Population dynamics of the endangered salt creek tiger beetle Ellipsoptera nevadica lincolniana (Casey, 1916) (Coleoptera: Cicindelidae) are sensitive to temperature and precipitation during the egg stage

Abstract

Despite ongoing conservation efforts, populations of the Salt Creek tiger beetle ( Ellipsoptera nevadica lincolniana ) remain critically low. Using a 30-year dataset of adult counts and historical climatic and creek water flow records, we investigated which, if any, Salt Creek tiger beetle life stages are sensitive to means and extremes in temperature, precipitation, and creek flow. Our analyses revealed that eggs are particularly vulnerable to climatic conditions, with higher temperatures and lower precipitation negatively impacting population growth. These findings suggest that hotter and drier conditions may be limiting oviposition and egg survival and they highlight the need for targeted conservation strategies, including habitat manipulation to maintain soil moisture and strategic timing of supplemental releases. Implications for insect conservation We identify previously unknown limitations to Salt Creek tiger beetle population growth rates: higher temperatures and lower precipitation in June negatively affect egg hatch and/or egg laying behavior. We provide analyses that are critical for determining the optimal timing and locations for releasing lab-reared individuals to support this species’ recovery. In addition, these analyses will be used to plan new saline wetland restorations and modify existing habitat management activities to benefit Salt Creek tiger beetle survival and reproduction.

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