Examining the influence of garden land use, management practices, and landscape context on pest and beneficial insects in urban vegetable gardens

Compared to their rural counterparts, urban gardeners and farmers face reduced abundance and diversity of beneficial insects and increased invertebrate pest density.  Fostering conservation biological control of insect pests in urban gardens could substantially enhance the productivity and sustainability of urban agriculture.  As a basis for developing ecologically-based pest management strategies for urban gardens, we sought to answer the question: How do garden-level land use & management practices, and landscape context, affect pest and beneficial insect populations in urban vegetable gardens?

From June through September of 2011, we collected biweekly scouting data and yellow sticky card data on insect pests and beneficials on tomatoes, brassicas, and cucurbits in 24 community gardens in Brooklyn, Harlem, and the Bronx.  Pests monitored included: aphids; flea beetles; Lepidopteran larvae; whiteflies; cucumber beetles; squash vine borer; squash bugs; thrips; and two-spotted spider mites.  Beneficial arthropods monitored included: larvae of ladybird beetles, syrphid flies, and lacewings; minute pirate bugs; spiders; and parasitic wasps.  In each garden, we collected information on land use and plant diversity, average light availability, and garden management practices.  We also conducted GIS analysis of the landscape context for each garden in 200- and 500-m buffers.

Using multiple regression, various land use and management characteristics were found to be associated with the different groups of pest and beneficial insects.  We discuss the implications of our findings for urban gardeners and provide recommendations for garden land use patterns, plantings, and management practices to attract beneficial insects and reduce insect damage on crops.