Location: Insect Behavior and Biocontrol ResearchTitle: Acoustic detectability of Rhynchophorus cruentatus (Coleoptera: Dryophthoridae) Author
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2014
Publication Date: 6/1/2014
Citation: Dosunmu, O.G., Herrick, N.J., Haseeb, M., Hix, R.L., Mankin, R.W. 2014. Acoustic detectability of Rhynchophorus Cruentatus (Coleoptera: dryophthoridae). Florida Entomologist. 97(2):432-437. Interpretive Summary: Scientists at the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, and the Center for Biological Control at Florida A&M University, Tallahassee, FL, have investigated sounds produced by pest insect larvae in palm fronds in open urban environments and acoustically shielded environments to determine the capability of detection of early and late instars in a variety of different urban and shielded environments. The results can help regulatory agencies and pest surveyors determine the feasibility of using acoustic methods to reduce the inadvertent transport of palm weevils from infested to uninfested regions.
Technical Abstract: The palmetto weevil, Rhynchophorus cruentatus Fabricius, native to Florida, attacks palm trees. Like its economically destructive relatives, R. ferrugineus (Olivier) and R. palmarum L., it feeds internally and often is not detected until irreparable damage occurs. Acoustic methods previously used successfully for field detection of R. ferrugineus were adopted to investigate the detectability of R. cruentatus in different noise conditions. Neonates were placed into holes drilled into the bases of palm fronds and five 2-min intervals were recorded from 10 fronds at 7-d intervals for 56 d in an urban arena and an acoustically shielded arena such as would be available for testing of offshoots before sale or transportation. The sounds were classified by automated spectral analyses into multiple categories, including bird calls, car noises, and broadband, 0.3-3-ms larval sound impulses. Because spectral characteristics alone are not always reliable for identification of larval impulses over long distances in wood, the analyses also identified temporal patterns, trains of 6 or more closely spaced impulses categorized as larval bursts, used as indicators to classify fronds as infested or uninfested. Larval bursts were produced at sufficient rates to classify infested fronds correctly on each day of testing, although molting and resting behaviors resulted in the absence of bursts in 6-50% of individual recordings, depending on day tested. The rates of larval sound bursts were not significantly different in paired comparisons of recordings obtained from the same frond on the same day under urban and shielded conditions, which suggests that bursts are useful as indicators of Rhynchophorus infestations in a variety of conditions.