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Genetic and Mechanistic Basis of Tick Traits

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Ticks are a major health threat to humans and other animals. The bite of these blood-feeding ectoparasites leads to direct damage, toxicoses, allergies and transmission of a diverse set of pathogens (bacteria, viruses, protozoa and nematodes).

 

Developing successful interventions that limit a host’s exposure to ticks requires a comprehensive understanding of tick biology. My research program investigates the sexual biology and host-seeking behaviour that underpin the highly specialized parasitic life history of ticks. These findings will provide the fundamental building blocks for developing innovative methods for targeted tick control and tick bite prevention.​​

Sexual biology of ticks

For the most medically important tick genus (Ixodes) adult females, but not males, bloodfeed to engorgement from their host and transmit disease-causing microbes. Understanding the genetic and mechanistic basis of tick sexual biology is critical to developing new methods for tick control. I use molecular techniques and laboratory experimental studies to investigate the sexual biology of the key tick species implicated in Lyme disease in the United States of America, the black-legged tick (Ixodes scapularis).

Key publications:

Host-seeking behaviour of ticks

Tick-host interactions start with the host-seeking behaviour of ticks, so this behaviour is a major determinant of disease risk. My research investigates the genetic and mechanistic basis of tick host-seeking behaviour. I developed a behavioural assay to assess how ticks interact with novel hosts, which established that a newly invasive tick species in the United States of America (Haemaphysalis longicornis) has an aversion to the mouse species that is the reservoir host for the Lyme disease bacteria. Therefore, we have found that this tick species is unlikely to be involved in the transmission of the Lyme disease bacteria to humans in the United States.

In collaboration with the Glenn lab at the University of Georgia and the wider tick research community, we conducted a comprehensive phylogeographic study of genome-wide markers for Ixodes scapularis to genetically characterise the population in the northeastern United States, which has a unique host-seeking behaviour and is associated with high Lyme disease risk. We identified the DNA variants that genetically differentiate this northeastern population and can be used as a starting point in future studies to investigate the genetic basis of host-seeking behviour.

Key publications:


Genetic and Mechanistic Basis of Worker Sterility

Understanding the genetic and mechanistic basis of novel biological traits can lead to insights into how these traits evolved. The evolution of an ‘altruistic’ sterile worker caste in the social insects has been a major question for evolutionary biology, as it requires the existence of genes that reduce personal reproduction. Therefore, the molecular and developmental mechanisms regulating the sterility of the worker caste are important to understand.
 

In honey bee (Apis mellifera) colonies the presence of the queen, secreting her pheromones, inhibits ovary activation in workers. My Ph.D. research identified a genetic (Anarchy) and mechanistic (programmed cell death) basis underlying worker sterility in the honey bee. These findings provide a foundation for understanding how the unique traits of the social insects evolved from a solitary insect ancestor.

Image of a honey bee with word cloud embedded
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