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- Ph.D., University of California Los Angeles, 2006
- B.A., Reed College, 1997
- 2016-present, Supervisory Research Biologist (Research Leader), USDA-ARS, Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, Hilo, Hawai'i
- 2010-2016, Research Biologist, USDA-ARS, Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, Hilo, Hawai'i
- 2007-2010, Postdoctoral Fellow, NIAID-NIH, Laboratory of Malaria and Vector Research, Bethesda Maryland
My current research focuses on the ecology and behavior of Tephritid fruit flies and other invasive tropical pests that threaten US agriculture. It comprises two disparate but complementary components: 1) Computer modeling and simulation and 2) field experiments, often with application of novel sensing or computer-assisted approaches. Results are applicable to surveillance and eradication programs, including those employing sterile insect technique (SIT) and emerging genetic control technologies.
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. TrapGrid has been used by USDA-APHIS to generate population size estimates for systems approaches against Mediterranean fruit fly and inform trap density decisions in Florida, as well as for a risk analysis for cherry fruit fly in New York. Recently, TrapGrid has been used extensively to improve delimitation in fruit flies and other species including moths and beetles by USDA-APHIS. It has been adapted by CSIRO (Australia) researchers to determine pest prevalence at a farm level. A web-based implementation of the model was commissioned by the International Atomic Energy Agency (IAEA), which has also made it a central feature of an ongoing Research Coordination Project, to be used by researchers from Israel, Mauritius, Australia, South Africa, and Argentina.
Improving Male Annihilation Technique
Male Annihilation Technique (MAT) is a key technology for management and eradication of some Bactrocera fruit flies around the world. MAT is based on application of spots of a powerful male attractant plus an insecticide to attract and kill a large proportion of males thus reducing the growth rate of the population and even eradicating it. The prevailing notion was that the higher the application density (spots per unit area), the higher the effectiveness against males. I designed and led a series of field experiments that collectively indicated that the optimal application density for effective MAT against Bactrocera dorsalis fruit flies is much lower, under half, of that currently used in California and other parts of the world. The finding that a lower density of application points is more effective than a higher one is counter-intuitive and unexpected, though it can be explained by the principle of trap interference, known in the literature for decades, but never considered or tested in the context of MAT. As a result of this work, USDA-APHIS has revised their guidelines on application density to half the previous value as of January 2023, as have agencies overseas (e.g., an Australian areawide project in Malaysia). A reduction in application density will result in improved biosecurity, large cost savings for the material used and labor needed to apply over invasion areas, as well as reduced environmental consequences of the insecticide used in conjunction with the attractant in MAT. For a high-detection year in California such as 2015 the change is estimated to result in $380,000 in direct savings.
Modeling coffee agroecosystems and the pest coffee berry borer
Coffee growers in Hawaii and Puerto Rico have recently been challenged by the introduction of a new invasive pest, the coffee berry borer (CBB) Hypothenemus hampei, first reported in Puerto Rico in 2007 and on Hawaii Island in 2010. The CBB spends the majority of its life cycle within the coffee berries where it is highly protected from control measures. Each attacking female may produce many progeny within a single coffee berry, increasing over 1-2 generations within a single bean before dozens of offspring emerge to attack more beans.
I was the lead scientist in an Areawide IPM project funded by USDA-ARS from 2017 - 2022. I led a comprehensive monitoring system backed by a network of sensors and GIS data integrated with ground data collection on farms within four coffee growing areas on three islands. This monitoring program was the scaffold that enabled research, outreach/technology transfer and assessment components by 1) serving as a baseline against which to compare IPM variations in nearby farms; 2) serving to parameterize the models in development to produce projections of CBB for ecologically diverse locations; and 3) serving as a natural experiment to help us understand how environmental factors affect CBB population dynamics at a fundamental level.
Transfer of the parasitoid Fopius arisanus to Brazil
I performed the transfer, assisted with colony establishment, and participated in host specificity research on the fruit fly natural enemy Fopius arisanus in Brazil, where a member of the oriental fruit fly complex has invaded and is poised to cause serious damage. This accomplishment is critical to the eventual release of F. arisanus in the North of Brazil for control of Bactrocera carambolae, the carambola fruit fly. In support of this accomplishment I produced and published a peer-reviewed video article documenting an ARS-developed rearing methodology for F. arisanus and was consulted by colleagues at The Brazilian Agricultural Research Corporation (EMBRAPA) on implementing this methodology in Brazil. I led and completed experiments on host sex and its effects on F. arisanus to improve safety of parasitoid shipments. I also participated in team research with colleagues at EMBRAPA to examine the host specificity of this parasite when presented with native Brazilian hosts. As of 2023 this parasitoid wasp is established in quarantine in Brazil, awaiting regulatory review and approval for eventual release.
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:
- Member of International Steering Committee, International Symposia on Fruit Flies of Economic Importance (FAO/IAEA) (2020 – present)
- President, Hawaiian Entomological Society (2021 – 2022)
- Editorial Board Member PLoS ONE (2018 – present)
- Editorial Board Member J. Insect Behavior (2018 – present)
- Editorial board member (Ecology and Evolution), Scientific Reports (2015-2018)
- Member of Technical Advisory Group on tephritid trapping; New Zealand Fruit Fly Council (2017-2018).
- Member, American Association for the Advancement of Science
- Member, Entomological Society of America
- Member, Hawai'i Entomological Society
- Led a class on Dynamical Systems Modeling at the Foundation for Advanced Education in the Sciences (NIH) 2009-2010
- Judge, California State Science Fair 1998-2002
Honors, Awards, Achievements and Recognition:
- Elected member, Sigma Xi, The Scientific Research Honor Society, 2021
- Selected by ONP and OIRP for 12-month temporary duty station at the European Biological Control Laboratory in 2019
- Recipient of ESGR Patriot Award 2016
- Recipient of Systems and Integrative Biology Training Grant 2003-2004
- Recipient of California Genetic Resources Conservation Grant 2000-2001