The Behavioral Ecology and Abundance of Tiger Beetles Inhabiting the Eastern Saline Wetlands of Nebraska

Cicindela nevadica lincolniana has one of the most restricted ranges of any North American insect and is endemic to the remnant of Eastern Saline Wetlands in Lancaster County, Nebraska. Research in the early 1990s identified remaining populations and documented numbers annual adult populations of ca. 600 adults. C. nevadica lincolniana, is a tiger beetle endemic to only the Nebraska’s Eastern Saline Wetlands. The beetle’s annual average total population size over 14 years of study was 437 adult beetles (by visual counts), and known populations have declined from 5 to 3 over 14 years. To validate visual counts, I compared visual counts to mark-recapture techniques. From visual counts the total abundance of C. nevadica lincolniana in the Arbor Lake population was 511 in 2002 and 583 in 2003 adult beetles. Mark-recapture estimated the same population to number 1,094 in 2002 and 930 in 2003. Visual counts underestimated C. nevadica lincolniana populations by about 40-50%. Therefore, a 2X correction factor for visual counts is recommended. Both methods are discussed along with the status and distribution of C. nevadica lincolniana. In a second study, I determined the habitat requirements for C. nevadica lincolniana and determined how saline-restricted tiger beetles partition larval habitats. In no-choice oviposition tests, C. nevadica lincolniana and C. circumpicta johnsonii significantly preferred saline treatments over non-saline treatments. The presence of salt is a stimulus for oviposition in both C. nevadica lincolniana and C. circumpicta johnsonii. From these experiments and field measurements, soil moisture and salinity are determinants for oviposition and, therefore, location of larval burrows. These results imply that species-specific oviposition requirements are important to niche partitioning. Finally, I considered the effect of ecological light pollution on tiger beetles. In choice tests, tiger beetles were attracted to all lights tested, and significantly higher counts of tiger beetles were attracted to UV emitting lamps than to non-UV emitters. Moreover, beetles were significantly attracted to lamps at the lowest measurable light intensities. Potential impacts form attraction to light by tiger beetles could include disruption of oviposition behavior and mortality. For species with critical nocturnal behaviors and limited populations, my results indicate light pollution may significantly contribute to population decline. Advisor: Leon G. Higle