Dates: October 1998 - December 2001

Funding: DFID Crop Protection Programme

Countries: Ghana, West Africa

Collaborators: Dr Beatrice Padi, Cocoa Research Institute of Ghana (CRIG) Dr George Oduor, CAB International Africa Regional Centre

NRI Project Leaders: David Hall

Background

© University of Greenwich

Cocoa is the main export crop of Ghana, maintaining directly or indirectly the livelihoods of over six million people. Capsids are the most important insect pests causing losses estimated at 100,000 tonnes or 25% of the crop. Currently conventional insecticides provide the only effective methods of control, but the recommended spray programmes are rarely used by farmers because of expense and difficulty of application. This project aims to develop an effective mycoinsecticide against the two main species of cocoa capsid in Ghana and to identify the sex pheromones of these capsid species. These project outputs will make possible evaluation of new approaches to monitoring and control of cocoa capsids that are appropriate for use in Ghana and environmentally acceptable.

Male capsid attracted to female in cage © University of Greenwich

Results

Methods have been developed at CRIG for rearing both species of capsid, Distantiella theobroma and Sahlbergella singularis. Fruits of Desplastsia dewevrei (Tiliales: Tiliaceae) have been found convenient as feed for the capsids. Three collecting trips have been carried out to collect entomopathogenic fungi. Five isolates of Beauvaria bassiana, including one originating from Ghana, are being evaluated against S. singularis in the laboratory.
In field trapping experiments, attraction of male S. singularis to virgin females has been demonstrated for the first time, complementing previous results for D. theobroma. Various designs of sticky trap have been evaluated. Volatiles collected from virgin female capsids have been analysed by GC-EAG and two EAG-active compounds detected. These are produced in very small quantities and their structures are novel, but they have been identified and synthesised and are currently being evaluated as attractants in the field.

Uptake

The project will be continued with funding from the USAID Sustainable Tree Crops Programme and from the Cocoa Industry.

Publications

SARFO, J.E., PADI, B., HALL, D.R., DOWNHAM, M.C.A. and ACKONOR, J.B.(2006) Effects of cocoa mirid pheromone trap positioning and density on trap catches. In: Proc. 15th Int. Cocoa Res. Conf. San Jose, Costa Rica, 9th-13th October, 2006.

PADI, B., HALL, D.R., SARFO, J.E., DOWNHAM, M.C.A. and FARMAN, D.I. (2004). Development of sex pheromone traps for the monitoring and control of cocoa capsids in Ghana: Update on field trials. In: Proc. INCOPED 4th Int. Seminar, Accra, Ghana, 19th – 21st October, 2003.

PADI, B., DOWNHAM, M.C.A. and SARFO, J.E.(2001). Evidence of sex attractants in the cocoa mirids Distantiella theobroma (Dist) and Sahlbergella singularis Hagl. (Heteroptera: Miridae) in field trapping experiments. In: Proc. 13th Int. cocoa conf., Kota Kinabala, Sabah, Malaysia, 9th – 14th October, 2000.

DOWNHAM, M.C.A., CORK, A., FARMAN, D.I., HALL, D.R., INNOCENZI, P.J., PHYTHIAN, S., PADI, B., LOWOR, S.J. and SARFO, J.E. (2002). Sex pheromone components of the cocoa mirids, Distantiella theobromae and Sahlberghella singularis (Heteroptera: Miridae). Poster presented at the International Society of Chemical Ecology, 19th Annual Meeting, University of Hamburg, Germany. 3-7 August 2002. (http://www.chemecol.org/meetings/hamburg_02.htm; Abstract at p.164 of programme).