Eavesdropping on Herbivores: Using contact microphones to quantify Plant-Insect Interactions

Abstract

O_LIHerbivorous insects are major crop pests whose feeding often results in significant economic damage. Detecting and monitoring insect herbivory is crucial for effective pest management, but manual methods can be time-consuming, inefficient, and destructive. This study investigates the use of contact microphones as a non-invasive and efficient tool for detecting, identifying, and monitoring insects feeding on plants. C_LIO_LIApproach and methods: Contact microphones connected to a Raspberry Pi were clipped onto plant stems and programmed to record sounds made by the feeding insects. Three combinations of herbivorous insects and plants were evaluated: tobacco hornworm (Manduca sexta Linnaeus) on tobacco, Colorado potato beetle (Leptinotarsa decemlineata Say) on potato, and European corn borer (Ostrinia nubilalis Hubner) and Northern corn rootworm (Diabrotica barberi Smith & Lawrence) on corn (Zea mays Linnaeus). Sound recordings were analyzed to determine the presence and absence of insects and to quantify differences in feeding activity between different insects. The laboratory study was repeated in a corn field to observe corn rootworms (Diabrotica spp.). C_LIO_LIMain results: Contact microphones successfully detected insect herbivory on the tobacco, potato, and corn plants in the lab and field, demonstrating the use of substrate-born acoustic signals for detecting both large and small-bodied insect pests. The recordings also revealed differences in the feeding patterns, frequency, and amplitude between insect species. Field experiments indicate low background noise relative to lab experiments. C_LIO_LIConclusions and implications: Contact microphones offer a promising cost-effective, non-destructive, and efficient method for monitoring insect herbivory. This approach has the potential to improve scientific observations of insect herbivores and pest management strategies by enabling early pest detection and measuring the success of interventions. Early field results indicate the viability of this approach under realistic conditions in the field. The results highlight the importance of considering the acoustic environment in agricultural ecosystems, suggesting sound can be used to better understand the behavior of insects and their interactions with plant hosts. Contact microphones could have widespread applications in agriculture and ecology by providing a simple and effective tool for detecting and monitoring insect activity. C_LI