Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2003
Publication Date: 12/1/2003
Citation: Mankin, R.W., Lapointe, S.L. 2003. Listening to the larvae: acoustic detection of Diaprepes abbreviatus (L). Proceedings of Florida State Horticultural Society. 2003. v. 116. p. 304-308. Interpretive Summary: Scientists at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL, and the U.S. Horticultural Research Laboratory, Ft. Pierce, FL, have cooperated in developing and testing new instrumentation to detect hidden infestations of the Diaprepes root weevil in citrus groves. In this study, we tested the operation of a new sensor designed specifically for use in detecting hidden insects in soil. We examined the distributions of sounds and insects around individual trees to consider how the acoustic tools may be used in the future in specific insect detection and control applications.
Technical Abstract: Diaprepes abbreviatus (L.) is an important pest of citrus trees in Florida and the Caribbean. The larvae feed underground on the root systems, reducing productivity and facilitating invasion by root pathogens, including Phytophthora spp. Field studies to survey or control larval populations typically involve labor-intensive, destructive excavation of root systems. However, nondestructive, portable instruments are now available that can detect sounds made by insects moving and feeding underground. Several different instruments have been tested successfully for detection of subterranean D. abbreviatus larvae and other insects, but many questions remain about the use and reliability of acoustic detection tools in specific insect-detection applications. This report describes recent experiments with currently available acoustic systems to assess the detectability and interpretability of sounds produced by D. abbreviatus larvae and other organisms in root systems of individual trees in citrus groves. It was confirmed that such instruments could successfully predict the presence or absence of subterranean insects under individual trees. However, the instruments do not provide a comprehensive picture of the distribution of sounds (or insects) around a tree unless multiple samples are recorded at ca. 10-cm spacings within the root system. The rates of sounds detected from a subterranean insect can vary considerably at different times, depending on its patterns of behavioral activity. The rates also can vary considerably at different positions within a sensor's detection range, depending on the types of sound produced and the presence of roots or stones between the insect and the sensor.