Promising new biological control agents for Queensland

Abstract

A range of promising new biological control agents are being assessed and released in Queensland: (1) five different biotypes of the cochineal insect, Dactylopius tomentosus (Lamark), are being field-released on several cactus species (Cylindropuntia spp.). One biotype is achieving excellent results, killing coral cactus (Cylindropuntia fulgida (Engelm.) F.M. Knuth var. mamillata (Engelm.) Backeb.) around Longreach (central Queensland) and Hebel (southwestern Queensland). This is an exciting development for a weed species that represents a serious long-term threat to pasture production across vast areas of arid and semi-arid rangelands; (2) the gall-fly, Cecidochares connexa (Macquart), has achieved excellent control of chromolaena (Chromolaena odorata (L.) R.M. King & H. Robinson) in Papua New Guinea. Testing for specificity has been completed and an application seeking field release in Australia was submitted to the Australian Government in 2015; (3) host-specificity testing has been completed for the fungal pathogen, Puccinia spegazzinii de Toni, for the control of Mikania micrantha Kunth, a major weed of wet tropical areas overseas and a target of eradication in Australia; (4) biology studies on a root-feeding beetle for mother-of-millions (Kalanchoe delagoense Eckl. & Zeyh), a widespread, toxic weed of pastures are currently being undertaken prior to host-specificity testing; and (5) research has commenced to find potential agents for giant rat’s tail grasses (Sporobolus spp.). Recent prospecting in South Africa has identified several species of stem-boring insects that are now being assessed for possible release in Australia. A new project based in Vanuatu and funded by the New Zealand Government will enable exploration in South America and south-east Asia for biological control agents targeting Solanum torvum Sw. (devil’s fig) and Senna tora (L.) Roxb. (sicklepod).