Entomology: Martha S. Hunter

Professor

B.A. in Biology, Brown University 1980
M.Sc. in Entomology, Cornell University 1987
Ph.D. in Entomology, Cornell University 1991.

Visit Molly Hunter's Lab Website

Understanding the role of heritable symbionts in natural enemy or pest biology has not been widely accepted as an important research objective of biological control programs. Yet, vertically transmitted secondary symbionts have been shown to play critical roles in the ecology and evolution of their arthropod hosts. Symbionts are often a cryptic but important component of the life history of biological control agents, and it may often be appropriate to think of species of natural enemies as composite genotypes with a nuclear (host) and cytoplasmic (symbiont) component, each with independent and sometimes conflicting genetic interests. Parasitoid Hymenoptera, in particular, appear to have higher levels of symbiont infection than other taxa. My laboratory is currently studying the role of microbial symbionts in parasitoid-host interactions.

• We are investigating Cardinium, a recently described intracellular bacterial symbiont that manipulates the reproduction of its parasitic wasp hosts in ways that enhance its transmission to the next generation.  Like the better characterized symbiont Wolbachia, Cardinium causes parthenogenetic reproduction in some species of its haplodiploid wasp host, such that incipient male eggs double their chromosome complement and develop as females.  Cardinium also causes cytoplasmic incompatibility, a condition in which bacteria in infected male wasps effectively sabotage the reproduction of any uninfected female the male mates with, in this way increasing the fitness of infected females.  We are studying the spread of Cardinium infections in natural populations of wasps, the interaction of Cardinium with Wolbachia in doubly infected hosts, the effects of Cardinium on behavior and life history of its host and the mechanisms of reproductive manipulation by Cardinium.  Jen White, an Insect Science (PERT program) postdoc in the laboratory is taking the lead on the Cardinium/ Wolbachia interactions, and much of the Cardinium work is a collaboration with Steve Perlman at the University of Victoria. 
• We are studying the influence of facultative bacterial symbionts in pea aphids on resistance of the aphids to parasitism by a parasitic wasp. This is a collaboration led by postdoc Kerry Oliver and including Nancy Moran’s laboratory. In this project, we are studying what determines the variation among aphids in resistance to wasps, whether resistance in other insects is also caused by symbionts, and how symbionts that cause resistance are distributed among insects.
• Cara Gibson, a graduate student in the laboratory, is studying the role of yeast symbionts in chalcidoid parasitoids in the family Encyrtidae.
• We are investigating the role of Rickettsia on whiteflies and their parasitoids. This work is a collaboration with Einat Zchori-Fein (Newe Ya’ar Research Center, Israel).
• We are collaborating with Matthias Horn’s laboratory at the University of Vienna to isolate Cardinium DNA for genome sequencing by the Community Sequencing Project of the Joint Genomics Institute.

Selected publications

Kenyon, S.G., and M.S. Hunter.  2006.  Manipulation of oviposition choice of the parasitoid wasp, Encarsia pergandiella, by the endosymbiotic bacterium Cardinium.  In press.  Journal of Evolutionary Biology pdf

Perlman, S.P., M.S. Hunter and E. Zchori-Fein. 2006. The emerging diversity of Rickettsia. Proceedings of the Royal Society of London, Series B. 273:  2097-2106. pdf

Oliver, K.M., N.A. Moran and M. S. Hunter. 2006. Costs and benefits of a superinfection of facultative symbionts of pea aphids. Proceedings of the Royal Society of London, Series B. 273:  1273-1280.  pdf

Hunter. M.S. and E. Zchori-Fein. 2006.  Inherited Bacteroidetes symbionts in arthropods.  In:  K. Bourtzis and T.A. Miller, eds., Insect Symbiosis, 2nd Ed., CRC Press, New York.

Gibson, C. M. and M. S. Hunter.  2005. A reconsideration of the role of yeast associated with Chrysoperla lacewings.  Biological Control  32(1):  57-64.  pdf

Oliver, K.M., N.A. Moran and M.S. Hunter 2005. Variation in resistance to parasitism in aphids is due to symbionts, not host genotype.  Proceedings of the National Academy of Sciences USA 102: 12795-12800.  pdf

Zchori-Fein, E., S. J. Perlman, S. E. Kelly, N Katzir, and M. S. Hunter. 2004.  Characterization of a Bacteroidetes symbiont in Encarsia wasps (Hymenoptera:  Aphelinidae):  A proposal of ‘Candidatus Cardinium hertigii’  International Journal of Systematic and Evolutionary Microbiology 54: 961-967.  pdf

Hunter, M.S., S. J. Perlman, and S. E. Kelly.  2003  A bacterial symbiont in the Bacteroidetes induces cytoplasmic incompatibility in the parasitoid wasp Encarsia pergandiella.  Proceedings of the Royal Society of London, Series B.  270: 2185-2190.  pdf

Oliver, K.M., J.A. Russell, N.A. Moran and M.S. Hunter 2003. Facultative bacterial symbionts in aphids confer resistance to parasitic wasps. Proceedings of the National Academy of Sciences USA 100: 1803-1807.  pdf

Hunter, M.S., Collier, T. R, and S. E. Kelly. 2002. Does an autoparasitoid disrupt host suppression provided by a primary parasitoid? Ecology 83: 1459-1467.  pdf

Donnell, D.M. and M.S. Hunter 2002.  Developmental rates of two congeneric parasitoids, Encarsia formosa and E. pergandiella (Hymenoptera:  Aphelinidae), utilizing different egg provisioning strategies. Journal of Insect Physiology 48: 487-493.  pdf

Zchori-Fein, E., Gottlieb, Y., Kelly, S.E., Brown, J.K., Wilson, J.M., Karr, T.L., and M.S. Hunter 2001. A newly-discovered bacterium is associated with parthenogenesis and a change in host selection behavior in parasitoid wasps.  Proceedings of the National Academy of Sciences 98: 12555-12560.  pdf

Hunter, M.S. and J. B. Woolley. 2001. Evolution and behavioral ecology of heteronomous aphelinid parasitoids. Annual Review of Entomology 46: 251-290.  pdf

Collier, T. R. and M.S. Hunter. 2001.  Interference competition between whitefly parasitoids, Eretmocerus eremicus, and Encarsia transvena. Oecologia 129-147-154.  pdf

Petersen, M. K. and M. S. Hunter. 2001. Variation in the outcome of competition between two aphid species on pecan:  Plants matter more than predators. Oikos 92: 107-118.  pdf

Netting, J.F. and M. S. Hunter.  2000. Ovicide in the whitefly parasitoid, Encarsia formosa.  Animal Behaviour 60: 217-226.  pdf