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Fruit flies (Diptera: Tephritidae) are considered as the most destructive insect pests of fruits and vegetables in the world. The oriental fruit fly, Bactrocera dorsalis was first detected in Manica province, in 2008 causing huge economic losses. However, there were no systematic trapping data of B. dorsalis seasonality, damage assessments and factors determining the changes in the pest population. Additionally, there was no information on economic injury levels (EIL) for B. dorsalis in Mozambique. Therefore, the present study was conducted to describe B. dorsalis dynamics, assess the associated damage and yield losses on mango and to determine the EIL for B. dorsalis in Manica province. From September 2014 to August 2015, methyl eugenol baited traps were placed in three selected orchards (Trangapasso, Produssola and Pandafarm) and mango fruits were collected and reared. Data on potential yield was estimated and the owners were interviewed to collect information regarding mango selling prices. Bactrocera dorsalis catches per trap per day (FTD), percentage of damaged fruits and infestation rates were determined and submitted to ANOVA, Chi-square and Pearson’s correlation analysis in R. The EIL was determined for each orchard. The population started to build up in November 2014 reaching its peak in January 2015 (40.26 FTD) and the population pattern was determined by temperature, month and host availability. The highest percentage of damaged fruits (77.16%) and the highest rates of infestation (68.57 flies/kg and 41.27 B. dorsalis/kg) was also recorded in January. The FTD and infestation parameters were significantly affected by the month with the highest levels recorded at the peak of mango ripening stage. Yield losses associated with fruit flies were estimated at 28.27 t/ha with the total financial loss of USD 17,144.84 per ha. EIL varied among orchards and was estimated at 33.14 B. dorsalis/trap/week in average.

Keywords: Bactrocera dorsalis, population dynamics, yield losses, infestation rates, economic injury level.