Ecosystem services in the face of invasion: the persistence of native and nonnative spiders in an agricultural landscape

Abstract

The presence of intact natural ecosystems in agricultural landscapes can mitigate losses in the diversity of natural enemies and enhance ecosystem services. However, native natural enemies may fail to persist in agroecosystems if invaders dominate species interactions. In this study, native and nonnative spiders were sampled along transects that extended from oak woodland and riparian zones into surrounding California vineyards, to assess the role of natural habitat as a source for spider biodiversity in the vineyard landscape, and to compare the dominance of exotic Cheiracanthium spiders between habitats. Many spider species were more abundant in natural habitat than in vineyards, and numbers of spiders and spider species within vineyards were higher at the vineyard edge adjacent to oak woodland. These results suggest that natural habitat is a key source for spiders in vineyards. The positive effect of oak woodland on the vineyard spider community extended only to the vineyard edge, however. Proportions of Cheiracanthium spiders increased dramatically in the vineyard, while numbers of native wandering spiders (the native ecological homologues of Cheiracanthium spiders) decreased. Dispersal limitation and strong habitat preferences may have prevented native wandering spiders from establishing far from the vineyard edge. Exotic Cheiracanthium spiders, in contrast, may possess specific adaptations to vineyards or to a wide range of habitats. Results suggest that the ecosystem services provided by intact natural habitat may be limited in agricultural landscapes that are dominated by invasive species.

Native grass ground covers provide multiple ecosystem services in Californian vineyards

“…We suspect that native grasses may have benefited spiders by impacting the temperature or humidity in the vines, rather than acting as a source for spiders. Similar to increased numbers of C. inclusum in the irrigated grass treatment, densities of the congeneric spider Cheiracanthium mildei L. Koch appeared to be influenced by habitat condition (Hogg & Daane, ) and may negatively affect other spider species in the vineyard in turn (Hogg & Daane, ).…”

“…The leafhopper predator community in California vineyards consists almost entirely of spiders (Costello & Daane, ). Spiders have been shown to suppress leafhopper numbers (Hogg & Daane, ), and spider species composition and/or abundance can change in the presence of ground covers (Costello & Daane, ). Here, field experiments were conducted to examine the effects of native grass ground covers on (1) leafhopper abundance, (2) natural enemy abundance and impact, (3) vine condition, (4) soil properties and (5) crop yield and quality.…”

Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens

“…Fraser and Frankie (1986) compared spider communities in urban and natural habitats in Berkeley, CA, and found a total of 20 families and 75 morphospecies, with Gnaphosidae and Lycosidae dominant in pitfall traps for both habitat types. Further, Hogg and Daane (2011) found an average of 15 families and 40 species in both natural and agricultural habitats in California. Our morphospecies richness of 46 seems in line with other research, and is relatively high especially considering that we only sampled from one habitat type.…”

The roles of top and intermediate predators in herbivore suppression: contrasting results from the field and laboratory

“…The exotic wandering spider Cheiracanthium mildei L. Koch (Miturgidae) dominates most vineyards in the Napa area (Hogg et al , ; Hogg & Daane, ) and is likely to act as a top predator in this ecosystem. Some of the effects of C. mildei on a range of spider species have been reported elsewhere (Hogg & Daane, ).…”