Biology of Diatraea saccharalis under different temperatures

Abstract

The biology of Diatraea saccharalis (Fabricius 1794) Lepidoptera, Pyralidae was studied in the laboratory on an artificial diet and under five constant temperatures (20°C, 22°C, 25°C, 30°C and 32°C). The objective of the study was to optimize the technique for mass rearing of the D. saccharalis in the laboratory. The duration of the incubation period and the larval phase decreased with increasing temperatures, and the pupal phase was shortened, for both sexes, with increasing temperatures in the range from 20°C to 30°C. The number of instars was affected by temperatures; larvae maintained at 20°C and 22°C always had six instares, while those reared under 25°C, 30°C and 32°C had five or six instars. Pupal weight was lower at 32°C for both sexes. Pupal weight of females was higher than that of males under all temperatures. Longevity of adults decreased with increasing temperatures in the range from 20°C to 30°C. Female adults lived longer than males under all experimental conditions. Temperature did not affect the period of pre-oviposition. The number of egg-layings decreased with increasing temperatures. The most favorable temperature for egg-laying was 20°C, and the highest number of egg-layings occurred between the first and the fourth days. The insect's total life cycle decreased with increasing temperatures. The highest viability was obtained at 30°C. The most favorable temperature for maintaining D. saccharalis eggs, larval and pupal was 30°C, while 32°C proved to be harmful for the insect's normal development.