Relative Efficiency of Pitfall Trapping vs. Nocturnal Hand Collecting in Assessing Soil-Dwelling Spider Diversity along A Structural Gradient of Neotropical Habitats

Abstract

Assessing spider diversity remains a great challenge, especially in tropical habitats where dozens of species can locally co-occur. Pitfall trapping is one of the most widely used techniques to collect spiders, but it suffers from several biases, and its accuracy likely varies with habitat complexity. In this study, we compared the efficiency of passive pitfall trapping versus active nocturnal hand collecting (NHC) to capture low understory-dwelling spider taxonomical (morpho-species) and functional (hunting guilds) diversity along a structural gradient of habitats in French Guiana. We focused on four habitats describing a structural gradient: garden to the orchard to the forest edge to the undisturbed forest. Overall, estimated morpho-species richness and composition did not vary consistently between habitats, but abundances of ground-hunting spiders decreased significantly with increasing habitat complexity. We found habitat-dependence differences in taxonomic diversity between sampling strategies: NHC revealed higher diversity in the orchard, whereas pitfalls resulted in higher diversity in the forest. Species turnover resulted in high dissimilarity in species composition between habitats using either method. This study shows how pitfall trapping is influenced by habitat structure, rendering this sampling method incomplete for complex, tropical environments. However, pitfall traps remain a valuable component of inventories because they sample distinct assemblage of spiders.

Pitfall trap design affects the capture efficiency of harvestmen (Opiliones) and millipedes (Diplopoda)

“…The effectiveness of pitfall trapping for the capture of epigaeic fauna has been widely discussed (Luff, 1975; de Oliveira et al., 2019; Privet et al., 2020; Saska et al., 2013; Southwood, 1978; Topping & Sunderland, 1992). For example, the effectiveness of pitfall trapping was evaluated by capturing all individuals in a specific area by Adis (1979) and Petruška (1969).…”

A standardized multi‐method survey to enhance characterization of riparian invertebrate communities

“…Each hand search and each pitfall trap replicate set were considered comparable because the two methods can capture a similar number of taxa and, where differences occur, there is no consistent pattern on which to base different weightings (e.g. Melbourne, 1999; Phillips & Cobb, 2005; Privet et al, 2020; Zanetti et al, 2016). Neither hand search duration nor the number of pitfall traps were considered as a weighting factor, because of diminishing returns on increased effort (e.g.…”

Living on the edge: Predicting invertebrate richness and rarity in disturbance‐prone aquatic–terrestrial ecosystems

“…Pooled pitfall traps and ground searches can capture a similar number of taxa (e.g. Melbourne, 1999; Phillips & Cobb, 2005; Privet et al., 2020; Zanetti et al., 2016), so were also considered comparable (also see Webb et. al., 2022).…”