Bionomics of Aphis gossypii1 on Resistant and Susceptible Cantaloupe

Abstract

Bionomics of the melon aphid, Aphis gossypii Glover, were studied on resistant and susceptible cantaloupe, Cucumis melo L., plants. In the field, there was no difference between the age distributions of populations on resistant and susceptible plants. However, late in the season, a significantly greater proportion of the population on susceptible plants consisted of alatoid nymphs. Alate adults confined to resistant plants in the greenhouse suffered significantly greater mortality and produced only ca. 25% as many progeny as their counterparts on susceptible plants. Apterous aphids on resistant plants were smaller, had a significantly longer prereproductive period, and significantly shorter reproductive and postreproductive periods than those on susceptible plants. Approximately equal percentages of aphids on resistant and susceptible plants produced offspring, but the <mml:math><mml:mrow><mml:mover><mml:mtext>x</mml:mtext><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math> fecundity on the former was only ca. ⅓ that on the latter. This was attributable to both a lower reproductive rate among reproducing aphids and a higher mortality rate during the reproductive period on resistant than on susceptible plants. Populations of A. gossypii were maintained for up to 5 generations on resistant plants, with no danger of extinction.