The diversity of organisms is essential for the proper functioning of the ecosystem and it is absolutely essential for the survival of civilization because man has not only benefited but has adjusted himself to surrounding diversity. To get sustainable benefits from diverse organisms, it is essential to know each of the organisms. Taxonomy the science which is essential in the theoretical and applied biology helps in the description and classification of organisms. The contribution of taxonomy to the applied sciences has been both direct and indirect. It relates to medicine, public health, agriculture, conservation, management of natural resources, etc. Without proper taxonomy of organisms, many studies on agriculture, ecology, behavior, and population dynamics to name but a few would be of little value.

Image:  "Troll-haired" bug, metallic wasp or Eucharitid wasp.

Animal taxonomy endeavors to order the rich diversity of the animal world and to develop methods and principles to make this task possible. Taxonomic study of animal diversity plays a significant role in biodiversity conservation and management.

In the past 250 years of research, about 1.78 million species of Biological specimens have been scientifically identified based on morphological structures while an estimated up to 1 million or more await to discovery. A baseline study is essential to gain an understanding of the animal present in a habitat, vegetation, seasonal and climatic changes on an area. Without the baseline data of faunal study and the animal diversity of the species in a region, no one can move forward in proper planning for their conservation or their control. Reliable identification of pest species with their respective natural enemies is an important prerequisite for effective control and quarantine measures especially if Integrated Pest Management or biological control is applied. Taxonomic confusion is a major problem in the areas of controlling pest species.

Insects are the earth’s most diverse organisms, accounting 1,013,825 species out of total 1,635,250 species(Table 1; Fig. 1); representing around 80% of the world's recorded fauna and acting as central players in most of the major biomes of the world notably tropics where they display an enormous species richness and range of specializations. Due to their enormous existence in all habitats and in all likelihood exert a greater impact of the terrestrial ecosystem than any other type of animal.

The presence of insects is a good criterion for judging the health of a terrestrial ecosystem where diversified plants provide shelter and food for huge insects and most of the terrestrial vertebrates are dependent on these insects for their survival as they are important links in the food chain in that ecosystem (Patel 2015). Due to our very limited knowledge regarding the exact number of species of insects, their distribution and rarity, only a small number of species have been listed in regional and global conservation lists.

Hymenoptera is the third-largest order of insects estimating over 110,000 species which contains about 8% of all described species.  Economically, aesthetically and biologically Hymenoptera is very important to mankind. Their high position in food chains and makes them particularly liable to extinction and also likely to include many keystone species.

Parasitic Hymenoptera is one of the species-rich and abundant components of the terrestrial ecosystem, and most ecologically important groups directly beneficial economically, perhaps essential in preserving ecological balance and managing biological diversity in the terrestrial ecosystem. Their importance is due as they are consumers (third and fourth trophic level) in the food web and play a vital role, in a multitrophic interaction context, in natural communities.

Parasitic Hymenoptera is typically much specialized and occupies a high trophic level, species in this group are likely to be particularly vulnerable to local or even global extinction as they are more susceptible to extinction than phytophagous arthropod groups. However, they are neglected in insect conservation strategies.

Parasitic Hymenoptera constitutes about 20% of all insect species and some 80-85% of hymenopterous species and a total number of 68,918 species of parasitic Hymenoptera has been described (Table1). Nearly 20% of parasitic Hymenoptera have been described and at least 77% of them are still undescribed due to their very small in size.

Table1. Number of Parasitic Hymenoptera
Existing species in the world
1,635,250 .
Insect species
1,013,825
 Hymenopteran species
153,088
Parasitic hymenopteran species
68,918
Bangladesh
182
Reference Roskov et al. (2015); Wisegeek (2015); Gapud (1992).
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