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The relationship of time of year, geographic location, insecticide exposure and the genotype of red and green morphs of the tobacco aphid, myzus nicotianae Blackman, in Virginia
Barnes, Martha Letcher
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The relationship of geographic location, insecticide exposure, time of season and the genotype of red and green morphs of the tobacco aphid, Myzus nicotianae Blackman, on tobacco was investigated in Virginia in 1988 and 1989. Color morph and karyotype were found to be highly related. The translocated karyotype was associated with the red morphs and the normal karyotype was associated with the green morphs. The karyotype of red and green morphs did not change markedly from the beginning to the end of the tobacco growing season. Studies were also conducted to determine if the red and green morphs of the tobacco aphid were developing resistance to acephate (Orthene Tobacco Insect Spray), the most commonly used aphicide on flue-cured tobacco in Virginia. Slight resistance was present in both red and green aphid populations from several counties. Studies were also conducted to determine if males were present in tobacco aphid populations in Virginia. Cool temperatures and short photoperiods which initiate male production in Myzus persicae (Sulzer) with holocyclic life cycles did not cause the production of males in M. nicotianae native to Virginia.
- Masters Theses