Aphids are insects that tap plant sap as a sole food source. As a consequence of their feeding mode, aphids have sedentary life styles and often build up very large populations. Many aphids in the lineage Aphidinae have specialized in feeding on plant hosts that are important agricultural crops and horticultural species (e.g., many grain crops and fruit trees). Thus, several Aphidinae constitute significant agricultural pests, some quite devastating. Some species also have evolved complicated life cycles that incorporate obligate, seasonal migrations between unrelated plant hosts (for example, between a fruit tree and a grain) over several clonal generations. Aphidinae are also exceptionally species-rich in the northern hemisphere, with only ~1% of the 2500 species native to the southern hemisphere. Several compelling questions concerning the biodiversity, biogeography, and host-plant evolution in this group remain unanswered, however, because relationships among the component species-which could be used to address these questions-are not well understood. This project aims to initiate the study of relationships among Aphidinae aphids, in order to answer questions such as: despite their high biodiversity in the northern hemisphere, did Aphidinae originate in the southern hemisphere? How have host-plant relationships changed through time, and how have these shifts impacted species diversifications? Have complicated life cycles originated multiple times in Aphidinae history? We will collect data from external morphological features and from gene sequences to reconstruct relationships among Aphidinae species. This project will support a graduate student for one year, and will build international collaborations between scientists in the U.S, Canada, New Zealand, China, Argentina, and Europe. Increased insights into morphology of aphids may help in future classification schemes. An improved understanding of Aphidinae relationships may also assist with future biocontrol efforts, informing the selection of appropriate biocontrol agents.
