Effects of host availability on seasonal abundance of the fruit fly bactrocera invadens drew, tsuruta & white in Morogoro

Fruit flies (Diptera: Tephritidae) are listed among the major fruit pests distributed in all fruit growing areas of the world. Fruit flies compete with human beings for food resources by causing direct damage to fruits and vegetables. The damage they cause brings about negative economic and social impacts to man since he depends on fruits for important food nutrients, employment and income. The fruit fly problem in Tanzania and Africa has been aggravated since the invasion of the new fruit fly probably of Asian origin, described as Bactrocera invadens (Drew, Tsuruta and White). The newly invasive fruit fly that was first reported in Kenya in 2003, then in Tanzania in 2004, thereafter from the rest of Africa, has shown ability to spread fast within a short time as it is suspected to displace the indigenous fruit flies in the African region. Earlier studies in Morogoro, revealed that the fruit fly does well in low to medium altitude areas than in high altitude areas of the region. This study was conducted at SUA horticultural unit in Morogoro, to assess the temporal and spatial presences of B. invadens in relation to the fruiting of economically important fruit crop species. To achieve the objective, phenological events of important fruit species and varieties were recorded while fruit fly trapping was also done. At the same time weather parameters including temperature, rainfall and relative humidity were recorded. The data were all recorded at weekly basis for a period of 48 weeks. The phenology recording experiment followed a Randomized Complete Block Design while the trapping experiment followed a split-split plot design. Fruit fly trapping results were analysed using Genstat Statistical Package whereby Analysis of Variance (ANOVA) was performed to determine the efficacy of attractants and the difference in fruit fly catches between sub-orchards. The study results reveal that temperature, rainfall and relative humidity influence phenological events in plants which as a result influence the abundance of fruit flies and that weather has a direct impact on the population dynamics of fruit flies. It is therefore recommended that knowledge in fruit phenology can be used as a tool in Integrated Pest Control because of the quick response plants have to weather changes hence become accurate timers as to when to start fighting against fruit flies for effective and inexpensive pest management.

Belgian Directorate General for Development Co-operation (DGDC) through the fruit flies project (RAACF 13), collaboration between Sokoine University of Agriculture (SUA), Morogoro, Tanzania and Royal Museum for Central Africa (RMCA)