ABSTRACT
Pseudococcus affinis (Maskell) is a new pest of French Riviera citriculture, particularly damageous to industry of luxury clémentines from 1978 to 1984. Incomplete control with usual scalicides (methidathion, white oil) needs a revision of citrus protection plan, on biological grounds stated in special agronomical context of local citrus plantings. Observations during summer scalicide applications show that cloud-like chemical product mainly covers leaves, twigs and fruits whereas most of bugs inhabiting trees are on crownwoods. As a result of biological study, two behavioural features, i.e. sheltering and crawling, explain partial inefficacy of sprays and leads sampling plan available for setting up patterns of within-tree spatial distribution, which can contribute to improve control of the mealybug and to choose adequate dates of intervention. Repeated applications of insecticides against the new pest, up to 4 per year, are costly and alternative to present artificial rain as water-supply system, both with modification or replacement of chemical control programme, is discussed.
