Gall wasps are small, neutral colored plant parasites that elicit a strange reaction from their host plants (Fig. 1). The gall wasps are able to stimulate a buildup of plant tissues surrounding them, which becomes both home and food for the immature wasp (Fig. 2). Although these galls are often species-specific in shape, color, size, host plant, and location, the relationship between different species of gall wasps remains shrouded in uncertainty. Cooke’s research centers around discovering how many species of gall wasps exist today and how they fit onto the tree of life. One of the best and newest ways to answer these questions is to use Ultra Conserved Elements (UCEs). These are regions of the genome that are exactly the same between species, but the flanking regions (the sections immediately before and after the UCE) have changed over time and can help scientists track the evolution of different species. Using UCEs, Cooke was able to identify several genera of gall wasps that are polyphyletic (a group of organisms that do not share a recent common ancestor), suggesting that our current hypotheses of evolutionary relationships need a major overhaul. One of the explanations for this problem is that the global distribution of wasps has changed through time, with several groups shifting between the Palearctic (northern Africa, Europe, and northern Asia) and Nearctic (North America) realms. This led to scientists overlooking the relationships between gall wasps on different continents.
S. Augusta Maccracken is a 4th year PhD Candidate in the Department of Entomology at the University of Maryland, College Park and in the Department of Paleobiology at the Smithsonian Institution National Museum of Natural History. She studies insect mediated damage on fossil leaves to reconstruct ancient plant-insect associations.
Jackie Hoban is a Masters Student in the Department of Entomology at the University of Maryland, College Park. She studies emerald ash borer biological control under the direction of Dr. Paula Shrewsbury.