Drosophila suzukii

I am into my third week with Oregon State University extension and I have broadened my scope of knowledge in two directions I never could have predicted.  The direct object... blueberries. The subject... an invader: only millimeters in size, he boldly wears his identification on his sleeve (well, wing) while she takes refuge in the disguise of similar, but innocuous species, until you see her ovipositor that is: a specialized organ used for egg laying, hers has a hardened and serrated edge that she uses to ruthlessly cut open the sweet, fresh skin of our most beloved of fruits. That's right... it's the dreaded Drosophila suzukii or spotted-wing Drosophila.
Little is known about this infamous creature.  She has traveled the globe looking for her next victim. Native to southeast Asia, they have only been in Oregon since 2008. Unlike most vinegar flies (fruit flies as we laymen like to call them) D. suzukii prefers to lay her eggs in fruit that is just becoming ripe.  The larvae then destroy the fresh fruit, damaging the commercial value.  Each female can lay up to 350 eggs in her short (30 day) life.  With around six generations within a year, each generation increases the population exponentially.  It could become a major pest to northwest growers as it attacks many kinds of fruit: blueberries, cherries, strawberries, peaches, and more.  For blueberry growers, this is the first major pest, and historically they have needed few, if no, pesticides.
The goal of research now is to fully understand the life cycle and control of the flies in this climate.  Where do they overwinter and on what do they feed? What will the best baits be for catching them and monitoring population size? Could we find an attractant/pesticide combo that diminishes the population early in the growing season thereby making the rest of the year manageable? With these important questions, I began my work.
First, we had to go find ourselves some flies.

Off to a local blueberry grower that is a partner for the OSU research.  We set up some traps with various baits. The traps are intended to be easy and cheap for a grower to make themselves.  They are red, Solo party cups, holes drilled in the side with a lid on top to keep out irrigation and dew and filled with a concoction of temptations like banana or apple-cider vinegar. We wait a week and have more flies, even at the end of January, than we could easily count.
Next to the identification:
Male spotted-wing Drosophila are easy.  That's right... they have a spot on their wing.

male D. suzukii

As stated earlier, female spotted-wing Drosophila look a lot like other vinegar flies... red eyes, auburn thorax and banded abdomen.

female D. suzukii

until you pop out her ovipositor.

female ovipositor

The ovipositor of the female spotted-wing Drosophila is unique. Hers is a sclerotized (hardened) ovipositor with serrated edges used to slice open the skin of ripe fruit.

Becoming familiar with spotted-wing Drosophila means being able to distinguish it from similar flies.

One of these flies is not like the other...

With time, the color of her thorax looks slightly off the color of other Drosophila, the bands of her abdomen aren't quite as clear as the others' bands, and the unaided eye starts being able to pick them out with reasonable accuracy that is easily checked under the microscope.

Here lies the foundation for the coming months; hundreds (sometimes thousands) of flies to count in a week, subsampling methods to design and test, numbers to crunch, theories to formulate and test.  It is the scientific process from inception to resolution.  With any luck, it will lead to increased understanding of the flies, more fresh fruit with fewer pesticides.