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Kenyan scientists discover cause of coffee berry pest

Researchers at the Kenya-based International Center for Insect Physiology and Ecology (ICIPE), in collaboration with colleagues from Germany, have for the first time decoded the chemical signals that attract the coffee berry borer Hypothenemus hampei, the most important pest of coffee worldwide

According to the research finding published in the PLoS ONE journal recently, the scientists have revealed that coffee berries release chemical signals that enable the pest to locate and attack them. At the same time, researchers noted that the coffee berry borer also responds negatively to other chemicals produced by other plants, allowing scientists to develop repellents to the borers.

Using these findings, a proposed ‘pull-push’ tactic can now be employed to manage this pest. Scientists also proposed that instead of growing coffee as monocultures, it should be interbred with crops that act as repellents to the coffee berry borers.

Researchers estimate that the coffee berry borer causes more than US$500mn in damages each year, making it the most costly pest affecting coffee today.

The scientists forecast that by 2050, populations of the coffee berry borer will increase in southwest Ethiopia, the region where Arabica coffee is grown. Also affected will be the areas of Mt Kenya, Meru and Embu districts of Kenya.

Coffee farmers in Uganda, Rwanda and Burundi will also have to grapple with an increased population of coffee borers.

Female borers kill coffee plants by burrowing into coffee berries to lay their eggs. Each female can lay up to 200 eggs and the resulting damage attracts pathogens, damaging the coffee berries.

Two other coffee diseases – the Coffee Berry Disease (CBD) and leaf rust have also attracted research as they continue to rampage coffee production in East Africa.

Over the last few years, the Coffee Research Foundation (CRF) at Ruiru, near Nairobi, has developed two varieties resistant to CBD and leaf rust, two main scourges in coffee growing.

The two varieties – Batian and Ruiru 11 – are expected to lower cost of production as the two diseases need huge investment in chemicals and equipment.

“There are considerable savings from cost of fungicides and labour used to control CBD and leaf rust. Batian is a high yielding variety with good bean and cup quality. It is also suited for all agro-ecological zones,” said Joseph Kimemia, CRF executive director.

The two varieties – grown at a narrower spacing of two square metres – have a higher bushel population at 1,000 per acre compared to traditional varieties, which, planted in an area of 2.7 square metres, can only attain a population of 540 bushels per acre.


Mwangi Mumero