Acoustic activity cycles of Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) early instars after Beauveria bassiana (Hypocreales: Clavicipitaceae) treatments

Authors: JALINAS, JOHARI - Universidad De Alicante; GUERRI-AGULLO, BERENICE - Universidad De Alicante; DOSUNMU, OMOTOLA - University Of Florida; LOPEZ, LLORCA - Universidad De Alicante; Mankin, Richard

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2017
Publication Date: 11/6/2017
Citation: Jalinas, J., Guerri-Agullo, B., Dosunmu, O.G., Lopez, L.L., Mankin, R.W. 2017. Acoustic activity cycles of Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) early instars after Beauveria bassiana (Hypocreales: Clavicipitaceae) treatments. Annals of the Entomological Society of America. 110(6):551-557.
DOI: https://doi.org/10.1093/aesa/sax061

Interpretive Summary: The red palm weevil (RPW) is an invasive pest from southern Asia that is devastating commercial and ornamental palm treeS in the Middle East, Southern Europe, the Caribbean, and potentially spreading to the southern US. The larvae feed internally tunneling inside tree trunks and cannot be detected visually until extreme damage has occurred. RPW is becoming resistant to pesticides, and insect-killing fungus is under study as a pest management tool. Scientists at the University of Alicante, University of Florida, and the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, investigated methods to acoustically monitor the impact of the fungus on RPW larvae activity hidden inside infested trees. One successful method identified significant reductions in sound-producing activity and survival of larvae exposed to two different fungal treatments. Potential applications are discussed for the incorporation of these treatment and detection procedures into new, innovative insect pest management programs.

Technical Abstract: Rhynchophorus ferrugineus (Olivier) is a pest of many crop and ornamental palm tree species in subtropical regions worldwide. Larvae tunnel and feed unseen in the trunks, ultimately causing irreparable harm and killing the palm. Beauveria bassiana (Balsamo-Crivelli) Vuillemin is under evaluation as a biological control agent for R. ferrugineus management but its effects are difficult to monitor under field conditions except by acoustic methods. Older (> 30 d) larvae treated with B. bassiana display statistically significant reductions in acoustic activity in semi-field studies, but activity of younger larvae has been more difficult to analyze due to their short-duration cycles of feeding and molting. A procedure was developed to characterize effects of B. bassiana treatments by subdividing long-term recording periods into activity cycles. Treatment effects were compared within and across cycles. The procedure demonstrated statistically significant differences among acoustic activity rates over time for 15-d-old instars exposed to control, 104, or 108 conidia ml-1 B. bassiana treatments. The results suggest that acoustic technology has considerable utility for monitoring of larval development and for evaluating efficacy of pest management treatments in environments where the targeted insect pests are hidden from view.