Insect-Plant Interactions
Participants |
Behaviour and ecology of Australian psylloids of eucalypts
Our major research focus is on the chemical and physical plant cues psylloids (also commonly called Jumping plantlice and psyllids) use when locating and differentiating host eucalypts from non-host eucalypts and the impact of these traits on the survival of nymphs. Field studies are used to track changes in hosts and the incidence and abundance of psylloids while manipulative laboratory bioassays are used to study psylloid responses to specific plant stimuli. We collaborate with psylloid experts in other Australian universities and State Government research institutions. We also have strong synergies with the Peters Lab at La Trobe University and ongoing collaborations with labs in Europe.
 |
An adult Amorbus rubiginosus on a eucalypt. These True bugs produce fruity-smelling secretions from glands on their thorax when stressed.
The liquid ejected is considered a “defensive secretion” and is thought to protect the bugs against ants but the validity of this suggestion has
never been tested. (Photo Ben Twist)
The larvae of many eucalypt-feeding insects remain in groups from the time of hatching often until late in their development, e.g. these chrysomelid leaf beetle larvae.
Recent research has shown that group feeding may be an adaptation that enables larvae to feed on the tough leaves of eucalypts. Nevertheless, most group feeding
larvae also produce strong smelling or even toxic secretions when agitated (the elevated abdomens of some of these larvae indicates they are agitated).
Is this trait simply a way of dealing with feeding on leaves with high oil contents or does it have a defensive significance?
A clutch of eggs of a mistletoe-feeding psylloid with three recently hatched nymphs visible. Psylloids differ in the way they lay their eggs;
some lay in groups on the leaf surface and others lay them individually with their bases inserted into the leaf tissues. The reasons for these
differences have never been addressed. (Photo Anna Burns) - 
Adult Christmas beetles are major defoliators of eucalypts of woodland habitats and revegetation plantings, yet their subterranean larvae feed on grass-roots.
This shift in food plants is unusual among eucalypt-feeding insects because adult and immature stages usually feed on eucalypts (or the adults do not feed).
What changes in the digestive physiologies of adults and larvae permit this shift to occur?
All reproductively mature animals need to find individuals of the opposite sex with which to mate. Among Australian psylloids, adults communicate using vibrational signals with
some species engaging in synchronized duetting during courtship. We intend to study the efficacy of this mode of communication and whether chemical sex pheromones also play a
role in initiating courtship. (Photo Anna Burns)Behaviour and ecology of insect folivores of eucalypts
We are interested in the roles of leaf surface waxes on host selection and assessment by lepidopterans, especially native geometrid moths. We are also interested in the roles of foliar monoterpenes on host selection and herbivory by chrysomelid leafbeetles as well as ruteline and melolonthine scarab beetles. A schema of host selection by the Autumn gum moth using volatile, non-volatile and physical traits of their preferred eucalypts, based on the findings of past research, can be viewed by clicking on the link provided below. We have a strong track record in providing applied research findings on lepidopteran and leafbeetle pests of eucalypt plantations to foresters. We collaborate with experts in vertebrate herbivory of eucalypts and organic chemistry in other Australian universities.
General principles in insect-plant interactions
We are interested in identifying general principles that explain the diversity and abundance of Australian insects on eucalypts and acacias. Our long-term objectives are to link the incidence of specific plant secondary metabolites (PSMs) to the radiations of different insect taxa and seasonal variations in plant nutritional quality to the population dynamics of important herbivores.
Students
- 2011 – Kevin Farnier, PhD Student
Host plant specificity, selection and performance of eucalypt-feeding psyllids - 2012 – Umar Lubanga, PhD Student
Vibrational communication in psylloids and relationships to nymphal biology and host specificity - 2012 – Beryn Otieno, PhD Student
Host plant specificity of Leptocybe invasa (Hymenoptera: Eulophidae) and potential to use plant volatiles for monitoring
Potential PhD topics
The Faculty will consider any research topic that interests potential PhD students; however, students will benefit from researching in areas that align with the Faculty’s strengths. Please find a relevant supervisor to discuss your PhD topic. Alternatively you may contact one of our academics below to discuss your area of interest
- Endosymbionts of psylloids and role in nutritional ecology – Dr Martin Steinbauer
- Eucalypt foliar versus floral volatiles and effects on scarab beetle behaviour – Dr Martin Steinbauer