Natural and factitious prey for rearing the predacious miteAgistemus exsertusGonzales (Acari: Stigmaeidae)

Abstract

Agistemus exsertus Gonzalez (Acari: Stigmaeidae) has been reported from Africa, Asia and Europe. In Egypt, it was noted to be associated with Tetranychus urticae Koch (Acari: Tetranychidae), one of the most important pest of fruit trees, vegetables and field crops. In this study, we test the hypothesis that factitious prey such as eggs of the greater wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae) could be a suitable food source for the predatory mite A. exsertus. In the laboratory, we compared the developmental times, survival and life table parameters of the predatory mite A. exsertus feeding on the natural prey (T. urticae eggs) or the factitious prey (eggs of G. mellonella) as primary / alternative or supplementary food at 30 °C, 70–75% RH and photoperiod of 16: 8 (L: D) hours.Total developmental time of A. exsertus females was faster on eggs of G. mellonella than eggs of T. urticae. A total of 131.5 and 97.9 eggs per female, respectively, were obtained when A. exsertus was fed on eggs of above factitious and natural prey. Life table parameters were estimated as net reproductive rate (Ro) 92.30 and 57.291, intrinsic rate of increase (rm) 0.2384 and 0.2084 days−1, finite rate of increase (λ) 1.2692 and 1.2318, mean generation time (T) 18.98 and 19.41 days and doubling time (DT) 1.26 and 1.44 days when the predator fed on eggs of G. mellonella and T. urticae.Thus, it is concluded that A. exsertus can be considered as a valuable addition to the existing biological control for the pyralid insect, G. mellonella and also the predator can gain equally benefits from predation on factitious and natural prey.