Host-plant relationships and natural enemies of the invasive mealybug, Rastrococcus iceryoides Green in Kenya and Tanzania

摘要

The invasive mango mealybug, Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae)believed to be native to Southern Asia has rapidly invaded Kenya and Tanzania. A survey wascarried out from February 2008–July 2009 to study its geographical distribution, host plantrelationships and associated parasitoids in both countries. Our results infer that R. iceryoides iswidely distributed across the coastal belts of both countries. Rastrococcus iceryoides wasrecorded from 29 cultivated and wild host plants from 16 families. Twenty-one of these hostplants are new records. Among the cultivated host plants, M. indica (8153.6±19.2/20 twigs and6054.3±29.2/80 leaves in Kibaha, and 2979.3±33.8/5 fruits in Kinondoni) and Cajanus cajan(L.) Millspaugh (1452.2±44.7/80 leaves and 4672.3±54.7/twig in Morogoro) recorded thehighest levels of infestation. Parkinsonia aculeata (7892.3±25.1/20 twigs, 11.6±1.25/80 leavesand 42.2±5.1/5 fruits in Kinango), Caesalpinia sepiaria Roxb (266.3±6.3/80 leaves and3116.1±17.5/20 twigs in Kinondoni) and Deinbollia borbonica Scheff., (215.7±10.3/80 leavesand 2253±22.9/20 twigs in Kibaha) were found to be the most heavily infested wild host plants.Six parasitoid species were recovered and are reported here for the first time to parasitize R.iceryoides. Anagyrus pseudococci Girault was the most dominant species accounting for 21%parasitism on M. indica and 20% parasitism on P. aculeata in Tanzania and Kenya, respectively.Despite this, the ability of the parasitoid to regulate the population of R. iceryoides wasinadequate. Therefore, there is a need for foreign exploration and introduction of efficientcoevolved natural enemies from its aboriginal home of Southern Asia to minimize its impact onhorticulture in Africa.