LIFE-HISTORY AND FEEDING BIOLOGY OF THE PREDATORY THRIPS, ALEURODOTHRIPS-FASCIAPENNIS (THYSANOPTERA, PHLAEOTHRIPIDAE)

Details of the life history, the effects of relative humidity and temp erature on survival and reproduction, and the predatory ability of Ale urodothrips fasciapennis Franklin were examined under laboratory condi tions. Stage-specific development and adult longevity were similar bet ween sexes, and the adult sex ratio was 1:1. Females laid 23.3 +/- 18. 0 eggs of which 83% hatched. The survival rate of first instars to adu lthood was 82%. The intrinsic rate of natural increase (r(m)) was 0.04 , assuming a zero or 5.4 day pre-oviposition interval. Temperature did not affect the proportion of eggs that hatched, the proportion of fir st instars surviving to adulthood or adult sex ratios. However, female fecundity was dependent on temperature being highest at 24-28 degrees C. Relative humidity did not affect adult sex ratio or female fecundi ty but the proportion of eggs hatched and the survival of first instar s to adulthood increased as relative humidity increased. Few eggs hatc hed when relative humidity was <65%. Larval and adult female A. fascia pennis were voracious feeders but the number of prey killed per progen y was high, suggesting A. fasciapennis was inefficient at converting p rey into progeny biomass. The potential value of A. fasciapennis as a biocontrol agent of Aonidiella aurantii (Maskell) on Australian citrus is discussed in terms of its r(m), prey killing power and environment al adaptability. It is concluded that population growth of A. fasciape nnis should exceed that of A. aurantii under field conditions but A. f asciapennis may be of little value against A. aurantii on citrus grown under conditions of high temperature and low humidity, or when prey d ensities are low.