Effects of some non-host plant components on oviposition behavior of the red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae)

The red palm weevil, Rhynchophorus ferrugineus (Olivier) is the most destructive pest of palm trees. In this research, the anti-ovipositon effect of the leaf extracts of 3 plant species, including Rhazya stricta Decne. (Apocynacea), Ferula assa-foetida L. (Apiaceae) and Azadirachta indica A. Juss. (Meliaceae), together with three plant volatile compounds, including alpha-pinene, eugenol and thymol, were studied on red palm weevil in a choice test. Each leaf extract and volatile compounds were used in 3 doses (1, 5 and 10%). The number of eggs laid by red palm weevil on the treated tissues were compared to that on untreated date core (as control) during 3 days. Anti-oviposition index (AOI) was used to evaluate the effects of different treatments. The results indicated that the number of eggs on treated palm tissues were significantly lower compared with the untreated ones, except when the tissue was treated with 1% of eugenol or 1% of A. indica. The least number of eggs was observed on tissues treated with 10% of thymol (1.5±0.54) and 10% of R. stricta (1.6±0.66). Also significant differences were found among the AOIs of the tested deterrents. The least AOI was seen for F. assa-foetida (33±6) significantly less than those of thymol and R. stricta. The most AOIs were for 10% of thymol (85.63±4.75%) and 10% of R. stricta (83.32±7.70%). These results suggest that thymol, can be used, as oviposition deterrence, for treating wounds produced on palm trunks, to prevent the new infestations by the red palm weevil.