Antagonistic effects of floral scent in an insect–plant interaction

Abstract

In southwestern USA, the jimsonweed Datura wrightii and the nocturnal moth Manduca sexta form a pollinator-plant and herbivore-plant association. Because the floral scent is probably important in mediating this interaction, we investigated the floral volatiles that might attract M. sexta for feeding and oviposition. We found that flower volatiles increase oviposition and include small amounts of both enantiomers of linalool, a common component of the scent of hawkmoth-pollinated flowers. Because (þ)-linalool is processed in a female-specific glomerulus in the primary olfactory centre of M. sexta, we hypothesized that the enantiomers of linalool differentially modulate feeding and oviposition. Using a synthetic mixture that mimics the D. wrightii floral scent, we found that the presence of linalool was not necessary to evoke feeding and that mixtures containing (þ)-and/or (2)-linalool were equally effective in mediating this behaviour. By contrast, females oviposited more on plants emitting (þ)-linalool (alone or in mixtures) over control plants, while plants emitting (2)-linalool (alone or in mixtures) were less preferred than control plants. Together with our previous investigations, these results show that linalool has differential effects in feeding and oviposition through two neural pathways: one that is sexually isomorphic and non-enantioselective, and another that is female-specific and enantioselective.

Natural selection on floral volatile production inPenstemon digitalis: Highlighting the role of linalool

“…That phenotypic selection on scent was stronger than for other corolla characters, such as floral color and size in P. digitalis, which was particularly interesting for two reasons. First, because pollinators frequently show consistent color preferences, floral color is generally hypothesized to be adaptive and a likely the insect potentially allows for alternate ecological functions of the enantiomers 18 and, thus, differential natural selection on the two compounds. Therefore, to better understand how linalool might function in P. digitalis, we used a chiral column (Cyclosil-B, Agilent-J&W GC columns) to analyze its optical characteristics.…”

Increased plant volatile production affects oviposition, but not larval development, in the moth Helicoverpa armigera

“…At high concentrations, linalool can be toxic to a variety of insect species (Abdelgaleil et al, 2009;Chang et al, 2009;Phillips et al, 2010), affecting mortality, growth, activity and feeding in lepidopteran larvae (Rajwinder et al, 2010;Singh et al, 2009). This volatile occurs naturally in two isomeric forms, and a recent study using artificial odour blends has suggested that the R and S isomers of linalool may be perceived differently by the moth Manduca sexta, with both isomers being attractive to nectar feeding moths, but only the R isomer deterring ovipositing moths (Reisenman et al, 2010).…”

Systemic defense priming byPseudomonas putidaKT2440 in maize depends on benzoxazinoid exudation from the roots

“…[26][27][28] Ref. 29 reported that VOC blends with higher levels of (-)-isomer deterred oviposition on Datura wrightii by Manduca sexta moths. More recently, ref.…”