LIFE CYCLE RESPONSES OF THE MIDGE OF CHIRONOMUS SPECIES (DIPTERA: CHIRONOMIDAE) TO SUGARCANE AND PAPER PULP EFFLUENTS EXPOSURE

Abstract

The aim of this study was to assess the life cycle responses of the midge of Chironomus species (Diptera: Chironomidae) to sugarcane and paper pulp effluents exposure in order to ascertain their use in the monitoring of freshwater ecosystems. Fourth instar of Chironomid midges were sampled on two locations in rivers Nzoia and Mbogo, a tributary joining River Nyando within the Lake Victoria Basin. All midges were taken to the laboratory and acclimatized in a controlled climate room for 24 hours. They were then exposed to the effluent dilutions (i.e. 100%, 50%, 25%, 12.5% and 6.25%) collected from Webuye Paper Mill and Chemelil Sugar Factory treatment ponds/lagoons. Complete Randomized Design was used, with ten midges put in each of the treatments replicated four times. Results indicated that emergence of the Chironomus species decreased with increase in the effluent concentration. Higher effluent concentration led to delay in emergence of chironomids over time. There was no significant difference (p<0.05) between the emergence of Chironomus species exposed to the two effluents. The study concluded that pulp paper and sugar cane effluents delayed the development of life cycle stages of Chironomus species. In conclusion life cycle stages of the midges, Chironomus species can be a good indicator of environmental degradation.