On the effectiveness of hand collection to complement baits when studying ant vertical stratification in tropical rainforests

Abstract

A key factor to study ants is the choice of an appropriate sampling method since distinct sampling methods can capture distinct ant fauna and, therefore, leading to bias in the interpretation and conclusion of the patterns observed. Despite it is well known that the ant fauna is vertically stratified, some of the sampling methods cannot be used throughout the whole vertical stratum (e.g., fogging and Winkler extractor). Here, we compared and evaluated the complementarity of distinct sampling methods in ant surveys on canopy and forest floor in a tropical rainforest of Mexico. Sampling in 10 trees in canopy and on the forest floor around the trees using two baits (tuna and honey) and a standardized hand collecting, we found a total of 44 ant species, belonging to 17 genera and five subfamilies. Ant species composition was different among sampling methods at both vertical strata. Besides, hand collecting yielded higher ant species richness and more exclusive species than either bait at both vertical strata, but both tuna and honey baits also led to the detection of some, though fewer, exclusive ant species. The combination of hand collecting, tuna, and honey baits should thus be considered complementary tools for ant inventories, since using the three methods together yielded more complete inventories at both vertical strata. All methods tested here can be used on distinct vertical strata, ensuring that data in different vertical strata are comparable, allowing more reliable comparisons among these different habitats, i.e., vertical stratification.