Short communication. Susceptibility of Phoenix theophrasti (Palmae: Coryphoideae) to Rhynchophorus ferrugineus (Coleoptera: Curculionidae) and its control using Steinernema carpocapsae in a chitosan formulation

Abstract

The invasive red palm weevil, Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) is the most destructive pest of palms in the world. It has been reported on 19 palm species belonging to 15 different genera. The host status of the Cretan Date Palm, Phoenix theophrasti, remains unclear. Therefore, the present study was carried out to ascertain the host status of this protected palm species. Additionally, the efficacy of entomopathogenic nematodes in a chitosan formulation to control this pest in P. theophrasti was assessed. Our results showed that healthy 4-yr-old P. theophrasti palms were not infested by adult females after 9 days exposure in a population density of 3 adults per plant. However, infestation was successful when neonate larvae were artificially introduced in palms. Therefore, natural populations of P. theophrasti could be at risk. Gummy secretion was observed in both naturally and forced infested palms indicating the existence of antibiosis in this species. Curative applications with the entomopathogenic nematode Steinernema carpocapsae in a chitosan formulation in early infested P. theophrasti palms managed to reduce insect's activity and could help the palms to recover.Additional key words: antibiosis; antixenosis; entomopathogenic nematodes; Phoenix canariensis. ResumenComunicación corta. Susceptibilidad de Phoenix theophrasti frente a Rhynchophorus ferrugineus y su control mediante el uso de Steinernema carpocapsae en una formulación con quitosano El picudo rojo de las palmeras, Rhynchophorus ferrugineus Oliv. (Coleoptera, Curculionidae) es la plaga de palmeras más destructiva del mundo. Se ha citado en 19 especies de palmeras pertenecientes a 15 géneros diferentes. El estatus de la palmera datilera de Creta, Phoenix theophrasti como huésped del picudo rojo no está claro. Este estudio se llevó a cabo para determinar la respuesta de la palmera datilera de Creta frente al ataque de este curculiónido. Además se evaluó la eficacia de una formulación del nematodo entomopatógeno Steinernema carpocapsae con quitosano para su control. Fue imposible infestar palmeras de 4 años de edad con hembras adultas tras 9 días de exposición con 3 hembras por planta. Sin embargo, la infestación fue exitosa cuando las larvas neonatas se introdujeron artificialmente en las palmeras. Por lo tanto, las poblaciones naturales de P. theophrasti podrían estar en riesgo. Se observó una secreción de goma, tanto en las palmeras infestadas de forma natural, como en las forzadas, que indica la existencia de antibiosis. Las aplicaciones curativas con los nematodos entomopatógenos en P. theophrasti redujeron la actividad de los insectos y podrían ayudar a esta especie de palmera en su recuperación.

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida)

“…In this work, we investigated the interaction of S. carpocapsae with R. ferrugineus ; in particular, some immunological features of the host and elusive/depressive strategies of the parasite have been elucidated, the obtained data could be of value to improve actions to control the insect pest. Some works on RPW have been performed in field (Dembilio et al ., ; Triggiani & Tarasco, ), but only a few papers address both host immunological responses and evasive strategies of the S. carpocapsae (Manachini et al ., , ).…”

Mobility and efficacy of abamectin and imidacloprid againstRhynchophorus ferrugineusinPhoenix canariensisby different application methods

“…To minimise resistance risk, rotation of compounds with different modes of action should be implemented. When available, biological control agents should be included in the sequence, as biological control does not favour the selection of pesticide‐resistant strains. Finally, area‐wide strategies aimed at reducing weevil populations such as mass trapping could prove to be highly effective if properly managed …”

Research activities focused on management of red palm weevil at the UJI‐IVIA Associated Unit (Region of Valencia, Spain)

“…This palm is native to the eastern Mediterranean region and grown in a very restricted distribution (Crete and some Aegean islands) (EU, 1992; IUCN, 2010). The susceptibility of this palm to R. ferrugineus was not clear and, in co‐operation with colleagues from the Benaki Phytopathological Institute in Athens, its susceptibility was compared with the highly susceptible P. canariensis (Dembilio et al. , 2011).…”