Tabela de esperança de vida e de fertilidade de Sipha flava (Forbes) (Hemiptera, Aphididae) alimentado com capim-elefante em diferentes temperaturas

Abstract

The objective of this study was to estimate the life expectancy and fertility tables of Sipha flava (Forbes, 1884) fed with elephant grass at different temperatures. The investigations were conducted in climate controlled chambers at 12, 16, 20, 24, 28 and 32ºC, UR 70 ± 10% and 12-hour photophase, with 150 insects at each temperature. There was gradual mortality at all temperatures studied. The longest life expectancy and longevity values for the aphids were at 12ºC. The highest net reproduction rates (Ro) and longest population doubling time (DT) were also found at 12ºC. The survival (lx) started to diminish after 3.5 days at 24ºC and after the first day at the other temperatures, gradually declining with the development of the insect. The time interval between each generation (T) decreased as the temperature increased up to 28ºC. The highest specific fertility (mx) and total fecundity were recorded at 24ºC. The smallest value for innate capacity to increase in number (rm) were at 12ºC. The finite increase ratio (λ) were highest at 20 e 24ºC. The temperature of 24ºC is most suitable for the population density of S. flava to increase on elephant grass because it provides the highest values for the reproductive parameters.