Studies on the diversity of macroinvertebrates in suburban and rural aquatic bodies of West Bengal: Implications of vector control

Abstract

Biological assessment of the freshwater habitats aims to characterize and monitor the conditions of the aquatic resources. Assessment of species assemblage in these habitats will indicate the possible variations in the resource exploitation and trophic interactions. Macroinvertebrates are the best indicators of aquatic ecosystem and play an important role in freshwater ecosystem functioning through nutrient cycling, primary production, decomposition and biological control of mosquitoes.

Observations revealed that the prey individuals of order Diptera were found to be highest (51.16%), however the cumulative predatory taxa including Coleoptera, Odonata, Hemiptera and Orthoptera accounted to 67.02% The values of diversity indices varied significantly across different sampling spots justifying the usage of those wetlands and potentiality of them towards conservation biological control. Based on the biotic index, rice fields at Panskura ranked ‘Good’ to ‘Fair’ while all others ranked ‘Fair’ or ‘Poor’.Irrespective of the classes and orders, the representative individuals were observed in high numbers during the post monsoon and the winter months which may be attributed to the fact that with the volume of water, the space available for the insects increases, thereby promoting population expansion and releasing the crowding effect. The result of three way factorial ANOVA on the number of macroinvertebrates considering the spots, sites and sampling months as explanatory variables, revealed significant differences across all the interactions. A correspondence of the taxonomic diversity with the functional role of the aquatic predatory insects of the order Coleoptera, Hemiptera and Odonata is well established, through their links with multiple prey species including mosquito and chironomid larvae. In an assorted species assemblage of both predator and prey species, conservation biological control may require habitat extension and modification to allow increment of niche width to sustain diverse species in the habitats. Therefore to comment on the chances of the potentials of conservation biological control, monitoring of the macroinvertebrate community becomes imperative.