research

Research in the lab is motivated by the need for a mechanistic understanding of the biotic and abiotic effects driving spatiotemporal patterns in insect or disease dynamics, with a goal toward mitigating impacts to agricultural, natural, and urban ecosystems. Our research draws from concepts and methods in invasion biology, plant-insect interactions, disease ecology, quantitative ecology, and regulatory entomology. This typically involves asking basic ecological questions, using experiments or field surveys complemented by a bit of modeling, in applied systems

The following sections highlight a handful of recent research projects

Minimizing the potential for nursery stock to contribute to GWSS spread

Following the invasion of the glassy-winged sharpshooter (GWSS; Homalodisca vitripennis) into California, restrictions were placed on the movement of plant material to limit the unintentional spread of this important vector of Pierce’s disease and other plant diseases caused by the bacterium Xylella fastidiosa. One of the challenges with GWSS is it's broad host range, which includes 100s of plant taxa, including some of the most commonly grown ornamentals. Ongoing research is assessing the effectiveness of a 25 year quarantine program and investigating other methods to further mitigate the impact of GWSS in nursery operations

Climatic effects on ACP and biocontrol

The Asian citrus psyllid (Diaphorina citri; ACP) and huanglongbing (HLB) have proven to be highly invasive throughout the Americas. Following the first detection of ACP in a residential area of Southern California in 2008, it spread rapidly throughout the region. Since then ACP has become established in areas further to the north, albeit at much lower densities. Currently, it not clear how suitable cooler growing regions are for ACP and HLB. A pair of projects are attempting to gain a better understanding of 1) the risk ACP and HLB may pose to cooler citrus growing regions of the US, and 2) the geographic range over which the parasitoid Tamarixia radiata is likely to contribute significantly to ACP biocontrol

Current status and impact of GWSS biocontrol

Biological control has been an important element of the statewide response to the invasion of GWSS in California for more than two decades. This has included a mass-rearing and release program for multiple species of egg parasitoids (Cosmocomoidea spp.) by the California Department of Food & Agriculture in select grape and citrus growing regions. However, little contemporary information exists on the impact of these biocontrol agents, including in areas that have recently seen a resurgence in GWSS populations. Working with CDFA personnel, we are analyzing long-term program data to estimate the magnitude of egg parasitism, identify the wasp taxa most strongly associated with parasitism, and explore temporal and spatial sources of variability in GWSS biocontrol

Effectiveness of ACP control programs in residential citrus

Residential citrus played a central role in the initial invasion of ACP and, more recently, HLB incidence in California. Attempts to slow HLB spread rely on removal of infected trees to limit inoculum supply, and vector control via insecticide treatments in the surrounding neighborhood and releases of Tamarixia radiata. However, despite well over a decade of vector control efforts in select residential areas of Southern California, it is not clear how effective they have been. Working in collaboration with CDFA personnel, we have been analyzing the individual and combined effect of treatments and parasitoid releases to quantify their impact on ACP populations in residential citrus

Geospatial analysis of insect invasions

State and federal regulatory agencies often conduct large-scale monitoring programs to track the spatial extent of plant and animal invasions. This information is typically used to define regulatory response, such as what areas to quarantine or prioritize for treatment. We have been repurposing these robust datasets, leveraging them to gain additional insights into the climatic, landscape, and anthropogenic factors driving invasions. For example, we've used a combination of geospatial tools and habitat suitability modeling to reconstruct the successful eradication of the European grapevine moth (Lobesia botrana), quantify the strength of urban spillover by the Asian citrus psyllid (Diaphorina citri) into commercial citrus groves, and generate predictions for the risk of establishment by a moth pest complex in vineyards along the West Coast

Factors affecting PD epidemiology

Pierce's disease (PD) has affected grape production for as long as grapes have been produced commercially in California. Yet the frequency and severity of disease epidemics are highly variable. Among the longest running research interests in the lab relate to the ecological and environmental factors that drive PD dynamics. Current research being conducted along with collaborators at UC Berkeley and UC Cooperative Extension focuses on characterizing the impact of climate on PD incidence, spatial epidemiology of PD, and the epidemiological significance of overwinter recovery of infected grapevines

Address:

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

Phone:

(951) 827-2246