Abstract

Al-Waleed Albutairi, Nasser G. Laden and Yasser Hariri Al Saud

The red palm weevil (RPW), Rhynchophorus ferrugineus, is one of the most devastating and invasive insect pests causing immense damage on date palms across the world. Natural insecticide Abamectin (ABM) has been evaluated against developmental stages of RPW under laboratory conditions. Insects were exposed to residual film of the insecticide on transparent cups using a Potter precision laboratory spray tower. Mortality of males, females, neonate larvae, larvae, eggs and pupae was recorded at different time intervals after treatment. Bioassay test showed that ABM at 600 ppm (µg/ml) caused 60% mortality against females and males after 24 h. By increasing the concentration to 1000 ppm, the mortality reached 100% for adults. The LC50-values calculated for females and males were 582.9 and 502.1 ppm and that of LC95 was 1226.9 and 967.2 ppm, respectively. Neonate larvae exhibited more sensitivity toward ABM, where 200 and 500 ppm caused 80 and 100% mortality at 24 h after treatment with LC50 98.7 ppm and LC 95 352 ppm. In the meantime, the toxicity effect of the treatment with ABM up to 500 ppm checked at the 24 h period was 0% mortality against 25-day old larvae, and then it reached 60% by the same concentration at 7 days after treatment. Other developmental stages, eggs and pupae, were dramatically affected by ABM, where 500 ppm caused 90.3% egg unhatchability and 100% mortality of pupae. Therefore, ABM can be a possible candidate to be applied on date palm by the Ministry of Agriculture after successful field experiments