Abas

Gerson, U., 2014, PEST CONTROL BY MITES (ACARI): PRESENT AND FUTURE Uri G, Acarologia 54 (4), pp. 371-394 : 380

ABAs in the soil

ABA activities in the soil were reported to limit the numbers of molting thrips, corn root worms ( Diabrotica virgifera LeConte , Coleoptera : Chrysomelidae ) and of nematodes, and in reducing the inoculum of plant-pathogenic fungi ( Gerson et al. 2003). The great abundance of predatory mites in soils ( Lundgren et al. 2009), including Phytoseiidae ( Mineiro et al. 2012) , suggests that they are an under-utilized BC resource.

Berndt et al. (2004) estimated the predatory capacity of S. scimitus and G. aculeifer (known in commerce as Hypoaspis ), which feed on the soilinhabiting molting stages of WFT. The latter, which was the better predator, had significantly more eggs, reproduced faster and raised larger populations. The authors concluded that G. aculeifer could control thrips populations with a release of 520 individuals/ square meter. Their efficacy is due to the fact that they inhabit the same soil strata; the presence of other prey (e.g. nematodes, Collembola) may however detract from their controlling effect ( Wiethoff et al. 2004). Another soil-borne predator, Lasioseius fimetorum Berlese (Ascidae) , was compared by Enkegaard and BrØdsgaard (2000) with S. scimitus . The former developed faster and had more progeny on thrips prey.

Large populations of G. aculeifer were associated with fewer numbers of the pest thrips Pezothrips kellyanus (Bagnall) , which molts in the soil, and with less damage to citrus fruit. Adding composting manure to the soil was advocated by Navarro- Camposa et al. (2012) as a means of increasing mite numbers, thereby promoting the pest’s control.

Species of Gaeolaelaps and of Stratiolaelaps feed on eggs and larvae of corn rootworm in the soil. Prischmann et al. (2011a) concluded that although they do not seriously reduce pest numbers, they may regulate immature rootworm populations. Qualitative and quantitative methods for monitoring ABA feeding in the soil are discussed below.

Plants may affect ABAs through their symbiotic associations with arbuscular mycorrhizal (AM) fungi and/or rhizobacteria. The growth rate of P. persimilis was enhanced when feeding on TSSM infesting these plants ( Hoffmann et al. 2011). Further, mycorrhyzal bean plants infested by TSSM attracted more predators than non-mycorrhyzal beans ( Schausberger et al. 2012). These results were obtained with plants grown in pots; their validity in the field remains to be determined. More P. persimils occurred on cucumbers treated with plant growth promoting rhizobacteria than on untreated plants, and more prey (TSSM) were located thereon by the predator ( Tomczyk and Burda 2005).