Abstract

The sweet orange, Citrus sinensis L. is an important fruit crop in Nigeria and its production is seriously constrained at maturity by attack of the fruit fly, Ceratitis capitata which results in severe yield loss. Effects of attack by C. capitata on fruit morphology and nutritional characteristics of C. sinensis from selected sites in southwest Nigeria were investigated. Twenty five mother citrus trees with >45 cm diameter at breast height (DBH) were randomly selected at two plantation sites: Ede (Osun state) and Olodo (Ogun state) in southwestern Nigeria. Ten mature fruits, plucked randomly from four cardinal sections of each tree were classified based on levels of infestation. Effects of attack on fruit morphometrics were assessed by standard measurements while the effects on fruit quality were determined by proximate and mineral analyses. Results indicated that attack by C. capitata was characterized by oviposition punctures which predisposed the fruit to secondary infection by Penicillium notatum. Fruits were attacked at any point on the surface but significantly more at about 2 cm from the fruit stalk scar. Multiple attacks did not follow a regular pattern. Fruit attack by C. capitata significantly decreased moisture content of fruit by 79% and mineral content; calcium, phosphorous, copper, zinc and iron  while percentage dry matter, crude protein and crude fiber decreased significantly (P<0.50) with increased infestation. Fruit infestation also caused significant decrease in the vitamin C content by about 50% but increased saccharose, maltose and glucose content of attacked fruits by about 10%.

Key words: Citrus sinensis, multiple infestations, Ceratitis capitata, fruit morphometrics, Penicillium notatum