Relationship between mango volatile organic compounds and gall fly attack.
Augustyn W. A., Plooy G. W. du, Botha B. M., Joubert V. P.
Author Affiliation: Departement Chemie, Tshwane Universiteit van Tegnologie, Pretoria, South Africa.
27 : 49-52
Abstract : Mango gall fly (Procontarinia matteiana) infestation is a potential economic problem facing the mango industry. Trees infested with gall fly exhibit reduced photosynthetic capacity. There are huge variations in susceptibility to gall fly attack between the different mango cultivars. 'Heidi' is heavily parasitized, while 'Keitt', although attacked, does not develop full blown galls, but forms pseudogalls. 'Sensation', on the other hand, seems to be resistant to gall fly attack. Plants emit volatile organic compounds (VOCs) that may act as attractants or repellants in plant-insect interaction. VOCs emitted by the leaves of three different mango cultivars, 'Heidi', 'Sensation' and 'Keitt', were collected at different stages throughout the growth season and analyzed by thermal desorption-GC-FID. The terpene profiles of 'Heidi', 'Keitt' and 'Sensation' cultivars were compared to identify specific terpenes or terpene combinations responsible for attraction or resistance to gall flies. From the terpene profiles it was seen that the levels of specific monoterpenes increase as the growth season progress. Flush leaves emit higher levels of all VOCs than mature leaves. Initial results indicate a link between susceptibility and high levels of specific volatile compounds. The monoterpene, ?-pinene, seems to play a role in gall fly attraction.