This study was carried out at Galangashie protected park located in the savanna region (Fig. 1) between 10°19'–20°28'N and 0°14'–0°27'E (northern part of Togo). It covers 7650 hectares, and it had been protected since its creation in September 1954. The study area has a Sudanian tropical climate characterized by a long dry season (November to May) and a long rainy season (June to October). The mean temperatures range from 30±3 °C (during dry season) and 29±2 °C (during the rainy season) with an annual rainfall of 986 mm. The landscape is a shrubby savanna.

Figure 1.

The location of the study area Galangashie.

Termites were sampled within the frame of belt transects. Three sets of three belt transects were laid at three sites: site 1 (10°26'42.6"–10°26'43.4"N; 000°23'52.4"–000°26'56.9"E) site 2 (10°27'30.8"–10°27'31.9"N; 000°23'39.5"–000°23'42.0"E) and site 3 (10°28'11.2"–10°28'10.8"N; 000°23'16.4"–000°23'16.6"E). The sets of three transects were at a distance of at least 2 km from each other, and two consecutive transects were separated by at least 15 m (Fig. 3). Each belt transect was 100 × 2 m divided into 20 units of 5 × 2 m as described by Jones and Eggleton (2000) for forest ecosystems. In our study, this standard protocol was adapted to the savanna ecosystems according to Dosso et al. 2010 and Hausberger et al. 2011. Each unit (5 × 2 m) was sampled for 15 minutes, according to Schyra and Korb (2019). During this period, termites were systematically searched in their microhabitats such as litter, dead wood, trees (up to 2 m above ground), grasses, uprooted grass tufts and inside mounds within each sampling unit by a well-trained collector. The search time of 15 minutes was chosen instead of 30 minutes (as proposed by Jones and Eggleton 2000) because available substrates or microhabitats are lesser in savanna ecosystems than in forest ones. The length of the belt transect (100 m) was kept in our study, instead of 50 m proposed by Schyra and Korb (2019) in order to increase the sampling effort. Termites were also searched throughout eight soil scrapes of 15 × 15 × 10 cm (Fig. 2) according to Schyra and Korb (2019) within each unit. Collected termites were stored in 95% ethanol inside labeled vials and kept in the laboratory for further processing.

Figure 2.

Scheme of transects with a sampling unit.

Figure 3.

Correlation between species richness and total organic material (Shrub savanna).

Termite specimens were sorted and grouped into morpho-species. The identification was based on morphological characters (antenna, mandible, head, labrum, pronotum, gula) and morphometric parameters (head length and width, mandible length, pronotum width, gula width, and hind tibia length). Measurements were made using a stereomicroscope (Leica EZ4) with an integrated camera connected to a computer. Las EZ software application was used for image acquisition and mensuration. The reference works of Grassé (1937), Bouillon and Mathot (1965), Silvestri (1912), Sands (1965, 1992), and Ruelle (1970) were used for the species identification.

The voucher specimens are conserved in the entomological collection of “Laboratoire d’Entomologie Appliquée” of the University of Lomé (Togo).

The obtained species list of this study was compared to previous studies (Anani Kotoklo et al. 2011; Kasseney et al. 2019; Schyra et al. 2019) carried on termites in Togo, in order to sort out the newly recorded species.

The identified species were classified within their corresponding feeding groups, according to Donovan et al. (2001).

Soil samples were collected in transects in which termites were harvested. An amount of 500 g of soil was taken from each sampling site and kept in plastic bags. They were brought to the Laboratory of Chemistry of the University of Lomé for chemical analysis. Five grams of each soil sample (previously dried at 220 °C) were burned at 450 °C for 3 hours. After cooling, the percentage of mass loss generated by the calcinations constitutes the soil samples’ total organic material content. The total organic carbon content was derived from the total organic matter. It was estimated to be 58% of the content of the total organic material.

For analysis smoothness, each set of three transects was considered as a replica. Data from each set of three transects were then pooled, and three replicates were obtained. We used the occurrence (presence or absence) and the relative abundance (the percentage of the occurrence of each single species in a sampling site) of specimen instead of a number of collected individuals because the occurrence of a single individual indicates the presence of a whole colony of termites around.

Alpha diversity indices, including the total observed richness (Sobs), Simpson index of diversity (1-D), and Shannon index, were calculated using Past 3.2 software (Hammer et al. 2001).

The test of Kendalls τ was run to examine the correlation between species richness, total organic material, and total organic carbon of the soils from each set of three transects. Because there were three sets of three transects, the sample size was 3: each set of three transects was combined to get one sample size. This test was carried out in SPPS 20 at the level of 0.01. The coefficient of Kendalls τ test ranges from -1 (a strong negative correlation) to +1 (a strong positive correlation) with 0 value indicating no link between the examined factors.

A total of 28 species belonging to 14 genera and 6 subfamilies were identified (Table 1). Macrotermitinae subfamily not only had a higher number of sampled genera (Ancistrotermes Silvestri, 1912; Macrotermes Holmgren, 1909, Microtermes Wasmann, 1902 and Odontotermes Holmgren, 1910) but also a higher number of species (9). Termitinae was the second most important subfamily in terms of the recorded number of genera (Amitermes Silvestri, 1901; Eremotermes Silvestri, 1911; Microcerotermes Silvestri, 1901) and also in term of sampled species (9). The other subfamilies (Apicotermitinae, Cubitermitinae, and Nasutitermitinae) were all represented by two genera except the Coptoterminiane subfamily, for which only Coptotermes intermedius Silvestri, 1912 was recorded.

Microtermes grassei Ghidini, 1955 was the most sampled species with 25.42% of occurrence (Table 1). It was followed respectively by, Microtermes toumodiensis Grassé 1937 (11.62%), Trinervitermes oeconomus Trägårdh, 1904 (11.62%), Microcerotermes sp (6.78%) and Fulleritermes tenebricus Silvestri, 1914 (5.33%). Besides these frequently sampled species, several species, including Amitermes sp. (0.48%), Coptotermes intermedius Silvestry, 1912 (0.48%), Odontotermes sp.1 (0.48%)and Trinervitermes togoensis Sjöstedt, 1899 (0.48%), were rarely found during our study. That represented precisely the double of the total occurrence (0.24%) of the less sampled species, Amitermes spinifer Silvestri, 1914, Ancistrotermes crucifer Sjöstedt, 1897, Cubitermes sp. and Noditermes sp. (Table 1).

Among the sampled specimens, 9 species to our knowledge were identified for the first time in Togo (showed in Table 1 with an asterisk). Two species, Amitermes sp., Eremotermes sp. could be new (not yet described) species for sciences.

The sampled termite species (from both landscapes) belong to 3 out of 4 feeding groups: feeding group I (FG I), feeding group II (FG II), and feeding group IV (FG IV) (Table 1). FGI was represented by the unique species of Coptotermes intermedius, a wood-feeding termite. FG II consisted of Macrotermitinae, Termitinae, and Nasutitermitinae subfamilies, the most important feeding group with 8 genera and 21 species out of 28. Species of this group essentially feed on wood and or litter and grasses (Trinervitermes species). The last feeding group (FG IV) found in our study included 2 subfamilies Apicotermitinae and Cubitermitinae, with 4 genera: Adaiphrotermes Sands, 1972; Aderitotermes Sands, 1972 (both belonging to Apicotermitinae subfamily), Cubitermes Wasmann, 1906 and Noditermes Sjöstedt, 1924 (both genera of Cubitermitinae subfamily).

The Simpson index (1-D) for sampled termites was 0.89 (Suppl. material 1). This value is close to 1 (the highest possible value), indicating a great diversity. The same pattern of great diversity was also shown by Shannon index 2.63.

The total organic material of soil was positively correlated with the species richness found in this landscape (Fig. 3, Suppl. material 1). The Kendall τ test (τ = 1) showed that this correlation was very significant (p < 0.001, N = 3). There was also a strong, positive correlation (Fig. 4) between species richness and its total organic carbon (τ = 1, N = 3, p<0.001).

Figure 4.

Correlation between species richness and total organic carbon.

The distribution of termites (like many other terrestrial arthropods) is driven by several factors, including soil richness (Park et al. 1994; Bourguignon et al. 2015), vegetation (Park et al. 1994; Gillison et al. 2003), and also the degree of anthropogenic disturbance (Hausberger and Korb 2016; Netshifhefhe et al. 2019). In our study, the main factors examined were the soil richness in organic matter and its total organic carbon. The computed diversity indices (Simpson 1-D close to 1, and Shannon over 2.5) showed that the study area was quite well diversified. Macrotermitinae subfamily, with 4 genera and 9 species, was by far the most important subfamily. Dosso et al. (2013) and Kaiser et al. (2015) carried out a similar study throughout several habitats, including semi-arid, semi-deciduous forest, food crop fields, fallow, and several agro-ecosystems. They found that fungus-growing termites were relatively more abundant in all their studied habitats.

The high percentage of Macrotermitinae species occurrences is certainly due to their feeding habit and, therefore, to their feeding group. Indeed, these species could feed on diverse sources of celluloses from dry herbs to dry wood as well as dry leaves, twigs, litter, and even animal dung (Freymann et al. 2008). All these cellulose resources can be found in several landscapes. Besides the ability to feed on large cellulose resources, Macrotermitinae species also developed a symbiosis with a basidiomycete fungus, Termitomyces, which contribute to the successful decomposition of lignocelluloses (Ohkuma 2003).

Coptotermes intermedius, feed essentially on wood (dry or still alive). The presence of many kinds of wood has facilitated its occurrence in the shrub savanna. Indeed, wood feeders were reported to be very sensitive to disturbance and therefore were less abundant in habitats with few and small trees (Dosso et al. 2013). Similarly, Fulleritermes tenebricus is also found in medium to densely shrub savanna as well as a forest ecosystem (Schyra et al. 2019).

Microtermes grassei was the most sampled species indicating its ubiquitous state and its ability to dwell on large food sources. This species was also sampled in the forest ecosystem (Schyra et al. 2019) as well as in the open grassy area of a botanical garden in the middle of a city (Kasseney et al. 2019).

A positive correlation was found between termite species richness and soil organic matter. Indeed, this landscape, as mentioned above, was a protected area since its creation. Fallen leaves, dry twigs, and branches from sampled trees are food for many termite species that recycle these plant parts (Ohkuma 2003; Brune and Ohkuma 2010). This recycling increases the amount of soil organic matter, which is beneficial for soil-dwelling termites such as Noditermes species.

The occurrences of newly recorded species underlined the importance and the contribution of this study to the knowledge of termite species in the country, in keeping with previous studies (Anani Kotoklo et al. 2011; Kasseney et al. 2019; Schyra et al. 2019). Indeed 9 out of 28 termite species were recorded for the first time in the country. Moreover, besides enlarging the country’s termites list, this study, with two potentially new species (Amitermes sp. and Eremotermes sp.), appeared to be a modest contribution to termites’ systematic and taxonomy throughout the entire world. Amitermes species are commonly found in arid zones as well as in wet areas (Sands 1992). The new record of these species in our study is due to the lack of available data on termites in this area. This study was the first on termites during the post-colonial period in this area to the best of our knowledge. The species of the genus Eremotermes were thought to occur exclusively in arid zones. Its presence in our study area (a Sudanian savanna) support the result of Ndiaye (2014) who sampled some species of Eremotermes in a relatively wet savanna in Senegal. Eremotermes species are very cryptic (Sarr 1999; Diop et al. 2013); for this reason they are usually not seen and sampled by the collectors in the field.