Invasive Species Compendium

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Abstract

Spatial distribution of citrus mealybug on grapefruit trees.

Abstract

Grapefruit trees, chosen at random in 5 orchards in Texas, were sampled monthly (from May to November) in 1977 and 1978 to determine the spatial distribution of populations of Planococcus citri (Risso) within infested trees during the fruiting season and the optimum sample unit (fruit, leaf or terminal) for estimating within-tree populations. The results showed that tree strata (0-0.91, 0.92-1.83 and 1.84-2.74 m) or quadrant (N, E, S and W) had little effect on the population size of the mealybug and that fruit was the optimum sample unit for indexing population densities; underneath the calyx proved to be the best place to search when there were extremely low population densities.