Odd Bug Out: A Leaf Insect Discovery
Every day amazing things are happening at the Museum, and one such thing happened on Monday. I received an email from Bill Reynolds, the Coordinator & Curator of the Arthropod Zoo, with the following text:
Subject: Odd bug in our stick insect colony!
WE have a male in one of our colonies!!!!
Thought it may be note worthy for the blog/twitter.
Of course when one receives an email like this one immediately goes in search of the source, and what I learned was pretty amazing. I knocked on the door and was led into the hustle and bustle of the Arthropod Zoo headquarters. Immediately, I am greeted by Bill, staff and intern. They were ready to reveal the mystery of the “odd bug”. They gently placed a container with leaf insects down in front of me, I looked closely and had to really focus to find the moving critters. A leaf insect is pretty exciting just by itself. For those who are unfamiliar I was looking at the giant leaf insect, which is a large species of leaf insect with the scientific name Phyllium giganteum, and looks exactly like a walking leaf. They are true masters of mimicry! Their camouflage is one of the best systems in nature – not only does their body have leaf “veins”, some of them develop brown edges that mimic a damaged leaf.
I leaned over to get a closer look, and the intern pointed at one slowly moving among the branches. “You see that one?” “That’s a female and the one next to it (she points to the other side) isn’t.” I stared at the two and immediately started to notice the differences – one seemed thinner, had antennae, and translucent wings. It clearly did not look like the others. “So…is something wrong with it? It looks really tiny next to the others,” I commented. At this point, I am still not quite understanding what I am looking at, until the intern points and says, “That’s not suppose to be male.” And then the light bulb goes off and I remember Bill explaining that leaf insects reproduce asexually, and here I was staring at a male. Wait! Aren’t they all suppose to be ladies?
Upon investigation I discovered that some stick insects produce offspring in a very different way: the females can produce young without needing a male! The eggs she produces are unfertilized. They do develop properly and grow into an adult female stick insect. The production of a new individual out of an unfertilized egg is referred to as parthenogenesis. The female that produces these eggs is called parthenogenetic, and is a form of asexual reproduction. It is particularly common amongst arthropods and rotifers, and can also be found in some species of fish, amphibians, birds, and reptiles.
In an email, Bill Reynolds explained the history and discovery of this mystery male:
A few years ago, the Arthropod Zoo received 3 adult Phyllium giganteum for our annual Bugfest event. Knowing these insects were parthenogenetic (all female and asexual), we kept the eggs and 2 years later, they hatched!
After several generations in captivity, we have had good success with these insects and as expected, all have been copies of their mothers – until today, 28 July 2014! While routinely caring for our colony, an oddball individual was picked up by an intern, she came running into my office …. “Look!,” She exclaimed,…”We have a male Phyllium!” At first I thought she had to be mistaken, but she was RIGHT!
The existence of males for this insect species was not proven until 1994. The males are slim, possess long antennae, long translucent green flight wings, and brown legs. The function, purpose or reproductive success of males in this species is debated, but nonetheless, we have a very special bug.
Why is this such an amazing discovery?
Males are very rare, especially in captivity. How this occurs is a very complex topic and researchers are still trying to wrap their minds around it. According to KeepingInsects.com, the leaf insect can be found in tropical forest in Malaysia. This species consists of only females. Two preserved museum specimens of Phyllium giganteum males have been found, but as these have never been seen alive or tested for reproductive capabilities it remains unclear what role males play in natural populations of this species. While there has been some documented cases this discovery is pretty spectacular for us; all thanks to the keen eyesight of an intern. Don’t worry… he is definitely getting the royal treatment in the Arthropod Zoo.
Here is a close-up of our mystery man and comparison with his female counterpart.
For more information about the Arthropod Zoo and Parthenogenesis: