Biocontrol

The Plant Pest Control Branch (formerly Entomology Branch) of the Hawaii Department of Agriculture has maintained a beneficial organism introduction program for many years. This paper provides notes on the status of some pests and their purposely introduced natural enemies and a list of insects introduced and released for biological control during 1979 and 1980. All beneficial introductions are thoroughly screened and studied in a quarantine facility and must go through a clearance process prior to being released.

Land snails of the genus Partula, inhabiting the high islands of the Pacific Ocean, have provided exceptional opportunities for studies on the origin and differentiation of species. The endemic taxa of Moorea, in French Polynesia, have been particularly well studied.

The papers in this volume were, with a few exceptions, presented at the third Island Invasives conference, held in Dundee, Scotland in July 2017. The papers demonstrate up-scaling in several aspects of eradication operations – not least in ambition, land area, operational size, global reach and of course financial cost. In the space of a few decades, the size of islands treated for invasive species has increased by five orders of magnitude – from a few hectares to over 100,000 ha or 1,000 km2.

Biological control of introduced weeds in the 22 Pacific island countries and territories (PICTs) began in 1911, with the lantana seed-feeding fly introduced into Fiji and New Caledonia from Hawaii. To date, a total of 62 agents have been deliberately introduced into the PICTs to control 21 weed species in 17 countries. A further two agents have spread naturally into the region. The general impact of the 36 biocontrol agents now established in the PICTs ranges from none to complete control of their target weed(s).

Invasive weeds are one of the most serious threats to biodiversity and sustainable development in the Pacific region. Biocontrol is likely to be the only feasible way of managing many widespread weeds, but is not always appropriate or successful. With so many weed species to tackle and inevitably limited resources, prioritising where to direct control efforts most effectively is of key importance. Landcare Research recently developed a framework for the Australian government that allows the best and worst weed targets for biocontrol to be identified.