1987 Volume 31 Issue 2 Pages 162-167
Population growth of the melon aphid, Aphis gossypii, on Veronica persica was studied in the field and in a non-heated glasshouse during the winter season (December, 1984-May, 1985) in Nankoku-City, Kochi Prefecture. The effects of temperature on the number of offsprings on Veronica persica, development or survival of the larvae and increase of the population were investigated experimentally in the laboratory. There were only a few melon aphids on Veronica persica in early December. Then the numbers increased slightly but the populations remained at a low level until February. The effect of low temperature in this season, was accounted for these findings because the fecundity of the females was low, the development of the larvae was delayed and the survival rate of the immature stages was low under low temperature conditions. On the other hand, in the non-heated glasshouse, the number of aphids increased gradually from late December presumably because the air temperature in the glasshouse was higher than that in the field. In March, the number of aphids increased gradually in the field as the air temperature was higher than in February.
