Economic Injury Level of the Oriental Fruit Fly, Bactrocera dorsalis (Diptera: Tephritidae), on Commercial Mango Farms in Manica Province, Mozambique

The present study describes the population dynamics of Bactrocera dorsalis (Hendel) in Manica Province (Mozambique), provides estimates of mango yield, economic losses and the economic injury level. 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 incubated. Data on potential yield was estimated in each of the orchards and the owners were interviewed to collect information regarding mango selling prices. Differences in B. dorsalis catches, percentage of damaged fruits and infestation rates were determined across locations as well as sampling dates. The economic injury level (EIL) was estimated for each orchard. The populations of B. dorsalis started to build up in November 2014 reaching an abundance peak in January 2015 (40.26 flies/trap/day). Population growth was correlated to average temperature, month and host availability. The highest percentage of damaged fruits (77.16 %) and the highest rates of infestation (41.27 %, B. dorsalis/kg) were recorded during January. Average yield losses associated with fruit flies were estimated at 5.65 t/ha with a financial loss of USD 3428.97/ha. EIL varied among orchards and was estimated at 33.14 B. dorsalis/trap/week on average.