Exposure of Brachycorynella asparagi (Homoptera: Aphididae) eggs to water vapor deficits: effects on water loss and mortality of eggs and longevity of first-instar fundatrices

Water vapor flux density of Brachycorynella asparagi (Mordvilko) eggs at 3.3 and 1.1 degree C increased with water vapor density deficit although the flux decreased over time of exposure. Weight change of the eggs due to net water loss from the surface of the eggs was inversely related to vapor density deficit days (= vapor density deificit x days of exposure). Apparent vapor diffusion resistance of the eggs increased with vapor density deficit days. It appears that as the eggs dried out, the egg matric water potential decreased resulting in a slower rate of water loss. There is some evidence that the eggs absorbed water from the air. The LE sub(50) for egg mortality due to desiccation was 192.3 vapor density deficit days. Hatching time and longevity of first-instar fundatrices that were not exposed to additional desiccation were not related to exposure of the eggs to different humidities.