Agistemus exsertus Gonzalez (Acari: Stigmaeidae) as a predator of citrus red mite (Panonychus citri [McGregor]).
The potential of using Agistemus exsertus to control Panonychus citri was studied on citrus in the laboratory and in an orange grove. Functional response studies showed that A. exsertus adult females had the highest instantaneous rate of discovery (a = 1.430) and shortest handling time (Th = 1.67 h) when provided with P. citri eggs compared with other prey stages. In comparison with adults of both sexes, A. exsertus deutonymphs had the lowest a (0.102) and longest Th (4.32 h) when P. citri eggs were provided as prey. A. exsertus females clearly exhibited a prey-stage preference; an average of 75.2% of prey consumed consisted of eggs compared with 16.6 and 8.2% nymphs and adult males, respectively. The intrinsic rates of natural increase (rm) of A. exsertus were higher at 20 and 25°C, but lower at 30 and 35°C than that of P. citri. A. exsertus demonstrated a satisfactory control of P. citri in the greenhouse release study. Under natural conditions, the population of A. exsertus was very low in the winter and increased steadily from May through October.