Biology of Willow Leaf Beetles
 

C. aeneicollis with eggs
Symmorphus with beetle prey
John Smiley1, Nathan Rank2,1, and Elizabeth Dahlhoff3,1
 Parasyrphus maggot hunting beetle larvae

resources and other links
reference list ***site info sheet (pdf)
catalog of study sites & logger data
1. University of California White Mountain Research Station
2. Sonoma State University
3. Santa Clara University
Individual web pages:
Dahlhoff, Rank, Smiley
Overview This project began as an attempt to characterize the ecology of a plant-feeding beetle along a montane elevation gradient, and has grown into a long-term research program studying the ecology, physiology and genetics of insect populations, environmental gradients, and climate change. Willows (Salix spp., family Salicaceae) were chosen as the host plant because their growth and foliage properties are relatively (but not completely) unaffected by seasonal rainfall. The Willow Leaf Beetle, Chrysomela aeneicollis (Coleoptera: Chrysomelidae; see above, center) is the dominant herbivore on willows in the subalpine zone of the east-central Sierra Nevada Mountains of California, between Tioga Pass and Taboose Pass. As shown in the figure below, the elevational range of the beetles has expanded and contracted over a multi-year time scale, and there seems to be a correlation to multi-year fluctuation in snowfall.

 

We have investigated different aspects of the ecology, evolution and physiology of this system, including (1) predator-prey-willow interactions, including the biology of two prey-specific predators (see photos above), (2) ecology and disctribution of willow salicylate chemicals, (3) ecology and genetics of adaptation to local sites and position on the elevation gradient, (4) physiology and behavior of locally adapted genotypes, (5) mechanisms of thermal adaptation. Several Sierran drainages have been studied, with long term data from North Fork Big Pine Creek, multiple Bishop Creek drainages, and Rock Creek. See the reference list for specific publications, and the history page for the history of the project. We have also prepared a poster entitled Genetics, Physiology And Ecology Of Subalpine Beetle Populations: Responses To Climate Change (powerpoint 5MB) which was presented at the 2006 PACLIM meetings, held at Asilomar, Pacific Grove CA on March 26-29.

Climate effects and need for long-term monitoring This system should be very useful for studying the biology of subalpine insects as their populations respond to climate change. We predict rising temperatures will interact with wet-dry cycles to produce stepwise but upward-trending populations of willows, beetles and their predators, with varying time-lags which can only be observed in 10-20 yr. data sets. It will be crucial to continue, and in some cases augment, annual monitoring efforts in order to be able to obseve these phenomena.

Acknowledgements: We wish to thank "team beetle" in all of its manifestations over the years, including students, family members and friends who have lugged equipment, endured mosquitos, slaved in the lab and counted "countless" beetles. This work has also been supported by the National Science Foundation and the University of California White Mountain Research Station.