Formation of resistance in the Chironomus plumosus to four pesticides over 45 generations

Author: Vedamanikam, V. J.

Source: Toxicological and Environmental Chemistry, Volume 91, Number 1, February 2009 , pp. 187-194(8)

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Abstract:

A study was conducted on the Chironomus plumosus larvae to determine initiation of resistance to four pesticides - chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, and malathion. First generational LC50 values were well within the threshold value for chironomids based upon the literature. Subsequent LC50 values were observed to increase, indicating a lessening of the toxicity of the pesticides to the chironomid. In the case of chlorfenvinphos, the 96 h LC50 for generations 1-23 was 6 µg L-1, in generations 3-7 was 8.57 µg L-1 and 11.14 µg L-1 for generations 8-9. Generations 10-12 had an LC50 value of 22.58 µg L-1 and generation 13 had an LC50 value of 35.08 µg L-1. Generation 14 had an LC50 value of 47.58 µg L-1. Generations 15-19 and 20-24 had 96 h LC50 values of 60.68 µg L-1, 72.58 µg L-1, 85.08 µg L-1, 97.58 µg L-1 and 110.08 µg L-1, respectively. Generations 25, 26 to 30, 31 to 38 and 39 to 45 had 96 h LC50 values of 160.42 µg L-1, 210.7 µg L-1, 262.24 µg L-1 and 274.36 µg L-1, respectively. The variation between LC50 values was found to be statistically significant. This was observed for most pesticides tested. Larval size and life cycle duration was observed to change from generation to generation with the body size decreasing markedly from 1 to 0.3 cm with life cycle increasing from 7 to 39 days.

Keywords: pesticides; multigenerational exposure; Chironomus plumosus; LC50; resistance

Document Type: Research article

DOI: http://dx.doi.org/10.1080/02772240802075196

Affiliations: 1: Institute of Oceanography, University Malaysia Terengganu, Kuala Terengganu, Malaysia

Publication date: 2009-02-01