Building a management package for six-spotted mite in vineyards

Abstract

Six-spotted mite is a comparatively new mite species recorded in Western Australian vineyards. Infestations of the mite result in premature loss of leaf function in late summer/autumn. To date the mite is known to occur in vineyards in Western Australia only, though it does occur in avocado orchards in eastern Australia. Since its discovery in vineyards in WA in 2006 the mite has been confirmed to be present in the Margaret River and Manjimup/Pemberton regions. This project sought to clarify its distribution in Western Australia, to quantify its pest status in vineyards and to assess whether introduced predatory mites could help manage it.

Summary

Six-spotted mite was found in 75% of vineyards in the southern Margaret River Region (13 vineyards surveyed) and 54% vineyards in the Manjimup/Pemberton region (26 vineyards surveyed). The level of mite infestation varied from finding the mite sporadically to high levels of infestation resulting in premature loss of leaf function. Six-spotted mite was not found in the northern Margaret River region (5 vineyards surveyed). Because of the vagaries of infestations of six-spotted mite, studies to quantify the pest status of the mite could not be completed. Likewise, assessing the effect of introduced predatory mites in one vineyard in season 2006/07 on the management of six-spotted mite has been compromised by the sudden unexplained disappearance of the mite from release sites the following season. At three vineyard study sites where predatory mites were released in season 2007/08, an increase in the abundance of natural control agents was assumed to be the cause for a crash in the population of six-spotted mite. The main naturally occurring predators involved included an unidentified species of predatory mite, six-spotted thrips and stethorus beetles. The predators failed to prevent severe leaf damage.