Geographic distribution of the African root and tuber scale (Stictococcus vayssierei) in Central Africa

Stictococcus vayssierei is a major pest of root and tuber crops in central Africa. However, data on its ecology are lacking. Here we provide an updated estimate of its distribution with the aim of facilitating the sustainable control of its populations. Surveys conducted in nine countries encompassing 13 ecological regions around the Congo basin showed that African root andtuber scale was present in Cameroon, Central African Republic, Congo, DemocraticRepublic of Congo, Equatorial Guinea, Gabon and Uganda. It was not found on the sites sur-veyed in Chad and Nigeria. The pest occurred in the forest and the forest-savannah mosaic aswell as in the savannah where it was never recorded before. However, prevalence was higher inthe forest (43.1%) where cassava was the most infested crop, compared to the savannah (9.2%)where aroids (cocoyam and taro) were the most infested crops. In the forest habitat, the pestwas prevalent in all but two ecological regions: the Congolian swamp forests and the SouthernCongolian forest-savanna mosaic. In the savannah habitat, it was restricted to the moist savan-nah highlands and absent from dry savannahs. The scale was not observed below 277 m asl.Where present, the scale was frequently (87.1% of the sites) attended by the antAnoplolepistenella. High densities (>1000 scales per plant) were recorded along the Cameroon–Gabonborder. Good regulatory measures within and between countries are required to control theexchange of plant materials and limit its spread. The study provides information for nichemodeling and risk mapping.