Environmental Effects and Damage Pattern of Insect Pests on Cocoa Production in Ibadan, Oyo State Nigeria
Paucity of information in recent times on major and minor insect pest status of cacao plantations in Nigeria necessitated this survey. Knowledge of the insect pest complex associated with any crop is essential for developing effective control strategies for such pests. A survey was conducted on the insect fauna associated with Theobroma cacao on a 10 hactare cacao plantation in Ibadan from 2005 to 2014. Insect abundance and the damages caused by each identified insect pest type were noted and described. The insects were monitored and assessed annually over the span of 10 years (2005-2014). Weather parameters such as rainfall, temperature and relative humidity were recorded from CRIN meteorological station. Data were analyzed through Excell and SPSS packages using descriptive statistics. There were myriads of insect pests identified with variations in percent damage by the observed insect pests viz., P. Njalensis (15%), Z. variegatus (15%), M. bellicocus (5%) and S. derogata (10%) are abundant during the dry spell, whereas Carlibatus spp (10%), B. thalassina (15%), E. Biplaga (10%), S. sjostedti (10%), S. singularis (25%) caused a lot of cacao damage
during the rainy season. The incidence of Sahlbergella singularis was observed throughout the period of investigation but most abundant/prevalent in the months of August to December. The physical environmental factors that recorded exhibited greater influence on the abundance of field insect pests of cacao, was rainfall. This study has provided information on relative importance of the environmental factors on activities of cacao insect pests which is vital for the development of sound and effective control measures.