Mosquito control practices from a conservation viewpoint
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Geology topics
Publications and source records attributed to W. H. Stickel.
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No abstract available.
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Residues of 1,1,1-trichloro-2,2-bis( p -chlorophenyl)-ethane (DDT) and 1,1-dichloro-2,2-bis( p -chlorophenyl)-ethane (DDD) in brains of cowbirds ( Molothrus ater ) killed by dietary dosage of DDT were similar in birds that died after various lengths of time on dosage and in birds that died of delayed effects after as much as 40 days on clean food. Residues of DDT and DDD, but not of 1,1-dichloro-2,2-bis-( p -chlorophenyl)-ethylene (DDE), were much lower in survivors 112 days after dosage. The relative importance of DDT and DDD in brains could not be determined, but DDE appeared not to be critical. Residues in brains of cowbirds were similar to those reported for robins, sparrows, eagles, and white rats. Residues in livers and carcass remainders (with the possible exception of DDD in the liver) appeared unsuitable for diagnosing the cause of death.
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The effects on woodcocks ( Philohela minor ) of eating heptachlor-contaminated earthworms were studied experimentally in a series of feeding trials in Louisiana in the winter of 1960-61. Six of 12 woodcocks fed worms which had been contaminated at an average of 2.86 ppm of heptachlor epoxide died within 35 days; 4 more had died by the fifty-third day, when the other 2 were killed for analysis. Worms from areas in Louisiana treated with 2 pounds of heptachlor per acre often contain more than 3 ppm of heptachlor epoxide. Eleven of 12 woodcocks fed worms contaminated at an average of 0.65 ppm survived the full 60 days of the experiment; one died on the forty-fifth day, apparently from other causes. All 11 untreated birds survived. Survivors were kept on one-quarter rations of untreated worms for 11 days. Two woodcocks, untreated previously, died during this starvation period. Five previously treated died; two were observed in spasms at death, and these contained 5.9 and 7.2 ppm heptachlor epoxide in their tissues, suggesting that the previous contaminated diet may have influenced mortality, even though the difference between two of nine dying and five of nine dying is not statistically significant. Surviving starved birds given an unrestricted supply of treated or untreated worms for 5 days survived and gained weight. Residues accumulated in their tissues in this time approached levels in birds that died of heptachlor poisoning. Residues in tissues of birds with different histories suggested residue loss at a rate of approximately 2.8 percent per day. Toxicant absorption was estimated to be in the approximate range of 16-20 percent. Residues in birds fed worms containing 0.65 ppm heptachlor epoxide were in the same general magnitude as those in field-caught birds, suggesting a similar average contamination of food supply. Weights and weight changes did not differ significantly between untreated birds and those receiving the lower level of toxicant. Among birds on one-quarter rations, the percentage of weight that could be lost without danger seemed to be near 20 percent. Woodcocks ate 18-208 grams of worms per day (average, 121 grams), representing 11-143 percent (average, 77 percent) of their body weights; birds ate contaminated and uncontaminated food in essentially equivalent amounts. Symptoms of heptachlor poisoning differed considerably between birds.
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Summary: Various workers have believed Contia to be related to or congeneric with either or both Sonora and Eirenis, the latter a genus of Western Asia. Study of hemipenes, teeth, and jaws indicates that these genera are not related to one another. The hemipenes of Eirenis modesta and Contia tenuis are described. Eirenis is thought to be a derivative of the racer group. Relationships of Contia are unknown. It is suggested that some North American genera with xenodontine-type hemipenes may not be of the South American faunal element and may have been in North America at least as long as the Old Northerners.
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