Emamectin Benzoate Residues in Fruits and Fronds of Date Palm Trees Following Trunk Injection

Abstract

Red palm weevil (RPW) is one of the most dangerous insect pests of the date palm. It primarily infests the palm trunk and, less frequently, the palm top. This study, conducted in the Kingdom of Saudi Arabia, is a continuation of previous work that demonstrated trunk injection with undiluted emamectin benzoate in date palm apically infested with RPW, resulting in approximately 91% complete healing. The same trunk injection achieved a 100% success rate in killing all RPW instars inside the palm trunk. In the present experiment, the same insecticide was injected at various intervals (between 1 and 12 months) into the trunks of healthy date palms, and subsequently, the residues of emamectin benzoate in fruits and fronds of the palm trees were analyzed. RPW larva rearing was conducted in the laboratory inside cut frond bases (karabs) of the injected palms. Results obtained indicated absence of emamectin benzoate residues in the fruits at all maturation stages: early ripening (Bisr) in late-June, mid-ripening (Rotab) in mid-August, and final ripening (Tamr = Date) in late-September. As for the insecticide residues, significant residues of emamectin benzoate (0.054 mg/kg) were detected in karabs after a trunk injection of only one month. In addition, RPW larva rearing inside the karabs, one month after trunk injection, gave a significant high larva mortality rate 83.3%. This study indicated that with the injection of the palm trunk by the undiluted pesticide emamectin benzoate, no pesticide residues were found in the palm fruits, and if the injection was made one month earlier, it provided significant protection to the bases of the fronds from attack by the red palm weevil.

Keywords:

Date palm, emamectin benzoate, insecticide residues, red palm weevil, trunk injection.