Morphological Identification of Edible Termites (Isoptera) in Luanda Sub-County, Kenya ()
1. Introduction
There are around 3000 species of termites in 280 genera that have been described worldwide, and about 39% of the total termite species are found in Africa [1]. Identification of termites is crucial to understanding their distribution and abundance [2] and their relationship to climate change and food security. Termites have important functional and ecological roles in Africa and the world. However, a few species are pests, while 99% of the more than 2000 termite species offer beneficial ecosystem services. Despite their importance, termites are largely understudied, and most ecological research in tropical ecosystems concentrates on mound building termites, while comparatively little is known about hypogeal termite species [3]. The taxonomy of African termites is challenging, and many new species are yet to be described [4]. Termites have excellent nutritional qualities, proximate composition indicates that termites all species of termites have low shelf-life, and a good source of crude protein of 45.85% [5], and other micro- and macro-nutrients. Consumption of termites should thus be encouraged in Africa and the rest of the world. Termites have a low phytic acid value and hydrocyanide value, which implies that they are harmless [6].
According to [7] the scientific classification of termites follows the pattern: Kingdom: Animalia Phylum: Arthropoda Class: Insecta Subclass: Pterygota Infraclass: Neoptera Superorder: Dictyoptera Order: Isoptera. Generally, termites are classified into 280 genera and over 2600 species within seven families and 14 subfamilies. [8] [9] further stated that isopteran are phylogenetically categorised into lower termites (Mastotermitidae, Kalotermitidae, Hodotermitidae, Termopsidae, Rhinotermitidae and Serritermitidae) and the higher termites (Termitidae).
There are many termite species across the world, [10] documented that termites are classified into nine families namely, Termitidae which is notably the largest family, that consists 14 subfamilies, 280 genera and over 2600 species identified in the world. In his work [11] found out that there are approximately 175 species of termites from 42 genera and three families (Kalotermitidae, Rhinotermitidae and Termitidae) all originating from Peninsular Malaysia. In a research conducted in India, [12] identified termites of the genus Odontotermes sp. The most abundant species was Odontotermes feae, Odontotermes obesus, and Odontotermes feoides. In Northern Africa: termite species diversity is low thus has less than 15 species. This is due to the arid and semi-arid conditions as reported by [13]. In East Africa, it was found that less than 143 termite species were present in the habitats. In Djibouti, Eritrea, Ethiopia, Somalia and Sudan to the North, and Malawi, Mozambique, Zambia and Zimbabwe and South Africa, Southern Africa accounted for more than 165 species. Despite the numerous efforts to identify termites, the taxonomy of African termites is challenging, as new species have not been characterized [14]. Predation on termites by wild animals such as snakes and birds also play a significant role in reducing the populations of termite [15].
Species diversity is assessed using Simpson and Shannon indices Simpson’s Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases. In a study by [16] documented that there were two species of termites in the study area in Pakistan. The Simpson diversity scale was 48% while Shannon scale was 97%. On the other hand, the species richness was 0.5917. In a study done in Indonesia [17] documented that the lowest termite species richness was 62.5%. According to [18] [19], termite species differ in their morphology and ecology, including colony size, nesting, feeding, grooming, swarming and reproductive behaviour. Accurate identification of termite species and information on their distribution are key in developing environmentally and sustainable pest control strategies. According to [20], termite identification, especially, Coptotermes species is very challenging as the morphological identification of this species cannot provide detailed taxonomic status. The overdependence on the soldier morphological features presents a major challenge to species taxonomy because of the intraspecific variation in morphological characters in soldiers thus molecular identification are needed to give clear information.
[21] documented that over 4300 samples of termite were used in the studies in Thailand. Termites were identified using morphological features of soldiers. The characteristics used in the identification of termite genera were the shape and size of head, fontanelle, labrum, clypeus, mandible and pronotum. Additionally, to mandible characteristics, the location of teeth and number of antennae were also used. Measurements were generally taken in ethanol-preserved specimens which were dissected out and placed on the petri-dishes. [22] in their research documented that eight species of termite noted in the study area belonged to the family Termitidae. The dominance of the genus Macrotermes could be due to their character as generalist feeders that eat organic material. M. bellicosus was dominant in fresh grasslands while M. subhyalinus which existed in both fresh grassland and dry wood unlike Macrotermes spp1 which was collected on the ground Odontotermes spp1, Macrotermes spp1 and Pseudocanthotermes spp1 were identified as crop pests.
2. Materials and Methods
2.1. Study Site
Luanda sub-county is located 0˚30'34˚35"E it has a population of 134,202 (2019 Census) who occupy an area of 1200 km2. The climate is mainly tropical with variations due to altitude. Luanda Sub-County is mainly warm with mean temperature of 21˚C and wet most of the year. The dorminant soil type is sandy loam which is a mixture of clay and sand soil. The soil is usually fertile, well drained, moderate moisture retention capabilities and varied particle size.
2.2. Economic Activities and Food Security
The main economic activity is farming, majorly, sugarcane and maize on large scale. Some farmers practice small scale farming by growing soybeans, cassava, beans, tea, millet and sorghum. Dairy farming is also practiced, specifically, zero grazing. The staple diet of the region is maize. Due to diversified farming, the study area is averagely food secure. In addition to the food crops, farmers in Luanda sub-County of western region also consume a variety of edible insects such as crickets, Locusts, Caterpillars and termites.
2.3. Sampling of Soldier Termites to Determine the Species Composition
The termites were sampled from farms in the study site. This is because they have high prevalence of termites. The habitats t sampled were grasslands, forests, farms and hills. Sampling was done in the agroecological zones as per soil map of Vihiga County.
2.4. Determination of Species Composition of Solder Termites in Each Habitat
The solder and worker termites were sampled as they come out from their nests in large numbers and are easily visible. One belt transect was conducted in each habitat. A transect 100 m long and 2 m wide and divided into 20 successive quadrate sections of 5 m × 2 m were used. Termites were collected in whole sections by searching all potential microhabitats including wood, leaf litter, and surface soil down to 10 - 15 cm deep, visible nests, and galleries up to the height of 2 m in trees nearby mounds. Sampling was done from the lowland areas near Maseno up to the highlands in Emmatsi. There were ten sampling points in each study area.
Solder termites, and workers were sampled in a grid, 20 cm below the ground, and 1 meter on trees. Each grid was thoroughly searched for any termite mud trails, tree trunk, fallen tree trunks, rotting vegetation, and termite mounds. The solder termites were hand sorted according to different castes and kept in tubes containing 70% alcohol then taken to the laboratory for identification. Information on the GPRS of the sampled site was recorded this and the procedure was repeated in grasslands, forested area and hilly sites.
2.5. Morphological Identification of Termites
The collected termites were examined at National museums of Kenya under real-time imaging dissecting microscope. Identification of termites was based on description from [23] and [24]. The identification was done up to species level. The features included head length, width, and height, pronotum and mesonotum length and width, body length, shape and segment number of antennae, mandible length, distance among marginal tooth, of mandibles, tibla length, femur length, segment number of tarsi, tibia and spur, labrum, fontanelle, width and length, postmentum length and width, and nasus length. The termite species were sorted in each habitat and labelled.
3. Results
3.1. Identification of Termite Species in Luanda Sub-County
Soldier termites were identified morphologically at the National Museums of Kenya and the species listed below were identified in the 47 sites within Luanda sub-county which lies on coordinates, 0.0692˚N, 34.6525˚E (source: Vihiga county GIS laboratory) (Tables 1-7).
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Table 1. Table showing Pseudocanthotermes militaris and site where it was collected.
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Table 2. Table showing Pseudocanthotermesgrandicepes and site where it was collected.
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Table 3. Table showing sites Macrotermesbellicosus and site where it was collected.
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Table 4. Table showing Macrotermesherus and site where it was collected.
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Table 5. Table showing sites Macrotermesspp1 and site where it was collected.
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Table 6. Table showing Macrotermes sp1 and site where it was collected.
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Table 7. Table showing Macrotermesspp2 and site where it was collected.
3.2. Photographs for Morphological Identification of Termites(Figures 1-7)
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Figure 1. photograph showing Macrotermes bellicosus.
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Figure 2. Photograph showing Macrotermes herus.
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Figure 4. Photograph of Macrotermesspp2.
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Figure 5. Photograph of Psudocanthotermesgrandiceps.
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Figure 6. Photograph of Pseudocanthotermesmilitaris.
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Figure 7. Photograph showingMacrotermes spp1.
3.3. Species Diversity of Termites in Luanda Sub-County
Soldier and worker termites were sampled in Luanda sub-County, in 47 sites. The Shannon diversity index was H = 0.3606685, while Simpson index was D = 0.2064429.
3.4. Species Richness
The total number of species identified in Luanda sub-county was 7 and the species accumulation curve is shown in Figure 8 showing the abundance of species in the 47 sites.
3.5. Analysis of Variance of Termite Species
The results from ANOVA show that the difference between soldiers and workers was significant at p < 0.05 (Table 8).
Comparison between the number of soldiers and workers.
Post hoc test was done to show that there was no significant difference between the number of soldiers and workers (Figure 9, Table 9).
Different letters indicate significant differences (the least significant difference at 5%).
3.6. Comparison between Different Termite Species
A total of 7 species were identified out of which six species had no significant difference (a) while there was significant difference in Macrotermes spp1 (a b) (Table 10).
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Figure 8. The species accumulation curve for species diversity data of termites in Luanda using the exact method.
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Figure 9. Boxplot of termite species count across the workers and soldiers.
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Table 8. The analysis of variance table termite species.
***indicates significance at 5%.
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Table 9. Mean summary of the termites.
Note: Different letters are used in the table as supercripts there is no significant difference.
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Table 10. Table showing mean termites of different species.
Note: Different letters are used in the table as supercripts there is no significant difference.
4. Discussion
4.1. Species Diversity of Termites in Luanda Sub-County
[25] in his work reported that there are many termite species in Africa, some have been poorly described due to lack of sufficient termite taxonomist. This study envisaged to identify termite species in Luanda sub-county in order to document on the species diversity of termites in the area. Termites were identified at the National Museums of Kenya; using termite identification keys as referred to by [26]. Specimens were identified to species level using soldier castes. Termite identification done on the termites collected in Luanda sub-county revealed that there were 7 species identified collected in 47 sites. The identified species include M. herus Table 4, Macrotermes spp1 Table 5, Macrotermes sp1 Table 6, P. grandiceps Table 2, M. bellicosus Table 3, Macrotermes spp2 Table 7 and P. militaris Table 1. Termites are widely distributed in tropical and sub-tropical savannas as elucidated by [27]. In western Kenya a number of species have also been identified and this illustrates the high species diversity of termites.
This study focused on 47 locations in Luanda sub, where soldier and worker termites were sampled, Shannon diversity index was H = 0.3606685, while Simpson index was D = 0.2064429, during the month of January to March, which is a dry season. This indicated a high species diversity of termites in Luanda sub-county. Out of the 47 sites there was seven termite species identified. M. herus had the largest species richness of 7.0 which was obtained at Ebukolo Table 4 and Table 10. Macrotermes sp1 had the lowest species richness among all the termites identified. The species richness was 1.8239 at Mwikunga.
Comparative studies on termite diversity conducted in West Islamabad, Pakistan by [28] revealed that Simpson and Shannon’s diversity indices reflected that on Simpson’s index, the overall diversity (D = 0.7034) was 70.34% and it was 99% in case of the Shannon scale. Odontotermes horai was the most dominant species with a value of 0.4332 on Simpson’s index.
4.2. Termite Species Richness in Luanda Sub-County
Species richness was assessed in all the 47 collection sites and the results show that P. militaris had a high species richness of 6.9140 at Ekwanda 2 while Mulwanda had the lowest species richness 5.95014 Table 1. M. bellicosus on the other hand had highest species richness at Ebukanga 1 while lowest species richness at Maseno 2. M. herus was collected in 18 locations and Ebukolo had the highest species richness of 7.000 while Ekwanda had lowest species richness of 2.98703. Comparatively at Ekwanda M. herus had a lower species richness but on the other hand had highest species richness for P. militaris. From this results the two species do not coexist fully in their natural habitats.
Macrotermes sp1 had the lowest species richness among all the six species, at Mwikunga it had a species richness of 1.822. In a similar study [29] recorded that the lowest species richness of termites observed in the grassy savanna could mainly be explained by the annual disturbance. Fire behavior intensity, the rate of spread, flame height, residence time, and surface temperature is influenced by a wide range of variables such as fuel characteristics, burning season, and weather conditions. The mean summary of workers and soldiers indicated that there was a significant difference Table 9 and Figure 9. Analysis of variance of the termite species shows that the difference between Soldier s and workers was significant at p < 0.05, Table 8.
The identified species based on body morphology include M. herus Figure 2, Macrotermes spp1 Figure 7, Macrotermes sp1 Figure 3, P. grandiceps Figure 5, M. bellicosus Figure 1, Macrotermes spp2 Figure 4 and P. militaris Figure 6. The species richness curve Figure 8 showed a higher termite species richness in the study site. Most termite species belong to the family Macrotamatinae of which Macrotermes herus (25.56%) was the most abundant species in most sites in Luanda sub-county while Macrotermes sp 1 was (4%). There was also no significant difference in the number of worker and soldiers collected in Luanda sub-county p > 0.05 Table 9. Termites are one of the soil macro fauna that have sensitivity to microhabitat variation as reported by [30]. Luanda sub-county has diverse features of termite habitats thus the presence of different species which contribute to food and feed for the local community. Luanda sub-county is characterized by farm forests. Grasslands, swamps, hilly terrain with rock outcrops. High species diversity was obtained in grassland mixed with trees habitat as they offered a ready feed source to the foraging termites. Termite sampling was done using the belt transect method which ensured that most locations were searched for the presence of termites. [31] in his study noted that although the geographical ranges of two Macrotermes species largely overlap, Macrotermes michaelseni prefer higher elevations. At Ebulako site Macrotermes sp1 was predominantly found at 18% of all the termite species collected. Ebulako is found on latitude 34.61169 E 34˚36'42.078" and longitude 0.00194 N 0˚0'6.978". Ebulako is characterized by rock our crops hilly terrain and shrubs with little grass. [32] found out that weather conditions precipitated by climate change favour the increased emergence of insects specifically termites. Moisture and temperature play a significant role in insect ecology. Climate change influence insect population by influencing benthic fauna and its biodiversity that supports the insects. In Luanda sub-County a large proportion of termites were collected during the wet months unlike the dry months. During the wet months there was abundance of vegetation thus food source for the termites to forage.
In a similar study in Ethiopia [33] a total of over 16,000 termite individuals representing one family (Termitidae), two subfamilies, i.e., Macrotermitinae and Termitinae, and five genera (Macrotermes, Odontotermes, Microtermes, Amitermes and Microcerotermes) were found. More Microtermes and Macrotermes termite individuals were found than on other genera. Microtermes and Macrotermes were more abundant. Shannon’s diversity index and Simpson’s index of diversity values appeared to be higher in the protected vegetation. The termite species identified are prevalent in Luanda sub-county due to presence of feed sources from plants which act as lures for termites to feed as described by [34].
4.3. Conclusion
This study addressed the gaps in the knowledge on edible termite species and their locations in Luanda sub-county. Having established the location and identities of edible termites will assist in the conservation efforts of the termites. Termites are used as food and feed in Luanda sub-county, therefore the knowledge on the species diversity in different habitats will inform termite harvesters on which areas to harvest.
Acknowledgements
The study has been supported by grants from the world bank ACEII grant to Jaramogi Oginga Odinga University of science and technology, Kenya. We sincerely thank the technical staff at the National Museums of Kenya, who played a key role in the study.