Why should we study caterpillars? Introduction Aug. 5, 2011

Climate change affects the number of caterpillars there are. Climate impacts parasitoids. If there are not enough parasitoids, there are too many caterpillars and plant bio mass decreases and the community structure changes.

“It is irresponsible to not study climate change and loss of biodiversity.”

     -Dr. Lee Dyer

Leading my Earthwatch expedition is biologist Lee Dyer from the University of Nevada. Lee has been working with Earthwatch volunteers studying biodiversity and climate change since 2002. Lee briefed us on the project by teaching terms for what we would observe. Here is a small part of what I learned. I will collect over 100 caterpillars. Our team will study multitrophic interactions. Studying multitrophic interactions means to study food chains, i.e., who eats who. Specifically we would be looking at tritrophic interactions, interactions between three types of living things: plants, caterpillars, and parasitoids. A parasite is a life form that lives off of another life form, like fleas on a dog. A parasitoid is a parasite that actually kills its host over time. Wasps and flies are the parasitoids whose eggs and larvae grow in caterpillars.

The parasitoid feeds off the host caterpillar and then bursts out of the caterpillar body as a larva or even an adult! The parasitoids of the project have ovipositors, which are modified stingers that females use to lay their eggs. Wasps have hard, piercing ovipositors that inject eggs into soft caterpillar bodies. Along with eggs, wasps may also inject viruses or toxins that make it hard for a caterpillar’s immune system to kill the eggs or kill the larvae once they hatch and begin to feed on them internally.  So, we will go out to collect caterpillars, put them in Ziploc bags with their plant material, take macro photos and data, and then feed and maintain them in our “zoo” (lab). Over time we will watch and see the internal parasitoids appear. 

 “The major goal of the project is to measure tritrophic interaction diversity: species richness, evenness, abundance, species turnover, keystone species.”