Composition, abundance and pest control potential of spider communities in agroecosystems: a comparison of European and US studies

Martin Nyffeler, Keith D Sunderland
2003 Agriculture, Ecosystems & Environment  
Current knowledge of spiders in agroecosystems (excluding tree crops) reported in European and US literature is discussed comparatively, in an attempt to relate spider community structure to pest control potential. The spider fauna of agroecosystems in the northern-temperate zone of Europe is strongly dominated by small linyphiid spiders that capture tiny insects in their sheet webs, including large numbers of pest aphids. In the US, spider guild structure is more complex, and hunters
more » ... y, Oxyopidae, Salticidae, Clubionidae, Thomisidae, and Lycosidae), that have broader diets (including lepidopteran and heteropteran pests), numerically prevail in many locations. Spider populations increase to high densities (2-600 m −2 ) in European field crops, but densities are typically much lower (0.02-14 m −2 ) in US annual crops. Agroecosystem spiders, in both Europe and the US, feed rather infrequently, but they contribute to pest control as part of larger assemblages of natural enemies, and there is potential for increasing their density and impact in both continents. Many of the differences between continents in spider guild structure, density and feeding patterns highlighted in this paper are likely to be attributable to climatic differences. Most of the US data originate from more southern latitudes (i.e., subtropical and Mediterranean climates) with distinctly higher mean annual temperatures compared to the European study areas, which are in the northern-temperate zone. Spider communities may respond to climate directly, and also indirectly via food availability and antagonists. In addition, differences in crop structure and cultural practices (including habitat diversification and the provision of ground cover) could influence spider density and community organisation. Mean farm size is an order of magnitude less in Europe than in the US and this is likely to be associated with greater habitat diversity, which is known to increase spider abundance. Currently, there is a dearth of field studies from southern Europe (Mediterranean climate) and the northern regions of the US (humid continental climate). The few data available from such regions indicate that the patterns of spider predation may differ less between the two continents if sufficient study areas with similar climatic conditions could be compared. The conclusions : S 0 1 6 7 -8 8 0 9 ( 0 2 ) 0 0 1 8 1 -0 580 M. Nyffeler, K.D. Sunderland / Agriculture, Ecosystems and Environment 95 (2003) in terms of biological control are, however, widely applicable, because a large proportion of the productive agricultural land area of Europe is located in more northern latitudes and the reverse is true in the US.
doi:10.1016/s0167-8809(02)00181-0 fatcat:ctxf2bbdmfhttknuy3ku43nyqa