Bioelectrical activity of citrus flower moth prays citri and host plant selection for oviposition

ABSTRACT

Electroantennogram [EAG] and oviposition responses of the citrus flower female moth, Yponomeuta prays citri to various citrus flower volatile chemicals were tested as possible attractants or deterrents for oviposition. This was also coupled with analytical chromatographic techniques to identify the organic pure compounds in the citrus flowers with the EA recording. Dose response relationships were established to compare the relative receptor sensitivities using different concentrations of these individual pure components and correlate them with ovipositional activities. The obtained results indicated that the volatile odors from different citrus flowers may activate [e.g. Limonene and Citronellol] or inhibit [e.g. Nerol, Terpineol, B-Caryophyllene, Methylantheranlate and Geraniol] the females to lay eggs. A good correspondence was found between oviposition and single sensillum EAg response. In conclusion, the sensory cues that mediate the P.Citri ovipositional response include visual and chemical information. The visual information [flower's shape, colour and size] direct the insect to land on the flower. Contact chemoreceptors present on the insect's antenna appeared to be involved in the assessment of flower surface chemistry which directs the insect to oviposit or deterred the unsuitable plants. Finally the insect's ovipositional response in mediated by a complex mixture of compounds of certain fixed concentrations instead of a single compound. The variation of these concentrations may change or reverse this response and hence it may serve in biological control of this insect