Developmental time and survival of Aphis gossypii glover (Hemiptera: Aphididae) reared on commercial chrysanthemum cultivars at different temperatures

摘要

The aphid Aphis gossypii Glover is associated with several vegetable and ornamental greenhouse crops, especially chrysanthemum (Dendranthema grandiflora Tzvelev). The effect of different temperatures and chrysanthemum cultivars (Yellow Snowdon, White Reagan and Dark Splendid Reagan) on developmental time and survival of A gossypii were evaluated. The trials were carried out at environmental chambers, at constant temperatures: 15,20,25 and 30 deg C, 70+-10 percent RH and photophase lOh. Nymphs of A.gossypii were kept individually on chrysanthemum leaf discs (2 cm diameter) of different cultivars in glass petri dishes, with 10ml of sterile solution of agar/water 1 percent. The increase of temperature from 15 deg C to 30 deg C, caused a significantreduction in the developmental time of the instars, and the first instar was the most affected. The survival of the nymphs of 1st and 2nd instars was affected by all chrysanthemum cultivars evaluated. These cultivars presented different densities of trichomes/mm~2 on the leaf (11.3,16.6 and 21.6 trichomes, respectively), which provided higher survival to nymphs maintained on Yellow Snowdon cultivars (88.5 and 96.6 percent for the 1st and 2nd instars, respectively). The nymphal period decreased from 13.5days at 15 deg C to 5.0 days at 30 deg C. Temperature and chrysanthemum cultivars affected the developmental time and the survival of the initial instars of A. gossypii, and this information is important for A. gossypii management in greenhouse crops.