Thermal requirements of Brevicoryne brassicae and prevision of populational peaks

Abstract

The objective of this work was to determine the thermal requirements of Brevicoryne brassicae L., Hemiptera: Aphididae under laboratory and field conditions and to predict the occurrence of peak population of adults, using a degree-day model. In laboratory, the experiments were conducted in climatic chambers at 15, 20, 25, 27 and 30^oC, and the lower developmental thermal threshold (Tb = 4.5^oC) and the thermal constant (K = 176.1 degree-day) were evaluated. The thermal requirements under field conditions were estimated in six experiments, to establish the average time of development of nymphs and the average environmental temperature. The results estimated for Tb and K were 3.5^oC and 180.0 degree-day, respectively. The results of Tb and K determined from laboratory data allow more accurate predictions of occurrence of B. brassicae adults than the results of Tb and K determined from field experiments.