Background: The fruit and vegetable sector in the world is severely hampered by tephritid fruit flies. Since the detection of the Oriental fruit fly Bactrocera dorsalis in Manica Province, in 2008, huge economic losses have been reported. An IPM for B. dorsalis control was developed in Tanzania by the Sokoine University of Agriculture (SUA) based on sanitation and calendar application of bait sprays. Optimizing of this package was suggested by introducing decision-making criteria to focus the control on pest hot spots. Methods: Trials were conducted in Manica Province, in four selected orchards (Produssola, Trangapasso, Chandroca and Frutis) for two seasons, each of them receiving one treatment (SUA IPM, optimized IPM, sanitation) or remaining untreated. The SUA IPM was evaluated during the 2015/16 mango season in Produssola, having Trangapasso under standard sanitation while the optimized IPM was tested in Chandroca during the 2016/17 mango season having a fourth orchard (Frutis) as untreated orchard. The SUA IPM included calendar GF 120 NF bait sprays and orchard sanitation while for the optimized IPM the GF 120 NF was only sprayed in the subplots inside the orchard when the threshold of 30 flies/trap/week was reached. B. dorsalis density as well as percentages of damaged fruits and infestation rates were calculated and repeated measures ANOVA was performed in R. Results: n general, the effect of the treatment was significant on the estimated variables. The untreated orchard had the highest percentage of damaged fruits, pupae/kg and adult flies/kg when compared to treated orchards. The SUA IPM recorded the lowest number of damaged fruits (23.29%) and infestation rates followed by the optimized IPM, sanitation and untreated orchard. However, the SUA IPM and optimized IPM mean number of damaged fruits, pupae and B. dorsalis infestation rate was not significantly different and both differed from the untreated orchard.
Conclusions: Spot application of GF 120 NF by using action thresholds can provide the equivalent level of the pest control when compared to calendar spraying, and should therefore be used by the farmers to prevent the fruit losses caused by fruit flies.