Curative treatment of red palm weevil, Rhynchophorus ferrugineus (Olivier) in infested date palms using an innovative fumigation technique

The red palm weevil (RPW) Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) is a key pest of date palm Phoenix dactylifera L. in the Near-East and North Africa region. RPW infested date palms respond to curative chemical treatments if detected and judiciously treated in the early stage of attack. However, the currently used curative treatments, involve either excessive tissue removal of the palm around the infested palm section (mechanical sanitization) making the palm weak and vulnerable to toppling, injecting insecticide into the infested palms which often does not kill all the stages of the pest within the palm, calling for repeated applications or fumigating the infested palm section with phosphine gas which is also not always effective possibly due to inadequate dose and escape of the gas. A new fumigation technique using a specially designed air tight fumigation sleeve to ensure complete entrapment of the fumigant gas or liquid was devised and field tested on (463) infested dates palms in various stages of attack using either aluminum phosphide tablets (3 g) or one of commonly used insecticides that has fumigant action. The trials were conducted in Al-Qassim, Kingdom of Saudi Arabia, during 2017-2020. The technique was tested in both young date palms (9-12 years old) as well in offshoots (4 years old) through a series of field trials to optimize the dose, duration of treatment. Results revealed that 100% mortality of the larval, pupal and adult stages of the pest inside the infested palm could be achieved within 5 days due to the fumigant action of either of the following treatments: 15 tablets (3 g) of aluminum phosphine gas, 120 mL of Deltamethrin 10% EC, 150 mL of Chlorpyriphos 48% EC, 150 mL of Marqiuse™ (combination of Phoxim 15%, Cypermethrin 5% and Monosultap 20%), 150 mL of Malathion 57% EC, 150 mL of Diazinon 60% EC or 250 mL Cypermethrin 25% EC. The method offers a simple and curative treatment of RPW infested palms and is currently the main treatment method used in Saudi Arabia and many other regions.