Manual for Diagnosis of Screw-worm Fly - xcs consulting

The predicted distribution of C. bezziana in Australia, using the CLIMEX computer program
for matching climates, is illustrated in Fig. 1 for winter and summer seasons (Sutherst et al.
1989). Large livestock rearing areas are at risk of permanent colonisation as far south as the
mid-coast of New South Wales in average seasons. Occupation of the predicted areas would
undoubtedly be influenced by non-climatic factors such as tree cover, host availability and
susceptibility (=wounds).
1.3 Australian research background
Agriculture, Fisheries and Forestry - Australia
Because of perceived dangers to the livestock industries if the Old World screw-worm fly
became established in Australia, CSIRO Division of Entomology, with support from the
Australian Department of Primary Industries and Energy, established a laboratory in Port
Moresby, Papua New Guinea, in 1973. The facility was dedicated to studying the basic
biology, physiology and ecology of Chrysomya bezziana, the Old world screw-worm fly.
Artificial cultures were established for the first time for this species, methods were developed
for trapping flies in the field to further population and dispersal studies, and the impact of
gamma radiation to sterilise flies was studied to enable sterile insect release (SIRM) trials.
In 1981, premises at Laloki on the outskirts of Port Moresby became the centre
for mass-rearing studies. At this time a SIRM study was carried out by the ground release of
sterile flies that resulted in 25% sterility in the local native fly population. The following year
a major SIRM trial was carried out at Safia in the Musa Valley in which sterile flies were
released from aircraft. The maximum sterility induced in the native Safia population was 33%.
During a mass rearing in 1987, 18 million flies per week were produced at Laloki.
In 1991 screw-worm fly operations in Papua New Guinea were closed down and in 1995,
a new facility established in Malaysia at the Institute Haiwan, Kluang, Johor, under a
memorandum of understanding between the Governments of Australia and Malaysia.
The Malaysian program’s brief was to develop innovative mass-rearing technologies and to
conduct a major SIRM trial to confirm that this technique is a viable eradication option for the
Old World screw-worm fly. In a SIRM trial carried out in Malaysia in 2000, the maximum sterility
recorded was 62%, thus confirming the validity of the sterile insect release method to
eradicate Old World screw-worm fly. The studies at the Institute Haiwan have enabled the
design of a large scale, 250 million sterile flies per week facility which could be constructed in
Australia should this pest become established.
3
Figure 2: Larva of the Old World screwworm
fly Chrysomya bezziana.
Scanning electron microscope
photograph by Helen Geier