pests have arrived in Australia in the ballast water of cargo ships. Marine pests include the black-striped mussel (Mytilopsis sallei), the Asian mussel, the New Zealand green-lipped mussel, and the European shore crab. The Northern Pacific seastar in Tasmania, Inverloch, and Port Phillip has caused much localised environmental damage. Invasive plant species Weeds invade natural landscapes, waterways, and agricultural land. Originally, plants were most likely to be considered weeds if they had a direct economic impact, especially on agricultural production. However, growing environmental consciousness since the 1970s has led to the recognition of environmental weeds; plants which have adverse effects on the natural ecosystem of an area. A list of Weeds of National Significance (WONS) was created in 1999 and updated in 2012 and now has 32 taxa. Not just the prickly pear: Hudson's Pears - Cylindropuntia tunicata and C. rosea - are also cacti of agricultural significance in Queensland. Weed management costs the Australian economy A$4 billion yearly; weeds are considered the second greatest threat to biodiversity after land clearing. Almost half of Australia's 220 declared noxious weeds (under legislation) were introduced deliberately, one third of these as garden ornamentals. Management of invasive species The management of invasive species is carried out by individuals, conservation groups, and government agencies. The Australian Quarantine and Inspection Service is responsible for ensuring that no new species with the potential to become invasive species enter Australia. To raise public awareness, Australian Quarantine has featured Australian celebrity nature lover Steve Irwin on a series of television commercials, with the message Quarantine – Don't mess with it. Several scientific bodies are involved in research for the control of invasive species. The CSIRO has released several successful biological pest control agents and developed chemical agents for pest and weed control. For example, the CSIRO released myxoma virus to control wild rabbits in Australia. Rabbit haemorrhagic disease escaped containment from an Australian Government research facility and spread across Australia. Rabbit hemorrhagic disease was subsequently legalised for the control of wild rabbits. The moth Cactoblastis cactorum was introduced for the control of prickly pear, and the salvinia weevil Cyrtobagous salviniae for the control of aquatic weed Salvinia. More doubtful biological controls were the cane toad, which was introduced to control the sugar cane destroying cane beetle; instead the cane toad ate anything and everything else—the beetle was not its preferred food source given choice. The cane toad in