Multi-scale drivers of parasitoid wasp communities in urban gardens: Local vegetation, landscape configuration and heterogeneity

Urbanization reduces insect biodiversity due to habitat loss and fragmentation through environmental filters that operate at multiple spatial scales. Local and landscape factors determine the establishment and survival of species in urban ecosystems. Particularly, green areas, such as gardens can play a role as refuges for parasitoid wasps, a highly diverse group essential for biological control and ecosystem functioning. In this study, we asked: 1) What is the parasitoid diversity, and which are the most common families in gardens? and 2) What local and landscape factors modulate parasitoid wasps abundance and diversity? We collected parasitoids using yellow traps in 13 gardens over a year in San Cristóbal de Las Casas, Chiapas, Mexico. We characterized local vegetation (flower abundance, canopy cover, herbaceous height and herbaceous richness), and at landscape scale, we used composition (forest proportion), configuration (aggregation and shape indices of green areas), and heterogeneity to analyze relationships with the abundance of common families and overall diversity of the parasitoid community in gardens using generalized linear models. We collected and identified 34 families of parasitoid wasps. At the local scale, flower abundance and canopy cover favored parasitoid diversity, while vegetation height reduced it. At landscape scale, aggregated patches and complex shapes of green areas, as well as landscape heterogeneity, increased parasitoid diversity. Most abundant families (i.e. Encyrtidae, Scelionidae, Figitidae, and Ichneumonidae) responded differentially to environmental factors according to their specific life histories. Our results show that structure of the surrounding landscape together with garden conditions helps maintain parasitoid wasp communities.