Codella's Research Program
As an evolutionary ecologist and entomologist, I have a wide variety of biological interests. For much of my career, I have investigated the strategies by which plant-feeding insects defend themselves against predators. This has included investigations of warning coloration and mimicry in swallowatil butterflies (Lepidoptera: Papilionidae), as well as studies of interactions between conifer sawflies and predaceous wood ants (Hymenoptera: Diprionidae, Formicidae). My sawfly-ant work first focused on the mediating effect of tree chemistry on sawfly chemical and gregarious defenses against ants; more recently, I have continued to explore this system from additional directions. Conifer sawflies have undergone rapid evolutionary diversification and show much interspecific variation in traits that affect predator avoidance. Thus, they present an excellent opportunity to compare the defense strategies of closely related species and to determine if natural selection has played a role in tailoring these traits to different environments. I am addressing this issue through the study of material housed at the National Museum of Natural History. From the ants' perspective, I am interested in how prey defenses in general alter the foraging dynamics of social insects. My previous work has suggested that sawfly defenses against ants function by altering the economics of food acquisition, thereby making defended prey relatively unprofitable to harvest. This aspect of my research entails field studies at Great Swamp National Wildlife Refuge, Morris County.
Currently, however, most of my research attention is focused on insect biodiversity, particularly in urban settings. I made this shift for several logistical and conceptual reasons. Biodiversity studies provide a clear path by which undergraduates in a metropolitan setting can participate meaningfully in my lab’s activities. Concerns about biological diversity are no longer limited to so-called “wilderness areas” but includes increasing study of urbanized environments. Urban agglomerations have dramatically increased over the past century; today, 47% of the world’s population lives in urban areas, and this is expected to increase to 60% by 2030. So investigations of urban biodiversity are highly relevant to the life of the average person, and such studies will play an increasingly important role in park design, groundwater management, public health, pest management, and other aspects of urban planning. Here in northeastern New Jersey, where undisturbed areas are scarce and development is ceaseless, the documentation of biodiversity requires immediate attention. We hypothesize that the “green islands” found within and near cities, including parks, cemeteries, vacant fields, corporate campuses, etc., harbor unexpected levels of biological diversity. This is especially likely for inconspicuous animals such as insects, which are overlooked by nearly everyone and yet play a key role in virtually all terrestrial ecosystems.
Within the hyperdiverse Arthropoda, the insect order Hymenoptera is a valuable focus for biodiversity surveys. This order includes the sawflies and ants, which were the focus of my previous behavioral work, as well as the wasps and bees. The Hymenoptera is one of the largest insect orders: over 100,000 species have been described, and the actual number may exceed 500,000. Through both detrimental (e. g., crop and timber destruction) and beneficial (e. g., pollination, biological control, nutrient cycling) pathways, the activity of these insects has profound effects on the global economy. Many hymenopterans are “keystone” species whose removal influences the status of many other species within an area; therefore, their diversity affects the overall “health” of an ecosystem. Ironically, hymenopterans are also very sensitive to environmental conditions, and so they are often negatively impacted by habitat degradation, including the residual presence of pesticides and other toxins.
Since 1998, my research assistants and I have collaborated on a variety of biodiversity assessments, both here in New Jersey and in the Cayman Islands in the Caribbean. Right now, our focus is Watchung Reservation, a 2000-acre preserve between Mountainside and Summit in Union County. This work has been carried out with the cooperation of the Trailside Nature and Science Center and the Union County Department of Parks, Recreation and Facilities. Watchung encompasses land whose historical significance dates back to presettlement times. Today, it is a large, heterogeneous green space amidst a densely populated urban area, and it includes a diverse array of forested, open and aquatic habitats. Due to its many recreational attractions, the Reservation is heavily utilized by the surrounding communities. In 1986, after years of legal battles, the Federal Highway Administration completed Interstate 78 by routing 3.5 miles of the highway through the Reservation. Despite its “environmentally enlightened” design, which minimizes the visual impact of the road and provides corridor bridges for wildlife, the presence of I-78 could have a potentially major impact on biodiversity. Since 2000, my students and I have been sampling Watchung’s hymenopterans, primarily in the conifer stands scattered throughout the Reservation. To date, we have processed over 3000 specimens representing at least 160 species. Ultimately, we are interested not only in documenting hymenopteran biodiversity at Watchung, but also in exploring the effects of human activity on this diversity.
My research program offers a variety of opportunities for motivated
undergraduates. Contact me
if interested!