EFFECT OF SELECTED PESTICIDES ON MICROBIAL COMMUNITY AND ENZYME ACTIVITY

Godwin Umoren Akpan

ABSTRACT

In modern agriculture, chemical pesticides are frequently used in agricultural fields to increase crop production. Besides combating insect pests, these insecticides also affect the activity and population of beneficial soil microbial communities. The laboratory studies were conducted to resolute the effect of Imidacloprid (Insecticides), Paraeforce (Herbicide), and ultramax plus (Fungicide) on microbial communities and enzyme activities using their recommended rates. The microbial populations were estimated using the standard Pour-plate technique. Urease and cellulase activities were determined using the respective protocols. The resolute showed that the insecticides (Imidacloprid) at 0.13g/g soil depressed bacterial population by 2 log orders of magnitude (from 20000000 to 200000 cells), paraeforce (herbicide) and Ultramax plus inhibited bacterial population by 2 log orders of magnitude respectively. Imidacloprid depressed fungal population from 2300000 to 40000 cells, paraeforce decreased fungal populations by 2 log orders of magnitude, whereas Ultramax plus inhibited fungal population from 2300000 cells to 10000 cells. Imidacloprid depressed the population of actinomycetes from 2500000 cells to 125000 cells. Whereas paraeforce completely wiped off actinomycetes in the soil. Ultramax plus inhibited actinomycetes by 2 log orders of magnitude. On the activity of enzymes in the soil, the three pesticides did not show any depressive effect on cellulase activity but rather stimulatory. The effect of the three pesticides on Urease activity was either stimulatory or to Urease activity. Thus, there is need to assess the effect of indiscriminate use of pesticides on soils microbes and enzyme activities to avoid destroying the beneficial ones.

Keyword: Pesticides, Enzyme, Microbial community, Imidacloprid, Ultramax plus, paraforce.