization (EPPO).

In Africa, spectacular outbreaks comparable to those caused by FAW have not been observed; however, preliminary data show that the species is present in at least four countries in West and Central Africa, where it can be found on cassava, tomato, amaranth, and maize.

It is uncertain how long the SAW has been present in West and Central Africa and its possible pathways of introduction into the continent are also unclear.

Since their identification is difficult, populations may have remained latent in the field and only been sporadically noticed especially when young caterpillars aggregate on individual host plants before they disperse upon maturation.

The fact that adult males react on pheromones of other Spodoptera species calls for a more thorough assessment of pheromone trapping when FAW populations are monitored. An interesting circumstance is that the southern armyworm and the fall armyworm share many important natural enemy species in South America.

Dr May-Guri Saethre, IITA’s Deputy Director General for Research for Development, said that while this trait may become a significant stabilizing factor for common natural enemy populations, more research is urgently needed to assess its effective pest status in tropical Africa.

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CABI Plantwise Blog

From Satellites to Stem Borers: Using Earth Observation to Forecast Pest Outbreaks

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Globally, over 500 million smallholder farmers provide food for two thirds of the world’s population. With 40% of crops lost annually to pests, achieving zero hunger by 2030 depends on increasing the productivity of these smallholders.

We already have weather forecasts, pollen forecasts and UV forecasts, but what if farmers had access to pest forecasts?

At the recent annual ICT4D Conference in Lusaka, CABI’s global director of knowledge management, Cambria Finegold, gave a talk on CABI’s Pest Risk Information Service (PRISE) for Sub-Saharan Africa commenting, “The ICT4D delegates were the perfect receptive audience for emerging technologies like PRISE, understanding the need for the tech and development sectors to work more closely together in order to accelerate progress towards achieving the global goals.”

By combining earth observation technology, plant health modelling, and real-time field observations, PRISE can deliver tailored pest alerts and actionable advice to farmers when and where they need it.

PRISE models risk to crop health from insects and diseases based on environmental data. Tailored messages are used to provide a risk assessment to growers in defined regions. Advice and support is offered via the Plantwise network and other extension services, and subscribers are prompted to provide crowdsourced feedback, which is used to validate the model. This feedback loop provides greater confidence in the forecasts.

PRISE-flowchart

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Mobile pest alerts

The first release of PRISE is currently live and being used by Plantwise plant doctors in Kenya, Ghana and Zambia. Plant doctors receive weekly alerts from a chatbot on the Telegram messaging system, translating risk levels into actionable information about the pest situation in their districts. A few days later, they receive a follow-up message asking for feedback on the accuracy of the model, which is then used to update it and improve the model.

As the system develops more data on pests and crops will be added, new features will be integrated and it will be made available to more users through more channels. This development is planned over the next few years to ensure that the system is sustainable and eventually able to run independently.

Innovation can provide new solutions and CABI is committed to a continued development of its work with new technologies.

Watch this video for more on PRISE

PRISE is funded by the International Partnership Programme (IPP) which is run by the UK Space Agency. IPP focuses strongly on using the UK space sector’s research and innovation strengths to deliver a sustainable economic or societal benefit to emerging and developing economies around the world

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From CABI

Farmers Need Long-Term and Short-Term Solutions to Combat Fall Armyworm in Kenya

Reblogged from Farming First.

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From a distance, Wycliffe Ngoda’s two acres of shiny green maize crops look healthy and lush. But the tell-tale holes in the leaves and debris on the stems give away an increasingly dangerous secret hidden in more and more maize fields across Kenya and sub-Saharan Africa. The rampant Fall Armyworm caterpillar is once again threatening harvests across the continent for a second year.

The pest, which arrived in Africa from the Americas in 2016, affected around 50,000 hectares of maize in Kenya alone last year, costing 25 per cent of the crop, according to government officials.

This year, the losses could be as high as 50 per cent, threatening Kenya’s food security and farmers’ economic security in a country where the average annual consumption of maize surpasses 100kg per person.

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“This is one of the deadliest crop pests in the world,” said Dr B.M. Prasanna, director of the global maize programme at CGIAR’s International Maize and Wheat Improvement Centre (CIMMYT), based in Nairobi. “It can have as many as six life cycles in a year and each female moth can lay as many as 1,500 to 2,000 eggs.

“There’s no single solution that will fight it in all the smallholder contexts. But we’re not starting from scratch.”

Government delegates and experts have recently travelled to Brazil to learn how Fall Armyworm is controlled in the Americas, including the use of pest-resistant varieties of maize.

Scientists at the African Agricultural Technology Foundation (AATF) have also found improved yields in controlled trials of transgenic crops as part of the Water Efficient Maize for Africa (WEMA) initiative.

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But while the Kenyan government considers such developments as part of a long-term strategy to reduce the impact of Fall Armyworm, the pest continues to pose a threat in the short-term.

In their desperation to ward off the caterpillar, which can reach the size of a little finger, some farmers even resorted to mixing homemade pesticides.

“I came across Fall Armyworm last year,” said Mr Ngoda, 65, from Mbale, Vihiga county. “We were taken unaware. It’s something that had not occurred here before. The attack was very fast and furious.

“We started looking for local solutions. We took liquid detergents and mixed it with some ash. Eventually we succeeded in fighting it off but the damage was already done. I lost about 50 per cent of my crop, others lost 70 per cent.

“We were using local innovations but it was more like guesswork.”

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This year, Mr Ngoda said he was better prepared thanks to training in detection and responsible pesticide use provided by the county government and NGOs such as Farm Input Promotions Africa (FIPs-Africa). He said he had applied pesticide to his crops once so far.

The advice included treating crops with pesticides in the morning or afternoon when the caterpillars are active, and spraying to the side to avoid direct contact with the product. FIPs-Africa also contracts specialist sprayers to help farmers safely apply the correct pesticide.

In the meantime, Kenya’s Pest Control Products Board (PCPB) has fast-tracked its approval process for products that can help tackle Fall Armyworm to help address the threat in the short-term. But the challenge in rural areas is ensuring the best advice and information reaches the smallholders.

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CropLife Kenya organises popular county farmer training sessions every month and CABI has more than 120 Plantwise clinics across Kenya where smallholders can bring in samples of their damaged crop to get expert advice on the necessary remedy.

But more is needed to teach farmers how to live with a pest that is here to stay.

“I wish we had more people,” said Mr Ngoda. “Sometimes, farmers don’t seek solutions and expert advice. We need more surveillance and on farm visits.

“I’m normally guaranteed 40 bags minimum. Last year, I didn’t get 20. I thank God I have a small family and none of them are going to school, otherwise it would have been a total disaster.”

Reblogged from Farming First. Read the original article here→

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SE farm press

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Aphid-transmitted virus found in lower Southeast cotton

Cotton blue disease is a big problem in Brazil, and it seems to have come to the U.S. by a hurricane, like soybean rust did with Hurricane Katrina.

Patrick R. Shepard | May 03, 2018

A virus that is previously known to be vectored by aphids into cotton has been recently identified as the primary suspect virus from limited samples of cotton in Alabama. Similar symptomology has been reported in the coastal counties of Alabama, Georgia and the Florida Panhandle.

“The cotton blue disease (CBD) symptomology was observed at the end of 2016 by one of my former graduate students, Drew Schrimsher, in his grower cotton variety trials,” says Auburn University plant pathologist Dr. Kathy Lawrence.

“He observed it again at the end of 2017 and it was much worse; symptomology was observed in areas beyond the area where it was first observed. CBD is a big problem in Brazil, and we hypothesize it may have come to the U.S. by a hurricane, like soybean rust did with Hurricane Katrina.”

Symptoms include mosaic cupping and thickening of the dark blue/green leaves, yellowed leaf veins, and dwarfing of the plant. Other symptoms include no boll set on new growth, swollen and brittle stems, and decreased yields; fields with symptoms in early bloom had fewer bolls per plant.

“Once the virus starts showing its symptoms, the plant stops producing any more cotton,” Lawrence adds. “There’s not a top crop, which many growers depend on for income.

 “We seldom spray for aphids in cotton, and we don’t recommend spraying for them to prevent this suspect disease, which would take out beneficials and flare other insect pest problems. We do encourage growers and consultants to watch for the CBD virus symptomology, and if they find it, to call their state plant pathologist to help us keep up with it.

“We also recommend keeping cotton fields and surrounding areas weed-free, especially of legume and malvaceae weeds including pigweed and sida as the literature shows they harbor the virus. If the virus is in the weeds, aphids can pick it up and transmit it to cotton. So management might come down to taking out weed host plants.”

Schrimsher, who is now an agronomist with AGRI AFC, observed mild leaf crumpling symptoms in his cotton variety trials that he was conducting in growers’ fields in south Alabama and the Florida Panhandle in late summer to early fall 2016. He observed extensive severe leaf crumpling in 2017.

Lawrence says, “The virus was much worse by that time; CBD had progressed beyond the area where it was found in 2016. However, infected areas were patchy like aphid infestations are patchy along the outer edges of a field, and close to areas with other plants and trees. It didn’t take over the whole field.

“Schrimsher told me about the symptoms in August 2017. We took samples, and found it’s a virus. We normally don’t have viruses in Alabama, so to get an identification, leaves, petioles and stems were collected from the newest terminal of plants expressing leaf crumpling symptoms and sent to University of Arizona plant pathologist Dr. Judy Brown, who researches the viruses in her state. She tested the samples and ruled out leaf crumple or leaf curl virus; instead, she found a virus associated with aphids that matches the one in Brazil.”

It appears from Schrimsher’s variety trials that the U.S. cotton varieties that were in the trials and are grown in the Southeast region all demonstrated the symptomology. “He saw the virus’ symptoms across all company varieties in his tests,” Lawrence says. “CBD is a big problem in Brazil, but they do have cotton varieties that are tolerant to the disease. The U.S. seed companies have gene markers in their breeding program. It’ll take time to develop resistant varieties for the U.S., but it’s not like starting from scratch.

“We will observe CBD closely this year. We’ve seen it for two years and hope it’s not here to stay. We hope that it will have a limited economic impact like soybean rust did.”

Official confirmation of the suspect virus will require additional sampling and verification by APHIS.

 

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WEMA Maize Shows Promising Resistance to Fall Armyworm in Mozambique

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

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

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

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

 

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Delta Farm Press 1

bollworm larvae

Biopesticide offers new form of control for bollworms, budworms

Helicoverpa NPV is found in nature as a pest of certain caterpillars. It does not kill other pests, and is harmless to humans

Apr 17, 2018

A host-specific virus is being used to control bollworms and budworms in Arkansas crops.

Helicoverpa nucleopolyhedrovirus, or just NPV, does not affect humans, plants or other insects, including those that are beneficial.

A fact sheet about Helicoverpa NPV is now available online at http://bit.ly/HelicoverpaNPV. The fact sheet is a joint publication of the University of Arkansas System Division of Agriculture, Southern Integrated Pest Management Working Group and the Mid-South Entomologists Working Group.

The bioinsecticide has been studied and in use for years. Gus Lorenz, Extension entomologist for the University of Arkansas System Division of Agriculture, said there is no shortage of research behind the use of this virus.

“This virus has been around for a long time,” he said. “The specific virus we’re looking at from AgBiTech, we’ve been looking at for about three years.”

The product is widely used and is currently in use in many different countries.

“It’s well-adopted in Australia and they’re selling it in South America,” Lorenz said. “It’s used all across the country and they’re pushing it pretty hard in the Mid-South.”

The virus only kills bollworm and budworm larvae that are less than a half-inch long and has no effect on later growth stages also known as instars. Because of this, Lorenz said, the virus should not be used if a producer finds more than five larger larvae in 25 scouting sweeps of a field.

Catch them early

“The virus doesn’t control the pests at later stages,” he said. “The younger larvae are smaller and more susceptible.Ninety percent of what bollworms consume is in the last instars, so you have to catch them before they cause that damage. It’s slow killing, so the last thing you want to do is put it on a late stage larva.”

The virus usually causes death in small larvae within four to six days and can show residual activity through several generations of pests if the conditions are right, according to the publication.

Lorenz said while there is always a possibility for resistance with any insecticide, it is not likely here in the Mid-South.

“If you expose larva to it in the front end of the season and the back end of the season, year in and year out, it could build resistance,” he said, “but it’s not probably anything we’re going to experience.”

As stated in the publication, the virus is safe for tank-mixing. However, along with some other mentioned precautions, Lorenz warns against mixing with high pH water.

“Water with high pH breaks down the matrix of the virus,” he said. “It’s extremely important that it’s not mixed with water with a pH of eight or higher.”

There are restrictions on when to use Helicoverpa NPV in relation to time of year.

TAGS: Insects

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Genetic literacy project

Cotton bollworm-corn earworm hybrid ‘megapest’ discovered in Brazil, could spread to US

It’s the stuff of science fiction. Hybridisation of two caterpillars in Brazil confirmed through extensive genomic testing by CSIRO researchers.

But it’s real and will enable the international agricultural community to stay ahead in the race to combat the megapest.

Helicoverpa armigera and Helicoverpa zea (commonly known as the cotton bollworm and corn earworm, respectively) are the world’s greatest caterpillar pests of broad-acre crops, causing in excess of US $5 billion in control costs and damage each year across Asia, Europe, Africa, America and Australia.

Researchers have used world-first genome mapping technology to confirm the bollworm has been spreading rapidly in Brazil and hybridising with the earworm.

The caterpillar is retaining the strongest characteristics of both species posing a real threat that the new and improved “superbug” could spread into the United States and cause widespread crop destruction.

The hybridisation research is outlined in a paper published in the Proceedings of the National Academy of Sciences of the USA (PNAS) journal….

“No two hybrids were the same suggesting a ‘hybrid swarm’ where multiple versions of different hybrids can be present within one population,” CSIRO scientist Dr Tom Walsh says.

Read full, original post: Hybridisation and the new frontier against spread of global pests

The GLP aggregated and excerpted this article to reflect the diversity of news, opinion, and analysis. Click the link above to read the full, original article.

 

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