Longevidade de Dysdercus. I - Fêmeas adultas de Dysdercus mendesi bloete, em condições de laboratório

Estudando a biologia de Dysdercus mendesi Bloete, em condições de laboratório, e tendo sido feitas anotações concernentes às datas de emergência e morte de 539 fêmeas adultas, foi possível fazer um estudo sôbre a longevidade dêsse inseto, naquelas condições. O efeito da temperatura, na sobrevivência do inseto, também é estudado. Verificou-se que, em média a fêmea adulta viveu 24,78 dias, em laboratório ; a temperaturas de 15-18 °C, a longevidade foi de 38,69 dias, enquanto para 24-25°C foi de somente 9,26 dias. The longevity of 539 adult females of Dysdercus mendesi Bloete was studied under laboratory conditions during various seasons of the year. After the date of adult emergence had been recorded, female and male insects were paired in individual rearing cages until their death. A study of the temperature records corresponding to the adult life of the females showed a marked influence of this factor on the insect longevity, mortality and life expectation. The mean longevity was 24,78 days, the temperature averaging 20°C for the entire period of the observation. Insects reared when the temperatures averaged 15°-18°0 lived 28.69 days; increasing temperatures decreased longevity, and when the temperatures averaged 24°-25°C the mean longevity was only 9.26 days. The upper curve in fig. 7 shows the influence of temperature on longevity. For an average temperature increase from 15°-l8° to 18°-21°C, the decrease in longevity was very marked (from 30 to 23 days approximately); between average temperatures of 18°-21°C and 22°-25°C longevity remained rather stable, falling very rapidly for higher temperatures. The survivorship curve for the entire population was normal. The initial life expectation (mean lenght of life remaining to each individual alive at the beginning of the age interval) was approximately 25 days, and decreased rapidly during the first 20 days (fig. 5); between age intervals of 20 and 80 days, the life expectation decreased slowly (from 16 to 13 days); after an age of 80 days, the life expectation decreased very rapidly. The study of the graphs presented in figures 2, 4 and 6 sIioavs that there is a marked influence of temperature on survirorship, mortality and life expectation but that influence does not change the general shape of the curves.