Biological control training courses for advanced-level graduate students and junior faculty will concurrently be held in Beijing, China and Hanoi, Vietnam, September 02-09, 2017. If you are interested in further information or in applying to join these sessions please contact Dr. Kris Wyckhuys <firstname.lastname@example.org> or Mrs. My Hoang <email@example.com>.
Pakistan’s papaya pest squashed through biocontrol
Copyright: G.M.B. Akash / Pano
> With pesticides ineffective, mealybugs destroyed most of Pakistan’s papaya farms
An insect predator of the papaya mealybug now protects the crop in Pakistan
Success of the parasitoid deployment has encouraged replication in other countries
[ISLAMABAD] A severe infestation of the papaya mealybug (Paracoccus marginatus) nearly wiped out papaya orchards in Pakistan before the largely farmed country decided to replace conventional chemical pesticides that were ineffective with natural predators that proved to be successful.
The system was developed by agro-biotechnologists and entomologists at the Pakistani chapter of the UK-based Centre for Agriculture and Bioscience International (CABI) who introduced the use of Acerophagus papayae, a parasitoid (insects whose larvae parasite upon and eventually kill the host), to effectively control the mealybug infestation.
“Farmers are happy with this cost-effective, pesticide-free technique to deal with the mealybug and now see possibilities of recovering their papaya farms,” says CABI research coordinator Abdul Rehman.
He regrets though that by the time the biological method became available many farmers had already shifted to other crops.
Papaya once covered some 921 hectares in the two coastal provinces of Sindh and Balochistan, according to the National Agriculture Research Council (NARC). But, after the first mealybug attack on papaya was reported in 2008, the area under papaya had shrunk to 307 hectares by 2014.
“Demonstration of the bio-control technique and awareness building among farmers helped wide-scale adoption and resulted in over 80 per cent control of the papaya mealybug.”
Amjad Pervez, NARC
Rehman tells SciDev.Net that after the pest had gripped almost 80 per cent of the papaya orchards, CABI, US Development Agriculture and the US Agency for International Development initiated the biological control programme in close collaboration with NARC to stop the pest’s possible spread to other more important commercial crops.
In 2014, under CABI’s papaya pest management programme, A. papayae specimens were collected from the coastal areas near the port city of Karachi, reared in the laboratory and then released into papaya plantations after screening and environmental assessments.
CABI researchers also set up a Natural Enemies Field Reservoir on the farmers’ fields to breed the A. papayae parasitoid as well as eight other natural predators of the papaya mealybug.
Amjad Pervez, director-general at the NARC’s Karachi-based regional office, says that the advantage of the bio-control approach lies in its simplicity and in the fact that it is self-sustaining.
“Demonstration of the bio-control technique and awareness building among farmers helped wide-scale adoption and resulted in over 80 per cent control of the papaya mealybug,” Pervez says. “Besides, the process was non-laborious, highly affordable and simple enough for farmers not to need support from government agencies.”
Rehman’s team has hammered out a three-pronged plan to promote the field reservoirs through public-private partnerships.
“The bio-control approach has saved the papaya (farming) and also increased profits by reducing expenses on the pesticide sprays once used to fight the pest.”
Abdul Majeed Nizamani, Sindh Abadgar Board
“The plan shall be implemented to boost research and development to strengthen the bio-control process to completely contain papaya mealybug. Sindh and Balochistan provinces’ farmers’ organisations and vegetable and fruit traders’ associations will also be engaged in this regard as key stakeholders,” Pervez explains.
“Controlling the papaya mealybug has helped contain its potential spread to commercial crops like citrus, tomato, aubergine, peppers, mulberry, beans and peas, sweet potato, mango, cherry, and pomegranate. Annual losses, had these crops been affected, would have run into millions of dollars,” says Pervez.
Rehman says Pakistan’s experience in safely controlling the mealybug has been shared with CABI chapters in the Asia-Pacific, European, and African countries.
“Entomologists and fruit pest experts have already communicated possibilities for replication of the bio-control approach, with some necessary modifications in countries like Congo, Indonesia, Malaysia, Nigeria, Sri Lanka, Taiwan and Thailand” he says.
Mealybugs have great resistance to most pesticides. For one thing they exude waxy secretions that can insulate them against chemicals and for another they have developed resistance to most commonly used chemical insecticides, according to a comprehensive Indian study published by Springer earlier this year.
First detected in Mexico in 1955, the papaya mealybug had spread to the Caribbean and Latin America by the 1990s and to the Pacific and South Asian countries through the first decade of this century.
Abdul Majeed Nizamani, president of the Sindh Abadgar Board, a farmers’ organisation, believes that papaya farming would have been completely wiped out in Pakistan if not for the bio-control measures.
“The bio-control approach has saved the papaya (farming) and also increased profits by reducing expenses on the pesticide sprays once used to fight the pest,” Nizamani says.
An arundo gall wasp depositing eggs into the main stem of a giant reed. Photo by John Goolsby.
The release of tiny insects to combat an invasive weed is paying off, according to a recent study by the U.S. Department of Agriculture.Scientists from the USDA’s Agricultural Research Service released arundo gall wasps (Tetramesa romana) and arundo scale insects (Rhizaspidiotus donacis) several years ago as part of a biocontrol program to kill a weed called “giant reed” (Arundo donax) along the Rio Grande in Texas. The weed, also known as “carrizo cane” and “Spanish reed,” clogs streams and irrigation channels, weakens river banks, stifles native vegetation, affects flood control, reduces wildlife habitat, and impedes law enforcement activities along the international border.
Recent research conducted by entomologist John Goolsby demonstrates that these insects have helped control giant reed over more than 550 river miles. Measurements taken in 2014 documented a 22-percent decrease in plant biomass along the Rio Grande since the insects’ release in 2009. Measurements in 2016 show a further decrease of 28 percent and significant recovery of native riparian vegetation.
Giant reed grows between three and seven inches a day and reaches heights of 30 feet along the Rio Grande. The weed increases the population of cattle fever ticks by creating an ideal habitat for them, which makes it difficult for USDA inspectors to detect tick-infested cattle and deer. As the riverbank transitions back to native vegetation, the plant community supports greater abundance and diversity of tick-feeding ants and beetles that act as biological control agents.
To accelerate weed removal, scientists have combined “topping” — mechanically cutting cane — with insect releases. Topping suppresses growth for more than a year and makes plants more susceptible to insect attacks. Combining topping and insect releases gives a high, long-term suppression of cane and allows native trees to grow and start shading giant reed.
“We’ve thinned the cane out significantly,” Goolsby said. “The biggest decline in plants correlates with the greatest number of our biocontrol agents—the wasp and scale.”
Parthenium hysterophorus L. is a native plant of tropical and sub-tropical South and North America that adversely affects food security, biodiversity, and the health of both humans and livestock in East Africa. In East Africa, Parthenium reduces the yield of many major crops such as sorghum and corn, competes with preferred pasture species, and, when consumed by domestic animals, taints their milk and meat, thereby reducing their value. It also causes human health problems such as severe contact dermatitis and respiratory problems. In addition, because of its ability to release toxic chemicals, Parthenium can replace natural vegetation, thus adversely affecting plant biodiversity.
Zygogramma bicolorata, a leaf-eating beetle on Parthenium
In July, Zygogramma bicolorata, a leaf-eating beetle that feeds on Parthenium, was released at several sites around Wollenchiti, Ethiopia. The sites included a farmer`s field, a big uncultivated and a fenced area nearby a railway. The released Zygogramma, especially the second generation, has begun causing damage to Parthenium in cultivated as well as in non-cultivated areas. We are encouraged by the rapid establishment and spread of Zygogramma. Wollenchiti this year received heavy rain and that resulted in lush growth of Parthenium, which is ideal for the bioagent. Fencing the release plots also allowed Zygogramma to have adequate time to build its population before spreading to surrounding fields.
Zygogramma defoliated Parthenium in foreground. Near Wollenchiti, Ethiopia, September 7, 2016.
This release was done through the “Biological control of the invasive weed Parthenium hysterophorus in East Africa” project led by Virginia State University, which has been awarded a grant of $748,465 by USAID through the Integrated Pest Management Innovation Lab managed by Virginia Tech. The goal of the project is to build on the accomplishments of the two previous USAID IPM IL-funded Parthenium projects to abate the spread and impact of the weed in east Africa. One of the objectives of the project is to scale-up the rearing and release of approved biocontrol agents, Zygogramma along with the stem boring Listronotus setosipennis in Ethiopia.
The streets of Buñol, Spain, will run red this week as 20,000 people hurl tomatoes at one another during La Tomatina, the world’s biggest food fight.
It’s a luxury that others envy.
Around the world, tomato crops are being ravaged by an invasive moth no larger than an eyelash. Originally from Chile, Tuta absoluta, also known as the tomato leaf miner, was introduced to Europe in 2006 via a container of infested tomatoes imported to Castellón, a Spanish province not far from Buñol. It spread throughout Europe, then to the Middle East, Africa and Asia.
The toll is particularly devastating in developing countries, where many farmers can’t afford integrated pest management (I.P.M.), the multipronged approach that has proved most effective at keeping the moth at bay.
Earlier this year, officials in northern Nigeria, where tomatoes are a staple, declared a state of emergency in Kaduna State, a major producer of the country’s tomatoes. By May, the moth had destroyed more than 80 percent of tomato crops in Kaduna; the price for a large basket of tomatoes rose to $212, from just $1.50 to $7.50 before the shortage.
Though the leaf miner’s range in Europe is extensive, from Spain to Lithuania, many farmers have kept the moth’s numbers under control with an arsenal of specialized tactics. These include pheromones that lure the moths into traps or disrupt their mating; biopesticides based on bacteria, fungi or oils; chemical pesticides that are highly selective; and the introduction of the leaf miner’s natural enemies.
The last measure has been extremely effective in Spain, said Alberto Urbaneja, a professor at the Valencian Institute of Agricultural Research and one of the first to research the Tuta absoluta invasion in Europe. “If you can establish a good I.P.M. system based on biological control, it is possible to manage Tuta,” he said.
In countries with low financial resources, farmers often don’t take action until the pest has moved in. When it does, farmers turn to the pesticides they have on hand, which typically kill a broad spectrum of pests.
These chemicals are environmentally harmful and eventually lead to pesticide-resistant bugs.
In some countries, the problem comes down to a lack of technical knowledge or government support. With funding from USAID, Muni Muniappan, the director of the IPM Innovation Lab based at Virginia Tech, has been running workshops around the world to help farmers prepare for the inevitable spread of the leaf miner, which also attacks such crops as potatoes, eggplants and peppers.
Meeting the pest head-on “requires lots of training and information,” Dr. Muniappan said. But his work is currently limited to seven countries in Africa and Asia, including Bangladesh and Nepal, where scientists successfully caught the start of a Tuta absoluta invasion earlier this summer.
Experts say it’s only a matter of time before the moth invades the remaining countries within its geographical limits, including the United States, where the Agriculture Department has been monitoring Tuta absoluta and regulating the import of tomatoes since 2009.
The moths have a high reproductive capacity — each female produces up to 300 offspring in her lifetime — and they are small enough to be transported by wind, Dr. Urbanejo said. Their larvae devour tomato leaves, stems, fruits and flowers; uncontrolled, the pest can damage 100 percent of a crop.
Nevertheless, with the right combination of methods, countries should be able to keep the moth at manageable levels, Dr. Urbanejo said.
The problem is already showing signs of stabilizing in some African countries, including Kenya, where the moth was first detected in 2013. Farmers there are starting to use pheromone lures and adaptive practices like alternating tomatoes with other crops, said Fathiya Khamis, a scientist at the International Center of Insect Physiology and Ecology in Nairobi.
At least one company in Kenya, Kenya Biologics, now sells pheromone traps locally, and Dr. Khamis’s team is looking into other options as well, like fungal biopesticides and specialized nets.
As farmers adopt more sustainable strategies, tomato lovers may ultimately have to adjust to higher prices. Still, the drastic price hikes that initially accompanied outbreaks have settled down. In Kenya, tomato prices rose to $1.25 a kilogram after the moth outbreak from just 60 cents. Now, prices hover around $1. Tomato prices are now just slightly above what they were before the outbreak in Nigeria as well, said Orode Doherty, a doctor who lives in Lagos.
As for La Tomatina, its organizers say it is not contributing to tomato shortages; 145 to 160 tons of wild tomatoes are grown in western Spain just for the festival. These tomatoes aren’t cultivated, harvested or processed as they would be for human consumption, said Miguel Sanfeliu, a representative at La Tomatina.
“It’s like growing trees to make confetti for a party,” he said.
Correction: August 30, 2016
An earlier version of this article misstated the number of countries in which Muni Muniappan has been running workshops to help farmers prepare for the inevitable spread of Tuta absoluta. It is seven, not six.
The Sirex woodwasp (Sirex noctilo), is threatening South Africa’s pine forests, which makes up more than half of the 1.3 million hectares of plantation forests (trees planted to meet human demand for wood and wood products) in the country. This industry employs 170,000, and exports $1.7 billion worth of wood products annually.
The Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria has been working to combat Sirex woodwasp infestations. Together with industry and government partners, they have helped to control the infestations in South African pine forests. “Methods to control pests such as the Sirex woodwasp exist, but a solution that works elsewhere doesn’t always work as well here in South Africa as it does in Australia or Brazil,” advises research lead Professor Bernard Slippers. “It is essential that one finds local solutions that consider local forestry practices, genetic diversity and environment conditions.”
Researchers at FABI are using microscopic worms called nematodes against Sirex in an approach known as biocontrol. “The nematodes infect wasp larvae, and eventually sterilize the adult females that develop from these larvae,” explains Professor Slippers. “A fungus that lives in symbiosis with the wasp plays a key role in this biological control approach, since the nematodes must feed and breed on this fungus to infect the wasp larvae.”
The Nematode lifecycle:
The process is complex. By studying each organism’s genome (which is all the genetic information contained in its cells) and population, FABI can select and develop the best nematode and process for the job. For this purpose, the researchers are creating global maps of the natural distribution of different variants of nematodes, wasps and the fungus. The genomic information might one day even be used to create sterile male wasps, which might offer additional control options.
Impacting government and industry
FABI works in close partnership and regularly shares new findings with government and industry to help keep trees healthy. FABI, as a global front-runner in holistic tree health research, has called on world leaders to adopt a more integrated model to tackle similar problems on a global scale through international collaborations and multi-disciplinary research.
Discover the story in full at Research Matters, the University of Pretoria research website:
Cotton growers in the United States are concerned about native stink bugs that have attacked cotton and other crops for decades.
The green stink bug (Chinavia hilaris), southern green stink bug (Nezara viridula), and brown stink bug (Euschistus servus) continue to threaten cotton. But an Agricultural Research Service scientist in Georgia has found some environmentally friendly alternatives to insecticides.
“Cotton growers are increasingly interested in producing their crops in ways that have less impact on the environment,” says ARS entomologist Patricia Glynn Tillman, who is based in Tifton, Georgia.
The three native stink bugs are immune to the insect-killing toxins incorporated into most modern cotton varieties. Insecticides are effective, but they also kill the stink bug’s natural enemies, and they often require repeated use throughout the growing season. Organic growers can’t use conventional insecticides.
Stink bugs continue to pose a serious economic threat. Last year, they collectively infested roughly a million acres of cotton in Georgia alone, and growers there spent $12 million to control them. The bugs are a particular problem in the southeastern United States, where cotton is often grown alongside peanuts. Brown and southern green stink bugs develop in peanut fields and migrate into cotton. Green stink bugs move into cotton from nearby wooded areas.
Because of work by Tillman and others, some growers are planting “trap crops,” such as soybean and grain sorghum, to lure stink bugs away from cotton. Other options include pheromone-baited traps, which capture and kill stink bugs, and nectar-producing plants, such as milkweed and buckwheat, to feed native parasitoid wasps that attack stink bugs.
In previous work, Tillman showed the effectiveness of setting up plastic barriers between the cotton and peanut rows. Her recent study focused on whether combining a trap crop, a nectar-producing plant, and pheromone traps would control stink bugs where cotton and peanuts grow.
Tillman and her colleagues grew cotton and peanuts side by side for 2 years. In the first year, they planted soybeans as a trap crop (with and without pheromone traps), between the cotton and peanut plots. In other areas, they placed 6-foot-high plastic barriers between the plots.
In the second year of the study, they added nectar-producing buckwheat plants near the cotton. Each week of the May-to-October growing season, they counted stink bugs and stink bug eggs killed by wasps, and they documented damage to cotton bolls.
They found that the plastic barriers between peanut and cotton were the most effective tool, but the multipronged approach is an effective alternative if barriers are not feasible. Soybeans were an effective trap crop, pheromone traps killed stink bugs in the trap crop, and buckwheat plants fed beneficial wasps that reduced stink bug numbers.