Collaborative Research: Competition for acoustic space as a driver of species diversity in vibrationally-signaling insects

Alarming worldwide insect declines have widespread effects on ecological communities, ranging from bird population reductions to decreased ecological functioning. Understanding how the environment shapes insect diversity is critical to combat these rapidly declining insect populations. In this project, the researchers test whether vibrational communication in insects contributes to these patterns. While many insects use sound to communicate, the vast majority of singing insects (>90%) use sound that travels as tiny vibrations through plant stems and leaves. These vibrational signals are important for processes like territorial disputes and mate attraction. However, the signals may be disrupted if other insects living on the same plant produce similar vibrational signals. The researchers test whether communities of vibrationally signaling insects avoid overlap in their signals. If so, then this partitioning of vibrational acoustic space could shape which insects live together. Thus, anything affecting how many different types of vibrational signals can occur on the vegetation would also directly affect the number of insect species living there. The results of the work could open new avenues of research on insect diversity, highlight the untapped potential of vibrational signals to monitor insect communities, and provide insight into how human impacts on vegetation affects insect communities. In addition to testing a novel hypothesis for the environmental variables shaping insect communities, this project will provide multiple training opportunities for a diversity of students. The proposed work tests the acoustic niche hypothesis in shaping prairie insect communities through a novel lens—vibrational signaling space. Competition for the vibrational space on any given plant can restrict the types of vibrational signals that can coexist. Due to the species-specificity of vibrational signals, competition should therefore also restrict insect diversity. The researchers test this novel hypothesis in insect communities living in prairies with varying management histories and current practices. Vibrations and insects will be collected from multiple 1-m radius plots on each of six prairies. Using piezo recorders that pick up tiny insect vibrations from plants, the researchers will record the vibrations in each plot over 24-48 hours. Then, they will immediately collect insects from the plot using a standardized time period of beat netting. Additional intensive recordings from a subset of sites will be conducted to optimize longer-term vibrational sampling strategies. The researchers will process the vibrational data using machine learning algorithms and look for vibrational space partitioning, compare vibrational acoustic diversity indices to insect species diversity indices, and develop novel toolsets for using vibrations to monitor insect communities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.