Diversity of scale insects (Hemiptera: Coccomorpha) attacking citrus trees in Machakos, Makueni, Kilifi and Kwale Counties, Kenya

Abstract

Citrus farming is a major source of revenue for large and small-scale farmers in Kenya. Citrus production is confronted with threats from pests and diseases. Surveys of citrus farms in Kilifi, Kwale, Machakos and Makueni counties, Kenya in July/August (dry season) and in November/December (wet season), 2019 were conducted to identify scale insect pests (Hemiptera: Coccomorpha) attacking the trees (Sapindales: Rutaceae), and their related biota. A total of 22 scale insect species belonging to four families, namely Diaspididae (armoured scales), Coccidae (soft scales), Pseudococcidae (mealybugs), and Monophlebidae (giant mealybugs) were found infesting citrus trees in the two regions surveyed. Among the scale insects reported, four species were newly introduced in Kenya; three armoured scales Parlatoria ziziphi (Lucas), Parlatoria pergandii (Comstock), Aonidiella comperei (McKenzie), and a soft scale, Pulvinaria polygonata (Cockerell). The scale insects were closely associated with predators (coccinellids and lacewings) and attendant ants. This information will be helpful in the development of efficient management strategies against the scale insect pests, thus improving citrus production in Kenya. The scale insect pests identified in this study will be useful to plant quarantine facilities in Kenya to help to prevent and detect accidental introductions of exotic scale insect species.