Spatial and temporal heterogeneity in population dynamics of citrus aphids at a regional scale

A quick method of evaluating aphid infestations on young clementine trees is developed. It uses visual abundance classes. This method is used to compare the population dynamics of two aphid species in 11 orchards in Corsica (France). The curves describing the succession of the abundance indices on each sampling tree between April and July are compared using principal component analyses. The first three factorial axes illustrate the intensity, precocity and flatness of the infestation curves. For each species, a significant between-orchard variability is demonstrated by comparing the mean factorial coordinates of the sampling trees of the different orchards. The validity of such methods for analyzing the demographic strategies of phytophagous and entomophagous insects at a large scale is discussed.