100 Chapman Hall
University of California, Riverside
Riverside, CA 92521

(951) 827-2246






.Research Positions.


picture1Studies of biotic interactions are foundational to developing solutions to applied ecological problems, such as: conservation of threatened species, biological control of agricultural pests, and for predicting the timing and severity of disease outbreaks. Research in the lab is motivated by the need for a mechanistic understanding of how species interactions drive insect and disease dynamics. This typically involves asking basic ecological questions, using both experiments and a bit of modeling, in applied biological systems. The following sections highlight recent research projects.  

Transmission ecology and epidemiology of a vector-bourne plant pathogen
Recently a major focus of research has been the ecology of Pierce's disease in vineyards. Ongoing projects are investigating why the invasive vector, glassy-winged sharpshooter (Homalodisca vitripennis), has caused such severe disease outbreaks in the past and what risk it poses for future outbreaks. This work involves collaboration with other researchers at UC Riverside, UC Berkeley, and UC Cooperative Extension.
1. How important is vine-to-vine spread? One of the main hypotheses for why the glassy-winged sharpshooter can cause more severe disease outbreaks relative to native sharpshooters, which are actually more efficient at pathogen transmission, is that it is more likely to promote secondary spread. We're using a combination of epidemiological modeling, a field experiment, and field surveys to test this hypothesis.
2. What role does climate play in Pierce's disease epidemiology?  Several lines of evidence suggest that local evironmental conditions, especially temperature, influence the distribution and abundance of sharpshooters and the pathogen responsible for Pierce's disease. We are using greenhouse transmission studies and field measures of infection dynamics at sites that differ climatically to evaluate the consequences of climate and climate change on disease severity. picture2
3. How does vector behavior influence disease spread? If vectors discriminate between infected and healthy hosts, as is the case with sharpshooters and other vectors of plant pathogens, tolerant host types may be important sources of pathogen spread to more susceptible host types. This hypothesis is being tested by screening several grapevine varieties for resistance versus tolerance to infection, behavior observations of vector preference, and epidemiological modeling. 

Food web complexity, plant productivity, and the biological control of an orchard pest

picture4Omnivorous predators may contribute to or disrupt effective pest management compared to strict predators, depending on the specific form of omnivory. We studied the role food web complexity and plant productivity play in a relatively complex arthropod food web associated with pear trees in California. In this system an exotic pest, pear psylla (Cacopsylla pyricola) responds strongly to fertilizer additions but is also attacked by a diverse array of generalist predators - which feed on other herbivores, engage in intraguild predation, and even feed on pear tree foliage. Research has involved a suite of omnivory models to predict food web dynamics, stable isotopes to attempt to quantify trophic structure, and field experiments to evaluate the relative importance of top-down versus bottom-up pest control.

Context dependent interactions in container insect communities
Traditionally, species interactions were viewed as static in nature, consistently fitting into one of a handful of discrete categories. More recent work has documented that the strength or type of interaction shifts according to the specific ecological context. Work with Steve Juliano investigated interactions among filter-feeding mosquito larvae (Aedes triseriatus) and leaf scraping Scirtid beetles to test for context-dependent shifts predicted by processing chain interaction models.  

Department of Entomology
University of California, Riverside
Riverside, CA 92521