EFFECTS OF AN ORGANOCHLORINE AND PYRETHROID PESTICIDE FORMULATION ON SOIL’S CULTURABLE MICROBIAL POPULATION
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Date
2020
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Publisher
International Journal of Technical Research & Science
Abstract
Non-target effect of pesticide on soil organisms is an important area of ecotoxicology, due to their roles in
ecosystem sustainability. Thus, the effects of an organochlorine (endosulfan) and a synthetic pyrethroid
(cypermethrin) pesticide formulation on soils’ culturable microbial population were investigated. The study was
carried out on loamy sand soil sample types collected from Ondo State, Forest Reserve, Owena, Nigeria. Pesticide
application rates in the range of half of the normal field rate (0.5FR), the normal field rate (FR), two times the
normal field rate (2FR), four times the normal field rate (4FR) and eight times the normal field rate (8FR) were
applied to the soil microcosm design in the laboratory; while the untreated soil serve as control. The experiment set
up was completely randomized in three replicates and soil samples were collected from each of the set up at 5 days
interval over 35 days period of exposure for analysis. The pour plate technique was used for the enumeration of
bacterial and fungal colonies on nutrient agar and potato dextrose agar respectively. The results indicated that both
pesticides had effects on the population of bacterial and fungal counts of the soil samples with significant (p < 0.05)
adverse effect observed at the treatment rate above the normal field application rate. At lower application rates
(0.5FR, FR and 2FR), temporary inhibitory effect on bacterial and fungal population were observed. The progressive
increase in inhibitory effect with corresponding increase in concentration of endosulfan and cypermethrin were
noticed.