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Prickly Pear in Central Queensland
Prickly pear (Opuntia stricta) exists on the central Queensland coast of Australia and a number of islands in
the region. In most cases the plants are individual specimens; along the fore dune or beach – vegetation
interface of islands. Dense infestations spreading well inland of the coasts exist on some islands - in some cases this
can be across the entire island. On Curtis Island, Prickly Pear is of particular concern as it has become a food source
for feral pigs for which there is a major pig trapping project aimed at reducing threats to nesting Flatback Turtles
(Natator depressus) and Yellow Chats (Epthianura crocea macgregori). It is believed that Prickly Pear
was introduced to the Whitsunday Islands as a food source for marooned sailors. It is unknown how it reached other
islands but it may have been distributed through birds or floating on water.
Prickly Pear has the ability to displace native vegetation communities including:
Casuarina, Spinifex, & Goats Foot Convolvulus - of concern
Microphyll vine forest on coastal dunes - critically endangered
Bloodwood, Melaleuca & beach scrub spp. - of concern
Spear, Blady & Kangaroo grasses on coastal dunes - of concern
It is also a threat to native animals including the Beach Stone Curlew (Esacus magnirostris) (vulnerable) and the
Pied Imperial Pigeon (Ducula bicolour), & Osprey (Pandion cristatus) for which beach scrub is a known
habitat. Beach Stone Curlews are particularly vulnerable as they are known to nest at the beach-vegetation interface
where Prickly Pear is most common. Indirectly, Prickly Pear is also a threat to the Yellow Chat which is endangered
under the Nature Conservation Act and critically endangered under the Environmental Protection and Biodiversity
Conservation Act and the Flatback Turtle (Natator depressus) - vulnerable. Prickly Pear is a food source for
feral pigs on Curtis Island which threaten these species. In addition pigs up root plants and cause significant
damage on Curtis Island to the vegetation of the marine plane which is listed as a significant wetland.
While it is well known that insect biocontrols have virtually eradicated the pear from inland areas, to date
biocontrols such as the Cactoblastis moth or Cochineal insects have been ineffective in coastal areas. It is
thought that this is because Prickly Pear develops a thicker 'skin' to assist in salt tolerance. This thicker
skin may be impenetrable/indigestible to larvae which leave viable portions of the plant to the extent that the
pear survives. Cochineal bugs can be more effective but often require dispersal assistance. It is thought that
repeated introductions of biocontrols will eradicate the pear and/or may eventually produce a generation of insect
which is able to penetrate the coastal Prickly Pear
Author: Kerensa McCallie
For more information on the history of Opuntia in Australia and control measures, see these brochures produced
by The State of Queensland Department of Primary Industries and Fisheries:
