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Biological control of coffee green scale


PNG Coffee Board

Project Description

Coffee Green Scale

Problem/Issue. Coffee green scales (Coccus spp.) are native to Africa but with the development of coffee in other continents, have spread around the world and cause significant damage to coffee in some countries. Pesticides are commonly used but frequently aggrevate population outbreaks because of difficulties of achieving complete coverage of the target scale insect. In Africa, outbreaks of green scale are not a major problem; previous work also suggested that the scales have several natural enemies. This project was set up to investigate the possiblity of introducing natural enemies into PNG, where green scales are a major problem

CABI Commodities input. We made a study of the natural enemy complexes that attack green scales in Kenya. Many species of parasitoid and invertebrate predators were identified. In particular, two species of parasitoids were selected as potential biological control agents: Metaphycus baruensis and M. stanleyi. These species were found to be specific to green scales. The studies also indicated that both agents would be required for substantial control of the scale populations. We also made a survey of the problem scales (Coccus celatus and C. viridis) in PNG for the Coffee Industry Board and made recommendations for the introduction, quarantine, rearing, release and monitoring of biological agents. Metaphycus baruensis was introduced and released in the mid -1980s.

Project Successes. This represented the first attempt at biological control of coffee green scales. Metaphycus successfully established in the western highlands of PNG. Assessments have shown that the parasitoid has spread to new areas but, as predicted, additional biological agents are required for full control of the scale populations.

What Next

Green scales represent a major problem in other coffee growing countries. The important ground work on biological control has been completed and thus CABI Commodities is able to supply parasitoid agents to other coffee growing countries.

Dr S T Murphy (Co-ordinator) s.murphy@cabi.org

Start date: 1982

End date: 1986

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Contact CABI Commodities:
CABI Commodities Coffee Co-ordinator - Dr. Peter Baker - p.baker@cabi.org
CABI Commodities Cocoa Co-ordinator - Dr. Keith Holmes - k.holmes@cabi.org
CABI Commodities Project Administrator - cabi-commodities@cabi.org