Preliminary Studies on the Predation of the Mite Blattisocius mali (Acari: Blattisociidae) on Various Life Stages of Spider Mite, Thrips and Fruit Fly

SIMPLE SUMMARY: Although our knowledge of the interactions between the underground and aboveground communities of organisms is growing, little is known about the impact of soil predatory mites on aboveground communities of plants, herbivores and their natural enemies. Blattisocius mali is a polyphagous predatory mite that disperses on the bodies of drosophilid fruit flies, on which it feeds; after disembarkment, it also preys on their eggs. This mite is mostly associated with soil or litter, but it has also been found in fruit and seed storage sites and on plants. In our tests, the starved predatory females readily fed on various stages of the common herbivores two-spotted spider mite and western flower thrips as well as the fruit fly Drosophila hydei. The predator came from cultures fed on acarid mites, and its identity was validated molecularly. Although B. mali shows the potential to prey upon herbivorous insects and mites, to determine whether it can also effectively reduce their population densities, further studies, including tests on the predator’s survival, fecundity and prey preference, are required. ABSTRACT: Research in recent years has shown that some species of predatory mites, considered to be typically associated with soil and litter, can also be found on plants. Such species include Blattisocius mali, which is an effective predator of acarid mites, nematodes and the eggs of moths and which can disperse by means of drosophilid fruit flies. Apart from soil and litter or storage, it has also been recorded on the bark of apple trees and the leaves of strawberries, thus suggesting its possible predation of/feeding on herbivorous mites and insects. Our goal was to examine whether B. mali could consume different development stages of two polyphagous herbivores, the two-spotted spider mite, Tetranychus urticae, and the western flower thrips, Frankliniella occidentalis, as well as the drosophilid fruit fly Drosophila hydei. In 24 h cage tests, single, starved B. mali females consumed all types of prey offered, i.e., the eggs, males and females of spider mites; the first-instar larvae and prepupae of thrips; and the eggs and first-instar larvae of fruit flies. The potential for B. mali to prey upon these insects and mites was confirmed. However, to estimate whether it can also effectively reduce their population, additional tests on the predator’s survival, fecundity and prey preference are needed.