Daily activity and non-random occurrence of captures in the Asian palm weevils

Abstract

Red Palm Weevil (RPW), Rhynchophorus ferrugineus represents one of the most dangerous pests of several species of palms. It spread from its native range (southeastern Asia) to the Middle East and then to the Mediterranean. Preliminary laboratory observations carried out on a group of males and females of RPW showed differential distribution of activity during daylight. Then we performed a field study comparing the time of captures of RPW across native populations (Vietnam) and invasive ones (Italy and Greece). Time of captures was also recorded for Rhynchophorus vulneratus from Malaysia (its native range). Weevils were trapped via traps baited with aggregation pheromone, kept continuously active for at least 20 days. Trapping times were recorded, and individuals were sexed after capture. Circular summaries indicate that arrivals at all the sampled localities were non-random, often with one or two peaks of arrivals during daylight. However, the distribution of trapping times was not consistent across populations and probably represents an answer to local environmental conditions.

KEY WORDS:

• Rhynchophorus ferrugineus
• Rhynchophorus vulneratus
• daily activity
• pheromone traps
• Asian palm weevil

ACKNOWLEDGEMENTS

This research received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 264089 (MARBIGEN project).

The research was supported also by a grant to Giuseppe Mazza from the Ministry of Agricultural, Food and Forestry (MiPAAF) national project “Protection of ornamental and indigenous palms from the biological invasion of the Red Palm Weevil – PROPALMA” (D.M. 25618/7301/11, 2012/12/01).

We also thank Roberto Fanini and Franca De Vita for their support at the collection point in Greece; Alessandro Cini, David Baracchi and Stefano Turillazzi at the collection point in Malaysia; Fabio Cianferoni, Luca Bartolozzi, Valerio Sbordoni, Vu Van Lien, Eylon Orbach and Saulo Bambi at the collection point in Vietnam. We wish to thank three anonymous referees for their helpful comments on the manuscript.