Blends Of Pheromone Components Research Articles

Synergism between Enantiomers Creates Species-Specific Pheromone Blends and Minimizes Cross-Attraction for Two Species of Cerambycid Beetles.

Research over the last decade has revealed extensive parsimony among pheromones within the large insect family Cerambycidae, with males of many species producing the same, or very similar aggregation pheromones. Among some species in the subfamily Cerambycinae, interspecific attraction is minimized by temporal segregation, and/or by minor pheromone components that synergize attraction of conspecifics or inhibit attraction of heterospecifics. Less is known about pheromone-based mechanisms of reproductive isolation among species in the largest subfamily, the Lamiinae. Here, we present evidence that the pheromone systems of two sympatric lamiine species consist of synergistic blends of enantiomers of (E)-6,10-dimethyl-5,9-undecadien-2-ol (fuscumol) and the structurally related (E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (fuscumol acetate), as a mechanism by which species-specific blends of pheromone components can minimize interspecific attraction. Male Astylidius parvus (LeConte) were found to produce (R)- and (S)-fuscumol + (R)-fuscumol acetate + geranylacetone, whereas males of Lepturges angulatus (LeConte) produced (R)- and (S)-fuscumol acetate + geranylacetone. Field experiments confirmed that adult beetles were attracted only by their species-specific blend of the enantiomers of fuscumol and fuscumol acetate, respectively, and not to the individual enantiomers. Because other lamiine species are known to produce single enantiomers or blends of enantiomers of fuscumol and/or fuscumol acetate, synergism between enantiomers, or inhibition by enantiomers, may be a widespread mechanism for forming species-specific pheromone blends in this subfamily.

Coastal movements of migrating sea lamprey (Petromyzon marinus) in response to a partial pheromone added to river water: implications for management of invasive populations

How sea lampreys (Petromyzon marinus) search for and select reproductive habitat is poorly understood. Manual tracking of acoustically tagged migrants confirms the hypothesis that sea lampreys transition from extensive search to intensive search upon encounter with river water and return to extensive search upon leaving the plume. In addition, we document a previously unknown search tactic used to localize river mouths termed coastal rebounding. Increased intensive search in the river plume and subsequent approach to the river mouth is hypothesized to occur as a consequence of detection of a pheromone released by river resident larvae that indicate the presence of high-quality reproductive habitat. Application of two synthesized pheromone components caused migrants to increase time spent searching a plume by 57%; applications did not increase the likelihood of river entry. These findings suggest that partial pheromones constitute information that facilitates the search for river entrances, but prove insufficient to affect the decision to select a habitat. Proposed management tactics that rely on luring migrants into rivers with larval odor may prove ineffective without a complete blend of pheromone components.

Field bioassays of cerambycid pheromones reveal widespread parsimony of pheromone structures, enhancement by host plant volatiles, and antagonism by components from heterospecifics

Recent research has revealed extensive pheromonal parsimony within the large beetle family Cerambycidae, with closely related species producing the same or very similar pheromone components. This article summarizes research that evaluated attraction of cerambycids to individual pheromone components, blends of pheromone components, and combinations of pheromones with host plant volatiles. Field bioassays were carried out, in collaboration with the Pennsylvania Department of Agriculture and the USDA Cooperative Agricultural Pest Survey program, in 10–25 counties of Pennsylvania over 3 years. A total of 15,438 cerambycids of 134 species were captured, including two exotic species. Semiochemical lures attracted significant numbers of beetles in species of the subfamilies Cerambycinae, Lamiinae, and Spondylidinae, but were not attractive to species in the Lepturinae, Parandrinae, and Prioninae. These experiments reconfirmed the behavioral roles of semiochemicals for a number of species that have been studied previously, and yielded new information about semiochemistry of several species. The host plant volatile α-pinene enhanced attraction of species that were conifer specialists, whereas ethanol enhanced attraction of some species of hardwood specialists. The data suggest that species which share dominant pheromone components avoid cross attraction by differing in seasonal activity period, and by antagonistic effects of minor pheromone components on attraction of heterospecifics. This study further supports the concept that with careful choice of components, multiple pheromones can be deployed as single blends, and paired with host plant volatiles, to maximize the number and taxonomic diversity of cerambycid beetles that are attracted to a single lure, so that the number of different lures that must be deployed can be minimized.

A neuronal network model for the detection of binary odor mixtures

Event Abstract Back to Event A neuronal network model for the detection of binary odor mixtures In many lepidopteran species, males are attracted to females by pheromones, which typically are specific blends of two or more components. We constructed a minimal model, consistent with the known electrophysiology and structure of the Macroglomerular Complex (the site of odor processing specific to the male antennal lobe), that selectively responds to a blend of pheromone components in a fixed ratio over a wide range of concentrations. In the model the olfactory receptor neurons (ORNs) are represented by two groups of 200 Poisson neurons, each group responding specifically to one pheromone component. The concentration of the sensed component is encoded as the firing rate of the Poisson neurons. The ORN populations project to three groups of primary local neurons (LNs). These inhibit both each other and two intrinsically active secondary LNs, which in turn inhibit an intrinsically active projection neuron (PN). The underlying principle is the competition of the three primary LNs: given appropriate component concentrations and inter-LN synaptic strengths, the generalist LN becomes active and suppresses the two specialist LNs, both secondary LNs are inhibited and the PN is disinhibited to signal the presence of the correct blend. All LNs and the PN are implemented as Hodgkin-Huxley neurons. We tested the model with stimuli including all combinations of component concentrations, where the frequency of ORNs was in the range of 10 to 100 Hz in 10 Hz increments. Calculating the spike density function for the PN at midpoint of each stimulus presentation, we obtained a 10×10 response matrix for all combinations. An optimal response corresponds to a matrix with maximal values on the diagonal and 0 off-diagonal. We designed a 'success functional' by convolution of the response matrix with such a target response profile and, to optimize it, adjusted the synaptic strength on the following connections: ORNs to primary specialist LNs, ORNs to primary generalist LNs, and on all interconnections between primary LNs. We observed that (a) the relative strength of inputs from ORNs to specialist and generalist primary LNs must be specific (55-65% specialist compared to generalist strength for 1:1 pheromone ratio); (b) similarly, generalist-specialist, specialist-generalist and inter-specialist connections must have balanced synaptic strengths (in a ratio close to 0.94:1.20:1.10 for 1:1 component ratio). Modulation of ORN-LN connections ensures proper ?engagement? of the generalist LN, while LN interconnections appear essential in narrowing the generalist LN response, failing which the responses lose specificity to the component ratio. Finally, the number of ORNs needs to be large enough (hundreds) to avoid instances of 'false starts', where the generalist LNs starts spiking at the onset of a stimulus with an inappropriate pheromone component ratio simply due to the irregularity of ORN input. A further improvement is achieved by using LN groups (of 3 in this model) instead of individual LNs. This work was supported by the Biotechnology and Biological Sciences Research Council (grant number BB/F005113/1). Conference: Computational and systems neuroscience 2009, Salt Lake City, UT, United States, 26 Feb - 3 Mar, 2009. Presentation Type: Poster Presentation Topic: Poster Presentations Citation: (2009). A neuronal network model for the detection of binary odor mixtures. Front. Syst. Neurosci. Conference Abstract: Computational and systems neuroscience 2009. doi: 10.3389/conf.neuro.06.2009.03.236 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Feb 2009; Published Online: 03 Feb 2009. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract Supplemental Data The Authors in Frontiers Google Google Scholar PubMed Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

DNA sequence variation at the mitochondrial cytochrome oxidase I subunit among pheromotypes of the sibling taxaDiachrysia chrysitisandD. tutti(Lepidoptera: Noctuidae)

We surveyed variation in the mtDNA cytochrome oxidase subunit I (COI) gene in the noctuid sibling speciesDiachrysia chrysitisandD. tutti, whose taxonomic status has been queried. Taxonomically, these taxa are separated on the basis of wing pattern and time of flight period. Samples were field‐collected from different geographical sites where pheromone traps were baited to attract males containing different mixtures of two blends of pheromone components: (Z)‐5‐decenyl acetate and (Z)‐7‐decenyl acetate. Most specimens were sequenced over a 709‐bp segment of the COI gene. Single specimens each ofD. chrysitisandD. tuttiwere sequenced over a region of 1.5 kilobases. mtDNA variation within and amongD. chrysitisandD. tuttiis most simply interpreted as DNA polymorphism within a complex of closely related, but well‐differentiated pheromotypes. Maximal nucleotide difference per site among haplotypes was 0.28%, which is at the lower end of the range for interspecific mtDNA nucleotide diversity in Lepidoptera. Coefficient of differentiation Gstwasc. 76.3% ± 11.7%, a typical value at the intraspecific level. Sequences revealed stable diagnostic differences between pheromotypes irrespective of geographical origin. Identification of pheromone‐trapped males based on morphology remained vague and uncorrelated to mtDNA haplotypes. The survey illustrated the potential utility of direct DNA sequencing in assessing lineage structures or taxon limits among moths that have been previously found to be different using the pheromone mate recognition system, but which have not been subjected to DNA analysis. The results of mtDNA analyses presented here support recognition ofchrysitisandtuttilineages as presented in previous allozyme studies.

Differential Bio-Activity ofIpsandDendroctonus(Coleoptera: Scolytidae) Pheromone Components forMonochamus clamatorandM. scutellatus(Coleoptera: Cerambycidae)

Male and female Monochamus clamator (LeConte) and M. scutellatus (Say) are able to detect bark beetle pheromone components electrophysiologically and are attracted to traps baited with blends of pheromone components of scolytid bark beetles. We investigated the effect of individual pheromone components (ipsenol, ipsdienol, 3-methyl-2-cyclohexen-1-one (MCH), frontalin, verbenone, cis- and trans-verbenol, and endo- and exo-brevicomin) on Monochamus Dejean trap catches. Only traps baited with ipsenol and/or ipsdienol together with the host volatiles ethanol and α-pinene caught significantly more male and female M. scutellatus and M. clamator than traps baited with host volatiles alone. Ipsenol and ipsdienol are aggregation pheromones of secondary bark beetles in the genus Ips DeGeer while the other components are pheromones of primary bark beetles in the genus Dendroctonus Erichson. The former should be the most reliable indicators of suitable host material because most Ips spp. attack weakened or moribund trees or trees already successfully under attack by primary bark beetles, and their pheromones may be more persistent in space and time than those of Dendroctonus spp. In two successive years in an operational (commercial) mass-trapping program, traps baited with ethanol, α-pinene, and ipsenol captured twice as many beetles as traps baited with host volatiles alone. These results suggest that operational monitoring or mass-trapping programs could be improved significantly by the inclusion of ipsenol in baits at a minimal cost.

Responses in highly selective sensory neurons to blends of pheromone components in the moth Agrotis segetum

Pheromone detecting sensory neurons in moths are known to be highly sensitive and selective. Female-emitted sexual pheromones are normally mixtures of a few to several components. However, not much is known about how receptor neurons respond to blends of compounds. In the present study we investigated how four physiological types of pheromone component-selective neurons responded to binary mixtures or to the complete blend in the turnip moth Agrotis segetum. We found that responses to mixtures only rarely differed from that to the excitatory component alone. The mixture interactions were exclusively suppressive and occurred only at high concentrations. Therefore we conclude that the, in A. segetum, commonly observed mixture interactions observed in higher brain centra are mainly the result of central nervous processing and that information about the pheromone components reaches the antennal lobes virtually unaltered. In addition, we found a physiological type of receptor neuron, responding selectively to one of the female-emitted pheromone components, that has previously not been observed in the Swedish population.

Combinatorial odor discrimination in the brain: Attractive and antagonist odor blends are represented in distinct combinations of uniquely identifiable glomeruli

The rules governing the central discrimination of odors are complex and poorly understood, but a growing body of evidence supports the hypothesis that olfactory glomeruli may represent functionally distinct coding modules in the brain. Testing this hypothesis requires that both the functional characteristics and the spatial position of the glomerulus under study be uniquely identifiable. To address these questions, we examined a specialized array of glomeruli (the macroglomerular complex; MGC) in the antennal lobe of male moths that receives input from olfactory receptor cells tuned specifically to female-released odorants that either promote upwind flight (conspecific sex pheromones) or inhibit it (interspecific antagonists). By using a three-dimensional reconstruction method based on high-resolution laser-scanning confocal microscopy, we generated precise spatial maps of the MGC glomeruli in two related noctuid species with similar pheromone chemistry, Heliothis virescens and Helicoverpa zea. To determine the breadth of tuning of individual MGC glomeruli in processing information about these social signals, we used intracellular recording and staining methods to examine the responses of projection (output) neurons that innervate MGC glomeruli and that each project an axon to higher integrative centers. In both species, a close correspondence was found between the odor specificity of the projection neurons and the glomerulus (or glomeruli) supplied by them. The binary blend of pheromone components for each species was represented by neural activity in only two distinct glomeruli in both H. virescens and H. zea. Odorants that antagonize upwind flight when they are added to the respective pheromonal blends evoked excitatory activity in output neurons restricted to a third glomerulus in the MGCs of both species. In summary, these results suggest that the selective activation of different combinations of functionally distinct MGC glomeruli is a general means for discriminating these specific attractant and antagonist chemical signals in the brain.

Combinatorial odor discrimination in the brain: Attractive and antagonist odor blends are represented in distinct combinations of uniquely identifiable glomeruli

The rules governing the central discrimination of odors are complex and poorly understood, but a growing body of evidence supports the hypothesis that olfactory glomeruli may represent functionally distinct coding modules in the brain. Testing this hypothesis requires that both the functional characteristics and the spatial position of the glomerulus under study be uniquely identifiable. To address these questions, we examined a specialized array of glomeruli (the macroglomerular complex; MGC) in the antennal lobe of male moths that receives input from olfactory receptor cells tuned specifically to female-released odorants that either promote upwind flight (conspecific sex pheromones) or inhibit it (interspecific antagonists). By using a three-dimensional reconstruction method based on high-resolution laser-scanning confocal microscopy, we generated precise spatial maps of the MGC glomeruli in two related noctuid species with similar pheromone chemistry, Heliothis virescens and Helicoverpa zea. To determine the breadth of tuning of individual MGC glomeruli in processing information about these social signals, we used intracellular recording and staining methods to examine the responses of projection (output) neurons that innervate MGC glomeruli and that each project an axon to higher integrative centers. In both species, a close correspondence was found between the odor specificity of the projection neurons and the glomerulus (or glomeruli) supplied by them. The binary blend of pheromone components for each species was represented by neural activity in only two distinct glomeruli in both H. virescensand H. zea. Odorants that antagonize upwind flight when they are added to the respective pheromonal blendsevoked excitatory activity in output neurons restricted to a third glomerulus in the MGCs of both species. In summary, these results suggest that the selective activation of different combinations of functionally distinct MGC glomeruli is a general means for discriminating these specific attractant and antagonist chemical signals in the brain. J. Comp. Neurol. 400:35–56, 1998. © 1998 Wiley-Liss, Inc.

Chemical communication in heliothine moths. VII. Correlation between diminished responses to point-source plumes and single filaments similarly tainted with a behavioral antagonist

Addition of (Z)-11-hexadecenyl acetate (Z11-16:Ac) into a normally attractive binary blend of Heliothis virescens pheromone components resulted in a suppression of upwind flight and source location by males. Male response was reduced even at the lowest dosages of Z11-16:Ac tested but upwind flight and source location were most clearly reduced when the loading of Z11-16:Ac reached 10% or more of the (Z)-11-hexadecenal (Z11-16:Ald) loading (the major component present in the binary blend). Similar patterns of suppression in response were noted when Z11-16:Ac was added to binary blends of pheromone components at both 10 and 100 μg loadings of Z11-16:Ald. Males in casting flight following upwind flight in a mechanically generated pulsed plume, responded to the interception of a subsequent, single binary-blend filament by making a toward-source upwind surge. Responses of males to a single filament that was tainted by a level of Z11-16:Ac that had allowed some reduced level of upwind flight and source location to occur in the previous plume experiments were diminished compared with their control counterparts. Analysis of the flight tracks revealed that the surges in response to single tainted filaments were stunted because males made fewer significant changes in course angles steered, airspeeds generated, and in the tempo of counterturns executed.

Electroantennographic responses differentiate sibling species of dingy cutworm complex,Feltia jaculifera (GN.) (Lepidoptera: Noctuidae)

The dingy cutworm is one of the more common and widely distributed of North American noctuids. Determination of the antennal responses of field-collected male moths to a standard test blend of pheromone components shows that two pheromonal phenotypes of the dingy cutworm occur throughout the prairie region of western Canada and at least two others occur in eastern Canada. The pheromone types are morphologically indistinguishable and, so far as is known, have similar life histories and biology. The two prairie types are broadly sympatric with partially overlapping seasonal flight periods. Although hybrids can be easily produced in the laboratory, there is no evidence of hybridization in the field. The pheromone system of the dingy cutworm is apparently rather plastic, resulting in a mosaic of pheromone types (sibling species) that appear to be reproductively isolated but have not differentiated morphologically.

Heritable variation in pheromone response of the pink bollworm,Pectinophora gossypiella (Lepidoptera: Gelechiidae)

Heritability of variation in male pheromone response by pink bollworm moths,Pectinophora gossypiella (Saunders), was examined using a still-air, wing-fanning bioassay. Heritability (±SE) of overall responsiveness, as measured by the mean duration of wing fanning to the blend of pheromone components produced by females [44∶56 ratio of (Z, E)- to (Z, Z)-7,11-hexadecadienyl acetate], was 0.385 ± 0.095. Heritabilities of wingfanning duration to blends with 25 and 65%Z, E isomer were 0.377 ± 0.113 and -0.145 ± 0.103, respectively. These findings indicate an asymmetry in the genetic component of variation in response to pheromone blends with high and low proportions of theZ, E isomer. An index of response specificity for individual males was developed based on the response to an off-blend (either 25 or 65%Z, E isomer) relative to the response to the 44%Z, E blend. Heritabilities of response specificity were 0.117 ± 0.059 and -0.043 ± 0.067 for the 25 and 65%Z, E blends, respectively.

Disruption of pheromone communication in moths: is the natural blend really most efficacious?

AbstractIt is widely assumed that a blend of pheromone components, that is qualitatively and quantitatively similar to the natural sex attractant, is the most effective mating disruptant for moths. However, the literature contains only limited evidence supporting this assumption. The authors discuss the importance of comparing the relative effectiveness of complete and incomplete pheromone blends when evaluating the potential of mating disruption for controlling pest moths.

Spodoptera exigua: Capture of feral males in traps baited with blends of pheromone components

Field tests were conducted with various blends of acetates and alcohols previously identified as components of the sex pheromone for the beet armyworm (BAW),Spodoptera exigua (Hübner). The compounds were formulated on rubber septa and placed in sticky traps positioned in fields populated withAmaranthus sp., a favored host of this species. Moth captures were highest in traps baited with septa containing a blend of 0.1 mg (Z,E)-9,12-tetradecadien-1-ol acetate (Z9,E12-14∶Ac) and 0.01 mg(Z)-9-tetradecen-1-ol (Z9-14∶OH). Additionally, we confirmed that all combinations of acetates tested alone captured significantly fewer males than blends containing a 10∶1 ratio ofZ9,E12-14∶Ac andZ9-14∶OH. A 10∶1 formulation ofZ9,E12-14∶Ac andZ9-14∶OH in hollow fibers was also attractive to feral BAW males.