The taxonomic revision of the genus thaumastocoris and the biology and chemical control of the eucalypt pest thaumastocoris peregrinus (heteroptera : thaumastocoridae)

Abstract

The dramatic infestation of Sydney’s eucalypts by Thaumastocorisperegrinus in 2001 and its subsequent invasion of South African and South American eucalypt plantations highlighted the paucity of, and the need for, taxonomic and biological information on this enigmatic group of land bugs. This species had been repeatedly misidentified as T. australicus which narrowed attention of the species taxonomy of the type genus Thaumastocoris. As a consequence my thesis provides the first modern systematic revision of this genus. This includes the redescription of the five previously described species of Thaumastocoris and the description of an additional nine new species. A diagnostic key to all these species is provided, supported with illustration of the key character systems and maps depicting their distributional range. Their host plants as we know them are tabulated and these associations are discussed. Laboratory studies were undertaken to elucidate life history parameters such as instar duration, adult longevity and reproductive potential of the two most pestiferous species, T. peregrinus and T. safordi n. sp. At 17-22 °C the eggs of both species hatched in approximately six days. The duration of stadia was similar in both species, with T. peregrinus taking 4.6, 3.5, 3.3, 3.7 and 5.3 days, whereas T. safordi took 4.7, 3.4, 3.5, 4.0 and 5.2 days. Adult males and females of both species can live for approximately 40 days and females can produce at least 60 eggs during that lifetime. xv The abundance and distribution of T. peregrinus on three specimens of Eucalyptus nicholii trees were examined and explained in terms of vertical stratification and aspect. This species prefers vegetation on the middle to upper canopy and on the northern aspect of these trees, with ovipositional preference for the midvein of leaves. The chemical control of T. peregrinus was also investigated. Mature E. scoparia street trees growing in a southern Sydney suburb were micro-injected with the insecticide imidacloprid at three concentrations and monitored for three years. The abundance of T. peregrinus on treated eucalypts declined significantly compared to untreated trees over this time. It was found that at the lowest concentration of this insecticide T. peregrinus was effectively controlled for two years. The thesis concludes with a combined summary and discussion of my findings, and an outline for future research outlining the difficulties to be overcome when working with these insects.