Spatial distribution of Rastrococcus invadens Williams (Hom., Pseudococcidae) in mango trees.
The spatial dispersion pattern and intracanopy distribution of Rastrococcus invadens were assessed between 1988 and 1990 in a small mango plantation in southern Benin, in order to develop sampling plans and facilitate sampling in mango trees. The mean number of R. invadens per leaf differed significantly between trees for most sampling dates, between old and young leaves, and between geographical quadrants. Nevertheless the only stratification of samples recommended is the one between age classes of leaves. Because of an almost total overlap of generations, the number of females corresponded closely to that of the total population. To analyse the dispersion pattern of the pseudococcid, Taylor's power law was applied to the sampling data. The index of aggregation did not change significantly with season. On this basis, a common index of aggregation was calculated, which was incorporated into Wilson & Room's and Karandino's equations to develop enumerative and binomial sampling plans.