Vol 116 (2003): Proceedings of the Florida State Horticultural Society
Citrus

Listening to the larvae: acoustic detection of Diaprepes abbreviatus (L.).)

Richard W. Mankin
USDA
Published December 1, 2003
Keywords
  • diaprepes abbreviatus,
  • citrus,
  • root damage

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.