Acoustical detection of early instar Rhynchophorus ferrugineus (Coleoptera: Curculionidae) in Canary Island date palm Phoenix canariensis (Arecales: Arecaceae)

Authors: HERRICK, NATHAN - Florida A & M University; Mankin, Richard

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2012
Publication Date: 12/1/2012
Citation: Herrick, N.J., Mankin, R.W. 2012. Acoustical detection of early instar Rhynchophorus ferrugineus (Coleoptera: Curculionidae) in Canary Island date palm Phoenix canariensis (Arecales: Arecaceae). Florida Entomologist. 95:983-990.

Interpretive Summary: Scientists at the USDA, Agriculture Research Service, Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Florida, and Florida Agricultural and Mechanical University in Tallahassee, Florida, have conducted experiments to acoustically detect very young, small larvae of an invasive beetle pest, the red palm weevil, that attacks and kills ornamental and fruit crop palm trees. These insects are difficult to detect because they feed inside the tree trunk, hidden, and by the time damage is visible, the tree is irreparably damaged. The beetle has caused extensive damage in the Middle East and Southern Europe and recently invaded two Caribbean islands and California. The results will help make it possible for pest managers to identify infestations early, before visible damage occurs, and avoid transport of infested trees to uninfested areas.

Technical Abstract: The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier), is of international concern due to destructive larval feeding within palm trees. Originating from tropical Asia, RPW has spread throughout the eastern hemisphere where it has become a significant economic pest to the ornamental and date palm industries. By the time a palm infested with RPW displays symptoms of damage, larvae are late in development and it is often too late to prevent tree mortality. Acoustic technology is under consideration as a means to enable pest managers to detect early infestations for the treatment of RPW before tree mortality and to reduce unwanted importation and/or exportation of infested palms. Experiments were conducted to determine the detectability of sounds produced by early instars in unshielded open environments and in easily constructed, enclosed environments that reduced background noise levels by ca. 10 dB. Early instar RPW produced sound impulses with a wide range of amplitudes and spectral features. Late instars produced similar sound impulses along with others of higher amplitudes. Larval bursts (specifically, groups [trains] of 7-200 sound impulses in which a majority of impulses had spectra that matched known larval spectral profiles) were detected in all the open-environment recordings and in all but one of enclosed-environment recordings. There were no significant differences between sound rates in the enclosed and open environments, but the enclosed environment shielding enabled detection of early instars over 2-4-fold longer distances. Thus, except in areas with very high background noise levels, there is potential to use acoustic technology to detect early instar RPW infestation in either minimally shielded or open environments.