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My current research focuses on the ecology and behavior of Tephritid fruit flies, particularly on C. capitata, B. orientalis and B. cucurbitae, three of the four species of economic importance in Hawai'i. These pests are a major threat to mainland US agriculture as they are not established there. Previously I spent nearly a decade studying the malaria mosquito A. gambiae in Mali, West Africa.
Estimating the time to extirpation of invasive Medfly
Ceratitis capitata, Medfly, is a major pest of fruit crops around the world. In many areas where it is not established it is seen to recurrently invade, such as in S. California. When Medfly is found in these areas by monitoring programs intensive and costly quarantine and population elimination measures are put into place (in California the latter includes insecticide spraying, host fruit stripping, increased trapping and increased Sterile Insect Releases).
One important question is how long to maintain the quarantine after Medfly is no longer detected. Currently, officials rely on traditional deterministic degree-day modeling to estimate how long, given historical temperature profiles, it should take for three generations of Medfly to pass. Depending on where the find is made, a quarantine can last 9 months or longer. I have developed an Agent Based Simulation (ABS) that allows increased specificity, realism and uniform margins of safety when estimating quarantine lengths. This model is implemented in the software MED-FOES, available for download.
Development and Parametrization of a Trap Network Model
Attractant-based trap networks are important elements of invasive insect detection, pest control, and basic research programs. I led development of a landscape-level, spatially explicit model of trap networks, focused on detection, that incorporates variable attractiveness of traps and a movement model for insect dispersion. The model furthers efforts to optimize trap networks by 1) introducing an accessible and realistic mathematical characterization of the operation of a single trap that lends itself easily to parametrization via field experiments and 2) allowing direct quantification and comparison of sensitivity between trap networks. TrapGrid is a software implementation of the model.
New approaches to quantifying tephritid behavior
Though a lot is known about pest fruit fly behavior, some apects have remained stubbornly hard to measure. This includes the how and why they move over the landscape, and details on their attraction to semiochemicals.
In my laboratory we are addressing both these questions using new approaches. We have been successful in examining the time of attraction to cuelure by Bactrocera cucurbitae, the melon fly, by using a computer vision approach. You can see some details on this method here in a video and there will be more details in an upcoming paper.
We are also attempting to use RFID technology to measure some of the finer-scale life-time behaviors of individual flies. There will be more details on these experiments soon.
The dance of An. gambiae in mating swarms
Anopheles gambiae is currently described in general terms: they form crepuscular swarms near markers of horizontal contrast, and mate recognition may be mediated by wing beat frequencies or through>chemical cues. A more detailed view this process and of differences between known subgroups chromosomal/molecular forms regarding male swarming behavior will significantly improve our understanding of natural selection and mate specificity in the field. Since early 2007 I have been working to localize and trackindividual mosquitoes within swarms in the field using stereoscopic video together with Dr. Tovi Lehmann and Malian collaborators at MRTC. Since 2009 we have been working closely with the Paley Laboratory at the University of Mayland aerospace engineering department to create a semi-supervised 3D tracking system. You can read the first paper to come from this project here and follow later developments on my personal pages.
Service, Leadership and Participation in Professional Activities:
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