SPATIAL PATTERNS OF ALATE AND APTEROUS MORPHS OF THE BRACHYCAUDUS-HELICHRYSI (HOMOPTERA, APHIDIDAE) IN SUNFLOWER FIELDS

Spatial patterns of leaf-curling plum aphid, Brachycaudus helichrysi, aggregates and alate colonization of sunflower fields were studied ove r several years. Monte Carlo test procedures, based on indices of aggr egation and spatial autocorrelation statistics, were used for spatial data analysis. In most cases, neighboring plants were colonized and in fested independently. Over large areas, spatial structures could exist but temporal changes in spatial patterns from week to week were often observed for alatae as well as for apterae. Heterogeneity in plant de velopment seemed to be of importance for alate landing, apterous multi plication, and their spatial patterns. The implications for pest manag ement and sampling are discussed.