Effects of soil moisture, vegetation and food on adult activity, oviposition and larval development in the tiger beetle, Cicindela albissima Rumpp

Abstract

Predatory arthropods are one of the most successful groups in sand dune ecosystems despite the severe limiting factors in this environment. Important adaptive traits are nocturnal activity, low metabolism, generalist feeding habits, and ability to burrow or find refuge during unfavorable conditions. Tiger beetles are especially well adapted to and dominant invertebrate predators in western North American sand dunes. Many species are endemic and rare, including Cicindela albissima Rumpp which is restricted to a small area of the Coral Pink Sand Dunes in southwestern Utah. Previous work suggests that rainfall may be the main factor controlling their population size. This study used field and laboratory experiments to test how soil moisture and food affects adult and larval stages of this species. Laboratory tests found that adult females laid more eggs in chambers that were watered more frequently and development through the three larval instars was significantly faster at higher food levels. The field test of supplementary watering and vegetation removal found watered plots attracted more adults that produced greater numbers of first instars. Larvae had higher survival and developed more rapidly in the watered plots than in unwatered and vegetation removal plots. These results suggest that higher amounts of rainfall and associated soil moisture will result in an increase in adult numbers. If projections of increased droughts in the southwest from climate change materialize, supplementing moisture on a larger scale should be considered as a management strategy for improving beetle habitat and reducing their risk of extinction.