Effect of temperature on development and population growth of Acarophenax lacunatus (Cross & krantz) (Prostigmata : Acarophenacidae) on Rhyzopertha dominica (F.) (Coleoptera : Bostrichidae)

The parasitic mite Acarophenax lacunatus kills the eggs upon which it feeds and seems to have potential as a biological control agent of stored grain pests. The lack of biological studies on this mite species led to the prese nt study carried out in laboratory conditions at eight different temperatur es (ranging from 20 to 41 degreesC) and 60% relative humidity using Rhyzope rtha dominica as host. The higher the temperature, the faster: (1) the atta chment of female mites to the host egg (varying from 1 to 5 h); (2) the inc rease in body size of physogastric females (about twice faster at 40 degree sC than at 20 degreesC); and (3) the generation time (ranging from 40 to 22 0 h). In addition, the higher the temperature, the shorter the maximum fema le longevity (ranging from about 75 to 300 h). The two estimated temperatur e thresholds for development of A. lacunatus on R. dominica were 18 and 40 degreesC. The average number of female and male offspring per gravid mite w ere 12.8 and 1.0, respectively, with sex ratios (females/total) ranging fro m 0.91 to 0.94 (maximum at 30 degreesC). The net reproductive rate and intr insic rate of increase also presented maximum values at 30 degreesC (12.1 a nd 0.04, respectively).