Dr. Deane Bowers  ::  CU Museum and Department of Ecology and Evolutionary Biology    University of Colorado UCB 334  ::  Boulder, CO, 80309

Office Phone (303) 492 - 5530 :: E-mail deane.bowers@colorado.edu

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Active Projects

The Deane Bowers Lab Group

at the University of Colorado in Boulder

I. Plant defensive chemistry and its importance for herbivores and the natural enemies of these herbivores. 

I am especially interested in how variation in plant compounds is important for insects that sequester these compounds and how this plant variation and its consequences for herbivores affect interactions with natural enemies. My research has both ecological and evolutionary components:  how do the dynamics of these interactions affect ecological relationships among the participants and how do these interactions evolve.  While much of my research has used chemical attributes of plants, I am also interested in questions not directly related to plant chemistry. 

1)We are currently funded for a project investigating how chemical compounds sequestered by caterpillars affect their interaction with parasitoids.  This project is a collaboration with Lee Dyer, who has recently moved from Tulane to the University of Nevada at Reno.

Title:  Are sequestered plant allelochemicals benefits or detriments to generalist and specialist parasitoids?

Summary    

Host plant chemistry as a mediator of the interactions between plants, herbivores and the natural enemies of those herbivores, is a key concept in evolutionary ecology.  These interactions play a pivotal role in many currently investigated applied and theoretical topics such as the evolution of diet breadth, the ecology of plant-parasitoid mutualisms, and the ecology and evolution of terrestrial trophic cascades.  While several studies have examined the importance of plant allelochemicals for herbivore-predator interactions, very few have addressed the role of these compounds in herbivore-parasitoid interactions.  This  project examines how the sequestration of plant allelochemicals mediates multi-trophic interactions with special reference to parasitoids.   A model system of plants containing iridoid glycosides, three pairs of closely related caterpillar species (one pair each in the Arctiidae, Nymphalidae, and Sphingidae), and their parasitoids are being used to investigate the roles of sequestered plant allelochemicals in herbivore-parasitoid interactions. One species in each pair of caterpillars sequesters and one in each pair does not sequester iridoid glycosides. 

2)Several other current projects fall under this topic as well, including a study of variation in chemical defense in two native butterfly species and the effects of host plant and year on this variation; research on the effects of nitrogen deposition on plant-herbivore-predator interactions;  and an investigation of how plant chemistry affects fruit herbivory, microbial attack, and dispersal.

II. Response of insect communities to climate change and human disturbance

This research is looking at how grasshopper and butterfly communities have been affected by climate change and habitat fragmentation in the Colorado Front Range. 

1) The currently funded grasshopper project is a collaboration with Cesar Nufio and Rob Guralnick. We are using museum collections data coupled with current survey data to investigate these questions.

Title: A Multi-Species Study of Grasshopper Phenology, Distribution and Body Size Responses to Climate Changes in the Front Range of Colorado.

Summary

This project utilizes the recently curated and databased Alexander grasshopper collection coupled with a new resurvey program to measure the effects of climate change on regional insects. The Alexander collection is composed of over 24,000 pinned and labeled grasshoppers collected during the 1930’s to the 1960’s from the Rocky Mountain and plains regions of Colorado. Approximately 14,000 of the 24,000 grasshoppers that make up the Alexander Collection are voucher specimens from a three year (1958-1960) survey project.  During these survey years, Alexander processed over 65,000 grasshoppers from repeatedly sampled sites along an elevational gradient from Boulder (1530 m elev.) to Niwot Ridge (3,660 m) in the Colorado Front Range.  Because of the quality and type of data available, this project will be able to determine the effects of a changing climate on the 1) phenology (timing of life history events), 2) elevational ranges and 3) morphological characteristics (namely body size) of a well studied and economically important group of organisms. A unique contribution of this project is its ability to utilize over 36 species to determine which life history characteristics may make certain grasshopper (or other insect) species more likely to respond to climate change. 


2)Related to this is a long-term butterfly monitoring project, begun in 2001, to look at the status of butterfly communities in the native habitats surrounding Boulder Colorado.  We are looking at how butterfly communities were affected by the drought in 2002 and the ability of communities in different habitat types to recover from this drought.