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Queens Anniversary Prizes 2015

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Chemical Ecology - Safe Control of Mirid Pests on Cocoa in West Africa

Dates: 2007-2011
Funding: Cocoa Research Institute of Ghana (CRIG) Cocoa Research (UK)
Link Countries: Ghana, West Africa
Collaborators: Cocoa Research Institute of Ghana (CRIG) International Pesticide Application Research Centre (IPARC), Imperial College Sustainable Tree Crops Programme (STCP)
NRI Project Leader: David Hall

Background

mirfung

Mirid infected with Beauveria. © University of Greenwich

Approximately 70% of the world's cocoa comes from West Africa, with small family farmers producing the vast majority of the world's production. Recent studies indicate that about 25-30 % of the national cocoa acreage in Ghana has significant mirid damage, with an annual crop loss of about 100,000 tonnes. Industry sources suggest mirids cause global annual losses of some 250,000t of cocoa. The W. African cocoa mirids (Sahlbergella singularis and Distantiella theobroma) are the most damaging pests in the World's most important cocoa growing region. Besides damaging pods, especially at early development, they may preferentially attack flushing leaves and in extreme cases kill whole trees.

In previous work, a novel, two-component sex pheromone was identified that attracted males of both D. theobroma and S. singularis. The pheromone was synthesised and suitable traps developed. A strain of Beauveria bassiana was discovered in Ghana that was highly infective to cocoa mirids (right).

mirtrap

Mirid pheromone trap. © University of Greenwich

Objectives

This project will aim to investigate the use of pheromone traps (right) for monitoring mirid populations. The potential of the pheromone for control of the mirids by mass trapping or mating disruption will be evaluated. The entomopathogenic fungus discovered previously will be further developed for control of the mirids, alongside a programme to improve application procedures for pesticides in general on cocoa and promote Good Agricultural Practice.

The work will be based at CRIG. The pheromone work will be lead by a CRIG staff member, Joe Sarfo, who will register for a PhD at the University of Greenwich, and the mycopesticide work will form the basis for the thesis of a PhD student registered at Imperial College.

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