Insects exist on a different slice of reality. Even with their smaller brains, insects are able to see, taste, and smell many things that even the most anthropocentric among us cannot. As Dr. Zain Syed described in his Entomology Department colloquium seminar, the ways insects smell what we cannot are fascinating, and how we can take advantage of that fact can be very important.
Like all entomologists, Dr. Syed breaks the life cycle of insects into distinct stages of development. For the spotted wing drosophila (SWD or Drosophila suzukii), a serious fruit pest throughout the globe, the adult females cycle from mating on
When the female is ready to mate, she emits and senses a range of conspecific odors, commonly referred to as sex pheromones; when she is ready to lay eggs, she seeks the odors of fresh fruit. Just as you may follow the smell of fresh cookies into the kitchen, flies can recognize when objects produce scents that are important to them. Dr. Syed and his research team can further break this down into two parts: what does the fly smell and how do they smell it?
To answer this question, they sampled the odors that were produced by his yeasts using solid-phase microextraction (SPME) to see if they were different. They were in fact different – qualitatively and quantitatively - with each yeast isolate producing a very complex and wide range of odorant repertoire. Approaching the point of despair at interpreting all of his data, a statistician swooped in to save the day. The statistician was able to distinguish between the yeasts based solely on the odors they produce.
Since it is unlikely the flies have access to SPME and a statistician while searching for rotting fruit in the field, Dr. Syed is working to determine what chemicals in these odors flies use to identify these yeasts during each stage of their lifecycle. He then plans to use these chemicals to create traps for the Spotted Wing Drosophila that take advantage of their unique attraction to the smell of yeast growing on fresh fruit.
Scheidler, N. H., Liu, C., Hamby, K. A., Zalom, F. G., & Syed, Z. (2015). Volatile codes: Correlation of olfactory signals and reception in Drosophila-yeast chemical communication. Scientific reports, 5, 14059.
Hickner, P. V., Rivaldi, C. L., Johnson, C. M., Siddappaji, M., Raster, G. J., & Syed, Z. (2016). The making of a pest: Insights from the evolution of chemosensory receptor families in a pestiferous and invasive fly, Drosophila suzukii. BMC genomics, 17(1), 648.
About the author:
Brian Lovett is a PhD student in Dr. Raymond St. Leger’s Lab studying mycology and genetics in agricultural and vector biology systems. He is currently working on projects analyzing mycorrhizal interactions in agricultural systems, the transcriptomics of malaria vector mosquitoes, and the genomes of entomopathogenic fungi.
At the first Entomology colloquium of the Spring 2017 semester, Dr. Zain Sayed described his work on the agricultural pest spotted wing drosophila. His work unravels how female flies use odors from yeasts growing on fruit to find their mates.