IngentaConnect Effects of soil characteristics and human disturbance on tiger be...

Abstract:

1. Understanding species-specific habitat requirements is important in insect ecology. Co-occurrence of closely related species can provide insight into microhabitat segregation. Tiger beetles are well suited for such studies, as they occur in multi-species assemblages, exhibit species-specific habitat requirements, and are sensitive to anthropogenic modifications of the environment.

2. This study investigated ovipositional microhabitat choice of two sympatric tiger beetles at Point Reyes National Seashore, California, U.S.A., and evaluates how human activity affects that choice. Cicindela oregona is widespread and common whereas C. hirticollis, an undescribed subspecies, is locally threatened. Laboratory experiments tested oviposition-site selection of the two species in response to variations in moisture, pH, salinity, and grain size. Field experiments tested larval burrow location in response to experimental shading and experimental human disturbance.

3. Laboratory results indicated that while C. hirticollis females preferred a narrow range of moisture levels and fine sands, C. oregona females had more specific pH and salinity requirements and preferred coarser sands. They also differed in timing of activity. Preferences are probably related to prevention of fungal or bacterial infection and avoidance of desiccation and immersion.

4. In the field, significantly more larval burrows were found under experimental shading for both species. In addition, repeated human compaction of the sand significantly decreased the number of larval burrows.

5. Results suggest that protection of microhabitat, restoration of native plants, and limitation of human traffic are vital in the conservation management of tiger beetles.

Keywords: Tiger beetle; Cicindela; oviposition; disturbance; microhabitat; hirticollis; conservation

Document Type: Research article

DOI: 10.1111/j.1365-2311.2009.01093.x

Affiliations: 1: Department of Biology, San Francisco State University, San Francisco, California, U.S.A.

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Effects of soil characteristics and human disturbance on tiger beetle oviposition