Effects of Insecticides on Soil Microorganisms

Reddy, B. V. Prasad; Dhanaraj, Premnath; Rao, V. Venkat

doi:10.1007/978-3-642-69917-7_8

Cited by 10 publications

(2 citation statements)

References 117 publications

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“…Each exclusion plot received 3645 L of prepared insecticidal solution, and each water control plot received 3645 L of water, which we applied using a truck with water tank and PVC pipe rigging adapted to spray water to mimic rain. Synthetic pyrethroids have slight and short term effects (~4 weeks) on soil microflora (Tu ; Prasad Reddy, Dhanaraj & Narayana Rao ) and no effects on crop or plant germination (Tu ; Hanley & Whiting ; Silfver et al . ).…”

Section: Methodsmentioning

confidence: 99%

Direct measurement of ant predation of weed seeds in wheat cropping

Evans

Gleeson

2016

Journal of Applied Ecology

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Summary The ecosystem service of predation of weed seeds by naturally occurring seed‐eating animals, including ants, in agricultural fields has been suggested to be a potentially important biocontrol option. Laboratory and field tests have found high levels of seed removal from experimentally placed seed; however, the effect of predation on naturally dispersed weed seeds is unknown. We measured the effect of invertebrate seed predators on natural weed seed dispersal and germination in a field experiment under commercial growing conditions. The two‐factor, large‐scale field experiment in a field used to grow wheat with conservation tillage used an insecticide to remove soil invertebrates (ants had been reduced by 85% relative to water controls) and shallow tillage for mechanical weed removal (no effect on ants). There was one natural weed seeding event, when a wind storm blew one single incursion of Salsola australis (Chenopodiaceae) tumbleweeds across the field. We measured the number of tumbleweeds after 2 months and found the removal of ants resulted in a doubling of tumbleweeds: 3383 ± 513 weeds ha−1 in the insecticide treatment plots compared with 1768 ± 100 weeds ha−1 in the water control treatment plots, and 1948 ± 227 weeds ha−1 in the rest of the field. The difference in tumbleweed germination and growth was not due to growing conditions. We measured soil nutrients before the incursion and soil moisture during the weed growing period and found that there were higher levels of nitrogenous compounds in water control plots, but no other nutrient or moisture differences, than in insecticide exclusion plots. Synthesis and applications. Our results provide evidence that the ecosystem service of ant predation of naturally dispersed weed seeds limits weed abundance in commercial cereal fields in warmer climates. The fields were not managed to increase ants; alternative conservation agricultural management methods that promote agro‐ecology, including low or zero tillage and low insecticide use, could increase ant abundance and thereby reduce weeds. The use of seed predators as a type of biocontrol agent will need to be integrated with other weed management methods, including herbicides and shallow tillage, although the latter may conflict with ant survival. The use of seed predators may be particularly advantageous in organic systems, or locations where economic margins are low.

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Section: Methodsmentioning

confidence: 99%

Direct measurement of ant predation of weed seeds in wheat cropping

Evans

Gleeson

2016

Journal of Applied Ecology

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“…It has also been reported that the effect of insecticides on nitrogen fixation by cyanobacteria is independent of that on growth. 2 In the present study, the effects of two pesticides, a common weed killer 2,4-D (2,4 dichlorophenoxy acetic acid) and an insecticide methylparathion on growth and nitrogen fixation in a unicellular cyanobacterium Gloeocapsa, chosen as an indicator organism, were investigated.…”

Section: Introductionmentioning

confidence: 99%

Effects of 2,4‐d and methylparathion on growth and nitrogen fixation in cyanobacterium, gloeocapsa

Tözüm‐Çalgan

Sivaci‐Güner

1993

International Journal of Environmental Studies

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The response of a unicellular cyanobacterium Gloeocapsa to 2,4-D (2, 4 dichlorophenoxy acetic acid) and methylparathion was studied. 2,4-D inhibited growth when introduced at 175 and 200 ppm concentrations, whereas 100, 125 and 150 ppm concentrations had no pronounced effect. Nitrogenase activity was inhibited in the presence of 175 and 200 ppm 2,4-D. Meanwhile, methylparathion was found to be comparatively less toxic to Gloeocapsa, while 1 ppm methylparathion was a mere growth stimulator; 5, 10, 50 and 100 ppm concentrations had no significant effect on growth. However, 10, 50 and 100 ppm methylparathion inhibited nitrogenase activity considerably.

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Glyphosate effects on microbial biomass in a coniferous forest soil

Stratton

Stewart

1992

Environ. Toxicol. Water Qual.

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The herbicide glyphosate (Roundup) was applied aerially to a conifer forest that had previously been clear-cut and reforested. Glyphosate was tested for effects on microbial biomass, numbers of selected microorganisms, and soil respiration over a period of 8 months by comparing treated and untreated zones of the clay loam forest soil (FS) and the overlying litter (FL), both pH 3.8. With microbial biomass, glyphosate generally had a stimulatory effect in FL, but usually no significant effect in FS. Glyphosate had no significant effect on numbers of bacteria, fungi, and actinomycetes in either FL or FS. The herbicide generally stimulated respiration in both FL and FS. In laboratory bioassays using FL, FS, and three agricultural soils, glyphosate had no significant effect on respiration when used at concentrations up to 100 times higher than recommended field application rates. Respiration rates in FL, as measured with Warburg respirometry, were unaffected by glyphosate. Respiration rates in FS were stimulated by glyphosate concentrations 10 and 100 times higher than recommended field rates. Glyphosate should have no deleterious effects on microbial biomass and respiration in forest soils when used under recommended conditions. o

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Effects of Insecticides on Soil Microorganisms

Cited by 10 publications

References 117 publications

Direct measurement of ant predation of weed seeds in wheat cropping

Direct measurement of ant predation of weed seeds in wheat cropping

Effects of 2,4‐d and methylparathion on growth and nitrogen fixation in cyanobacterium, gloeocapsa

Glyphosate effects on microbial biomass in a coniferous forest soil

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