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Effects of chlorpyrifos ethyl on acetylcholinesterase activity in climbing perch cultured in rice fields in the Mekong Delta, Vietnam
Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
Stockholm University, Faculty of Science, Department of Physical Geography.
2015 (English)In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 117, 34-40 p.Article in journal (Refereed) Published
Abstract [en]

Climbing perch is commonly harvested in rice fields and associated wetlands in the Mekong Delta. Despite its importance in providing food and income to local households, there is little information how this fish species is affected by the high use of pesticides in rice farming. Organophosphate insecticides, such as chlorpyrifos ethyl, which are highly toxic to aquatic organisms, are commonly used in the Mekong Delta. This study shows that the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings cultured in rice fields, was significantly inhibited by a single application of chlorpyrifos ethyl, at doses commonly applied by rice farmers (032-0.64 kg/ha). The water concentration of chlorpyrifos ethyl decreased below the detection level within 3 days, but the inhibition of brain AChE activity remained for more than 12 days. In addition, the chlorpyrifos ethyl treatments had a significant impact on the survival and growth rates of climbing perch fingerlings, which were proportional to the exposure levels. The results indicate that the high use of pesticides among rice farmers in the Mekong Delta could have a negative impact on aquatic organisms and fish yields, with implications for the aquatic biodiversity, local people's livelihoods and the aquaculture industry in the Mekong Delta.

Place, publisher, year, edition, pages
2015. Vol. 117, 34-40 p.
Keyword [en]
Climbing perch, Chlorpyrifos ethyl, Acetylcholinesterase, Mekong Delta, Pesticides, Rice farming
National Category
Earth and Related Environmental Sciences Agricultural Science
Research subject
Physical Geography
Identifiers
URN: urn:nbn:se:su:diva-118332DOI: 10.1016/j.ecoenv.2015.03.020ISI: 000354501500005OAI: oai:DiVA.org:su-118332DiVA: diva2:842607
Available from: 2015-07-21 Created: 2015-06-15 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Pesticide use in rice farming and its impacts on climbing perch (Anabas testudineus) in the Mekong Delta of Vietnam
Open this publication in new window or tab >>Pesticide use in rice farming and its impacts on climbing perch (Anabas testudineus) in the Mekong Delta of Vietnam
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The intensification of agricultural production in the Mekong Delta has faced serious challenges with respect to increased use of agrochemicals and especially pesticides. The indiscriminate use of pesticide could potentially impact on the long-term food production, environmental and human health in the delta. The aim of this thesis was to investigate the negative side effects of the current use of pesticides on climbing perch (Anabas testudineus) in rice fields using brain acetylcholinesterase (hereafter referred to as AChE) activity as a biomarker. The empirical work, on which this thesis is based, includes structured questionnaires, laboratory and field experiments. First, a field survey using questionnaires was carried out to gain a better understanding of the current state of rice farming systems, the use of pesticides and attitude to pest management strategies among rice and rice-fish farmers, as well as to provide basic information for the set-up of the laboratory and field experiments. Secondly, laboratory studies were conducted to clarify if the selected insecticides applied alone and in mixtures caused negative side effects on climbing perch fingerlings. Thirdly, further toxicity studies were carried out, under rice field conditions, to further investigate the toxicity effects of the insecticides, applied alone, in mixtures and under sequential applications, on climbing perch fingerlings.

The results showed that although there were a more selective use of pesticides and an increased awareness among farmers of the negative side effects of pesticides in 2007 as compared to 1999, the current use of pesticide in the Mekong Delta still cause many problems to the environment and human health. Chlorpyrifos ethyl (hereafter referred to as CPF) was found to cause a significant and more prolonged inhibition on the brain AChE activity in climbing perch than fenobucarb (hereafter referred to as F). The inhibition by the mixture of CPF and F were significantly higher than the inhibition by only F, but less prolonged and significant lower than the inhibition by only CPF. The results suggest that the combined effect from a mixture of F and CPF can create both additive effects initially and later antagonistic effects.

CPF and F applied at concentrations used by farmers, either as separate doses, in a mixture or in sequential doses, decreased the brain AChE activity, growth and survival rates in climbing perch. The results demonstrate that brain AChE activity in climbing perch is a relevant biomarker for monitoring of exposure to, and sub-lethal impacts from organophosphates and carbamates under tropical conditions. The result also shows that 2-PAM re-activate the brain AChE activity, and can be used as an alternative method to assess the AChE inhibition level in organisms recently exposed to OP’s, in situation where it may be difficult to find unexposed individuals as controls.

In conclusion, this thesis shows that the current use of pesticides in the Mekong Delta has a negative effect on climbing perch living in rice fields. It indicates that a sustained long-term food production in the Mekong Delta must be based on ecological principles, taking advantages of ecosystem biodiversity and productivity, and not through intensified use of pesticides.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography, Stockholm University, 2016. 42 p.
Series
Dissertations from the Department of Physical Geography, ISSN 1653-7211 ; 55
Keyword
Mekong Delta, Rice field, Climbing perch, Insecticide, Chlorpyrifos ethyl, Fenobucarb, Mixture, Sequential applications, AChE
National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-128856 (URN)978-91-7649-415-8 (ISBN)
Public defence
2016-05-27, William Olsson-salen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 5: Submitted.

Available from: 2016-05-02 Created: 2016-04-05 Last updated: 2017-02-23Bibliographically approved

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