Insects Playing Role as Bio-Indicators
Abu Bakar Siddique
College of Agriculture, University of Sargodha.
Environment is polluted by different types of pollutants. The degree of pollution is estimated by the reaction of some species. Class Insecta is used as the bio-indicators because they are large in number and have high sensitivity.
Pollutants, Insects, Aquatic, Terrestrial
The environment in which we live, surrounded by different circumstances which make it more comfortable for the organisms to live in. But addition of pollutants, like toxins, chemicals and other waste pollute the whole zone. Pollution might be the water pollution, sound pollution or soil pollution. Some species react against these changes in the environment, these reactions are used as the parameter to estimate the intensities of pollutants in the environment.
A change in the environment affects the insects rapidly rather than any kind of taxa. Insects have more responsibility in the ecosystem in maintenance of several aspects, so their mortality gives serious economic loss to the whole community. So, to remain safe, strong interaction and a fair relationship is required between the insects and the human beings to build up a strong, healthy environment (NICHOLSA et al., 2007)
Group of Insects as Bio-indicator
- Aquatic Insects
Order Odonata is very sensitive to the aquatic changes, that’s why they are used as the aquatic environment bio indicators. Dragon flies and damsel flies are very sensitive to any alteration in their environment like ponds, lakes and other pure water places (CORBET, 1980).
Families Gyrinidae, Dytiscidae, Hydrophilidae, Notonectidae and Veliidae have some specific species which are sensitive to the aquatic change. Plecoptera and Ephemeroptera orders also play role in the geographical changes as well as aquatic bio indicators. The ability of aquatic insects to respond any aquatic change has been documented by Hamilton and Seather (1971) and Hardersen (2000). Genus Halobates have some species which indicate the Cadmium and Mercury (NUMMELIN et al., 2007).
- Land Insects
The insects living on land are much sensitive to any change in the environment. 20% variety of insect population is represented by the order Coleoptera. Flow of energy, regulation of the population and the soil fertility is maintained by the order Coleoptera (CARLTON and ROBISON, 1998). Family Scrabidae has high rate of indication of abnormality in crops and forest areas as bio-indicators Nummelin and Hanski (1989), Nestel et al. (1993).
Carabidae family of beetles, is the best predator. They support the biological control, against the pollution caused by sulfur oil, insecticide and herbicides.
Order Lepidoptera, butterflies and moths have great responsibility of change in the temperate and tropical region (GILBERT, 1984; ANDRADE, 1998).
Collembola is very sensitive about any slight change in the soil, because it enhances the soil fertility by its own activities. Any change in the soil by heavy metals, pesticides, soil water polluted by the wasted material and acidification is indicated by the collembola (RUSEK, 1998).
Ants play an important role in the indication of slight change in the environment. They show the change in the soil by leaf cutting in the tropical areas.
Order Diptera is not preferred to be used as the bio-indicator because some of its species are considered as ignorant about the ecological knowledge. Syrphidae family of order Diptera is well distributed on the earth. Considered as the good bio-indicator because its larvae needs an appropriate change In the environment, affected by the landscaping (SOMMAGGIO, 1999).
Pollinators are assumed as to be the best bio-indicators because they go flower to flower and plant to plant, which enhances the growth of plants. They can indicate the pollutants suspended in the air, by their death rate (GHINI et al., 2004).
Aphids are pollution indicators, when they come to the host exposed to the carbon dioxide, they tend to increase their population.
At the end, after a long study and practice, here we come to declare the class Insecta as the best bio-indicators specially the orders, Coleoptera, Isoptera, Homopptera, Hymenoptera and Diptera. Because they have many species which are too much sensitive and responsible about their habitat.