Termites are important ecosystem engineers, crucial for the maintenance of tropical biodiversity and ecosystem functioning. But they are also pests which cause billions of dollars in damage annually to humans. Currently, our understanding of the mechanisms influencing species occurrences is limited and we do not know what distinguishes pest from non-pest species. We analyzed how anthropogenic disturbance (agriculture) affects species occurrences. We tested the hypothesis that strong disturbance functions as a habitat filter and selects for a subset of species which are major pests of crop. Using a cross-sectional approach, we studied termite community composition along a disturbance gradient from fields to 12-year-old fallows in a West African savanna. We reliably identified 19 species using genetic markers with a mean of about 10 species -many of them from the same feeding type -co-occurring locally. Supporting our hypothesis, disturbance was associated with environmental filtering of termites from the regional species pool, maybe via its effect on vegetation type.The most heavily disturbed sites were characterized by a subset of termite species which are well-known pests of crop. This is in line with the idea that strong anthropogenic disturbance selects for termite pest species.

(1) Background: Termites are important ecosystem engineers, crucial for the maintenance of tropical biodiversity and ecosystem functioning. But they are also pests which cause billions of dollars in damage annually to humans. Currently, our understanding of the mechanisms influencing species occurrences is limited and we do not know what distinguishes pest from non-pest species. (2) Method: We analyzed how anthropogenic disturbance (agriculture) affects species occurrences. We tested the hypothesis that strong disturbance functions as a habitat filter and selects for a subset of species which are major pests of crop. Using a cross-sectional approach, we studied termite assemblage composition along a disturbance gradient from fields to 12-year-old fallows in a West African savanna. (3) Results: We reliably identified 19 species using genetic markers with a mean of about 10 species—many of them from the same feeding type—co-occurring locally. Supporting our hypothesis, disturbance was associated with environmental filtering of termites from the regional species pool, maybe via its effect on vegetation type. The most heavily disturbed sites were characterized by a subset of termite species which are well-known pests of crop. (4) Conclusion: These results are in line with the idea that strong anthropogenic disturbance selects for termite pest species.

1. Termites consume a wide range of plant material at different stages of decomposition and, accordingly, have been classified into ‘feeding groups’. African savannah ecosystems harbour many termite species, yet most belong to Termitidae. Especially striking is the co‐occurrence of up to eight Macrotermitinae and five Trinervitermes species, each having apparently identical trophic niches, i.e. fungus‐growers and grass‐feeders, respectively.2. This study examined stable isotope signatures of 15N and 13C of West African savannah termites to test the validity of existing feeding group concepts and whether there is fine‐scaled niche differentiation of species within feeding groups. Despite a phylogenetic signal that species from the same subfamily and congenerics have correlated isotope signatures, evidence of niche differentiation was found.3. Interestingly, species with similar δ15N values generally differed in δ13C values, and vice versa. The dominant mound‐building fungus‐grower Macrotermes bellicosus had the lowest δ15N values among all fungus‐growers, indicating that it occupies a different trophic niche.4. This fine‐scaled differentiation along the trophic niche axis can help to explain the coexistence of so many apparently identical termite species.

Termites (Isoptera) are important ecosystem engineers of tropical ecosystems. However, they are notoriously difficult to identify, which hinders ecological research. To overcome these problems, we comparatively studied termite assemblages in the two major West African ecosystems, savannah and forest, both under natural settings and along disturbance gradients. We identified all species using morphological as well as molecular markers. We hypothesized species richness to be higher in the forest than the savannah and that it declines with disturbance in both ecosystems. Overall we found more species in the forest than in the savannah. However, alpha diversity per site did not differ between both ecosystems with on average around ten species. For both ecosystems, species diversity did not decrease along the studied disturbance gradient but encounter rates did. For the forest, we did not detect a decline in soil feeding termites and an increase of fungus grower Macrotermitinae with disturbance as some other studies did. Yet, soil feeders were generally rare. Strikingly, the set of morphologically difficult-to-identify Macrotermitinae ( Microtermes and Ancistrotermes ) was as high in the forest as in the savannah with little species overlap between both ecosystems. Using phylogenetic community analyses, we found little evidence for strong structuring mechanisms such as environmental filtering or interspecific competition. Most local assemblages did not differ significantly from random assemblages of the regional species pool. Our study is the most comprehensive of its kind. It provides the most reliable termite species list for West Africa that builds the basis for further ecological studies.

The processes that structure communities are still largely unknown. Therefore, we tested whether southern African termite communities show signs of environmental filtering and/or competition along a rainfall gradient in Namibia using phylogenetic information. Our results revealed a regional species pool of 11 species and we found no evidence for phylogenetic overdispersion or clustering at the local scale. Rather, our results suggest that the assembly of the studied termite communities has as strong random component on the local scale, but that species composition changes along the climatic gradient.