BIOLOGY AND CONTROL OF HALOTYDEUS-DESTRUCTOR (TUCKER) (ACARINA, PENTHALEIDAE) - A REVIEW

Halotydeus destructor (Tucker) (Acari: Penthaleidae) is a major pest o f pastures, crops and vegetables, in regions of Australia, South Afric a and New Zealand, with cool wet winters and hot dry summers. The taxo nomy, distribution, biology, ecology and control of H. destructor are reviewed. Halotydeus destructor is essentially a soil mite, spending 9 0% of its time on or near the soil surface and moving up onto plants o nly to feed. After penetrating the epidermis, the cell contents are su cked up. Other mites are attracted to volatiles released from the leav es damaged by feeding mites and they usually feed in aggregations. Alt hough they feed on a wide range of plant species, their reproductive s uccess varies considerably on different plant species. Mites are more abundant and more eggs are laid on an annual pasture at a site with hi gh rainfall than one with lower rainfall. The rate of oviposition is p robably resource limited. When pasture is grazed short, the mites are less abundant, but the same number of eggs are laid. Halotydeus destru ctor requires a high relative humidity and the active mite mortality i s probably greater at low relative humidities in short pasture. Haloty deus destructor completes three generations a year. The summer is pass ed as a diapausing egg in the cadaver of an adult female mite on the s oil surface. Long-distance passive dispersal probably occurs when thes e female cadavers are blown by the wind. Plant varieties with resistan ce to H. destructor are being developed in subclovers (subterranean cl over, Trifolium subterraneum L.), medics (Medicago spp.) and canola (B rassica napus), to reduce the considerable economic losses caused by t he mites. Mechanisms of resistance have been identified in subclover s eedlings. It appears to be more beneficial to control H. destructor in spring than in autumn, particularly in a pasture before a crop. The f uture management of this pest will require the integration of plant re sistance with other control methods.