Assessing spider diversity in grasslands – does pitfall trap color matter?

Abstract

We analyzed effects of pitfall trap color on spider catches using four different pitfall trap colors (white, yellow, green, brown). For each color, we installed 17 pitfall traps at two grassland sites, respectively, and sampled 77 species from 6,202 individuals. Number of species showed no significant differences but Shannon- and Simpson-diversity were significantly higher in green and brown traps while number of individuals increased in white ones. Species inventories were not complete in the different pitfall trap colors but species accumulation increased significantly slower in white and brown traps. Trap color significantly affected hunting type with ground hunters being associated with bright and web-builders associated with dark colors. Attractiveness of different trap colors may arise due to differences in biological preconditions, albedo and microclimate which in turn can affect diversity and community structure of spiders. Trap color has a significant impact on spider catches and should be considered when planning surveys. We recommend the use of a combination of white and brown (or transparent) pitfall traps to gain complete and diverse species inventories in spiders.