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‘Push-pull’ strategy successfully controls pests, weeds

Research published online recently demonstrates the benefits of using ‘push-pull’ approaches for controlling insect pests and weeds. ‘Push-pull’ entails mixing, into a field of crops, plants that repel insect pests (‘push’) and planting, around a crop, diversionary trap plants that attract the pests (‘pull’).

The researchers, from Kenya and the UK, found that the approach produces real and tangible benefits for subsistence farmers and, if adopted widely in African countries, could have a huge impact in reducing crops lost to pest infestation. The main target was a series of lepidopterous pests attacking maize and other cereals.

Although the area given to the cereal crop itself is reduced under the ‘push–pull’ system, higher yields are produced per unit area. In areas of Kenya, Tanzania and Uganda where the approach has been adopted, the profit a farmer can produce per hectare has increased by between three and four times the amount generated by standard practices.

An important spin-off is that the companion crops are valuable forage for farm animals. Leguminous intercrops also provide advantages with regard to plant nutrition and some of the trap crops help with water retention and in reducing land erosion. A major benefit is that certain intercrop plants provide dramatic control of the African witchweed (striga).

The research was published in a special themed double issue on ‘Sustainable Agriculture’, in the journal Philosophical Transactions of the Royal Society B: Biological Sciences.


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Item 1

http://journals.royalsociety.org/content/p25069r627u83075

Integrated pest management: the push–pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry

Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 363, Issue 1491, p. 611-621.

(Theme Issue ‘Sustainable agriculture. I’ compiled by Chris Pollock, Jules Pretty, Ian Crute, Chris Leaver and Howard Dalton)

DOI 10.1098/rstb.2007.2173

Authors

Ahmed Hassanali [1], Hans Herren [1], Zeyaur R. Khan [1], John A. Pickett [2], Christine M. Woodcock [2]

[1] International Centre of Insect Physiology and Ecology, PO Box 30772, Nairobi, Kenya
[2] Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK

Abstract

This paper describes the ‘push–pull’ or ‘stimulo-deterrent diversionary’ strategy in relation to current and potential examples from our own experiences. The push–pull effect is established by exploiting semiochemicals to repel insect pests from the crop (‘push’) and to attract them into trap crops (‘pull’). The systems exemplified here have been developed for subsistence farming in Africa and delivery of the semiochemicals is entirely by companion cropping, i.e. intercropping for the push and trap cropping for the pull. The main target was a series of lepidopterous pests attacking maize and other cereals. Although the area given to the cereal crop itself is reduced under the push–pull system, higher yields are produced per unit area. An important spin-off from the project is that the companion crops are valuable forage for farm animals. Leguminous intercrops also provide advantages with regard to plant nutrition and some of the trap crops help with water retention and in reducing land erosion. A major benefit is that certain intercrop plants provide dramatic control of the African witchweed (striga). Animal husbandry forms an essential part of intensive subsistence agriculture in Africa and developments using analogous push–pull control strategies for insect pests of cattle are exemplified.

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Item 2
http://www.bbsrc.ac.uk/media/releases/2008/080108_pests.html

Diversionary tactics save crops from pests in developing countries

Biotechnology and Biological Sciences Research Council, UK

8 January 2008

Research published today (8 January) by scientists funded by the Biotechnology and Biological Sciences Research Council (BBSRC) reveals the effectiveness of using ‘push-pull’ agricultural techniques in developing countries to save crops from insect damage. Scientists at BBSRC-sponsored Rothamsted Research, working with researchers principally from icipe in Kenya, have found that the approach produces real and tangible benefits for subsistence farmers and, if adopted widely in African countries, could have a huge impact in reducing crops lost to pest infestation. The researchers also show that the ‘push-pull’ approach has intriguing potential for reducing animal infections, and potentially even to control human disease.

‘Push-pull’ entails mixing, into a field of crops, plants that repel insect pests (the ‘push’) and planting, around a crop, diversionary trap plants that attract the pests (the ‘pull’). In the Rothamsted studies, the ‘push’ plant, desmodium, was also found to give extremely effective control of the parasitic African Witchweed.

The research paper, published online in a special edition of the journal Philosophical Transactions of the Royal Society B, shows that using the ‘push-pull’ approach to manage pest problems offers real benefits in areas where economic and ecological factors provide disincentives to employ pesticides and fertilizers. In areas of Kenya, Tanzania and Uganda where the approach has been adopted, the profit a farmer can produce per hectare has increased by between three and four times the amount generated by standard practices. Currently, around 10,000 subsistence households in East Africa have adopted the approach, but the potential impact if the practice were to spread more widely is enormous.

‘Push-pull’ farming harnesses the power of semiochemicals (behaviour controlling chemicals). Scientists can exploit the properties of certain plants releasing semiochemicals that either attract or repel devastating insect pests. Up until now, the ‘push’ and ‘pull’ plants have been harvested and used as cattle feed, but new research in Kenya has shown that traditional food crops, such as beans, can be planted amongst the ‘push’ plants to provide additional food for the farmer’s family.

Professor John Pickett, a leading researcher at Rothamsted Research on ‘push-pull’ approaches, said: “For the first time, we have been able to show the real and tangible benefits that using push-pull farming brings to subsistence communities in Africa. Many farmers in developing countries do not have the resources or predictable rainfall needed to invest in fertilizers and pesticides. By exploiting ‘push’ and ‘pull’ crops, our research has shown that communities can significantly increase the benefit value of the crop their land can produce. At the moment, an impressive number of East African farmers have adopted the technique, but the overall proportion is still small. If more subsistence farmers used ‘push-pull’ approaches, there could be massive improvements in the amount of food they could grow.

“Western farmers could also benefit from adopting the practice. Most areas of farming are under pressure to reduce the amount of pesticide they use and planting complimentary ’push-pull’ crops could be an effective way of doing this.”

Professor Nigel Brown, BBSRC Director of Science and Technology, commented: “This project is an excellent example of the benefits of applying BBSRC science to issues facing farmers in the developing world.”

There are also other potential uses for ‘push-pull’ approaches. The Rothamsted scientists and other international groups are developing techniques that could help control further pests and diseases. Prof Pickett explains: “New studies have shown that the principles of ‘pushing’ an insect away from its target and ‘pulling’ it towards a diversion works effectively to control insect-spread cattle diseases and sleeping sickness, a human disease spread by the tsetse fly.”

The Rothamsted Research group, together with their colleagues at icipe, Kenya, will soon begin work on new BBSRC-funded research aimed at harnessing the weed-controlling properties of the ‘push’ plant, but in a less labour intensive way.

ENDS

Notes to Editors

New research on the effectiveness of ‘push-pull’ farming practices in East Africa and a review of the current state of research in this area is published online in a special edition of the journal Philosophical Transactions of the Royal Society B on January 8 2008. ‘Integrated pest management: the push–pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry’, Hassanali, Herren, Khan, Pickett and Woodcock.

The research conducted by Rothamsted Research is supported by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC), through grant funding and core support for the Institute. The research was also supported by Gatsby Charitable Foundation, UK and Kilimo Trust, East Africa.

About BBSRC

The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around Ł380 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. http://www.bbsrc.ac.uk

About Rothamsted Research

Rothamsted Research is based in Hertfordshire and is one of the largest agricultural research institutes in the UK. It is one of seven institutes sponsored by BBSRC. http://www.rothamsted.ac.uk

 


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