An effective strategy to obtain very rapidly the red palm weevil decline in an area planted with ornamental palms

Ferry, M., R. Cousin, D. Chabernaud and F. Ferrero. 2019. An effective strategy to obtain very rapidly the red palm weevil decline in an area planted with ornamental palms. Arab Journal of Plant Protection, 37(2): 188-197. To control successfully the RPW, it is essential to implement a programme conceived and applied to obtain the pest decline as fast as possible. Such objective is easy to reach when RPW is not yet too widespread and abundant. Unfortunately, in most of the infested countries, it is not at all the case anymore. The challenge now is to propose strategies and technical solutions sociologically, economically and environmentally sustainable. In a territory of five grouped municipalities in the French Riviera, has been applied since 2016 a strategy elaborated by the Phoenix Research Station (PRS) and implemented under the supervision of the inter-municipality authority in charge of this territory (CAVEM). Although the area is heavily infested by the RPW, the objective is to demonstrate that it is possible in few years to stop the palms hecatomb and to obtain a rapid decline of the RPW (“palms” refer generally in this paper to Phoenix canariensis that is by far the main target and main incubator of the RPW). The main challenge, here like everywhere in the infested countries, is to get the palm owners acceptation to the proposed strategy and their collaboration. One essential point that has contributed greatly to face this challenge has been the existence of a very active association of private palms owners (Propalmes 83). To obtain the public and private palms owners collaboration it was fundamental that the proposed strategy be conceived taking into consideration the capacities and economic means of these actors. Therefore, the PRS proposed that CAVEM organize the activities to facilitate as much as possible their grouping to reduce the costs to a minimum. Among the different activities, the PRS proposed that preventive treatment based on an injection technique, because of its much lower cost and its great safety compared with other techniques, be the core of the action plan. This proposal is based on the results of a theoretical analysis presented here on the evolution of the number of new yearly infested palms. This analysis allowed establishing, with a probability of 95% for the confidence intervals, the number of new yearly infested palms based on the percentage of treated palms. The field results available for the CAVEM territory for 2016 and partially for 2017, confirm the validity of this analysis. These results showed that, if as planned, the objective of 75% of injected palms on the total number of palms is reached, the number of infested palms will decrease very quickly in 3-4 years, leading to a considerable decline of the native population of RPW and of the number and size of the infested spots, that in addition will be perfectly located. Once this result will be reached, it will become quite feasible to treat all the palms, even with biological agents, in the infested spots and so finally to eradicate the RPW. Of course, the same strategy has to be followed rapidly by the surrounding territories, otherwise such result would be vain as re-infestation will occur.