Morphometry of the Citrus Mealybug Planococcus citri (Risso) and its Feeding Impact on the Proximate Composition of Citrus Species Leaves in Makurdi Southern Guinea Savanna, Nigeria

Abstract

The study assessed the feeding impact of citrus mealybug Planococcus citri (Risso) and its morphometry on (Citrus species L.) at the Teaching and Research Farm, Joseph Sarwuan Tarka University, Makurdi.  A 2x5 factorial experiment comprising five species of two-year-old citrus seedlings (C. sinensis, C. nobilis, C. reticulata, C. limon, and C. aurantium) each replicated three times were planted on the field under screen cages in a Randomized Complete Block Design (RCBD). Fifteen stands were infested with 20 young adult female mealybugs each while 15 were un-infested to serve as the control. Data collected was analysed using GenStat Release 2007 (7.2) and means were separated by Duncan’s Multiple Range Test (DMRT) at P = 0.05. Results showed that the percentage of dry matter content was highest on the control compared with the infested plants. The proximate content of the host plant leaves indicated that all the control plants had more sugar than infested plants. Crude fibre and Ash content of infested host plants were lower than that of un-infested.  The impact of mealybug feeding was most pronounced on C. sinensis and C. reticulata. Morphometrically, males of P. citri found on C. nobilis were in body length, width, and weight.  Adult females, however, showed no significant variation in length and width across all citrus species. C. aurantium produced the heaviest females while C. reticulata had females with the lowest weight. In conclusion, C. nobilis is suitable for commercial production of seedlings. Routine inspection for early detection of mealybug infestation is recommended.