Two designs of hypogean pitfall trap with differing sampling port areas: a comparison of their catch sizes, compositions and resultant biodiversity scores

Hypogean pitfall traps collect samples of unfer-ground soil-dwelling invertebrates. The way that such traps are deployed often results in disturbance of the surrounding soil profile, To avoid such soil disturbance a new design of hypogean pitfall trap (the “Fioratti trap”), was produced. The new-style trap can be deployed by means od a soil corer or auger, inserting the trap directly into the hole. The total area of the sample ports of the new trap (100 cm2) is 20% that of the old 11 cm diameter trap, and thus smaller samples are collected. These require less time to sort and identify. Ideally, trap design should not unduly influence the makeup of the resultant invertebrate samples it collects. To investigate this, the old and new designs of hypogean pitfall traps were deployed simultaneously along a field margin at Peartrees Field, Jealott’s Hill, Berkshire, and biodiversity indices calculated from the samples collected. hile the new traps collected a smaller number of specimens, they were observed to be 1.7 times more efficient (on a per area of soil sampled basis) than the old-style traps. The lower number of individuals collected in the new style traps resulted in a reduction in species richness. However, where aggregated non-metric dimensional scaling scores were computed, the same shifts in community composition were detected by the two types of trap. Given the practical benefits associated with the new traps, it is envisaged that the new design of pitfall trap is a good candidate for a standard device for sampling hypogean soil biota.