Video – Coffee Green Scale Symptoms – Papua New Guinea

See in this video how CABI worked to help combat Coffee Green Scale, a sap sucking insect, in Papua New Guinea.

17 July 2019 – CABI is working in partnership, as part of a Darwin Initiative-funded project, to help secure livelihoods and the food security of smallholder farmers and their families in Kenya blighted by scale insects such as coffee mealybug and cassava mealybug.

Experts in native and non-native crop pests and knowledge and data management, from organisations including the Natural History Museum in London (project lead), the National Museum of Kenya (NMK), the Kenya Agricultural and Livestock Research Organisation (KALRO), Kenya Forestry Research Institute (KEFRI), Kenya Plant Health Inspectorate Service (KEPHIS) and University of Nairobi (UoN) are striving to raise awareness of scale insects as well as equip extension workers to help farmers manage them more sustainably.

In Kenya, scale insects are threatening efforts to reduce poverty and hunger by damaging not only crops but also native tree species. Yield losses can be as high as 91 percent and the risk is growing with 66 potential scale insect pests (most of them non-native) already identified out of 227 species (29 percent) surveyed.

Previous attempts at biological control have failed due to mis-identifications resulting in mis-directed pest control efforts. For example, 15 years elapsed between the outbreak and control of the coffee mealybug, and 80% production losses over 10 years were caused by cassava mealybug.

As well as a lack of knowledge about the risks scale insects pose, the misuse of pesticides is exacerbating the problems – killing other beneficial organisms, such as natural enemies and pollinators, creating more pest problems.

CABI is creating information packages for stakeholders on the identification and management of scale insects that will improve practices and increase responses to pest invasions. CABI is also providing technical support, that will inform knowledge gaps through socio-economic surveys which are being led by KALRO.

Together, the partners will deliver taxonomic training on scale insects – something which was previously unavailable, produce natural enemy inventories and provide enhanced insect reference collections and identification aids.

Training of taxonomists of scale insect collection, handling and identification

Photo: the correct identification of scale insects in the field is vital for their effective control

Monica Kansiime, Scientist – Agricultural Economist, based at CABI’s Nairobi office, said, “Outbreaks of alien scale pests are impacting a wide range of crops putting smallholder farmers and foresters at risk of yield and income loss – yet their awareness of this growing problem is low to non-existent.

“Increasing the capacity of stakeholders on the identification and management of scale insects will not only raise awareness of the problems caused by these pests but will also provide a platform for stakeholders to respond to the invasions effectively.”

It is hoped that CABI’s ‘fit for purpose’ information packages on best practices for improving the management of scale insect pests will also be of benefit to policy makers and the general public. So far,15 taxonomists have been trained by the project in scale insect collection and handling, preservation, slide mounting and identification.

In the coming months the project will also aim to develop distribution maps of scale insects across Kenya as well as comprehensive reference collections and associated database – all with the intention of improving research and subsequent advice given to smallholder farmers.

Ms Kansiime added, “Biological pest control offers a solution because it facilitates a long-term reduction in pesticide use, and as a result, improves farm income, natural enemy diversity and reduces pest problems.

“Many scale insects have host-specific parasitoids suitable as biocontrol agents and these can be deployed so long as the pest species is accurately identified.”

Additional information

Project page

Find out more about ‘Addressing the scale insect threats in Kenya’, including the full list of partners, from the dedicated project page.


See also a blog on the scale insects project ‘Collaborative effort in Kenya to manage the impact of scale insect in coastal region’ which looks more closely at the training package offered to taxonomists.

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