TEMPERATURE EFFECTS ON THE EMBRYONIC-DEVELOPMENT OF APHTHONA-ABDOMINALIS (COLEOPTERA, CHRYSOMELIDAE), A NATURAL ENEMY OF EUPHORBIA-ESULA (EUPHORBIALES, EUPHORBIACEAE)

The flea beetle Aphthoma abdominalis Duftschmid was selected as a candidate for biological control of Euphorbia esula L. (leafy spurge) in North America, where this introduced plant is a serious weed. The insect was collected and studied in Italy, where it occurs naturally. As part of the study of its life history, the effect of temperature on embryonic development was investigated at constant temperatures of 12, 15, 20, 25, 30, 35, 38, and 41 degrees C, and variable temperatures were used as well. Survival and developmental rates were obtained. The median values used to calculate the time required for embryonic development-through the thermal summation, a linear regression, and the logistic equation are discussed. The experimental data gave a developmental zero between 12 and 13 degrees C. Embryos completed their development at constant temperatures from 15 to 38 degrees C. Development required from 32.6 d at 15 degrees C to only 4.5 d at 35 degrees C constant temperatures. A. abdominalis, was cleared and introduced into the United Stales during 1993.