Phenological stage dependent sensory and behavioral responses of Zeugodacus cucurbitae (Coquillett) to cucurbit volatiles

Zeugodacus cucurbitae (Coquillett) flies significantly impact vegetable production in many tropical regions. This study aimed to identify physiologically and behaviorally relevant volatiles from host plants that could potentially be used for future monitoring and control of female Z. cucurbitae flies. Volatile organic compounds were collected from flower, immature fruit, and mature fruit stages of Cucumis sativus L., Cucurbita pepo L., and Cucurbita mixta L. in field conditions, and were analyzed using gas chromatography/mass spectrometry (GC-MS). A total of 81 compounds were identified from across the three species and their phenological stages. Volatilome diversity was higher within phenological stages of each species than between species. Electrophysiological responses of sexually mature Z. cucurbitae females to host volatiles were recorded using gas chromatography coupled electroantennogram detection (GC-EAD). Active compounds were then formulated into blends for behavioral assays conducted in a six-choice olfactometer. Synthetic blends based on physiologically active compounds from flower and immature fruit headspace attracted more females than blends derived from mature fruit and the paraffin oil control (P < 0.001). Some of the physiologically active compounds were found to be behaviorally redundant. The performance of these blends needs to be assessed under field conditions.