Population dynamics and distribution of exotic and native frugivorous insects of citrus in Nsukka, Nigeria

Invasion of the exotic Bactrocera dorsalis (Hendel, 1912) (Tephritidae) has drastically reduced the abundance and distribution of native Ceratitis anonae Graham, 1908 (Tephritidae) and false codling moth Thaumatotibia leucotreta (Meyrick, 1913) (Tortricidae) in Nigeria. There is an overlap in resource use among the three frugivorous insects which could result in interspecific competition. Knowledge of the population dynamics and distribution of the three frugivorous insects in the study area is lacking and such data are indispensable for effective management of the tephritid and tortricid pests. The population dynamics and distribution of the three frugivorous insects were investigated to predict the route of invasion and the outcome of interactions among the three frugivorous insects. Bactrocera dorsalis occurred in all the seven Local Government Areas (LGAs) sampled while C. anonae and T. leucotreta occurred together in two LGAs and separately in two other LGAs. The population of B. dorsalis is significantly higher than either C. anonae or T. leucotreta in the study area. The three frugivorous insects are negatively associated with one another but only the association between B. dorsalis and C. anonae was significantly different. Bactrocera dorsalis invaded the study area from southern Nigeria and C. anonae is being driven towards northern Nigeria.