Studies on the biology of Unaspis citri
Laboratory studies have been carried out in USA to assess the influence of temperature and relative humidity on development and mortality of Unaspis citri (EPPO A1 quarantine pest). Nine different combinations of constant temperature (16, 21, 24, 28, 30 °C) and relative humidity (60, 70 % RH) were studied. Optimal temperatures for development ranged between 25 and 38 °C for all stages and both sexes. Upper developmental thresholds ranged between 34 and 44 °C, and the lower threshold was estimated at 12 °C,. In this study, the effect of relative humidity was not consistently significant. Temperature most notably affected mortality associated with 1st and 2nd instars and males. Relative humidity effects were shown to be important for survival of 1st and 2nd instars and for 2nd instars at low temperatures. It can be recalled that the scale armour is an effective protection against environmental hazards and that 1st instar lack this protection.
Sources
Arias-Reverón, J.M.; Browning, H.W. (1995) Development and mortality of the citrus snow scale (Homoptera: Diaspididae) under constant temperature and relative humidity.
Environmental Entomology, 24(5), 1189-1195.