Spring 9701082 The lubber grasshopper can take noxious chemicals (including herbicides) from its diet and store them in its body. The composition and quantities of these sequestered chemicals depends on the internal, physiological capabilities of an individual grasshopper. These qequestrative abilities, and the compositions of secretions, vary greatly among individuals. This physiological variation can be characterized by isolating segments of the grasshopper gut. Further, when attacked by predators, the grasshoppers secrete the noxious chemicals as a deterrent. The PI can perform experiments using collected secretion and live ants to test the defensive efficacy of specific secretion samples. This provides us with a system to examine the role of internal, physiological variations on an animal's interactions with other organisms. One of the chemicals that lubber grasshoppers sequester from their diet is the common herbicide 2,4-dichlorophenol (2,4-D). This herbicide is commercially available in radioactive form, making it relatively easy to detect and measure in the defensive secretion. The PIs can measure the amount of 2,4-D in the secretion of individual grasshoppers, and then test the relative level of ant deterrence for each secretion sample. Thus, we can not only measure the internal, physiological variation in the uptake of 2,4-D but also characterize the role of that variation in ecological interactions.
