EFFECT OF Nosema locustae Canning (Microsporida) AND THREE CHEMICAL INSECTICIDES ON MICROBIAL ACTIVITY IN SOIL

Abstract

Nosema locustae Canning is a potential biological control agent for grasshoppers but some aspects of its environmental impact have not been investigated. This study assessed the impact of N. locustae and the chemical insecticides carbofuran, deltamethrin and dimethoate on microbial activity and nutrient cycling in soil. In a laboratory study, the insecticides were applied to a Haverhill loam at recommended field application rates and 10 times the field rates. There was no adverse effect from N. locustae or the chemical insecticides on any of the measured parameters. Analysis of field soils 6 wk after application of a mixture of N. locustae and dimethoate indicated this treatment had no adverse impact on microbial activity. Key words: Nosema locustae, carbofuran, deltamethrin, dimethoate, microbial activity

Soil microbial properties in Bt (Bacillus thuringiensis) corn cropping systems

“…Other studies have also reported no or stimulatory effects of this insecticide on soil microorganisms (Germida et al, 1987;Vig et al, 2008;Munoz-Leoz et al, 2009) although an inhibitory effect on soil respiration was observed under anaerobic conditions in a wetland soil (Munoz-Leoz et al, 2009). Griffiths et al (2006) also found no effects of Bt corn or deltamethrin in a study that was designed similarly to our study to compare the effects of Bt trait with those of the insecticide that would otherwise be applied.…”

Field and Laboratory Studies for Evaluating the Toxicity of Some Pesticides on Soil Microorganisms.

“…In contrast to the results here, significant inhibition was observed in previous study (Das and Mukherjee 2000, Boucard et al, 2008, Rache and Coats, 1988Das et al, 1995) who reported that, tested insecticides(HCH, phorate, carbofuran and fenvalerate at their recommended field rates did not have any deleterious effect on the growth and activities of the major soil microorganisms responsible for the transformations of C, N and P. and. No adverse effect on fungal population were observed by (Tu 1995), no effects have been reported for l-cyhalothrin (Cycon et al, 2006) or deltamethrin (Germida et al, 1987;Vig et al, 2008Lupwayi, et al, 2009.…”