|JALINAS, JOHARI - Universidad De Alicante|
|GUERRI AGULLO, BERENICE - Universidad De Alicante|
|LOPEZ-FOLLANA, R - Universidad De Alicante|
|LOPEZ-LLORCA, L.V. - Universidad De Alicante|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2015
Publication Date: 3/17/2015
Citation: Jalinas, J., Guerri Agullo, B., Mankin, R.W., Lopez-Follana, R., Lopez-Llorca, L. 2015. Acoustic assessment of Beauveria bassiana (Hypocreales: Clavicipitaceae) effects on Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) larval activity and mortality. Journal of Economic Entomology. 108(2):444-453.
Interpretive Summary: Scientists at the USDA-Agriculture Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida, and the Laboratory of Plant Pathology, University of Alicante, Alicante, Spain, used acoustic methods to eavesdrop on activity of hidden infestations of red palm weevil larvae after treatments with different doses of the entomopathogenic fungus, Beauveria bassiana. The red palm weevil is an important economic pest that recently invaded the Caribbean and may soon enter the United States. Fungi can be used to reduce populations of these pests as an alternative to chemical pesticides, but it is difficult to study the effects of treatments in field environments because the larvae remain hidden inside the trees until they emerge as adults. Three methods of analyzing insect sounds were identified that can be used as indicators of the magnitude of larval activity. The use of such methods can assist researchers in developing better ways to deliver fungal treatments against insects and analyze their effectiveness
Technical Abstract: Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae), the red palm weevil, is an economically important palm tree pest in subtropical regions of the world. Previous studies have shown that R. ferrugineus can be infected and killed by the entomopathogenic fungus, Beauveria bassiana. However, because these insects remain hidden inside the trunks until adulthood, the time course of B. bassiana treatment effects on larvae inside palms has never been established. To explore the potential of acoustic methods to assess B. bassiana treatment effects, sounds produced by untreated larvae and larvae treated with two different sublethal doses of B. bassiana were sampled over a 23-d period, after which the trees were dissected and the larvae were examined for signs of infection. Signal processing software was used to identify trains (bursts) of sound impulses which occurred frequently in palms when larvae were present but only rarely when larvae were absent. It was found that the rates of bursts, the counts of larval sound impulses per burst, and the rates of impulses in bursts decreased significantly over time after both treatments. This included a reduction in the counts of larval impulses per burst, possibly because the larvae made briefer movements as they became weaker during the progress of infection. It also included a reduction in the rate of bursts, possibly because the larvae reduced the quantity of food eaten. Thus, there is considerable potential for acoustic methods to be useful for non-destructive assessment of effects of biological control treatments against important, internally feeding insect pests.