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Importance of the Eastern Region of Bangladesh in Insect Conservation with Special Reference to Odonata

Shafique Haider Chowdhury
Ex-Faculty, Department of Zoology, University of Chittagong, Chittagong 4331, Bangladesh.

Abstract/ Executive Summary:

Studies on Odonata of the eastern region of Bangladesh revealed some interesting intraspecific variations. The landscape of this region with hills and forests has resulted into isolated habitats for the weak-flying odonates. Such isolation causes intensive inbreeding and resultant intraspecific variations are likely to lead to speciation. Early measures of protection of this area are recommended for conservation of odonate species.

Keywords: Conservation, Odonata, Eastern region, Bangladesh.

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Start Date:

End Date:

Program Area: Conservation and Biodiversity

Commodity: Animal

Objectives:

Early measures of protection of this area are recommended for conservation of odonate species.

Methodology:

The eastern region of Bangladesh from Cox’s bazaar to Sylhet and Sunamganj is bordered by Myanmar in the south and then by Mizoram, Indian Tripura, and Assam gradually north-ward and by Assam and Meghalaya in the north. It is now generally accepted that in the past, insects spread through migration mainly from the east and southeast Asia gradually to the Indian sub–continent. It is also assumed that large-scale migration/dispersal took place after the rise of the Himalayas. The region in this paper (eastern region of Bangladesh) falls along this route. Continuous distribution of a large number of odonate species from: a) Australia to Peninsular India, b) Malaysia to peninsular India, and c) Indo-China, all through the Gangetic plains and Assam bear testimony to this. In doing so, the eastern region of Bangladesh acted as the corridor. Now, let us take a look at the geography, vegetation, and general climatic pattern of this all important region. The concerned area falls in the Moulvi Bazar and Sylhet districts in the north and Chittagong and four Hill Tracts districts in the south. The landscape of two northern districts is a mixture of hillocks (locally known as Tillas) and broad plain land. The hillocks range from 100 to 200 feet msl in its northern part and from 50 to 100 feet msl in the south. The hillocks are occupied by patchy forests and about 130 tea gardens and the valleys by paddy fields. Earlier reports show that these lands once supported rich forests. The annual temperature ranges from 8.30 C to 32.70 C. This area has the highest rainfall in Bangladesh and humidity consequently is high, but there is also a prolonged dry season from November to mid-May. The mercury occasionally dips down to 00 C. A large number of mountain streams, almost all with sandy bottoms course down the hills and across the valleys. Some are slow and others quite swift flowing. Thick growth of shrubs adorns their banks. The southern districts are bound by the Bay of Bengal in the south, by Myanmar in the entire east side, and by Indian Tripura in the north. The hills in this part are much taller, some rising to approximately 1,200 feet msl. The temperature ranges from 12.70 C to 31.60 C. Annual rainfall amounts to 2,540 mm in the southern part and 3,558 mm in the north. Humidity is high almost all year round. The climate is typically subtropical and there is a dry season from November to May. A number of hilly rivers run through this area and also a large number of small to large streams. Some of these have sandy bottoms whereas others, mostly in the Chittagong Hill districts, flow over stones. The forests of the entire area are under consideration is basically of the same type, except the coastal forests of in the extreme south and some moist deciduous forests of Sylhet. The forests of the entire region are classified as tropical evergreen and semi evergreen. The top canopy ranges from 30 to 50ft. The second canopy is from 15 to 25ft. The third story mostly comprises of the saplings. There is a thick undergrowth of bamboos, canes, ground orchids, Eupatorum spp, Lantana camara, and a profusion of creepers. Vast areas of forest have been clear-felled for plantation of commercially important species like teak, garjan, gamari, mahogany, telsur, and jarul (Queen’s flower). This area supports a large variety of odonate species occupying various biotopes. The odonate fauna of eastern India, Gangetic plains, and Assam are closer to the Indo-Malayan forms (Mitra 2002). The fauna of the eastern region of Bangladesh are no different. The area with hills and valleys make very suitable biotopes for different species of Odonata. Various species show intra-specific variations, which Mitra (2002) did not consider to be of taxonomic significance. Here, I cite some of these variations not recorded earlier.

Source of Information: Proceedings of the International Conference on Biodiversity – Present State, Problems and Prospects of its Conservation January 8-10, 2011 University of Chittgaong, Chittagong 4331, Bangladesh

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Achievement/Findings:

Actions for preserving the rich insect fauna of this region are certainly called for. Effective implementation of strict conservation laws brooks no delay if we want to conserve these beautiful insects which are also known as useful biological control agents for pests and disease vectors.

Knowledge Management: Report/Proceedings