Earthwatch Scientists: Dr. Lee Dyer, Dr. Harold Greeney,
Dr. Tom Walla, and Andrea Glassmire
On this project- Climate Change and Caterpillars in Arizona- we examine the factors that affect interactions among plants, caterpillars, and their natural enemies. This
is an important area of study for both agricultural and basic ecology. This three-tiered study system allows for insights into
“tri-trophic” interactions— in other words, it examines the relationships among three distinct levels of the food web. You
will conduct caterpillar research in the deserts and mountains around the Southwest Research Station in the Chiricahua
Mountains and the nearby Santa Rita Experimental Range in the Coronado National Forest. Other Earthwatch teams
conduct work throughout the year in forests and mountains in Nevada and California; a rainforest at La Selva Biological
Station in Costa Rica; a cloud forest at Yanayacu Biological Station in Ecuador; and in urban areas, swamps, and
bottomland hardwood forests around New Orleans, Louisiana.
The natural enemies of caterpillars that the project studies are called “parasitoids.” They include many species of wasps and flies that kill caterpillars by depositing their eggs on them. This ensures that the parasitoids’ offspring will have both a safe environment in which to grow (inside the caterpillar) and a good supply of food (caterpillar tissue). We are rearing caterpillars of over 300 species and recording the mortality caused by the parasitoids. In addition, we isolate specific chemical compounds from some species of caterpillars and food plants to examine them as potential defenses against parasitoids.
By comparing the results from different sites, we can test hypotheses about the effects of climate on interactions between
caterpillars and parasitoids. Our study also collects essential natural history information about plants, caterpillars, and
parasitoids. Based on our data, we are developing models to predict which parasitoids might be used to control specific
insect pests of human crops, which will benefit farmers who are attempting to control pests without using pesticides.
Some of the species that we study (such as army worms and owl butterfly caterpillars) are agricultural pests; others (such
as some rare day flying moths) are threatened by habitat loss and fragmentation.
The caterpillars are fascinating: they come in a spectacular diversity of shapes, colors, and forms that
function to defend them against their enemies. Many of the species found by this project will be new to science.
