HOST PLANT INTERACTION OF SOUTH AMERICAN TOMATO LEAF MINER, Tuta absoluta (Meyrick): DECIPHERING POTENT KAIROMONES
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Date
2017-06
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bengaluru).
Abstract
Tomato leaf miner, Tuta absoluta (Meyrick) is an invasive pest of tomato introduced into India very recently. The objective of this study was to understand its interaction with the selected solanaceous host plants viz., tomato, potato, brinjal, ashwagandha, nightshade, wild tomato, tobacco and datura. Ovipositional preference of tomato leaf miner under no-choice condition revealed that the gravid females preferred tomato (66.53±3.30 eggs per plant) for egg laying the least number of eggs were laid on ashwagandha (0.81±0.38) and tobacco (4.31±0.73) and did not prefer to lay eggs on datura. Similar trend was also observed in subsequent larval count per plant under no-choice assay. Under choice condition also females preferred to lay eggs on tomato (276±22.56) and very few eggs were laid on ashwagandha (0.25±0.25) and tobacco (0.50±0.50) whereas, datura was not at all preferred. Larval survival was more on tomato. A positive behavioural response was observed when gravid females of T. absoluta were exposed to tomato plant headspace volatiles. In dual choice assay, tomato plant volatiles were found to be more attractive than other host plant volatiles. Electroantennography with gravid females revealed that mean depolarization was significantly more towards tomato, potato, ashwagandha and brinjal compared to empty air and honey. Seventy volatile compounds were revealed in the GC-MS analysis across the selected eight host plants headspace samples and terpenoids were abundant. Gaschromatography- Electroantennographic detection with gravid females revealed four active fractions viz., Nonane, 5-(2 methylpropyl); δ-2-carene; Ethanone, 1-(1, 3-dimethyl-3-cyclohexen-1-yl) and Nonane, 3,7-dimethyl-. When synthetic sample of carene was tested in olfactometer, no significant differences were noticed between control and treatment was observed.