Promoting Beneficial Arthropods in Urban Agroecosystems: Focus on Flowers, Maybe Not Native Plants

Urban Farm DB summary

This study examined how native plant species richness, garden management, and landscape composition affect the abundance and richness of native and non-native bees, ladybeetles, ants, and ground-foraging spiders in urban community gardens (urban agroecosystems) in California, United States. Native plants — about 10% of species but only about 2.5% of plant cover — had little influence on arthropods overall, with the only significant effect being a negative one on non-native spider richness, likely reflecting native plants' low cover. Garden size increased native and non-native bee abundance and richness and non-native spider richness; floral abundance increased non-native spider abundance and native and non-native spider richness; mulch cover and tree/shrub abundance increased non-native spider richness; and natural habitat cover increased non-native bee and native ant abundance but was associated with fewer native ladybeetle species. The study concludes that native plant richness does not strongly influence the abundance and richness of beneficial arthropods.