Integrated Management of Woolly Whitefly [Aleurothrixus Floccusus (Maskell) Homoptera: Aleyrodidae] on Citrus at Adama, East Shewa Zone, Ethiopia

Abstract

The woolly whitefly, Aleurothrixus floccusus (Maskell), (Homoptera: Aleyrodidae), is a new invasive alien insect pest of citrus crop recorded in Ethiopia in 2001 in Adama town. Woolly whiteflies are the most destructive pests of citrus in Ethiopia particularly in Central Rift Valley of Ethiopia. It causes tremendous yield loss. In the present study, woolly whitefly management by the integration of fertilizer (DAP), irrigation and sticky gum banding on citrus were investigated in Adama under field condition under natural infestation. The field study was carried out in Adama, East Shewa, Ethiopia in 2011. The experiment was designed in randomized complete block design in three replication in a factorial arrangement where a tree represents one replication. Pre-treatment assessment of woolly whitefly population and weekly assessment after treatment application were done to select the best treatment. The pre-treatment woolly whitefly assessment indicated that 80-100% twig infestation, 60-99% leaf infestation and 35-37% fruit infestation indicating that twig and leaf of the citrus trees are the most preferred plant parts by woolly whitefly, where as low proportion of percent infested citrus plants (0.5% - 2.08%), (0.18% - 1.38%) and (0.56% -1.95%) were recorded in the treated citrus plant in studied area respectively. Significantly low twig infestation, low leaf infestation, low number of woolly whitefly colonies in the twig and leaf, low status of ants and high status of predator (ladybird beetle) and parasitoids (Cales noacki) in the twig and leaf were recorded from citrus plants. Integrated effect of fertilization, irrigation and sticky gum banding effectively increased the yield and quality of citrus fruit.  The data obtained indicated that effect of fertilizer; irrigation and sticky gum banding were significant in reducing woolly whitefly infestation on citrus. All infested plant parts were also attended by several ant colonies. However, significant variations were observed among the treatment in fruit yield. From the present study it can be concluded that by providing the citrus plant with appropriate/optimum nutrient and water at the right time which mainly strengthen and help the plant to produce leaves and flowers, and enhance the activity of the natural enemies mainly by disconnecting the symbiotic relationship between the woolly whitefly and ants by using sticky gum banding. As the management of commercial citrus production is very intense the likely problem of woolly whitefly in such a farm is almost nil. Thus, the current technology is fit to small scale citrus production system which has to be extended by the extension agents. Therefore, the use of fertilizer (DAP), irrigation and sticky gum banding could play a vital role in integrated management of woolly whitefly on citrus.

Key words: Citrus, A. floccusus, fertilizer, irrigation, sticky gum banding.