How whiteflies (Bemisia tabaci) make the choice for a host plant prior to landing, is not precisely known.
Here we investigated whether they respond to specific volatiles of tomato. Zingiberene and curcumene
were purified from Solanum habrochaites (PI127826), characterised by NMR and X-ray analysis and identified
as 7-epizingiberene and R-curcumene. In contrast, oil from Zingiber officinalis contained the stereoisomers
zingiberene and S-curcumene, respectively. Using a combination of free-choice bio-assays and
electroantennography, 7-epizingiberene and its dehydrogenated derivative R-curcumene were shown
to be active as semiochemicals to B. tabaci adults, whereas the stereoisomers from ginger were not. In
addition, R-curcumene elicited the strongest electroantennographic response. Bio-assays showed that a
cultivated tomato could be made less attractive to B. tabaci than its neighbouring siblings by the addition
of the tomato stereoisomer 7-epizingiberene or its derivative R-curcumene. These sesquiterpenes apparently
repel adult whiteflies prior to landing, presumably because it informs them that after landing they,
or their offspring, may be exposed to higher and lethal concentrations of the same compounds.
How whiteflies (Bemisia tabaci) make the choice for a host plant prior to landing, is not precisely known.Here we investigated whether they respond to specific volatiles of tomato. Zingiberene and curcumenewere purified from Solanum habrochaites (PI127826), characterised by NMR and X-ray analysis and identifiedas 7-epizingiberene and R-curcumene. In contrast, oil from Zingiber officinalis contained the stereoisomerszingiberene and S-curcumene, respectively. Using a combination of free-choice bio-assays andelectroantennography, 7-epizingiberene and its dehydrogenated derivative R-curcumene were shownto be active as semiochemicals to B. tabaci adults, whereas the stereoisomers from ginger were not. Inaddition, R-curcumene elicited the strongest electroantennographic response. Bio-assays showed that acultivated tomato could be made less attractive to B. tabaci than its neighbouring siblings by the additionof the tomato stereoisomer 7-epizingiberene or its derivative R-curcumene. These sesquiterpenes apparentlyrepel adult whiteflies prior to landing, presumably because it informs them that after landing they,or their offspring, may be exposed to higher and lethal concentrations of the same compounds.
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