Africa and UK scientists make a significant breakthrough in protecting crops from pests

15th Aug 2011

In research published by a team of scientists from Africa and the UK have made a breakthrough that will help in developing novel and ecologically sound approaches to controlling destructive insect pests in maize crops, specifically the spotted stemborer (Chilo partellus) which destroys the plant by tunnelling into the stalk and disrupting the flow of nutrients. This finding will help in increasing maize yields and improving food security.

Scientists at the Kenya-based International Centre of Insect Physiology and Ecology, icipe, and UK-based Rothamsted Research, discovered that certain maize landraces obtained from South America (where maize originated), have sophisticated defence strategies against insect pests. These maize plants produce chemicals (herbivore induced plant volatiles) that attract parasitic wasps as soon as the stemborer moths lay their eggs. These parasitic wasps kill the stemborer eggs and caterpillars preventing the crops being damaged.

The team's findings suggest that the release of these chemical attractants is absent from commercial hybrid maize varieties, possibly having become lost through conventional crop breeding, and could therefore be valuable in future breeding to ensure sustainable agriculture, e.g. through the reduced need for certain insecticides. The use of insecticides for pest control is not only expensive, in the context of smallholder farmers, but may also have undesirable consequences such as resistance development, secondary pest outbreaks and environmental pollution.

This collaborative work, between icipe, which receives funding from European Union and Rothamsted Research, which receives strategic funding from the Biotechnology and Biological Sciences Research Council of the UK, offers an alternative control option that makes use of natural plant defence responses and provides a cost effective and environmentally benign method for maize farmers at the front line of dealing with food security and climate change issues.

The immediate targets of this work are smallholder farmers in East Africa, but the findings are applicable to maize crops elsewhere in Africa and more globally.

Prof. John Pickett, leader of the UK contribution to this work, said "At a time when we need new science for the further intensification of sustainable food production, finding a defence trait in maize which is absent from commercial hybrids offers new opportunities, both for resource-poor farmers such as those in Africa with whom the discovery was made, as well as for improving commercial hybrid maize varieties".

Prof. Zeyaur Khan, leader of the Habitat Management Programme at icipe, noted "The green revolution in African agriculture will come from 'smart' crop varieties which will be able to switch on or switch off genes to defend themselves against attacks by insect pests, diseases and weeds. These crop varieties will not need extra resources for crop protection and will be developed by understanding and exploiting chemical ecology and biodiversity''.

Prof. Maurice Moloney, Director of Rothamsted Research, stated "This discovery is a great example of the close links between fundamental science and its direct application to the global food security problem. The work shows that there is enormous genetic potential in landraces of staple crops and that this aspect of biodiversity can be harnessed beneficially to increase yields in the most needy geographies".

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