LC50 24h of paraquat herbicide and permethrin insecticide and their effect on reproduction and population growth of freshwater rotifer (Brachionus calyciflorus)

Azad, M. (2014) LC50 24h of paraquat herbicide and permethrin insecticide and their effect on reproduction and population growth of freshwater rotifer (Brachionus calyciflorus). Masters thesis, University of Zabol.

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Rotifers are a group of zooplankton that due to the sensitivity to chemicals, their central position in food chains, reproduction rapid, short-term generation and distribution vast global ecotoxicology studies seems significant. One of important factors in ecosystem pollution is agricultural pesticides that are very dangerous for aquatic communities. Lethal concentrations (LC50 24) of Paraquat and Permethrin on freshwater rotifer (Brachionus calyciflorus) were determined and the impacts of sub-lethal concentrations of these pesticides on this zooplankton were studied. Rotifers cultured at highly controlled conditions by using chlorella (chlorella vulgaris) as food. The LC50s were calculated for pesticides based on O.E.C.D standards. We determined lethal concentrations of Paraquat herbicide and Permethrin insecticide 0/541 mg l-1 and 8/997 mg l-1 respectively and based on these consent rations, four treatments plus one control group determined for each pesticide.Treatments concentrations were 0/027, 0/054, 0/1 and 0/27mgl-1 for Paraquat and 0/449, 0/899, 1/799 and 4/498mgl-1 for Permethrin. Effects of these two pesticides on population growth and reproduction of Fresh water rotifer B.calyciflorus were studied using these four treatments. The results showed that difference in density of rotifers in all treatments compared to the control group on tenth day of the experiment were significant (P < 0/05). Specific growth rate (per day) did not show a significant difference compared to control group for Paraquat herbicide at concentration of 0/027 mg l-1. Compared to control group, the ratio of vigorous females to non-vigorous females and ratio of mictic females to amictic females at all concentrations of both pesticides were impressed significantly. Increasing in mictic/amictic ratio at the end of the experiment, increasing by concentrations of pesticides, indicates the dominance of sexual reproduction in the rotifer life cycle. For Paraquat at concentration of 0/27 mgl-1 and Permethrin at concentration of 4/498 mgl-1 ratio of mic/amic not defined because of stop in reproduction and population growth. Paraquat and Permethrin classified as high and average toxic for aquatic communities respectively. Specific growth rate is the most sensitive indicator to study the effect of these pesticides on rotifer population growth.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Paraquat, Permethrin, Rotifer, Brachionus calyciflorus, LC50
Subjects: S Agriculture > SH Aquaculture. Fisheries. Angling
Depositing User: admin admin1 admin2
Date Deposited: 25 Jun 2016 05:52
Last Modified: 25 Jun 2016 05:52

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