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Tomato leaf miner, Tuta absoluta is a ravaging pest of tomato in many countries of the world including Tanzania. The pest inflicts substantial damage to tomato crop that causes a huge loss to farmers. This study focused on evaluating potentials of shared volatiles emanated from four hosts of the pest, namely tomato, aubergine, sweet pepper and watermelon in formulating attractant for female T. absoluta. Y-tube olfactometer was used to evaluate attractiveness of leaf volatiles from four hosts and a blend of shared compounds and GC-MS was used to identify volatile constituents of the four hosts. Results indicate that, female T. absoluta were attracted to volatiles of tomato volatiles (χ2 = 4.9, P < 0.05) and repelled by watermelon volatiles (χ2 = 6.4, P < 0.05). We further observed high composition of terpenes in tomatoes (70%) as compared to other hosts, which might have contribute to its observed attraction compared to the other hosts. On the other hand, watermelon was highly constituted by green leaves volatiles (GLVs) which is suggested to account for the observed repellency. Thus, shared compounds that do not contain GLVs significantly attracted female T. absoluta at a dose of 10 μl (χ2 = 8.1, P < 0.05). Our findings have revealed that, compounds shared by hosts attract females T. absoluta. Therefore, results from this study have laid groundwork in the development of attractant for management and monitoring of the pest. [ABSTRACT FROM AUTHOR]

Bactrocera dorsalis, (Tephritidae) presented a grave threat to a broad range of fruit and vegetables in the tropics, including Tanzania. Bactrocera dorsalis is among the most destructive tephritid fruit fly, causing devastating loss of fruits especially mango. Insects use olfactory cues to locate hosts, oviposition sites and mating, in which pheromones are believed to be a strong cue used by insect to locate their mates. However, due to their high ability to adapt and occupy different ecological niches into various agroecological zones, there is a need to evaluate pheromonal composition from time to time to improve their control strategies. Therefore, this study conducted olfactometric assays and Gas Chromatography-Mass Spectrometry (GC-MS) to evaluate attractiveness and identity, respectively, of constituents of volatiles emitted by both sexes of B. dorsalis. The results show that volatiles emitted by males were more attractive to both female and their own male conspecific than female volatiles (PROC ANOVA, F (0.05, 4) = 71.05, P < 0.001). GC-MS analyses of volatiles from the two sexes comprise mainly by esters and spiroacetals. These results have contributed in understanding the pheromone communication; and have provided ground information for the development of control strategies to improve existing monitoring and control strategies for this pest. [ABSTRACT FROM AUTHOR]