Laboratory Evaluation of the Toxicity of Acetamiprid and Sulfoxaflor Against the Red Palm Weevil Rhynchophorus ferrugineus (Olivier)

The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, is becoming a real threat to date palm trees in different locations of Saudi Arabia. Therefore, control and management of RPW have gained the attention of government as well as private concerns. In this study, the toxicity of acetamiprid and sulfoxaflor on RPW was evaluated under laboratory conditions. RPW (larvae and adult) showed high susceptibility to both acetamiprid and sulfoxaflor. In addition, both insecticides had significant effect on the mortality of RPW (larvae and adult) except the pupal stage under laboratory conditions. After direct spray application of the recommended dose, the adult mortality percentages were 66.67, 73.33 and 100% for acetamiprid and 23.33, 60 and 96.67% for sulfoxaflor after 1, 24, and 48 h, respectively, whereas the larvae mortality percentages were 63.33, 73.33 and 100% for acetamiprid and 46.67, 73.33 and 96.67% for sulfoxaflor after 1, 24, and 48 h, respectively. Moreover, live RPW (larvae and adult) were found to be completely paralyzed after 24 h of exposure to both insecticides. Statistically, the difference between 1, 24 and 48 h in both adult and larvae at both application (direct spray or soaked palm tissue (contact/ingestion)) was significant (p < 0.05) except the for difference between 1 h and 24 hin larvae with direct spray treatment, which was insignificant (p > 0.05). The study concludes that new information regarding the efficacy of these two insecticides which can be used to replace the conventional, over-aged and less effective insecticides that have been extensively used in controlling RPW.