PhD. Thesis 2018
This study was undertaken to reduce the losses caused by Bactrocera dorsalis (Hendel) in Manica province, Mozambique, through an optimized integrated pest management (IPM) package. It involved interviews with farmers to collect baseline information on awareness of fruit producers regarding fruit fly pests and their management so that an IPM package can be developed based on the farmers’ needs. Additionally, systematic trapping data of B. dorsalis seasonality and damage were collected and economic injury level (EIL) for B. dorsalis was estimated. Based on EIL, the IPM for B. dorsalis control developed in Tanzania by the Sokoine University of Agriculture (SUA IPM) was optimized. 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. The effectiveness of SUA IPM and its optimized version were also tested. Results showed that fruit flies were the main pest problem in mango and citrus orchards. More than 70% the respondents indicated low fruit quality and increasing volumes of uncommercial zed fruits as consequences of fruit flies infestation. The monetary value of losses reached a value of USD 135,784.8 during 2014/15 mango season. Results on seasonality revealed that population of B. dorsalis started to build up in November and reaching its peak in January. It was significantly affected by temperature, month and host availability, being observed that B. dorsalis were most abundant during hot season and at mango maturation stage. EIL varied among orchards and was estimated an average of 33.14 B. dorsalis/trap/week. The SUA IPM and optimized IPM had significantly less number of damaged fruits, pupae and B. dorsalis iii infestation rate when compared to untreated orchard. However, the SUA IPM and the optimized IPM were not significantly different although in the optimized IPM significantly less volume of the bait was used. It can be concluded that spot application of GF 120 can provide the equivalent level of the pest control when compared to calendar spraying and should, therefore, be used to reduce the fruit losses caused by fruit flies.