Fluctuations in Natural Populations of the Leaf Miner (Coelaenomenodera lameensis) in Relation to Different Origins of Oil Palm (Elaeis sp.) in South Benin

Preferences of different oil palm crosses in the station of Pobè in Benin were tested on Coelaenomenodera lameensis by monitoring the natural population for 7 consecutive years. Experiments monitoring of developmental stages of the insect were performed on material types Elaeis guineensis and Elaeis oleifera. Observations were performed every two weeks on leaves of different ranks (25, 17 or 9) depending on the degree of defoliation by counting the different stages of insect development on leaflets. The results showed that the evolution of pest density is a function of species and the origin of the materials being compared. Population densities of different stages of C. lameensis were more abundant in the crosses from Yocoboué where average population indices were higher at all stages of development from early observations. By contrast, in crosses La Mé, Yangambi and Deli, the numbers of larvae, pupae and adults were lower. Among these three crosses infestation was more abundant in La Mé, followed by Yangambi and Deli. E. oleifera is much less or not attacked. The stages of development (larvae and adults) were also differently held in oil palm origins in comparison. The larval population is significantly important during the short rainy season and lesser important during the dry season. These results may contribute to the development of suitable materials for the genetic improvement of breeding tolerant oil palm material to leaf miner.