Hypsipyla Shoot Borers of Meliaceae in Sri Lanka - Australian ...

The use of artificial growth shelters, comprising
UV stabilised polyethylene tubing (Growtubes TM )
increased growth rates up to five times that of unprotected
trees (Applegate and Bragg 1989). Such
growth rates were maintained in Growtubes up to
3 m high but the resultant trees were very slender
and required continued support after their emergence
from the Growtube. By protecting against exposure,
stock, browsing animals, herbicide drift, and weed
growth, Growtubes could reduce maintenance costs
which would offset the high establishment costs.
Growth in areas remote from Toona ciliata
Several plantings of T. ciliata have been trialed in
sites a long way from existing stands of T. ciliata in
the hope that isolation will protect them from H.
robusta. Some of these, most notably those on
Norfolk Island (N. Taverner, Administration of
Norfolk Island) and around Darwin, Northern
Territory (D. Riley, Department of Primary Industries
and Fisheries, Northern Territory, pers. comm.),
have produced trees of good growth rate and form,
which have remained undamaged by H. robusta
many years after planting. The success of such plantings
depends on the careful choice of sites, ensuring
isolation from all H. robusta hosts, and taking into
consideration the soil preferences, moisture requirements
and frost susceptibility of the trees. Trees
planted on unsuitable sites trees perform poorly
regardless of the incidence of H. robusta. Successful
site selection requires an adequate understanding of
the flight capacity and host location ability of
H. robusta adults.
Host resistance
The existence of naturally-resistant strains or
individuals of T. ciliata in Australia has been frequently
alluded to but little investigated (FAO 1958;
Campbell 1966; Entwistle 1967). The species shows
great phenotypic variability under natural conditions
with variation in the degree of pubescence, growth
rates, form, degree of deciduousness, level of
anthocyanin in young leaves, and temperature tolerance
(Herwitz 1993; Griffiths 1997) Some of these
traits are likely to be heritable and have potential to
influence damage levels, therefore offering the
potential to breed for resistance. Recent trials in
southeast Queensland found differences in the level
of oviposition by H. robusta when comparing T.
ciliata trees from different regions of Australia
planted at a single site (Griffiths 1997). Trees from
the most northern collection site (Iron Range:
12 o 43′S 143 o 18′E) consistently received fewer eggs
than trees from five more southerly collection sites,
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although the success of early instar feeding did not
differ between provenances.
A series of trials undertaken in the 1950s aimed to
determine appropriate propagation techniques for T.
ciliata in the event that a resistant strain was located
(Sub-Department of Forestry 1956). Although some
success was achieved with both cutting and grafting
techniques, the potential of such methods for propagation
of resistant trees was never tested. In the
majority of experiments, resistance to H. robusta
was not a criterion for selection of the parent trees.
Most experiments were terminated prior to planting
out.
Current Researchers
Dr Tom Bellas (CSIRO Entomology) has conducted
much work investigating the pheromone blends of
numerous insect species in Australia. Tom has
undertaken a preliminary analysis of the chemical
components present in volatiles collected from
female H. robusta.
Dr Rob Floyd (CSIRO Entomology) is project
leader for the Australian Centre for International
Agricultural Research (ACIAR) funded project to
review the ecology and control of H. robusta in Asia
and the Pacific (these Proceedings). His specific
research interests are in the areas of host-plant resistance
and forest pest management.
Dr Manon Griffiths (CSIRO Entomology) completed
her Ph.D. studies addressing aspects of the
biology and host relations of H. robusta in Australia.
Her study highlighted differences in the biology of
H. robusta in Australia to that described from other
countries, confirms the host range of the species in
Australia, and investigates interspecific variability in
host use. Dr Griffiths contribution to these Proceedings
has been funded by ACIAR project FST/95/103.
Dr Marianne Horak (CSIRO Entomology) is a
leading taxonomist of the Pyralidae, and is currently
undertaking preliminary taxonomic analysis of H.
robusta in Australia.
Dr Jianhu Mo (Department of Forestry, Australian
National University) completed his Ph.D. on
the ecology and behaviour of H. robusta. Dr Mo
investigated temporal and spatial patterns of infestation,
temperature-dependant development, feeding
behaviour of larvae, reproductive activities and host
selection behaviour.
Dr Don Sands (CSIRO Entomology) is assisting
in the ACIAR project FST/95/103 to review the
ecology and control of H. robusta in Asia and the
Pacific. He has significant expertise in the biological
control of insect pests which he is interested in
applying to Hypsipyla.