Taxonomy and biology of a new species of Zaphanera (Hemiptera : Aleyrodidae) and its association with the widespread death of western myall trees, Acacia papyrocarpa, near Roxby Downs, South Australia

Abstract

Bailey, P. T., Martin, J. H., Noyes, J. S. & Austin, A. D. (2001) Taxonomy and biology of a new species of Zaphanera (Hemiptera: Aleyrodidae) and its association with the widespread death of western myall trees, Acacia papyrocarpa, near Roxby Downs, South Australia. Trans. R. Soc. S. Aust. 125(2) 83-96, 30 November, 2001. An outbreak of western myall whitefly, a new species of Zaphanera (Hemiptera: Aleyrodidae), is associated with dieback and death of western myall trees, Acacia papyrocarpa Bentham, in a desert area of about 10,000 km2 in South Australia. Both young and mature trees up to several hundred years old are affected. Death of foliage appears to be related to large numbers of the whitefly feeding on phyllodes. A new species of the parasitoid Zarhopaloides (Hymenoptera: Encyrtidae) emerged from whitefly pupae and appears to be the first encyrtid authenticated as a true parasitoid of aleyrodids. Possible causes of this outbreak are discussed and include (1) a temporary parasitoid asynchrony with its hosts population, (2) the possibility that western myall whitefly has been newly-introduced to the area on another plant host and has adapted to western myall trees and (3) that the outbreak is symptomatic of a widespread decline in the health of trees. All life-history stages of the new species of Zaphanera and the new species of the parasitoid Zarhopaloides are described. Key Words: Zaphanera, Zarhopaloides, Acacia papyrocarpa Bentham, western myall whitefly, western myall tree, outbreak, tree death.