A global review of termite sampling methods

Abstract

Termites are globally dominant and functionally important soil organisms. While their role in ecosystems is being increasingly recognised and understood, methods that adequately sample termite communities across habitats can be challenging and have not advanced at the same pace as studies of termite ecology. Moreover, the appropriateness of sampling methods varies with habitat and biogeographic region due to differences in termite communities. Focusing largely on tropical systems where the majority of termites occur, we review currently available termite sampling methods and provide recommendations for sampling across different biomes and biogeographic regions. Active searching transects are most effective in rainforest habitats, whereas reduced transects, baiting and mound surveys are more appropriate in grassy systems and seasonally dry forests. Baiting is recommended for deserts. Recent advances in termite sampling, such as the use of remote sensing and DNA metabarcoding, and outstanding challenges, such as sampling episodic grass-feeding termites, are also discussed. Improved use of standardised termite sampling methods, as we recommend, should lead to increased knowledge of the patterns and drivers of termite diversity, which will, in turn, facilitate the quantification of the influence termites have on ecosystems and lead to new insights into the functioning of tropical systems.

Glossary

Active searching

Searching for termite individuals in microhabitats, such as soil pits, dead wood, mounds, runways, leaf litter accumulated in the buttress roots of trees, under dung, and other microhabitats.

Baiting

Using cellulose-rich material as baits to attract termites. Baits often include toilet-rolls (using the full roll) but can also consist of wood and/or other dead-plant material. Termites attracted to the baits can then be collected.

Castes

In termites these are: reproductives (including the queen and king), workers and soldiers. Soldiers are particularly important as they are the main caste used for identification.

Continuous foraging

Termites that forage at all times of day, and therefore can be found in their feeding substrate continuously.

Ecological sampling

Sampling to collect data that can be compared statistically between sites, but does not necessarily produce an exhaustive species list.

Encounter

A recorded presence (same as an ‘occurrence’) of a group of termites, or sometimes just an individual termite, during active searching, either foraging or in a colony centre. Each time such a group or individual termite is found during sampling, a single encounter is recorded, regardless of whether the different encounters were in one or multiple transect sections. Some discretion will be needed to assess whether two encounters are distinct. For example, two termite groups sampled within a single piece of wood would generally be considered as one encounter (unless they are several meters apart on a large log), whereas two groups in two pieces of wood would generally be counted as two encounters.

Episodic foraging

Termites that forage intermittently depending on climatic conditions, time of day or other conditions. Episodic foragers are often found only in their nests.

Full transect

A 100 m × 2 m belt transect, sampled by active searching for a total of 20-person hours. In statistical terms, a single large quadrat.

Inventory sampling

Sampling that aims to produce a complete species list for a single site and is harder to use for statistical comparisons between sites.

Microhabitats

Places where termites can be found. These include, amongst other locations, soil pits, dead wood, animal dung, mounds, runways and leaf litter accumulated in the buttress roots of trees.

Mound sampling

Quantifying the density of mounds within a given area, and also sampling termites directly from their colonies in epigeal mounds.

Reduced transect

A 100 m × 2 m belt transect, sampled by active searching for a total of 200-person minutes (3.3 h). This reduced time is appropriate for wetter savannas, where termite species density is lower than tropical rainforest, and there are fewer termite microhabitats. In statistical terms, a single large quadrat.

Species density

The number of species found in a particular area. In the case of transects this is species/200 m². This contrasts with species richness, which is a dimensionless number and should not be referred to with sample data.

Study plot

Area of interest within which sampling is undertaken.

Termite feeding groups

There are usually considered to be four groups: Group I (non-Termitidae, wood and grass-feeders), Group II (grass, wood and litter feeders, which is sometimes divided into non-Macrotermitinae Termitidae, and Macrotermitinae Termitidae (i.e., fungus-growers, which can be designated as Group IIF), Group III (humus-feeders), Group IV (true soil-feeders). See Donovan et al. (2001) for a full description.