[Effects of constant and varying temperatures on life-span, food utilization and fertility of adult crickets, Gryllus bimaculatus]

Abstract

1. Adult males and females of Gryllus bimaculatus were kept at 8 constant temperatures and 8 temperatures that varied during the day-night cycle. These covered the entire scope of temperature tolerance of the crickets. Longevity, food consumption, production of excrements, rate of food passage through the alimentary canal, chemical composition of excrements, and the fertility of females were analyzed. 2. The crickets were found to have different temperature requirements for all physiological parameters. Adult animals live the longest at 20°C; food uptake starts at 10°C, and a maximum of food utilization is reached between 27° and 34°C. Molting occurs only at temperatures above 20°C; temperature preference is 34±2°C, where mortality is highest. Egg production starts at 20°C; a maximum of 1000 eggs per animal is reached at 34°C, with a hatching rate of 53%. Embryonal development starts at 16.6°C, with the shortest period of larval development occurring at 34°C. 3. Temperatures varying during the day-night cycle do not accelerate physiological functions, except for life span and egg production. The number of eggs per female is 1.4-3 times greater at alternating temperatures than at the medium constant temperatures. Results comparable with those of 34°C (1000 eggs per animal, hatching rate of 53%) are obtained only with fluctuating temperatures around 27°C (1300-1400 eggs per animal, hatching rate of 50%). 4. The production of organic substances and the time for embryonal development approximately correspond to the calculations of Kaufmann (1932). 5. Quotients of food consumption and defecation increase from Q=4-6 between 20° and 38°C to Q=7-39 at 10° at 10° and 13°C, which within this temperature range means a storage of lipids, proteins and carbohydrates. These results are in agreement with the chemical composition of Gryllus bimaculatus analyzed by Hoffmann (1973). 6. Temperatures varying during the day-night cycle are characterized by their amplitude, the velocity of heating and cooling, low and upper temperature limits, and the temporary relation of warm to cold period. Physiological functions are determinated by a light-dark cycle, the relation of temperature to the change from light to dark, and endogenous rhythms of the organisms.