Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 35: 2251 - 2259. Published November 8, 2010.
Seasonal variations of the population of Eulophonotus myrmeleon Felder (Lepidoptera: Cossidae) in the Sud-Bandama region of Côte d’Ivoire.
*N’Guessan K. F*, Kébé I.B and Adiko A.
Centre National de Recherche Agronomique (CNRA), BP 808 Divo, Côte d’Ivoire
*Corresponding author e-mail: nguessankf_fr@yahoo.frABSTRACT
Objectives: The cocoa stem borer, Eulophonotus myrmeleon Felder (Lepidoptera: Cossidae) has recently become a serious pest of cocoa in west and central African countries. This study aimed to determine the periods of severe attacks of this new pest in the Sud-Bandama region, a major cocoa growing area of Côte d’Ivoire.
Methodology and results: The experiment was conducted in 2005-2009 at the CNRA research station in Divo, Côte d’Ivoire. Six cocoa plots, planted in 1972, 1984, 1987, 1988, 1993, and 2000, and naturally attacked by Eulophonotus myrmeleon were selected. In each plot, a bloc of 300 cacao trees was demarcated and the trees were numbered from 1 to 300. Every tree was inspected monthly and the fresh holes of E. myrmeleon were counted till hand height. Rainfall data was taken twice a day (morning and afternoon) at the station. The results revealed two periods of severe borers’ attacks during the year. Heavy damages of occur from May to August with a peak in June, and from November to February with a peak around December-January. These two periods correspond to the time when the larvae excavate and tunnel in the cocoa trees. The attacks usually start in May and November each year. Adults’ emergence starts three months later in August and February. The levels of attacks seemed to be directly influenced by the rainfall pattern and drought seemed to adversely affect the level of borers’ attacks.
Conclusion and application of the findings: The results of this study could be helpful in decision making regarding the application of control measures directed against the larvae or the adults. For example a rational insecticide application should be done during the periods of severe borers’ attacks or when adult moths are active in the field in order to reduce the population for the next generation. In addition, any investigation regarding the use of pheromone against E. myrmeleon will take into account the emergence period of the adults.
Key words: Cocoa, stem borer, Eulophonotus myrmeleon, population dynamic.
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