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Science/AAAS

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Scientists uncover trick to spider’s stealth

You almost never notice a spider descend from the ceiling until it’s right in front of you. Coming down on its silk thread—the dragline—it barely moves or spins. Now, scientists have figured out why. In a study published this month in Applied Physics Letters researchers collected some golden silk orb-weaver spiders (Nephila edulis and N. pilipes, the latter pictured), raised them in the lab, and collected their dragline silk. They used a device that can measure extremely small forces—the torsion pendulum, the same apparatus that Henry Cavendish used to estimate Earth’s mass about 200 years ago—now equipped with image processing capability. All the other fibers they tested—including human hair, metal wires, and carbon fiber—behaved like an elastic material when twisted, just like a rubber band that comes back to its original shape when twisted or stretched. But, the dragline silk underwent permanent molecular deformation upon twisting. This warping rapidly slows down any movements, steadying the spider. The unique arrangement of molecules in dragline silk—rigid structures that help maintain its overall shape, and soft structures that act like a cushion, absorbing any motion—is responsible for this behavior, the authors suspect. The findings could lead to ropes for rescue helicopter ladders or rappelling climbers that don’t throw us into a spin.

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Broad mites in ornamental crops – Part 1: Challenges and treatments

Broad mites can be controlled using insecticides or biological control.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

 

Western flower thrips and aphids have long been the most challenging insect pests in greenhouses. More recently, broad mites (Photo 1) have been posing a more serious threat for greenhouse growers. Broad mites are a potential threat to some of the most important Michigan floriculture crops. According to my previous article, “Attention scouts: Crops that are insect “magnets” in the greenhouse,” the top 10 plants that are attractive to broad mites are New Guinea impatiens (Photo 2), zonal geraniums, Thunbergia, Torenia, verbena, Rieger begonias, Scaevola, angel wing begonias, ivy geranium and buddleia.

So, why are broad mites so concerning? Broad mites are concerning because they are microscopic and are very difficult to see with the common 5x to 10x hand lens. You must send samples to a diagnostic lab or contact your local Michigan State University Extension floriculture educator for a positive diagnosis.

In addition, greenhouse scouts and growers usually notice the plant damage after the populations are already very high and the crops are unsalable. Often times, the damage to the upper leaves near the apical meristem is only noticeable 20 to 30 days after they began infesting the crop.

The greatest populations of broad mites when scouting crops are often not on the plants with the greatest amount of damage. By the time the damage is significant, broad mites have moved on to the neighboring plants with “fresh, new, tasty” tissue. Therefore, greenhouse scouts should actually sample the plants adjacent to those with heavy feeding damage.

broad mite damage

Photo 2. Broad mite damage on New Guinea Impatiens. Photo by Heidi Lindberg, MSU Extension.

The following products are recommendedfor broad mites: Avid, Akari, Judo, Pylon, SanMite, and 2% horticultural oil. For growers interested in using biological control, the predatory mite, Amblyseius swirskii (Photo 3), has been shown to be effective against broad mites. However, cuttings and propagules must be free of pesticide residue in order to effectively use biological control for broad mites. Contact your young plant or cutting supplier to learn about the plant’s pesticide history.

a. swirskii

Photo 3. Amblyseius swirskii. Photo by Evergreen Growers Supply.

One study in Belgium showed that using A. swirskii is actually more effective than the standard chemical treatment (Abamectin) in Belgium. When researchers released broad mites (P. latus) on Rhododendron plants, all of the following treatments were more effective than the weekly abamectin spray:

  • Three weekly releases of A. swirskii beginning in April
  • One release of A. swirskii during April
  • One release of A. swirskii during May
  • One release of A. swirskii with the additional food source Artemia during April
  • One release of A. swirskii with the additional food source Artemia during May

Greenhouse growers who are not getting adequate control of broad mites may want to consider a weekly release of A. swirskii. Contact your local biological control specialist or consultant to develop a strategy for preventative broad mite control.

For more information on the location of broad mites in the crop and about an intensive sampling program, read “Broad mites in ornamental crops – Part 2: Scouting and sampling.

The study referenced in this article is: Gobin, B., E. Pauwels, E. Mechant, and J. Audenaert. 2017. Integrated control of broad mites in ornamental plants under variable greenhouse conditions. IOBC-WPRS Bulletin Vol. 124: 125-130.

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Human health issues arising from the use of synthetic pesticides and concerns about their environmental toxicity are making lower-risk alternatives increasingly attractive. Biological control agents are living organisms which reduce harmful pest populations. Many people know of the common ladybird, whose larvae feed on aphids, but a wide range or biological control agents – e.g. […]

via CABI scientists shed light on factors affecting the use of biological control — The Plantwise Blog

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Nebraska Today

25 April 2017

Jeepers creepers: Massive spider eyes shrink 25% in adulthood | Nebraska Today | University of Nebraska–Lincoln

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Development of strategy to reduce Cambodian farmers’ reliance on pesticides is on track

 Rica Joy Flor   |  

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Mr. Chou Cheythyrith, EPIC project partner from GDA, (facing camera) explains the experiment on Trichoderma and pest-resistant rice varieties to visiting farmers and representatives from various NGOs, and public and private institutes. (Photos: EPIC project)

PREY VENG, Cambodia—An important strategy to reduce reliance on chemical pesticides in Cambodia is steadily moving through a project that encourages the use of environment-friendly biological control agents (BCA).

Over the last decade, Cambodian rice farmers have mainly relied on chemical pesticides as a major method for controlling pests and diseases. Experts warn that the rampant use of toxic chemicals is likely to lead to numerous long-term effects on the health of farmers and the environment. Integrated pest management (IPM) and BCA provide an alternative to chemical pesticides. BCAs include insects, fungi, and other natural products to manage pests.

The project, EPIC (Development of ecologically-based, participatory IPM package for rice in Cambodia), is helping pave the way for the greater use of BCAs by providing policymakers with science-based information on the effectiveness of BCAs and their benefits on the environment and human health.

Participants from government institutions discuss the effectiveness of BCAs during the site visit.

On 17 March, officers from Cambodia’s Department of Agricultural Legislation, various departments from the General Directorate of Agriculture, and private companies visited the EPIC trial site on Trichoderma (a common soil fungus), pest-resistant rice varieties, and weed management in Prey Veng. The participants were able to observe the practice of IPM using a bio-control agent on commonly used and pest-resistant rice varieties. They also discussed with the researchers the effectiveness and possible effects of Trichoderma on the environment and human health, the responses of the farmers who observed the experiments, and the possible steps for their respective organizations in promoting the technology.

Following the visit, a consultative meeting was held on 27 March with officials from various departments under the Ministry of Agriculture, Forestry and Fisheries, research institutes, and private-sector groups to discuss the registration form for BCAs. All these aim to facilitate the endorsement from the Ministry that will lead to the production of effective, safe and good-quality BCA products in Cambodia that can be made readily available to farmers.

EPIC is a 4-year project led by the International Rice Research Institute and funded by United States Agency for International Development under the Feed the Future Innovation Lab for Integrated Pest Management. The site visit was implemented in collaboration with Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH (GIZ).

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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 <k.wyckhuys@cgiar.org> or Mrs. My Hoang  <m.hoang@cgiar.org>.

E.A. Heinrichs

IAPPS Secretary General

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Pakistan’s papaya pest squashed through biocontrol

  • Pakistan’s papaya pest squashed through biocontrol

Copyright: G.M.B. Akash / Pano

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       >   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.

Pesticide resistance

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.

This piece was produced by SciDev.Net’s Asia & Pacific desk

This article is part of a series on invasive species supported by CABI

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