INVESTIGATIONS ON BEHAVIOUR AND CHEMICAL ECOLOGY OF MELON FLY, Zeugodacus cucurbitae (Coquillett) (DIPTERA: TEPHRITIDAE)
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Date
2019-12-27
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
The volatiles of host plant stimulate a wide range of behavioural response in the
insects that are associated with them. The melon fruit fly, Zeugodacus cucurbitae
(Diptera: Tephritidae) being oligophagous in nature deals with widely cultivated
cucurbitaceous crops. Nevertheless, their mechanism of finding preferred host plant as
well as conspecific mate and the molecular basis of olfaction is unknown. In this study,
we show the ovipositional preference of melon flies and the behaviour eliciting host
chemical cues. We studied the response of melon flies to immature and mature stage
fruits of four different cucurbits. The gravid female flies preferred the mature ridge gourd
fruits over other cucurbit hosts. On further investigation analytically the eight specific
molecules which the melon fly uses in locating their host, viz., 1-Octen-3-ol, α-Pinene, p-
Cymene, p-Ethyl-benzaldehyde, Methyl salicylate, p-Cymen-7-ol, Benzoic acid, 4-ethyl
methyl ester and Heptacosane were identified. On molecular front, we developed the
transcript assembly of melon flies antennae using the Illumina Next Seq 500 system. A
total of 21,504 unigenes along with 137 chemosensory genes responsible for the odour
detection mechanism in flies were covered. The homology model of 23 select odour
binding proteins was built and In-silico docking analysis was performed against the eight
host identified chemical cues. Docking results disclosed that 1-Octen-3-ol had very
interactive energy with the selective odour binding proteins (5, 7) than any other ligands.
Our results suggest that the flies deploy unique proteins to determine the specific
molecules present in their preferred host ecospace. Further, we established that the
synthetic blend of behavioural active chemical cues is equally attractive to gravid melon
flies when compared to natural fruit sample. This study opens up huge arenas to evaluate
the identified chemical cues in the field ecosystem for its potential to trap female melon
flies.