Geostatistical Analysis of Cydia funebrana (Lepidoptera: Tortricidae) Pheromone Trap Catches at Two Spatial Scales

Abstract

In the Molise region of central Italy, spatial relationships between pheromone catches of male Cydia funebrana (Treitschke) were studied at local scale inside and around a single plum orchard as well as at regional scale comprising selected sites including orchards. From these relationships we infer adult movement patterns with particular relevance to pest control operations. At local scale, kriging procedures applied to pheromone trap catches showed that the number of male C. funebrana was lowest in the interior of a plum orchard and highest around a ravine, near irrigation channels, and along hedgerows in the orchard surroundings. The degree of aggregation of trap catches was influenced by daily temperature minima during the first of three flights. The correlation coefficients of trap catches inside and outside the orchard significantly decreased with increasing distance. Moran's I index revealed no significant autocorrelation and, therefore, no influence from neighboring traps. However, correlograms showed slightly positive values (i.e., slight aggregations at low distances, decreasing values with increasing distance up to 400 m, and even more decreasing values thereafter). At regional scale, a cluster analysis of the data of the first year grouped the sites according to host plants. The same analysis of the data of the second year grouped the sites primarily by altitudes and distance from the sea and suggested a slight effect of between site distances. Among others, the selection of distant sites and the influence of host plant type as well as the geographical location may confound the effect of distance: the distance did not have a significant effect on correlation coefficients for site trap catches. The results are discussed with respect to orchard-specific and regional monitoring, pest control operations, and planning of future research work.