Termite Diversity under Different Land Use Regimes of Dindigul District, South India

Keywords: termite, species diversity, dindigul district, ecosystem engineers

Termite Biodiversity

Termites are the most abundant terrestrial isopteran insects in many tropical and subtropical ecosystems. They are often known as “white ants”, however, they differ from ants in morphological and phylogenetical traits. The word Isoptera refers to the two pairs of identical wings in the adult (Harris, 1957, Thorne & Carpenter, 1992). Termites are polymorphic, eusocial insects, living in large communities of several hundred to several million individuals, composed of reproductive (winged) forms together with numerous apterous sterile soldiers and workers. All termites live in colonies within the confines of excavations within wood above-ground, or in subterranean and epigeal nest systems. They are a key functional group of animals in the tropics and can achieve high dense population. Their numerous colonies have great influence in ecosystems.

Materials and Method

The project was undertaken in the various blocks of Dindigul district in Tamilnadu, India. Sampling was carried out in different land use patterns,as plains, woodlands and hilly areas. Dindigul District is located between 10 degree 5 minutes and 10 degree 9 minutes north latitude and 77 degree 30 minutes and 78 degree 20 minutes east longitude.. The main rivers of the district are Kodaganaru, Palar, Kuthiraiyar, Porandalar, Amravati, Manjalar, Varadhamanathi and Maruthanat. Geologically Dindigul District receives an average rainfall of 700 mm and the average temperature is relatively high varying from 26 degree Celsius to 38 degree Celsius. Semi and tropical monsoon type of climate is prevailing in the plains of the District. However upper Palani recorded low temperature and fairly heavy rainfall. This Division Contains 84564.87 ha. of Reserved Forests and 19730.40 Ha. of reserved lands. The reserved forest area of the district, is rich in flora and fauna. The forests of this division forms a part of rich bio-diversity which is ecologically very sensitive and economically important for agricultural production and food supply for India.

Termites were collected from ten sites from September 2009 to march 2010. At first in four sites the local assemblage was assessed using a standardized transect sampling protocol (slightly modified). Only casual collecting was undertaken at sites 5 and 6, with additional collecting from the other four sites when time allowed.

Results and Discussion

Although regarded as pests, termites are highly beneficial biological agents whose bioturbating and decomposing activities can be managed indirectly with organic matter to enhance primary production. There are about 2650 species of termites in 280 genera and seven families that have so far been described worldwide (Kambhampati & Eggleton, 2000). At present, 7 families and 14 subfamilies are recognized, while a large majority of genera are included in the most evolved family Termitidae. The families are usually divided into so-called “lower” and “higher” termites. All the families except Termitidae are assigned to lower termites, which generally harbor dense protists in their guts. Termitidae is the only family of higher termites which usually lack protists, lower termites, in contrast, depend on symbiotic protozoa in their intestinal tract for the degradation of lignocellulose (Cleveland, 1923).

• DBn – Dindigul Block
• ×   – Species Availability
• 0   – Non Availability

However being social insects termites tend to concentrate around colony centres in their termitaria nests. These nests are often distributed unevenly through different habitats. These nests are sites of activity for diverse microbial populations (Collins N.M., 1983). Moreover, these mounds act as foci for nutrient redistribution and promote inorganic nitrogen fixation focusing termite act as ecosystem engineers for the degradation in the formation of stable pools of soil organic matter. The impact of termites on ecosystem is governed by the species richness and their relative abundance (Eggleton, P.E., Bignell, 1995.) Of the species sampled, 6 genera representing 3 subfamilies were recorded from a total of 30,000 individuals sampled from the study sites. Macrotermitinae was the most dominant subfamily followed by termitinae and Nasutitermitinae. Workers, that could not be identified constituted 18% of total individuals. In all the study sites, either Labiocapviternies distortus, trinervitermes trinervius and Odontoteimes obesus were the most dominant species both in terms of abundance and biomass (table2). Although species richness did not vary significantly across different habitats the maximum number of species was recorded in sirumalai (DB 4), batlakundu (DB 7)and kodaikanal (DB 6) block areas.

Fequency distribution of ten species six genera, recorded for
the first time in different land use patterns of Dindigul District

Almost all species of termite are detritivorous. They consume wide range of organic constituents or decaying plant material including dung and humus. Subterranean termites, including mound building and arboreal species, account for 80% of the economically important species and the genus Coptotermes (Rhinotermitidae) contains the largest number of economically important subterranean termites. Odontotermes species locate their colonies underground, where they cultivate fungi that aid in cellulose digestion. The mounds enclose a ramifying network of tunnels that forms a ventilation system for the nest. Some species may build open chimneys or vent holes into their mounds Grass- and litter-feeding mound-building termites are often very abundant and widely distributed in Africa where these mounds are characteristic features of the landscape Mounds of Trinervitermes geminatus and Trinervitermes trinervius, (Sands 1965a), both grass-feeders, contained more clay, organic matter (OM), and exchangeable cations than the surrounding surface layer soil.

The poor diversity of termites recorded during our survey could be explained by the degradation of fragile ecosystem, soil texture, moisture content, human interference and hydrogen ion concentration plays a key role in determining the availability of termite population. The study of the frequency of species on the ten habitats showed the dominance of Odontotermes obesus which is constant in the reports of Lepage in those areas (1974). Consequently, while Odontotermes appeared to play a major role in clay dynamics and soil fertility in the tropical ecosystem, The biological attributes of each species (nest pattern, life-span and distribution of fungus-comb chambers) appear to be the main determinants to account for the relative importance of termite species in soil functioning. The distribution of termites in the ten selected habitats shows a gradual decrease in species diversity in the areas with more human interference (Wood, 1982).

There was variation in the species composition in the different habitats (table 2). Maximum termite abundance and biomass were recorded from the forest blocks. The overall total density of the soil fauna was also highest in the forest site as compared to the non-forest sites. The species diversity shows a striking difference in the wood lands rather than in plains and follows a random distribution. The biodiversity of this cryptic animal gains importance due to its increasingly recognized positive effects in nutrient cycling, pest population regulation, and plant growth.

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