Mutual interference of the predatory mite Macrocheles muscaedomesticae by feeding on eggs of the Musca domestica house fly

Macrochelidae are cosmopolitan free-living predators that inhabit habitats rich in decaying organic matter, such as manure. They feed primarily on small arthropods and nematodes. Macrochelidae predators are considered beneficial mites that have been identified as promising biological control agents for fly eggs and larvae, and other harmful organisms. Adult Macrocheles muscaedomesticae (Scopoli) prefers house fly Musca domestica L. eggs to first instar larvae. This predator has been observed to reduce fly populations in natural conditions significantly, and the reduction was considerably greater when the predator was augmented. The purpose of this study was to determine the effect of mutual interference on M. muscaedomesticae predation on house fly eggs at 27 ± 1°C and 33 ± 1°C.

In this study, we investigated the mutual interference of adult female predators M. muscaedomesticae on house fly eggs in an incubator at two constant temperatures of 27 ± 1°C and 33 ± 1°C, 65 ± 5% RH, 14:10 h (L: D) photoperiod. To this end, the per capita searching efficiency and per capita predation of 1, 2, 4, and 8 female mite M. muscaedomesticae were determined, and 100 house fly eggs were offered to 4-day-mated adult female mites in each predator density for 6 h. Before the experiments, female predators were fed and mated for 48 h and then starved for 24 h to obtain a cohort of M. muscaedomesticae.

A significant relationship was discovered between the logarithm of predator density and M. muscaedomesticae per capita searching efficiency. This dramatically decreased per capita predation rate and per capita searching efficiency as predator density increased at both temperatures. At 27 °C, once predator densities were increased from 1 to 8, per capita predation decreased from 16.70 to 4.69, and per capita searching efficiency decreased from 0.183 to 0.058. At 33 °C, when predator densities were increased from 1 to 8, per capita predation decreased from 9.20 to 4.81, and per capita searching efficiency decreased from 0.097 to 0.061.  

The negative slope of the regression line or interference coefficient of -0.6774 and -0.2448 at 27 and 33 °C, respectively, indicated that interference is a density-dependent factor and that per capita searching efficiency exhibits negative density-dependency. As a result, different predator densities may affect M. muscaedomesticae's efficacy. The findings could be applied to the mass rearing techniques of this predator mite in an insectarium.