Toxicity of Tobacco Smoke to the Spotted Alfalfa Aphid Therioaphis maculata (Buckton)

WE have been attempting to rear the spotted alfalfa aphid, biotype ENT B (ref. 1), on artificial diets after the manner of Auclair 2 and Dadd and Mittler 3 . Our initial unsuccessful attempts were conducted in an entomology laboratory. It was then observed that adults placed on potted alfalfa plants ( Medicago sativa L.) in the laboratory did not produce viable nymphs, and that some of the adults crawled from the plants. Removal of the plants to a small greenhouse enabled normal nymph production after 2 to 3 h. We suspected two factors to explain this : the differences in the illumination or in the atmosphere between the laboratory and the greenhouse. In the laboratory, even with overhead fluorescent light, the aphids were phototropic to daylight. Because of the temperature and humidity fluctuations that occur normally in the field, we ruled out these variables from our consideration.