International Journal of Agricultural Science Research Vol. 2(4), pp. 107-115, April 2013 Available online at http://academeresearchjournals.org/journal/ijasr ISSN 2327-3321 ©2013 Academe Research Journals Full Length Research Paper Toxicity of bio-insecticide, Abamectin, on red palm weevil, Rhynchophorus ferrugineus (Olivier) Mahmoud M. Abo-El-Saad*, Hamadttu A. Elshafie, and Ibrahim A. Bou-Khowh Date Palm Research Center of Excellence, King Faisal University, Alahsa 31982, P.O. Box 400, Saudi Arabia. Accepted 1 April, 2013 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 LC 50 -values calculated for females and males were 582.9 and 502.1 ppm and that of LC 95 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 LC 50 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. Key words: Abamectin, red palm weevil, bio-insecticide, bioassay. INTRODUCTION Abamectin (ABM) is a macrocyclic lactone product derived from the soil microorganism Streptomyces avermitilis. ABM is used as an insecticide and acaricide in many parts of the world, and acts as an agonist of γ- aminobutyric acid (Burg et al., 1979; Putter et al., 1981). Saudi Arabia is one of the main date palm producers in the world, with her production amounting to 986,000 tonnes in 2008 (AOAD, 2009). The number of date palm trees is over 18 million, with about 400 different cultivars grown in different regions of the Kingdom of Saudi Arabia (Anon, 2004). Nearly 90 million date palm trees are grown in the Arab world which produced about 5.4×10 6 t in 2001 and increased to 6.7×10 6 t in 2004. This yield represents about 75% of the world production (FAO statistics, 2009). Based on the above information, it has become necessary to maintain this wealth of food in such arid environment and this can be achieved by protecting the date palm from serious pests. The red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is one of the most invasive insect pests causing immense damage to date palms not only in Saudi Arabia and in the Arab countries, but all over the world (Abo-El-Saad et al., 2012). The RPW is an economically important pest of date palm with its origin from South Asia and Melanesia, where it is a serious pest of coconut palms. The pest infestation has spread westwards very rapidly since the mid 1980s (Gomez and Ferry, 1999). It reached the Kingdom of Saudi Arabia, United Arab Emirates, and Oman in 1985 (Abozuhairah et al., 1996; EI-Ezaby, 1997), Iran in 1996 (Faghih, 1996), Egypt in 1992 (Cox, 1993), Spain in 1994 (Barranco et al., 1996), and Israel, Jordan and Palestine in 1999 (Kehat, 1999). The RPW is *Corresponding author. E-mail: maboelsaad@gmail.com.