Evolution of Host Plant Use by Hawaiian Planthoppers

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9981513RoderickWhen organisms colonize or invade new habitats, their biology can change in dramatic ways. This process, called adaptation, is often critical to the success of biological organisms when faced with new environments. One way that plant-feeding insects can change when entering new habitats is to switch to feeding on new and different types of plants. A striking example of this type of change is seen in a group of sap-feeding insects called planthoppers in the family Delphacidae. Most delphacids world-wide are specialized to feed solely on grasses and sedges (both monocots). Planthopper species in this group include notable pests of rice and maize. After colonizing the islands of the Pacific, where there are relatively few native grasses and sedges, these insects have evolved to feed on an amazing variety of host plants. In fact, different species of planthoppers now feed on plants in a total of 28 plant families, mostly dicots, in Hawaii alone. Similar patterns are found on other Pacific archipelagos, including the Society Islands and the Marquesas in French Polynesia.This project will use information from DNA sequences to understand the pattern of changes that must have taken place for these insects to switch hosts. In addition, the results will shed light on the so-called adaptive radiation of insects which have now diversified in concert with these hosts within Hawaii and the insular Pacific. The project takes advantage of the historical temporal "snapshots" provided by the geological history of Pacific archipelagos such as Hawaii. The research also focuses on the diverse, yet little studied, endemic terrestrial fauna of this region.As part of this research, a graduate student and a postdoctoral fellow will be trained in the biology and systematics of this group of insects (the Delphacidae) and in particular, the tribe Delphacini, a taxonomic group of both great economic and scientific importance.