3-hexenylacetate and linalool

In response to insect herbivory, plants mobilize various defenses. Defense responses include the release of herbivore-induced plant volatiles (HIPVs) that can serve as signals to alert undamaged tissues and to attract natural enemies of the herbivores. Some HIPVs can have a direct negative impact on herbivore survival, but it is not well understood by what mechanisms. Here, we tested the hypothesis that exposure to HIPVs renders insects more susceptible to natural pathogens. Exposure of the caterpillars of the noctuid

Topics: Acetates; Acyclic Monoterpenes; Animals; Bacillus thuringiensis; Food Chain; Herbivory; Indoles; Larva; Monoterpenes; Spodoptera; Volatile Organic Compounds

Odorant receptors (ORs) play an important role in insects to monitor and adapt to the external environment, such as host plant location, oviposition-site selection, mate recognition and natural enemy avoidance. In our study, we identified and characterized OR12 from three closely-related species, Helicoverpa armigera, Helicoverpa assulta, Heliothis virescens, sharing between 90 and 98% of their amino acids. The tissue expression pattern analysis in H. armigera showed that HarmOR12 was strongly expressed both in male and female antennae, but not in other tissues. Functional analysis performed in the heterologous Xenopus expression system showed that all three OR12 were tuned to six structurally related plant volatiles. Electroantennogram recordings from male and female antennae of H. armigera closely matched the data of in vitro functional studies. Our results revealed that OR12 has a conserved role in Heliothinae moths and might represent a suitable target for the control of these crop pests.

Topics: Acetates; Action Potentials; Acyclic Monoterpenes; Amino Acid Sequence; Animals; Conserved Sequence; Female; Gene Expression; Insect Proteins; Male; Monoterpenes; Moths; Oocytes; Patch-Clamp Techniques; Phylogeny; Receptors, Odorant; Sequence Alignment; Sequence Homology, Amino Acid; Terpenes; Transgenes; Volatile Organic Compounds; Xenopus laevis

The essential oil composition of flowering aerial parts of Iranian Silene morganae Freyn (Caryophyllaceae) was analysed for the first time using gas chromatography and gas chromatography-mass spectrometry. Thirty-one compounds consisting of 90.3% of the volatile oil were detected. The major constituents were benzaldehyde (11.6%), (Z)-3-hexenyl acetate (9.6%), (E)-β-ocimene (8.2%) and linalool (7.4%). Terpenoids (43.5%), particularly monoterpene hydrocarbons (24.2%), had the highest contribution in S. morganae Freyn flowering aerial parts oil.

Topics: Acetates; Acyclic Monoterpenes; Alkenes; Benzaldehydes; Gas Chromatography-Mass Spectrometry; Molecular Structure; Monoterpenes; Oils, Volatile; Plant Components, Aerial; Plant Oils; Silene; Terpenes

The volatile compounds emitted from uninfested apple seedlings, cv. Royal Gala, and apple seedlings infested with generalist herbivore Epiphyas postvittana larvae were sampled using headspace collection and analyzed by gas chromatography-mass spectrometry. Nine additional compounds were only detected in infested apple seedlings [including benzyl alcohol, (E)-β-ocimene, benzyl cyanide, indole, (E)-nerolidol, and four unidentified compounds]. Infested apple seedlings produced larger amounts of (Z)-3-hexenyl acetate, linalool, 4,8-dimethyl-1,3(E),7-nonatriene, methyl salicylate, β-caryophyllene, germacrene D, (E,E)-α-farnesene, and (Z)-3-hexenyl benzoate than uninfested plants. Female parasitoids flew exclusively upwind to infested and not to uninfested apple seedlings in wind tunnel choice tests and preferred infested leaflets in still air, even after the removal of larvae. The attraction of a parasitoid to infested apple seedlings in the laboratory and in the field to apple and many other plants in at least six families supports considerable generality of the tritrophic signaling process.

Topics: Acetates; Acyclic Monoterpenes; Alkenes; Animals; Behavior, Animal; Feeding Behavior; Female; Gas Chromatography-Mass Spectrometry; Hymenoptera; Larva; Malus; Monoterpenes; Moths; Odorants; Seedlings; Sesquiterpenes; Trees; Volatile Organic Compounds

Parasitoids employ different types of host-related volatile signals for foraging and host-location. Host-related volatile signals can be plant-based, originate from the herbivore host or produced from an interaction between herbivores and their plant host. In order to investigate potential sex- and species-related differences in the antennal response of parasitoids to different host-related volatiles, we compared the electroantennogram (EAG) responses of both sexes of the specialist parasitoid, Microplitis croceipes (Cresson), and the generalist, Cotesia marginiventris (Cresson), to varying doses of selected plant-based host-related volatiles: two green leaf volatiles (cis-3-hexenol and hexanal) and three inducible compounds (cis-3-hexenyl acetate, linalool, and (E,E)-alpha-farnesene). Mating had no significant effect on EAG response. Females of both species showed significantly greater EAG responses than conspecific males to green leaf volatiles, which are released immediately after initiation of herbivore feeding damage. In contrast, males showed greater responses than conspecific females to inducible compounds released much later after initial damage. Cotesia marginiventris females and males showed greater EAG responses than counterpart M. croceipes to the tested compounds at various doses, suggesting that the generalist parasitoid shows greater antennal sensitivity than the specialist to the tested host-plant volatiles. These results are discussed in relation to the possible roles of green leaf volatiles and inducible compounds in the ecology of female and male parasitoids.

Topics: Acetates; Acyclic Monoterpenes; Animals; Electric Conductivity; Female; Hexanols; Male; Monoterpenes; Plant Leaves; Sesquiterpenes; Sex Factors; Sexual Behavior, Animal; Species Specificity; Wasps

We investigated volatile infochemicals possibly involved in location of the generalist predatory mite Neoseiulus californicus to plants infested with spider mites in a Y-tube olfactometer. The predators significantly preferred volatiles from lima bean leaves infested with Tetranychus urticae to uninfested lima bean leaves. Likewise, they were attracted to volatiles from artificially damaged lima bean leaves and those from T. urticae plus their visible products. Significantly more predators chose infested lima bean leaves from which T. urticae plus their visible products had been removed than artificially damaged leaves, T. urticae, and their visible products. These results suggest that N. californicus is capable of exploiting a variety of volatile infochemicals originating from their prey, from the prey-foodplants themselves, and from the complex of the prey and the host plants (e.g., herbivore-induced volatiles). We also investigated predator response to some of the synthetic samples identified as volatile components emitted from T. urticae-infested lima bean leaves and/or artificially damaged lima bean leaves. The predators were attracted to each of the five synthetic volatile components: linalool, methyl salicylate, (Z)-3-hexen-1-ol, (E)-2-hexenal, and (Z)-3-hexenyl acetate. The role of each volatile compound in prey-searching behavior is discussed.

Topics: Acetates; Acyclic Monoterpenes; Aldehydes; Animals; Chemotactic Factors; Female; Hexanols; Mites; Monoterpenes; Odorants; Phaseolus; Plant Leaves; Predatory Behavior; Salicylates; Smell; Tetranychidae; Volatilization

Topics: Acetates; Action Potentials; Acyclic Monoterpenes; Animals; Female; Ganglia, Invertebrate; Male; Manduca; Monoterpenes; Neurons; Olfactory Pathways; Olfactory Receptor Neurons; Sense Organs; Sensory Thresholds; Sex Characteristics; Smell; Stimulation, Chemical

We measured the effects of exposure to volatile compounds produced by host plants on the rate of capture of male Spodoptera exigua using synthetic sex pheromones. Exposure to volatile compounds stimulated strong electroantennographic responses of male S. exigua. The behavioral responses of male moths to combinations of sex pheromone and volatile compounds were tested in wind tunnel experiments. When lures were baited with synthetic sex pheromone plus benzaldehyde, phenylacetaldehyde, (Z)-3-hexenyl acetate, or linalool, respectively, the landing rate of S. exigua males was increased by 101.4%, 79.6%, 60.6%, and 34.3%, respectively, compared to sex pheromone alone. In field tests, traps baited with either pheromone + (E)-2-hexenal, pheromone + phenylacetaldehyde, pheromone + (Z)-3-hexenyl acetate, or pheromone + (Z)-3-hexenol enhanced moth catches by 38.8%, 34.6%, 24.6%, and 20.8%, respectively compared to traps baited with pheromone alone. In a second field experiment, more S. exigua males were trapped with a combination of a synthetic sex pheromone blend and several individual host plant volatiles compared to synthetic sex pheromone alone. These results suggest that some host plant volatiles enhance the orientation response of S. exigua male moths to sex pheromone sources.

Topics: Acetaldehyde; Acetates; Acyclic Monoterpenes; Animals; Benzaldehydes; Male; Monoterpenes; Plants; Sex Attractants; Sexual Behavior, Animal; Smell; Spodoptera; Volatilization