Discovery of potent, unsuspected sampling disparities for Malaise and Möricke traps, as shown for Neotropical Cryptini (Hymenoptera, Ichneumonidae)

Abstract

Malaise and Möricke traps, universally used mostly to sample wasps and flies, are compared for the first time at genus level, focusing on Cryptini, one of the most diverse parasitoid taxa. Conclusions are supported by 10,706 man-hours of activities, 5,569 specimens from 20 Atlantic Forest and Amazon Forest localities, 4.81 Malaise trap-years and 89.09 Möricke trap-years. Substantial taxonomic and sexual biases were detected and quantified for Cryptini and for each of its studied genera. Möricke captured a proportion of Cryptini to other Ichenumonidae almost four times greater than Malaise. Most genera were captured mostly or exclusively by one of the traps only. Generally, Malaise collected 2.4 times more males than females, and 20% more species for males than females; Möricke yielded 2.4 times more females, and 2–4 times more species for females than males. The study scrutinizes and reaches beyond an allegedly known, but widely neglected problem. Data interpretation strongly suggests the necessity of sampling with both traps at once, under the risk that biodiversity investigations might otherwise continue to generate grossly biased results. Trap equivalence is discussed and quantified.