Morphological variation in Planococcoides njalensis occurring on cocoa in Ghana.
A study was made to determine the extent of morphological variation in Planococcoides njalensis, the most important mealybug vector of cacao swollen shoot badnavirus (CSSV) in West Africa, and to resolve whether more than one Planococcoides species is present. Fourteen populations of P. njalensis collected on cocoa from different localities in Ghana and one population each on Gliricidia sepium and Coffea canephora were compared by measured and meristic female characters using 2 types of morphometric analysis, Discriminant Functional Analysis and Principal Component Analysis. The analyses showed that P. njalensis exhibited a wide range of intraspecific morphological variation, particularly in meristic characters, but failed to identify new Planococcoides species. The results are discussed in relation to the control of the mealybug vectors of CSSV and to the suitability of Gliricidia as a shade tree for cocoa.