Project Publications

This report describes a comprehensive risk analysis of releasing Wolbachia infected Aedes aegypti into the Australian environment. The report concludes that there is negligible risk that Aedes aegypti containing Wolbachia would “cause more harm” than the current Australian situation.

This paper describes an investigation to determine the robustness of the transcriptional profiling method for predicting the age of Aedes aegypti mosquitoes. The method was successfully applied to mosquitoes that were uncaged and free to engage in natural behaviour. We demonstrate that when applied to populations of mosquitoes, transcriptional age grading could be used to identify a 50% reduction in mosquito lifespan.

Previous mathematical descriptions of the population dynamics of Wolbachia causing cytoplasmic incompatibility assume non-overlapping generations and hence cannot describe the dynamics of strains that shorten life or lengthen development. This paper provides a mathematical framework for determining the initial frequencies needed for life-shortening infections to spread after introduction.

This paper demonstrates that Aedes aegypti mosquitoes containing Wolbachia have a greatly reduced ability to support infection with dengue virus as well as the unrelated human virus also transmitted by this mosquito, Chikungunya. It also demonstrates a reduction in the ability of the mosquito to be infected with avian malaria parasites. This paper demonstrates an alternative mode of action by which Wolbachia may reduce the ability of the mosquito to transmit dengue in addition to life-shortening.

This paper shows that different Wolbachia strains have varying abilities to protect the fruitfly Drosophila against pathogenic fruitfly viruses. As such not all Wolbachia strains can interfere with viruses. The reason for this is not currently understood.

This paper shows that Aedes aegypti infected with life-shortening Wolbachia have a reduced ability to bite people, particularly when they are old. This would reduce their ability to transmit dengue and other pathogens as they are transmitted between people by the bite of the mosquito. This paper also demonstrates that Wolbachia are not present in Aedes aegypti saliva and so cannot be transmitted to people.

This paper described the distribution and abundance of dengue mosquitoes on Tri Nguyen Island in central Vietnam. Depending on the time of the survey, we found that the average numbers of female mosquitoes could be as high as 43 individuals per house.

This paper investigates the population genetics of the dengue vector, Aedes aegypti, in Australia and Vietnam. It is shown that restricted gene flow occurs between populations of A. aegypti in northern Australia and that samples from Australia are genetically differentiated from Vietnam and Thailand samples. The implications for Wolbachia and other genetic control strategies are discussed.

Using videography techniques Evans et al. examined the locomotor activity of Wolbachia infected Aedes aegypti relative to uninfected over several adult ages. Wolbachia infection caused slight increases in the activity of the mosquitoes both during day and night but did not disturb circadian rhythms. The infected mosquitoes also show slightly higher metabolic rates. One possible explanation is that the Wolbachia are causing a metabolic drain on the host and the mosquitoes are spending more time seeking sugar water.

This paper demonstrates that old mosquitoes infected with life-shortening Wolbachia have difficulty in being able to insert their mouthparts into human skin. They display a “bendy” proboscis trait when they are old – which can be seen here.

This paper shows that life shortening effects of Wolbachia in Drosophila can be partly attenuated by the host genetic background following strong selection.

This paper demonstrates the reliability of simple evolutionary predictions that ignored host-population subdivision. Even extreme subdivision does not alter the prediction that natural selection on Wolbachia acts primarily to increase the number of infected progeny produced by infected mothers.

This paper demonstrates the successful transfer of life-shortening Wolbachia from the fruitfly into Aedes aegypti. In the mosquito it roughly halves adult female lifespan.

The field validation of model that predicts Aedes aegypti population dynamics is described here. By using readily available breeding site and meteorological data, dengue vector population size and structure can be predicted. This validated model (known as CIMSiM) is vital for developing and testing strategies for Wolbachia field release.

This paper describes the process of maintaining the life-shortening Wolbachia in mosquito cell culture to help adapt it to the mosquito intracellular environment prior to transfer into Aedes aegypti.

This paper demonstrates that Wolbachia can prevent pathogenic viruses from killing the fruitfly Drosophila – by interesting with the ability of the viruses to grow in the insect when Wolbachia is present.

Mathematical descriptions of the population dynamics of Wolbachia generally ignore the stochastic effects associated with finite population size. This paper shows that if many infected individuals are released such effects are indeed negligible for population sizes on the order of hundreds.

A general review article on Wolbachia insect interactions.

This paper describes in detail the protocol for applying the transcriptional age-grading method to Aedes aegypti.

This paper provides a review of the approach of reducing mosquito lifespan to reduce pathogen transmission.

This paper describes a new method to predict the age of field caught mosquitoes. It uses a transcriptional profiling approach to predict mosquito age and is considered an important tool for measuring the potential effect of Wolbachia on mosquito lifespan in the field.