[Rothamsted Research: 1 June 2010] With the need to feed an ever
increasing world population, we must reduce crop yield losses in new,
sustainable ways. A paper published in the journal Food Security by Dr Toby
Bruce from Rothamsted Research (an institute of BBSRC), emphasises the need to
reduce crop losses caused by pests. The Food and Agriculture Organisation,
predicts that by 2050 global food production needs to increase by 70%. As an
alternative to agrochemicals, natural plant defence could be induced with
activators.
Toby Bruce said, "Natural plant immunity is likely to become more important
in the future; this is an approach which exploits natural chemicals as
treatments to modulate defence responses." Signals released by damaged plants
activate the defence mechanisms of neighbouring plants and make them more
resistant to the impending insect attack. According to Dr Bruce, such signals
could be used as alternative treatments to replace synthetic insecticides which
could then be reserved for particularly bad pest infestations. Furthermore, by
encouraging natural enemies of pests, plant activators are compatible with
integrated pest management systems.
In 2009 the European review of
pesticide approval passed a new directive (EC/91/414) which reduced the number
of active ingredients authorised for use in pesticides. Scientists predict that
this could ultimately reduce agricultural productivity. The new directive will
necessitate finding new ways to minimise crop losses due to insect
pests.
An example of this, in Africa, is a mixed cropping system known as
push-pull. This system, devised at Rothamsted Research with collaborators from
the International Centre of Insect Physiology and Ecology (icipe),
Kenya, optimises yields and is already working effectively in over 30,000
smallholder farms. The intercrop, planted with the main crop, releases signals
(semiochemicals) that repel pests out of the main crop (push) but attract the
natural enemies of the pests into the crop. A trap crop is planted around the
outside which attracts the pests of the main crop (pull). This method has
collateral benefits as the companion plants (the intercrop) produce animal
fodder and improves soil quality.
Although several different techniques
show potential for reducing crop losses, there is not one simple solution. Dr
Bruce emphasises that "we cannot rely on one method alone since that would
increase the likelihood of pests adapting to become resistant". The limited
number of pesticides now available increases the chance of resistance developing
and more research into crop protection is urgently needed to provide effective
control alternatives. There is sometimes a 10-20 year lag time between initial
experiments and commercial use, partly due to stringent regulatory
requirements.
Development of resistant crops could provide a good way
forward. If the genes responsible for resistance to pests could be identified,
they could be bred into specially selected crops by either conventional or GM
methods. GM crops that are resistant to pests have already been proven to be an
important tool in developing sustainable alternatives to chemical pesticides. GM
is not the only option we have available for crop protection, but given the
challenges we face in securing future food supplies all technologies need to be
considered, keeping possible social, economic and policy implications in
mind.
This research is published in the current issue of Food
Security (Food Security: Volume 2 (2) (2010): 133, http://www.springerlink.com/content/c420085g7783v606/.)
as "Responding to the threat to food security caused by crop pests in the new
millennium by Toby J. A. Bruce. Rothamsted Research receives grant-aided support
from the Biotechnology and Biological Sciences Research Council (BBSRC) of the
UK.
Global Food Security BBSRC is leading and contributing to
Global Food Security a multi-agency programme to bring together the food-related
research interests of Research Councils, Government Departments and Executive
Agencies.
About icipe icipe is a tropical organisation
established in Kenya in 1970 to research tropical insects and their impact on
food security and health. icipe's mission is to help alleviate poverty, ensure
food security and improve the overall health status of peoples of the tropics by
developing and extending management tools and strategies for harmful and useful
arthropods, while preserving the natural resource base through research and
capacity building.