4: Tidy vs. messy gardens: Implications for natural enemy and herbivore communities and pest control services

Vegetation diversity, structure, and connectivity support biodiversity and ecosystem services in agroecosystems, but vegetation complexity may not match human aesthetic preferences for tidy, manicured spaces. Urban agroecosystems provide an ideal location in which to examine this apparent contradiction between vegetation complexity and gardener management preferences. In this study, we asked whether increasing ‘tidiness’ or decreasing ‘messiness’ in gardens affects herbivore and natural enemy abundance, richness, and community composition or pest removal. We conducted a manipulative experiment in eight gardens where we created ‘tidy’ (weeds removed, pathways mulched) and ‘messy’ areas (added weedy plants in pathways) and assessed background vegetation complexity. Before and after the manipulation, we sampled natural enemies and herbivores with pitfall and sticky traps and visual surveys and conducted sentinel pest removal experiments with two species of garden pests.

The tidy/messy manipulation strongly affected natural enemy composition within garden plots, but did not alter natural enemy or herbivore abundance or richness. The manipulation also affected short term gains in predation services: the messy manipulation immediately boosted egg pest removal, while mulch already present in the system lowered egg removal. Aesthetic preferences for ‘tidy’ green spaces often dominate urban landscapes. Yet, in urban garden, such aesthetic values and management preferences may create a fundamental tension with provisioning of ecosystem services. Though human preferences may be hard to change, we suggest that gardeners allow some ‘messiness’ in their garden plots as a “lazy gardener” approach may promote particular natural enemy assemblages and may have no downsides to natural predation services.