Comparison of two methods for sampling orthopterans in grassland: differences in species representation and sex ratios

Authors: STANISLAV RADA

Abstract: Orthopterans are convenient indicators for threatened grassland ecosystems. Many sampling methods are known; among them, sweep netting is the most common. This study compares sweep netting with less common pan trapping and quantifies differences in species representation and sex ratio between the two sampling techniques. Sampling took place in the submontane grassland in the northeastern part of the Czech Republic (Central Europe) during July, August, and September 2010. Both sweep netting and pan trapping were used concurrently in 11 meadows. Sampled orthopteran adults were determined to the species level and their sex was noted. Both methods recorded the same pool of 14 species. A chi-squared test showed significant differences in representation of 7 out of 8 analyzed species in sweep-net and pan-trap samples. Sex ratios also noticeably differed. Possible causes of the differences are discussed. This study showed that pan trapping is a solid alternative to sweep netting.

Keywords: Sweep netting, pan trapping, Orthoptera, grasshopper, relative abundance, species composition, sex ratio, incidence, Czech Republic

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