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Jeff Doherty

Entomology, Parasitology, and Behaviour

I am a doctoral candidate in the Department of Zoology (Evolutionary and Ecological Parasitology Research Group) at the University of Otago in New Zealand. My research is focused on studying the behaviour of native cave wētā and other insects experimentally infected with hairworms (pictured left, a hairworm exiting a tree wētā). We also aim to identify the biochemical pathways (i.e., proteomics and transcriptomics) possibly manipulated by the hairworm, which could increase the likelihood of infected insect hosts entering a source of water and drowning in it.

 
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Bio

I hail from the land of the Great Moose, also known as Canada. Born and reared in Ontario, I moved to Québec to my French Canadian roots, where I completed my BSc and MSc in biology at Université Laval and University of Oslo (Norway). An entomologist at heart, I studied the effects of temperature on the development of arthropod pests found in commercial Christmas tree plantations and developed models predicting their springtime eclosion. During this period, I happily discovered the fascinating subject of behavioural manipulation by parasites whilst writing a graduate course paper. Therefore, I intend to pursue my doctoral studies in this area by experimentally infecting native cave wētā (large nocturnal wingless orthopterans) and other insects with nematomorphs (hairworms) and conducting behavioural assays as infection progresses. In doing so, I hope to better understand how these parasitised insects end up drowning in a source of water during their nightly escapades.

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Doctoral project

Ethology and interactions of insects harbouring hairworms (Nematomorpha)

Hairworms (phylum Nematomorpha) are parasites with a complex life cycle including multiple invertebrate hosts, an aquatic and terrestrial phase, and five recognised life stages. Interestingly, mature hairworms must enter water in order to mate and lay their eggs. However, they reside within a land-dwelling host that actively avoids bodies of water (e.g., crickets and cave wētā). Currently, it is thought that hairworms adaptively manipulate their invertebrate hosts to somehow enter water and drown, once the hairworms are mature and ready to exit. But despite their notoriety, hairworms remain mysterious in several biological aspects. 

Since experimental infections are important in demonstrating that host behavioural change is indeed the result of a manipulative parasite ensuing infection, the overarching theme of my doctoral research project is to elucidate the hidden interactions between hairworms and their insect hosts by combining field data with experimental infections.

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Infecting insect hosts with hairworms

To study the behaviours of insects harbouring hairworms, they first have to be infected experimentally. Freshwater macroinvertebrates (e.g., the caddisfly larva pictured above) naturally harbour dormant hairworm cysts. Therefore, it is possible to isolate cysts from these intermediate hosts and feed them directly to potential insect hosts reared in the laboratory.

Behavioural studies of insect hosts infected with hairworms

Little is known about the behavioural changes occurring in insects infected with hairworms. Naturally infected individuals exhibit erratic movements and may respond differently to external cues such as light. Studying the behaviours of experimentally infected insects throughout the development of the hairworm could elucidate the behavioural changes that cause parasitised insects to enter water and drown.

Mapping the distribution of hairworm cysts in New Zealand subalpine streams

Little is known about the distribution of hairworm cysts in freshwater macroinvertebrates and how it varies throughout the year. Therefore, studying these patterns could help understand how and when the cyst is transported to land by their intermediate hosts to be ultimately consumed by the definitive terrestrial host.

 

Integrative ethology

Animal behaviour is an intrinsically complex phenomenon resulting from the interactions of the internal and external environments of an organism. A simple observed change in behaviour is likely the culmination of a myriad of cascading physiological processes triggered by the environmental cues experienced by an animal. Evolution has undoubtedly played a fundamental role in shaping and refining the processes that cause behaviour, but the physiological basics still remain largely open to debate. Relatively simple model organisms, such as insects, have been used to study the great complexity of behaviour. Although these studies have resulted in promising lines of research, there is still much to discover.


Given the notable complexity of animal behaviour and our incomplete understanding of its physiological foundations, my ambition is to establish an international collaboration between researchers focusing on all aspects of animal behaviour, from the molecular to the ecosystemic. This integrative approach to ethology is essential if our goal is to understand behaviour from all possible scientific perspectives.

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Contact information

Department of Zoology, University of Otago

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