EDUCATION

 

B.A. Zoology	1983	University of Washington, Seattle
Ph.D. Zoology	1991	University of Texas, Austin

CURRENT RESEARCH

I joined the USDA-Agricultural Research Service as a Research Ecologist in November 2006. In the insect pest management unit, our primary focus is on understanding grasshopper and Mormon cricket ecological interactions as a foundation for developing sound management practice. My group is interested in the ability of grasshoppers and Mormon crickets to defend themselves from natural pathogens. We are interested in how those defenses change as the insects develop, migrate, and reproduce. Our objective is to find weaknesses in the immune system of these agricultural pests so that natural pathogens might be applied when and where they are most effective in pest control. Generally, insect migration away from natal sites is associated with lack of food or local crowding. So we are investigating whether the insects compromise the immune system to enhance locomotion when food is limited. In addition understanding band movement, individual dietary requirements and insect survivorship will improve forecasting of movements, damage to humans, and improve integrated control. To this end, we are applying what we have learned about the orientation of migratory butterflies and adaptations to minimize energetic costs of long distance movement to grasshoppers and Mormon crickets (see below). It is likely that the environment plays a major role in the direction of the migration. However the environment has three types of features each of which might contribute to the insects’ movement across the Earth: features that are stable over ecological time scales, those that are periodic, and those that change unpredictably. We will begin by investigating their ability to orient using a stable feature: the Earth’s magnetic field; and a periodic feature: the position of the Sun in the sky.

RESEARCH EXPERIENCE

Prior to joining ARS, I was a Brainpool Professor of Biological Sciences at Seoul National University, South Korea where I researched prey selection by the Korean magpie and mentored students. For 16 years, I have been affiliated with the Smithsonian Tropical Research Institute conducting research on insect migrations in Neotropical rainforests on the isthmus of Panama with funding from the National Geographic Society for ten of those years. My colleagues and I tracked the insect flyway over the Caribbean Sea and the ithmus of Panama, investigated the butterflies’ use of the sun and geomagnetic fields to orient globally, and the use of landmarks and optic flow of a ground reference to compensate for drifting off course in variable winds. We have recently been testing models that indicate that insects have sophisticated orientation mechanisms to minimize energetic expenditures when crossing large bodies of water and the isthmus of Panama. From 1998-2001, I was a Fellow of the Department of Zoology at the University of Oxford where I used smoke to visualize vortices generated by the wings of butterflies, dragonflies, and damselflies in an investigation of high-lift aerodynamic mechanisms used by insects. My interest in flight grew from my dissertation research comparing the rapid, maneuverable flight capacity of butterflies that are palatable and pursued by birds to the slow, deliberate flight of butterflies that are protected by distasteful chemicals and ignored by birds. Recently I have shown that although too fast for humans to see, the slow, deliberate flapping of distasteful butterflies heralds a motion signal to birds that the bearer is distasteful. This signal has an aerodynamic cost, and cheaters that present the signal to birds without truly bearing distasteful chemicals pay an additional energetic cost.

For more information on these research topics, please refer to the following Web site: http://users.ox.ac.uk/~zool0206
(Note: This link will take you to a non-federal site)
 

Grasshopper Info Page

Research on Grasshoppers

PUBLICATIONS
Please note: The most recent publications by this scientist may not yet be listed here. Please check the ARIS "Publications" page for possible new titles.

• Srygley, R. B. 2007. Evolution of the wave: aerodynamic and aposematic functions of butterfly wing motion. Proceedings of the Royal Society London B. 274:913-917.

• Srygley, R. B., R. Dudley, E. G. Oliveira, A. J. Riveros. 2006. Experimental evidence for a magnetic sense in Neotropical migrating butterflies (Lepidoptera: Pieridae). Animal Behaviour. 71:183-191.

• Srygley, R. B. 2003. Wind drift compensation in migrating dragonflies Pantala (Odonata: Libellulidae). Journal of Insect Behavior. 16:217-232.

• Srygley, R. B. and A. L. R. Thomas. 2002. Unconventional lift-generating mechanisms in free-flying butterflies. Nature. 420:660-664. http://users.ox.ac.uk/~zool0206/flow.html