Population dynamic of the cocoa stem borer, Eulophonotus myrmeleon Felder (Lepidoptera: Cossidae) in the Haut-Sassandra region of Côte d'Ivoire.
Objective: The cocoa stem borer, Eulophonotus myrmeleon Felder causes today serious damage in cocoa farm in Côte d'Ivoire. This study was conducted to determine the outbreak periods of this new lepidopteran pest in the Haut-Sassandra region, the second largest cocoa producing area in Côte d'Ivoire. Methodology and Results: The study was conducted from 2009 to 2013 in farmers' cocoa farms in the Haut-Sassandra region in Côte d'Ivoire. Seasonal variation of the rate of Eulophonotus myrmeleon attacks were assessed by counting recent holes in six cocoa farms chosen in 3 counties with 2 farms in each county. Rainfall data were also collected during the same period. The results showed that there are two periods of severe attacks of E myrmeleon in the Haut-Sassandra region. These attacks occur from January to April with a peak in February and from June to November with a peak in August. During these outbreak periods, the larval population level is high in the cocoa farms, indicating intense larval activities in the farms. The results also showed that the level of attack increased from 2009 to 2013, indicating that this insect has become a serious problem for the farmers in this region. Rainfall seems to play a significant role in the breeding and population rise of these insects as periods of heavy attacks were observed after periods of rainfalls. Similarly, the lower temperatures seemed to favor an increase in Eulophonotus myrmeleon attack. Conclusion and applications: The results obtained in this study could be very useful for recommending control measures against larvae or adults. Indeed, periods of heavy attacks and adult emergence could be taken into account for rational insecticide application against this pest.