Six-spotted mite, Eotetranychus sexmaculatus (Riley), is native to central America. It was first recorded in WA in 1986 on avocado seedlings from eastern Australia.
In the same year and presumably from the same source, the mite was recorded for the first time on avocados in New South Wales, Queensland and South Australia. It also occurs in New Zealand where it is also important in avocado orchards and is also present in parts of Asia, the Middle East and USA.
The mite feeds primarily on the lower surface of leaves, concentrating its activity adjacent to leaf veins. This feeding is characterised by discolouration of leaf tissue, leaf death and premature defoliation.
Signs of feeding on white and red grape varieties are yellow or red shadows respectively, on either side of the veins and visible from both sides of leaves.
On avocado, six-spotted mite feeding appears as brown to purple discolouration next to leaf veins.
In citrus, primarily grapefruit but also oranges, feeding on the leaf stems and occasionally the fruit stems will cause the fruit to yellow and fall. Six-spotted mite has not been recorded on citrus in WA.
Kiwifruit is also a host for six-spotted mite, but this has not been observed in WA.
Heavy infestations result in severe defoliation. This results in delayed ripening or failure of grapes to ripen and reduced quality and yield of fruit.
Avocados are particularly susceptible to the mite and low numbers can defoliate trees, exposing fruit to sunburn.
Awareness of whether the mite is present is the first step in minimising its potential for damage.