Ecology and Behavior Acoustic Detection of Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) and Oryctes elegans (Coleoptera: Scarabaeidae) in Phoenix dactylifera (Arecales: Arecacae) Trees and Offshoots in Saudi Arabian Orchards

Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae) larvae are cryptic, internal tissue-feeding pests of palm trees that are difficult to detect; consequently, infestations may remain hidden until they are widespread in an orchard. Infested trees and propagable offshoots that develop from axillary buds on the trunk frequently are transported inadvertently to previously uninfested areas. Acoustic methods can be used for scouting and early detection of R. ferrugineus, but until now have not been tested on multiple trees and offshoots in commercial date palm orchard environments. For this report, the acoustic detectability of R. ferrugineus was assessed in Saudi Arabian date palm orchards in the presence of commonly occurring wind, bird noise, machinery noise, and nontarget insects. Signal analyses were developed to detect R. ferrugineus and another insect pest, Oryctes elegans Prell (Coleoptera: Scarabaeidae), frequently co-occurring in the orchards, and discriminate both from background noise. In addition, it was possible to distinguish R. ferrugineus from O. elegans in offshoots by differences in the temporal patterns of their sound impulses. As has been observed often with other insect pests, populations of the two species appeared clumped rather than uniform or random. The results are discussed in relation to development of automated methods that could assist orchard managers in quickly identifying infested trees and offshoots so that R. ferrugineus infestations can be targeted and the likelihood of transferring infested offshoots to uninfested areas can be reduced.