Seasonal occurrence of Characomastictigrapta (Lepidoptera: Noctuidae) damage on pods of two cocoa varieties in Ibadan, Nigeria

The cocoa podhusk borer ( Characomastictigrapta) isaneconomically important insect pest of cocoa in West and Central Africa. The seasonal damage by the larvae of the pest on pods of two major variety of cocoa (Amelonado and Amazon) in Ibadan, Nigeria was investigated between 2008 and 2010. A total of 200 cocoa trees for each variety were sampled from the base to a height of 1.5 meters on a fortnightly basis for active damage symptoms of C. stictigrapta . Field investigations were conducted to establish relationship between the burrowing activities of C. stictigrapta and the transmission of blackpod disease in cocoa. Monthly weather parameters were also recorded. More pods were damaged in the Amelonado cocoa (132.87) than in the Amazon variety (89.08). Damage peaked in November 2008 and 2010 and December in 2009 with 153, 138 and 115 damaged pods, respectively. The Amazon variety had pods throughout the cocoa growing season with highest pod damage in February 2008 (67), November 2009 (52) and September 2010 (50). The two cocoa varieties showed a positive correlation of 0.613 in terms of infestation by C. stictigrapta .The severe harmattan with a decline in relative humidity of 64.5%, 62% and 65% in December 2008, 2009 and 2010, respectively impacted negatively and led to upsurge of the pest in the early quarter of the preceding year in the Amelonado cocoa variety. There was decline damage on pods of the Amelonado and Amazon varieties during the peak of the rainy season. Only 10% of the Amelonado pod variety damaged by C. stictigrapta was infected with Phytophthora podrot disease. The study therefore demonstrates that varietal susceptibility as well as local environmental parameters does influence losses emanating from C. stictigrapta infestation and damage to cocoa pods. This further provides background information that will ultimately lead to the development of an appropriate control strategy for the pest in Nigeria.