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A field (Jackson Pike) population of Chironomus riparius (Meigen) and a laboratory-derived culture were compared in terms of components of biological fitness (female fecundity, male and female pupal weight, and larval developmental period), response to selected insecticide exposure (malathion, parathion, propoxur, and dichlorodiphenyl trichloroethane [DDT]), and several biochemical parameters (mixed function oxidase, general esterase, acetylcholinesterase and glutathione-S-transferase activity) to determine the extent of population divergence (differential population characteristics) as well as to assess the accuracy of results obtained from tests performed on laboratorycultured insect populations. Results from all comparisons suggest that these two populations have significantly diverged. For example, the laboratory larvae were characterized by enhanced susceptibility to malathion, parathion, DDT, and propoxur as determined at LC50s. Jackson Pike larvae, however, displayed resistance to these compounds, with LC50s values ranging from 13-250 times greater than that estimated for laboratory individuals. Furthermore, Jackson Pike individuals were characterized by significantly increased enzymatic activity (glutathione-S-transferase), differential oxidative metabolism (mixed function oxidase), reduced target site sensitivity to inhibition (acetylcholinesterase), and reduced general esterase activity compared with laboratory larvae. These results snuggest that the Jackson Pike population has developed an effective resistance strategy against toxicants, presumably as a result of site specific selection pressures. No such compensatory mechanisms were observed in laboratory larvae. Finally, the Jackson Pike population was characterized by heavier, more fecund individuals as compared to the laboratory population. Difference in life history characteristics between populations also indicates divergence. In summary, the results of our study indicate that long-tern) laboratory culture conditions do not necessarily provide selection pressures characteristic of those experienced by field individuals. Therefore, information obtained from laboratory individuals should be used with caution in representing field responses of field populations.
Document Type: Research Article
Publication date: April 1, 1994
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.