Professor Michael T Siva-Jothy
Tel: +44 (0)114 222 4111
Room B84, Alfred Denny Building
BSc University College London (1981)
PhD University of Oxford (1985)
Royal Society/JSPS Research Fellow, Nagoya University, Japan (1986-89)
AFRC Research Associate, University College London (1989-90)
Lecturer, Department of Animal and Plant Sciences, University of Sheffield (1990-2001)
Senior Lecturer, Department of Animal and Plant Sciences, University of Sheffield (2001-2003)
Reader, Department of Animal and Plant Sciences, University of Sheffield (2003-2006)
Professor of Entomology, Department of Animal and Plant Science, University of Sheffield (2006-present)
Head of Department of Animal and Plant Sciences, University of Sheffield (2012-2018)
Key Research Interests
My research focuses on understanding the causal mechanisms underpinning sexually selected and life history traits. There are currently two major strands to the research in my laboratory.
First, the determination of patterns of life-history investment in immune function, and the coordination of immune effector systems to provide immune function. These studies have direct bearing on (a) the interaction between insect hosts and the disease organisms they vector, (b) understanding the evolution of insect life-history strategies, and (c) the evolution and maintenance of epigamic traits.
Second, understanding the nature of sexual conflict in the bed bug Cimex lectularius. This organism provides a unique opportunity to study sexual conflict because of the relative ease in with which it can be observed and quantified in both males and females. Our work examining the nature of conflict in this organism is relevant to (a) fundamental questions in evolutionary biology, (b) understanding the evolution of mating systems, and (c) developing novel methods for pest control.
Professional Activities (2000 onwards)
Editorial board: Proc. Roy. Soc. ser. B
Editorial board: Behav. Ecol. Sociobiol.
Editor: J. Ethology
Member: Faculty 1000
Board member: British Dragonfly Society
Reviews Editor: Proc. Roy. Soc. ser. B
Editorial Board: Funct. Ecol.
Plenary Lectures (2000-08)
2000 XXI International Congress of Entomology, Iguassu, Brazil (Mating systems symposium).
2000 Special meeting of The Royal Entomological Society, London, UK.
2001 9th Congress of the European Society of Evolutionary Biology, Arhus, Denmark (Immunity symposium).
2001 9th Congress of the European Society of Evolutionary Biology, Arhus, Denmark (Sperm competition symposium).
2001 International workshop on Immunocompetence, Jyvaskula, Finland.
2002 CEE symposium, Ecological and Evolutionary Aspects of Diseases and Parasitism, London, UK.
2003 The Darwin Lecture, University of Glasgow, Glasgow, Scotland.
2004 22nd International Congress of Entomology, Brisbane, Australia (Sexual selection symposium).
2004 22nd International Congress of Entomology, Brisbane, Australia (Ecological Immunity symposium).
2004 Jacque Monod Conference on Host-parasite interactions, Roscoff, France.
2004 The Evolution of Adaptive Immunity, Workshop, Edinburgh, UK.
2005 Royal Society meeting on Sexual Conflict, London, UK.
2005 Swiss Universities conference on the Ecology of Parasite Resistance, Fribourg, Switzerland.
2006 Jacque Monod Conference on Insect Immunity, Roscoff, France.
2007 The Royal Entomological Society, Insect immunity, Edinburgh, UK.
2008 Experimental Biology. Immunity in non-model systems. San Diego, USA.
2008 International Congress of Zoology, Evolution of genitalia. Paris, France.
Sexual conflict in Bed bugs. Leverhulme research fellow
Sexual conflict in Bed bugs. Leverhulme RA
Current Research Projects
Long lasting immune responses
Paul Erlich's (Lancet ii, 445, 1913) maxim for administering antibiotics was 'Hit hard and hit early'. Our studies of the highly conserved, but effective, insect immune response suggest he should have added '...and keep hitting'. Antibiotic resistance is a major and increasing health problem. In order to prevent the spread of resistance against new drugs, different treatment protocols have been investigated. However, there are few new groups of antibiotic compounds and few are likely to be discovered in the near future. Perhaps the most promising 'new' group are insect antibacterial peptides. These peptides are highly conserved but, despite their conservatism and age, are still very effective in protecting insects from bacterial insult. For example, a single type of peptide can be employed to clear an infection of a whole class of pathogens such as gram-positive bacteria. This evolutionary success is an enigma but clearly if insects can use conserved antibiotics and avoid selecting for resistance in a group of pathogens they must be doing something right (cf. human use of antibiotics and the evolution of resistance in bacteria).
A relatively unexplored aspect of their success is how they control the titre of peptides during an insult. Understanding this aspect (control and coordination of effector systems in the face of evolving pathogens insults) of the host's response is an important part of the field of ecological immunology, and understanding its dynamic is probably just as important as the mechanism of action and the toxicity of the antibiotic.
Recent work in our laboratory shows that insect hosts produce a 'tail' to their antibacterial response, a phenomenon that produces some interesting host resistance outcomes. In the proposed project we will develop and test aspects of this phenomenon that are relevant to the notion that the size and time-course of the last phase of the antibacterial response are adaptive. By doing this, we believe the insect hosts prevent the evolution of pathogen resistance. This work is being conducted in collaboration with Y. Moret in Dijon, France.
Sexual conflict in bed bugs
Male bed bugs use their needle-like intromittent organ to stab through the female´s abdomen and inseminate directly into her blood stream. This trait has evolved despite the fact that the female has a genital tract which now only functions in egg-laying. This bizzare reproductive strategy is termed 'traumatic insemination' and work on the bed-bug suggests it is subjected to selection arising from reproductive conflicts of interest. Such conflicts are probably common in nature, yet have only twice resulted in the evolution of traumatic insemination in advanced metazoans (the Cimicidae and the Stripsiptera – both insect taxa, the latter a rare parasitoid). Understanding the anatomical, physiological and life-history consequences and responses of the sexes to traumatic insemination is of critical and direct importance to our understanding of the nature of sexual conflict, a new and increasingly important area of evolutionary theory. Previous work has explored, and defined, techniques for culturing bed bugs under controlled conditions, generating virgins for experiments, keeping mated bugs isolated whilst still feeding them, investigated the potential for artificial insemination and collecting eggs.
This project is currently examining how females respond to traumatic insemination both in the proximate sense (immune responses, wound repair, etc) and in the evolutionary sense (complexity in the paragenital system). Collaborations are currently in place with colleagues in Sweden (pheremones) and Germany (biomechanics).