Male annihilation technique using methyl eugenol for field suppression of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) on mango in Kenya

The Oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most devastating tephritid fruit flies of horticulture worldwide. Field trials were carried out for two seasons on mango (Mangifera indica L.) to evaluate the use of male annihilation technique (MAT) using methyl eugenol laced with deltamethrin instead of the commonly used malathion for the suppression of the pest on mango in coastal Kenya. Prior to application of the MAT, mean total numbers of B. dorsalis flies per trap per day (FTD) in pre-suppression monitoring data were comparable in orchards assigned to MAT treatment (FTD = 3.5) and those assigned to the control (FTD = 3.5) in season 1 and 12.4 and 10.5 FTD, respectively, in season 2. Following the application of MAT systems, total FTD were significantly lower in MAT-treated orchards (0.1 and 2.7 FTD, for seasons 1 and 2, respectively) compared to that in the control (18.6 and 21.5 FTD, for seasons 1 and 2, respectively) at 49 days after deployment of the control measures. This represented a reduction in the B. dorsalis population of 99.5% in both seasons, resulting in a significant reduction of fruit infestation in the MAT-treated orchards compared to the control. The percentage of infested fruit was 25 and 18 times lower in MAT-treated orchards compared to the control for the first and second season, respectively. The number of puparia/kg of mango fruit was 17 and 24 fold lower in MAT-treated orchards compared to the control for the two consecutive seasons. These findings demonstrate the suppression of B. dorsalis using the MAT, and subsequent reduction in fruit damage by the pest. It is therefore recommended that MAT be adopted within a holistic Integrated Pest Management (IPM) approach in the mango agro-system, preferably covering large areas.