Monitoring of infestation percentages of the invasive red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae), and management tactics: a six-year study

Abstract

Red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera, Curculionidae), is a devastating invasive pest, that invaded Saudi Arabia's date palms in 1987. Evaluation of the infestations and the efficacy of both preventative and control treatments have been studied from 2015- 2020 in Qassim. The results indicated that the number of infested date palms varied according to the years and locations. The infested date palm trees percentage was relatively high in 2016 (2.24%) and 2017 (3.19%), then gradually decreased to reach its lowest in 2020 (0.73%) due to the management protocol applied by the Ministry of Environment, Water, and Agriculture. Furthermore, the infested palm trees' percentage varied among the eight study locations, reaching the highest percentage in location G (SA7) with a general average of 4.31%. While in the other locations, the general infested percentage average was very low when compared to location G (SA7) with 1.21 and 0.47% in locations A (SA1) and H (SA8), respectively. The effectiveness of control methods increased sharply from 52.141% in 2015 to 90.0% in 2020 with a general average of 72.73%. The quarantine and management protocols of R. ferruginous applied in Qassim decreased the number of palm infestations. Contrary, the intensive use of insecticide in the last two decades promoted genetic mutations within the Rhynchophorus, which led to the emergence of a new species R. bilineatus. This leads to increase pesticide pollution, and control costs and the insect becomes more resistant to pesticides.