Soil arthropods recovery rates from 5-10cm depth within 5 months period following endosulfan (an Organochlorine pesticide) treatment in designated plots in Benin city, Nineria

摘要

A 5-month durational period of the recolonisation of soil arthropods was monitored on endosulfan treated soil from April to August, 2007 within the 5-10cm depth at varying concentrations of the pesticide. Berlese Tullgren Extraction method, sorting and identification of sampled species were adopted and soil parameters (soil pH, temperature, moisture and hydrocarbon content) were measured. The result obtained showed that, there was consistent decrease in the mean numbers of soil arthropod sampled from April to June and the decrease was more as concentration of applied endosulfan increased. However, July to August witnessed very remarkable increase in mean soil arthropod sampled compared to the controlled stations, an indication of recolonisation. Among the 7 groups of soil micro arthropod sampled, the mean number from groups were statistically different (P<0.05) at all concentrations compared to the control with Acarina, Collembola, Coleoptera and Myriapoda being the most abundant while Hymenoptera, Isoptera and Crustacea were least in abundance. The most recovered group was the Acarina while the least was Crustacea with recolonisation ability being greatest in stations with higher concentration. On the basis of concentration of endosulfan pesticide applied, the soil hydrocarbon content was significant (P<0.05) while soil pH, soil temperature and soil moisture were not. However, increase in soil moisture from April to August was observed to result in the increase in mean numbers of soil arthropod groups sampled. Besides the enhancement of agricultural productivity when the pesticides are properly applied, the problem of ecosystem imbalance has a natural solution path.