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No Nose, No Mouth, No Problem: the Silkmoth Story

Hi all! I’m Jess. I’m a senior neuroscience major from Westminster College in Salt Lake City, UT. It’s a small, private liberal arts school you’ve probably never heard of, but I promise you it’s the best small, private liberal arts school you’ve probably never heard of (with an awesome neuroscience program). Prior to my academic endeavors, I was a U.S. Ski Team member and competed in the sport of slopestyle, which involves a variety of jumps, spins, and grabs through the terrain park.

Training at Keystone Mountain, CO in December 2015

After four seasons on the ski team, I retired to pursue my degree. I still ski in my free time, but have also picked up a variety of hobbies including, climbing, mountain biking, and canyoneering. So far, the mountain biking in the Ann Arbor area has been amazing, and I look forward to exploring more!


This summer I will be working on Bombyx mori, or the domestic silkworm moth. In addition to producing valuable silk, this species has been well studied due to its interesting mating behavior. As shown below, silkworm moths go through multiple stages of development. Most of their life is spent in a larval stage eating mulberry leaves. Once they are large enough, they spin a silk cocoon around themselves and develop into a moth.

Silkworm moths only live to 5-10 days after emerging from their cocoon because they are incapable of eating or drinking. Their singular goal during this time is to find a mate as quickly as possible and reproduce. Observations from the early 1900s reported that female moths were unable to attract males if they were covered by a glass cup. This suggested that the females were emitting some sort of chemical to attract the males, but how could the male silkmoths sense it without a nose?


It turns out that silkmoths males have extremely sensitive antenna that are capable of detecting pheromones, or chemical substances that cause a change in behavior. Further, female silkmoths release a pheromone called bombykol that attracts males up to 10 kilometers away. Crazy. This discovery initiated a field of research investigating the molecular and neural mechanisms responsible for mating behavior in silkmoths.


Adult male silkmoth with pronounced antennas

This is an accessible insect that has a tractable behavior, so you may ask yourself, “How has Backyard Brains never studied this!?” Well, we have. While significant progress was made in the summer of 2015, the project was never completed. This summer, I will be revamping this project with the goal of producing a lab for the classroom. I will be changing the behavioral task, adding some different stimulants, and investing local field potentials in higher order brain structures in addition to electroantennogram recordings.


I am currently in the midst of ordering materials. The moths are going to take a bit of time to get here and hatch, so in that time I will be trying out my new methods on cockroaches and seeing if they will work. Wish me luck!

Smells like teen spirit-Moth antenna pheromone receptors

Greetings, this is Trevor coming live from Ann Arbor in a basement…








We have one week left in the internship and things are finally starting to come together. Last time I made a post, I was without a doubt on the struggle bus in terms of getting data worthy of a poster, let alone a journal article. Since that point I have learned a hell of a lot of what not to do while recording data. First, always make sure everything is plugged in, second, make sure your specimen is alive, and last always make sure your equipment is hooked up everywhere it should be. You may think I’m weird for this, but I think my moths are pretty cute. A couple weeks ago I was having a really hard time getting clear recording from the BYB Spikerbox due to so much activity happening in the antennae, and as a result we switched to the SpikerShield to get an electroantennogram recordings. Electroantennogram recordings are low frequency, are the preferred way to record antennae stimulus and look like this:

Before I started testing the sex pheromone bombykol on the moths, I characterized how the male moths responded when introduced to their female counterparts, and it is best described as a circling motion in a zigzag path towards the female. It happens almost every time a female is brought within a couple feet of a male, but is not present when stimulated with just any odorant, like lemon oil or peppermint.The male seems significantly less enthused about the lemon than about the female, I wonder why?

The male seems significantly less enthused about the lemon than about the female-I wonder why?


Once I had that complete I began trials with bombykol using a new delivery system that went through many revisions. At first we were using a valve system to deliver odors via an air stream, but we observed a change in airflow when opening valves, which meant we couldn’t be sure if the neuronal responses we got were from the change in airflow or the added odorant. To fix this problem, we inserted syringes into the piping with some T-junctions on the way to the moth, thus keeping a constant air stream.

Now I needed a way to consistently empty the syringes, so for that I added a linear actuator and a wood based housing to hold the actuator and syringes. The housing, entitled “Mr. Orange” due to its bright orange paint job and my love for Reservoir Dogs, has three ports for three syringes, to serve as an air control, other odorant positive control, and pheromone syringes all in one recording. Along the way, thanks to our fearless leader Greg I had to edit the housing from two to three syringe ports just minutes after completing the project…


Are you happy now, Greg?

Before “Mr. Orange” was built I was able to successfully record a bombykol stimulus on the last day of my second batch of moths. Displayed below is Bombykol compared to a negative control, aka clean air. Remember they only live 5-10 to days, and have to be ordered, so my time working with them is precious! I am currently awaiting new moths so that I can do my final trials which will involve mulberry leaves, which their caterpillars live on and eat, as a positive control for both male and female moths. This will allow me to show that both males and females react similarly to one stimulus (and ensure the prep is working), but also that they have evolved such that males are much more sensitive to bombykol than females.


Last but not least, the interns all presented last week at MID-SURE, a poster session on Michigan State University’s campus in East Lansing, and I have included my poster below for anyone curious.


Mothman Spotted in Ann Arbor

Hey! What’s up? My name is Trevor Smith, currently a senior at the fabulous Michigan State University, and I am lucky enough to be participating in an internship at Backyard Brains this summer. I am currently working on pheromone detection in moth antennae, specifically how sensitive male moths antennae are to the female pheromone used in locating a mate. Moths are renowned for their bushy antennae, which look much like combs. I have chosen to study the silkmoth (Bombyx Mori) as my test subject. They are very well studied, as their pupae are used for silk production. What’s novel about these moths is that the males can detect the female pheromone (Bombykol) from up to 11 km away! This is incredible as the pheromone is released and stays in the air for only a short time. The males sense the bombykol from great distances and travel to the secreting female to mate. It is very important that the male can detect the bombykol because once hatched from their cocoon they only have 5-10 days to mate before they die-try that one as a pickup line!


My task this summer will be to track the unique spikes from the antennae, and show just how sensitive the antennae are to this compared to other stimulation. It is my primitive hypothesis that the spikes from the pheromone will be easy to elicit upon first contact, and will linger for a short time after exposure. Silkmoths lifespans are very short and seasonal due to the metamorphic process they undergo, so although I am working with moths this summer, I am currently waiting for my moths to reveal themselves from their cocoons.


In the mean time I have been working with the main specimen of Backyard Brains, the beloved cockroach. As we all know from the remarkable SpikerBoxes BYB has created, we are now very easily and in a cost effective way able to track spikes off cockroach legs. (Thanks Trevor, your check’s in the mail-editor)  In preparation for my work with the moths I have been attempting to track spikes from cockroach antennae. Through the method known as an electroantennogram (EAG), in which you isolate the antennae and place two electrodes on both ends, I have been able to record spikes from these antennae.


Along the way I have encountered several hiccups, along with a learning curve to understand the basics of how these pheromone work in specific receptors in the antennae. From the simple problems, such as putting the wrong end of the aux cord into the Spikerbox, to figuring out how to properly use a Faraday cage to isolate the specimen I have been able to expand my knowledge on to properly conduct scientific methods and procedures. I am far from mastering this craft, but as Greg, a founder of BYB, has explained to us: Most people will quit after a few failures on the bench, it’s not until you use these failures to learn, that you will truly succeed. It is my full intention to continue upon my failures and strive to progress everyday on my project, and make meaningful goals each day.

Currently I am working on a new set-up based on an existing method to deliver olfactory stimulus to a cockroach antennae. In order to deliver a specific smell to an antenna you need a couple things. First you need constant airflow over the antennae to ensure you are not tracking the spikes from initial air stimulus. Second you need a way to deliver the stimulus under controlled setting, and third you need a way to combine the constant airflow and stimulus and be able to turn the stimulus on and off. Using an air mattress pumps, a series of clear tubing and a few self fabricated boxes I am reconstructing a way to deliver a stimulus to the antennae. I am currently still working on some of the kinks, but hope to soon track spikes specifically from an olfactory stimulus soon!

Air Pumps