TOXICOLOGICAL AND BIOCHEMICAL IMPACT OF SOME BIOINSECTICIDES AGAINST THE LARVAE OF THE RED PALM WEEVIL, Rhynchophorus ferrugineus (OLIVIER) UNDER LABORATORY CONDITIONS

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae), is one of the most important and destructive pests for date palms causing high economic losses. Several control methods have been applied to manage this pest. Intensive use of conventional insecticides to control RPW successfully minimized the weevil number, but they are still harmful for the environment as they cause pollution and damage other useful creatures. The present study aimed to find suitable, effective, and safe alternative control means. In addition, the impact of tested compounds on the enzymatic activity of the third instar larvae were assayed spectrophotometrically. Four commercial insecticides were applied against the 3rd instar larvae of RPW under laboratory conditions and the LC50 values were estimated. Larvae that survived treatment were collected 24h post treatment and were prepared for further enzymatic activities analysis. All experimentations were carried out at Wood and tree scavenger research department, Plant protection research institute, Agricultural research center. Results showed that Dr. Sure® was the most toxic compound according to low LC50 value obtained. In addition, results revealed that BIO-MAGIC® was the least toxic as the high LC50 value compared to the other compounds. In addition, results revealed significant impacts on the detoxifying enzymes in the 3rd instar larvae treated with LC50 of tested compounds as a defensive response against those compounds. These results reveal the suitability of the non-conventional insecticides to control the youngest larval instars effectively.