Abas (Elkawas, 2011)

Gerson, U., 2014, PEST CONTROL BY MITES (ACARI): PRESENT AND FUTURE Uri G, Acarologia 54 (4), pp. 371-394 : 375-376

HOW ABAS AFFECT PESTS (INCLUDING WEEDS AND FUNGI) AND REDUCE THEIR DAMAGES

ABAs reduce pest numbers and/or their damage by various modes; some examples are listed in Table 3. Predation is the commonest, phytoseiids being supreme in this respect. Parasitism (feeding on the host without killing it, but reducing viability and fecundity) is often observed with water mites of the family Arrenuridae ( Smith and McIver 1984) . Other parasites, feeding on their hosts and killing them, are Pyemotes spp. (Pyemotidae) and Hemisarcoptes spp. (Hemisarcoprtidae) (Ak¸sit et al. 2007; Calmaur and Ozbek 2007, respectively). Parasitic castration of the grasshopper, Hieroglyphus nigrorepletus Bolivar ( Acrididae ) is due to the feeding of Eutrombidium trigonum (Hermann) (Badruddin et al. 2003) (Trombididae) . Members of over 30 mite families (e.g. Acaridae , Alycidae , Galumnidae , Laelapidae and others) feed on nematodes, greatly reducing their numbers (Gerson, in press). The tydeid Orthotydeus lambi (Baker) grazed on the mycelia of grape powdery mildew and reduced its spread on the foliage and fruit of nine grape cultivars; extent of disease suppression depended on the specific grape genotypes, their susceptibility to the mildew and on mite numbers ( English-Loeb et al. 2007).

Indirect damage to a pest can be due to several species of Tarsonemus (Tarsonemidae) associated with the southern pine beetle, Dendroctonus frontalis Zimmerman ( Coleoptera : Curculionidae ), a destructive pest of pine trees in North America. The mites carry ascospores of the bluestain fungus Ophiostoma minus (Hedgcock) , which outcompete fungi carried by D. frontalis , critical for its nutrition. The pest larvae seldom survived in the presence of O. minus (compared to 83 % survival elsewhere). By disrupting beetle mutualism with O. minus the mites indirectly reduced pest numbers ( Lombardero et al. 2003). The water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae) , is a weed that forms dense mats in waterways in many parts of the world. Orthogalumna terebrantis Wallwork (Galumnidae) feeds on the weed, reducing its physiological activity ( Marlin et al. 2013a).

ABAs can damage pests by transmitting diseases. The Pales weevil, Hylobius pales (Herbst) (Curculionidae) , a forestry pest, carried a phoretic Macrocheles sp. (Macrochelidae) . The mites, contaminated with the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin ( Hypocreales : Clavicipitaceae ) transmitted it to the weevils, of which ca 80 % became infected (as compared to 7 % in the mite-free weevil control group) ( Schabel 1982).