INFLUENCE OF HEXYTHIAZOX RESISTANCE ON LIFE-HISTORY PARAMETERS IN THECITRUS RED MITE, PANONYCHUS-CITRI (MCGREGOR)

The life history parameters concerned with population growth were stud ied in the citrus red mite, Panonychus citri (MCGREGOR), among genotyp es, or tile hexythiazox resistant Haibara-R (RR), the susceptible Haib ara-S (SS) and their hybrids (SR and RS) which are the same origin fro m a citrus orchard at Haibara-cho in Shizuoka Prefecture, Japan. The d ifference in the intrinsic rate of natural increase (r(m)) among genot ypes was slight at 25 degrees C where r(m) decreased in the order geno type SS (0.2110), SR (0.2098), RS (0.2042), RR (0.1996). However, the fitness disadvantage was severe at 35 degrees C where r(m) were 0.1187 and 0.0123 in SS and RR, respectively. At any mite age at 25 and 35 d egrees C, reproductive values (V-x/V-0) in RR were smaller than those in SS. The reduction of values of r(m), and V-x/V-0 at both 25 and 35 degrees C seemed to be ascribed to the significantly shortened longevi ty and reduced fecundity of adult females in RR, compared with those i n SS.