Effect of elevation on spatio-temporal patterns of olive fly (Bactrocera oleae) populations in northern Greece I. Kounatidis 1 , N. T. Papadopoulos 2 , P. Mavragani-Tsipidou 1 , Y. Cohen 3 , K. Tertivanidis 4 , M. Nomikou 4 & D. Nestel 5 1 Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece 2 Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Volos, Greece 3 Institute of Agricultural Engineering, Agricultural Research Organization, Volcani Center, Bet-Dagan, Israel 4 Prefectural Administration of Chalkidiki, Halkidiki, Greece 5 Institute of Plant Protection, Volcani Center, Bet-Dagan, Israel Introduction Spatio-temporal distributional patterns of organisms are shaped by natural environmental factors, such as topography, climate and biotic interactions and by anthropogenic factors, such as agricultural, urbaniza- tion and industrial activities. Agricultural practices are themselves strong selective agents, carving popu- lation patterns in space (Tscharntke and Brandl 2004). Specifically, planted crops tend to attract and concentrate large populations of foraging herbivores, thus creating strong aggregations of these herbivores in relatively small areas (Altieri 1985). Humans tend to intervene (e.g. by applying pesticides), disrupting the established patterns and creating new distribu- tional patterns. Thus, human management activity is one of the most dynamic environmental factors shaping both the spatial and temporal distributional patterns of communities, species and populations in nature. In fragmented agricultural landscapes, common in these modern times, temporal and spatial patterns of herbivores are influenced by the suitability of the plant community for the herbivore and by the forag- Keywords dispersion patterns, elevation cline, regional management, spatial statistics, temperature Correspondence David Nestel (corresponding author), Institute of Plant Protection, Volcani Center, P.O. Box 6, Bet-Dagan 50250, Israel. E-mail: nestel@agri.gov.il Received: June 1, 2008; accepted: September 25, 2008. doi: 10.1111/j.1439-0418.2008.01349.x Abstract The spatio-temporal patterns of olive fly populations in a managed olive-growing region in the area of Chalkidiki in northern Greece were followed during 2005. The trapping grid consisted of 700 traps. Throughout the growing season (July–October), McPhail traps loaded with ammonium sulphate were inspected at 5-day intervals. Trapping data were analysed using Getis–Ord local spatial statistics. Clustering of trapped flies was significantly related to elevation, which ranged from sea level to 700 m above sea level. The effect of elevation upon cluster- ing depended on seasonal climatic patterns. During the summer, ‘hot- spots’ (i.e. significant aggregations of captured insects) were located at intermediate to high elevations and ‘cold-spots’ (i.e. areas with signifi- cantly low numbers of captured insects) were found in the valleys. In contrast, during the fall, ‘hot-spots’ were detected at lower elevations and ‘cold-spots’ at higher elevations. Population phenology seemed to affect spatial patterns. During periods of low population levels across the entire region, clusters of traps with relatively high amounts of captured insects were found at lower elevations. Pest management activities may have affected population levels throughout the region, but our data set does not allow quantifying their effectiveness. Our data suggest that dif- ferences in environmental temperature, as a result of altitudinal cline and season, may affect both the size of the olive fly population and its spatial patterns. The implementation of spatio-temporal analyses for management of the olive fly is discussed. J. Appl. Entomol. 722 J. Appl. Entomol. 132 (2008) 722–733 ª 2008 The Authors Journal compilation ª 2008 Blackwell Verlag, Berlin