Aquatic Insect Biodiversity of Northern Region of Bangladesh

Abstract

The experiment was under taken to investigate the ‘Aquatic Insect Biodiversity of Northern Region of Bangladesh’ during January to December 2009. The aquatic insects were collected at 15 days interval by using an aquatic net with fairly fine mesh from the three lakes, one pond, canal and bill from Dinajpur district. In these ecosystems, insects of three orders were found and biodiversity of insects (both species and number) of the order Hemipteran were highest followed by Coleopteran and Odonata. Biodiversity of Hemipteran insects were Water boatmen (Corixidae), Backswimmers (Notonectidae), Creeping water bugs (Naucoridae), Water scorpion (Nepidae), Giant water bugs (Belostomatidae), Water striders (Gerrididae), Broad-shouldered water striders/Ripple bugs (Veliidae),Velvety shore bugs (rare, Ochteridae); biodiversity of Coleopteran insects were Water scavenger beetles (Hydrophilidae), Crawling water beetle (Haliplidae), Diving beetles (Dytiscidae), Whirligig beetles (Gyrinidae); and biodiversity of Odonata insects were Damselfly nymph (Coenagriidae) and Dragonfly nymph (Aeshnidae). Water strider, Back swimmer, Water boatmen, Creeping water bug, Water scorpion (Ranatra sp) and Damselfly nymph were most common in all water ecosystems and season. Abundance of these insect was more in rainy season. Diversified insect was found in a pond and Ramsager lake. All aquatic insect are beneficial but Backswimmers and Giant water bugs (especially adult Giant fish killer, Lethocerus indica) and Diving beetle feed on fishes therefore they are harmful to fish cultivation. However, from the ecological point of view all aquatic insects are important and useful to nature. Diversified insect was found in a pond and Ramsager lake as these two water reservoirs were less disturbed by human and were not commercially fish cultivated. Giant water bug and Scavenger beetle were not caught by the aquatic net; however, large number of Water scavenger beetle were found in the beginning of winter season below the light sources and data were taken from their but Giant water bug were not found below the light sources though it attracted to light.