School is out, but the Spotted Wing Drosophila Research Group is doing all kinds of awesome science at the University of Hawai‘i, Hilo. Our research group is studying the evolutionary ecology of an invasive species- Spotted Wing Drosophila (SWD) also known as Drosophila suzukii in the Hawaiian Islands. SWD is a significant pest of important food crops like blueberries, strawberries, and raspberries. They are native to east Asia, and were unintentionally introduced to Hawai‘i in the 1980s. In Hawai‘i, SWD can use the fruits of the native ‘ohelo (Vaccinium reticulatum) as a host, as well as the highly invasive strawberry guava (Psidium cattleyanum). Female SWD damages these fruits by using their serrated ovipositor to lay eggs in the unsuspecting fruit. The eggs subsequently hatch into larvae in the fruit, and eat the flesh on the inside of the fruit to fuel their growth. Eventually the larvae pupates, and emerges as an adult from the compromised fruit to start the whole cycle again.
 
The University of Hawai‘i, Hilo research group is studying SWD’s ability to adapt to seasonal variation in Hawai‘i (yes it can get cold here in the winter, especially at high elevation!). NSF-REU intern Marcel Jardeleza is measuring wing size variation of natural populations of SWD on Mauna Loa Volcano collected over a 6-month period. She is interested in determining whether SWD wing size changes over time in response to seasonal temperature variability. USDA-ARS student technician Daniel Martinez is raising wild caught Hawaiian SWD populations in the lab to determine if wing size variation is genetically inherited in wild populations, or due to environmental variability. Below are some photos of the University of Hawai‘i, Hilo Research Group hard at work!

Last week I went to O'ahu to collect Drosophila suzukii (Diptera: Drosophilidae) for my National Science Foundation postdoctoral fellowship. As part of my postdoctoral fellowship I am studying the population genetic structure of D. suzukii in its invasive range in the Hawaiian Islands. One of the things I am interested in learning is whether D. suzukii populations have begun to diverge across the island chain.

I grew up in Wai'anae on O'ahu from the age of 9 on to high school, and then left for college at the University of Hawai'i in Hilo on the "Big Island". Mauna Ka'ala in Wai'anae was the first place D. suzukii was detected in the Hawaiian Islands (Kaneshiro, 1982). Thus, the most exciting coincidence about surveying for insects in Mauna Ka'ala is that this mountain was the backdrop of my childhood! My first home was behind Tamura Store in Wai'anae, then on Wai'anae Valley Road by "Ark of Safety" church, then in front of Tamura Store, then in Mā'ili across the street from "Tumble Land", then finally out in Mākaha on Holt Street. Now, if you grew up in Wai'anae, you would know location, and maybe significance, of  all of these places. 

It is crazy to think that while I lived in Wai'anae during an important portion of my life, I never actually went up to Mauna Ka'ala as a kid. For my family and even my friends, it wasn't very common to go hiking in the mountains. However, like many 4th graders at Wai'anae Elementary School I did visit the lo'i at Ka'ala farms, but never went up the mountain itself. So, it was exciting to go back home and do research that I think is constructive, and has real value for the place I call home. I hope that my current project on invasive D. suzukii in Hawai'i is just the beginning of the research I will be doing back in Wai'anae.

For more information on this project please visit the SWD Research Group page. 

References:

Kaneshiro K. (1983) Drosophila (Sophophora) suzukii (Matsumura). Notes and Exhibitions. Proceedings of the Hawaiian Entomological Society, 24, 179.

This summer, I had the pleasure of working with NSF-REU/PIPES intern Nadiatou Ouedraogo. Nadia is an undergraduate student majoring in Biology. For her internship, Nadia investigated body size variation of Spotted Wing Drosophila (SWD) in Hawai'i Island. SWD are invasive to many parts of the world, and Hawai'i is one of the first places they invaded outside of Asia. Given the amount of time that has elapsed since SWD colonized Hawai'i, we are in a prime position to study how this species has evolved to its new, tropical environment.

Body size variation has been identified to be a trait that can be measured in a rapidly invasive insect like SWD (Huey et al. 2000). Thus, Nadia wanted to determine if there were any body size differences in SWD populations across an elevation gradient. For her project, Nadia operated under the conceptual framework of the Temperature Size Rule in ectotherms (Walters & Hassall 2006), whereby insect body size can be predicted by temperature variability.  She measured thorax length, wing length, and wing loading in both males and females from different elevation sites.

Elevation gradients are fantastic analogs of temperature variability, as there is a generalizable negative relationship between elevation and temperature (i.e., increasing elevation = decreasing temperature). Over the course of her ten week PIPES internship, we surveyed SWD on Mauna Loa and Kilauea Volcano, and were able to hike to some pretty cool places in search of flies. At the conclusion of her internship she gave a wonderful presentation of her project, which you watch on YouTube! One of her primary findings is that in Hawai'i, SWD individuals are significantly larger in body size at higher elevations relative to low elevation individuals.

Given our results, we aim to to continue our survey, and are collaborating with a student here at the University of Hawai'i at Hilo to investigate body size variation across seasons. 

Our research is supported in part by a National Science Postdoctoral Fellowship to J. Koch (#1523661) and the National Science Foundation Research Experience for Undergraduates Site Program at the University of Hawai'i at Hilo.  We also would like to thank Dr. Jesse Eiben and Marlena at the University of Hawai'i at Hilo College of Agriculture, Forestry, and Natural Resource Management for kindly providing us with a dissecting scope! 

Last week I went back to the Pacific Northwest in search of bumble bees and their diseases. However, unlike previous years, I had the golden opportunity to survey with Dr. Amber Tripodi, a postdoc in the Strange Bombus Lab at the USDA-ARS Pollinating Insects Research Unit in Logan, UT. It was exciting to show Amber some of the sites and sounds of the an area that I thoroughly enjoyed hiking around and looking for bumble bees over the past several years. In the Pacific Northwest we went to McKenzie Pass, Oregon; Corvallis, Oregon; Lebanon, Oregon; Hoquiam, Washington; Olympic National Park, Washington; Port Angeles, Washington; and La Conner, Washington. I posted a couple of pictures from our trip. Enjoy!  

So I am not the most dedicated person to be writing a blog. And I highly doubt that this attempt will be any different (maybe?). Rather than write about what's new (*ahem* dissertation writing), I will post some pictures that summarize the last 7 years of graduate school. It's always good (but not necessary) to start in the beginning...so here we go- the year 2008, my first year of graduate school at Utah State University. This year also marked my tenure as biological science technician with the USDA-ARS Pollinating Insects Research Unit.