Enhancement of insect pheromone responses by green leaf volatiles (original) (raw)
Related papers
1994
Green leaf volatile odours (GLV) affecting host and pheromone attraction were investigated by field trapping and laboratory bioassays for European bark beetles, mainly Tomicus piniperda andlps typographus. A six component synthetic blend of GLV, based on literature data, was composed of hexanol and hexanal isomers and linalool. The different rates of evaporation of individual compounds were measured chemically (GC) and gravimetrically. In the laboratory, lps typographus and/. duplicatus were both inhibited in their.response to their pheromones (MB & cV and lpsdienol & E-Myrcenol, at 10� and 10-a g/min., respectively) by a combination of Vn and GLV at 10-9 and 10-7 g/min. lps typographus was inhibited by GL V alone at 1 o-7 g/min. In the field, components of the blend were released individually or in mixture from 3-5 dispensers adjusted to give an equal and sustained release rates of 1, 101, and 102 mg/day of each compound. There was an inhibitory effect of the GL V mix blend at all doses, especially in synergism with Verbenone (Vn at 1 mg/day and 101 mg/day of GLV) in the field. Both the attraction ofTomicus piniperda to a known kairomone blend of host compounds (a-Pinene, Terpinolene, and a3-Carene at 101 mg/day) and that of lps typographus to synthetic pheromone (Pheroprax® or methylbuthenol (MB) & cis-verbenol (cV) at 5 & 0.1 mg/day) was reduced. In contrast, Hylurgops palliatus appeared to be attracted to combinations including GL V.
The effects of host tree monoterpenes on primary and secondary attraction of the bark beetles, Ips pini and Ips grandicollis, and their associated phloeophagous insects were investigated. Monoterpenes alone were not attractive to I. pini. However, monoterpenes mediated the attraction of I. pini to its aggregation pheromones. With the exception of 3-carene, the effect of monoterpenes on I. pini's response to its pheromone, ipsdienol plus lanierone, was inhibitory. In contrast, (− )-a-pinene both attracted I. grandicollis and enhanced the attraction of I. grandicollis to its pheromone, ipsenol. No monoterpene inhibited the response of I. grandicollis to its pheromone. The inhibitory effect of host monoterpenes on I. pini response to its aggregation pheromone differs from previous work, in which monoterpenes either synergized responses or had no effect. In addition to possible geographic differences, the concentrations used in our study simulated trees that had begun to respond to attack, whereas previous studies deployed lower concentrations, which simulated constitutive phloem from unattacked trees. These results support the view that trees that undergo induced responses to bark beetles sometimes inhibit attraction of additional beetles, despite the beetles' production of aggregation pheromones. Neither species displayed cross-attraction to the pheromone of the other. The red turpentine beetle, Dendroctonus valens, showed weak and consistent attraction to (+)-a-pinene and in some cases to (− )-a-pinene. Attraction to (− )-a-pinene was usually enhanced by Ips spp. pheromones. The absence of strong attraction to (+)-a-pinene and partial attraction to (− )-a-pinene suggest that the effects of different stereoisomers of a-pinene on D. valens vary throughout its geographical range. Hylastes porculus was also attracted to some monoterpenes, particularly (− )-a-pinene. An additional 10 species of phloeophagous insects were caught in response to monoterpenes and / or pheromones, including the pine root weevils, Hylobius pales and Pachylobius picivorus, and the longhorned beetle, Monochamus carolinensis.
Oikos, 2003
Zhang, Q.-H. and Schlyter, F. 2003. Redundancy, synergism, and active inhibitory range of non-host volatiles in reducing pheromone attraction in European spruce bark beetle Ips typographus.-Oikos 101: 299-310. Host and habitat selection in flight by conifer bark beetles is governed by inhibition of attraction by non-host volatiles (NHV), in addition to the well-known attraction to kairomones from host plants and to aggregation pheromones from conspecifics. Antennally-active NHV from angiosperm birch and aspen trees were field tested on the European spruce bark beetle, Ips typographus (L.), by pheromone baited traps in Sweden using release rates of NHV comparable to those from a non-host tree. Trap catches were significantly reduced by 50-70% by individual NHV: trans-conophthorin, 3-octanol and 1-octen-3-ol from non-host bark, 1-hexanol and (Z)-3-hexen-1ol from both leaves and bark and (E)-2-hexen-1-ol from leaves. Combined NHV signals in binary and ternary blends with the same overall release rates (ca 5 mg/day) showed both redundancy and synergism in their inhibitory effects. The redundancy occurred among individual green leaf alcohols (GLV-alcohols or C 6-alcohols), C 8-alcohols, and between these two groups, while trans-conophthorin and verbenone (Vn, from unsuitable host trees) showed significant synergistic effects between each other and with GLV-alcohols or C 8-alcohols. The coexistence of redundancy and synergism in non-host chemical signals may indicate different functional levels (non-host habitats, species, and unsuitable host trees) of these negative volatile signals in the host selection process of conifer bark beetles. We showed an active inhibitory range (AIR) of a NHV-blend plus Vn on a standard pheromone bait to be at least 2 m, by using a central pheromone trap and surrounding concentric barrier trap rings with radii of 1, 2, and 4 m. The influx of bark beetles flying across concentric rings within the AIR was reduced by 55-99%, depending on the distance to the central pipe trap. Our findings support the hypothesis that as mixed forests have greater semiochemical diversity than pure host stands; they disturb olfactory guided host choice, and may reduce the possibility of outbreaks of conifer-infesting bark beetles. The synergistic effects as well as the active inhibitory range found in this study also suggest that optimal combinations of these NHV and verbenone may have potential in protecting forests against I. typographus by reducing or stopping attacks on suitable host trees. Mixed stands with higher semio-chemical diversity disturb olfactory guided host choice and reduce the risk for outbreaks of specialist herbivores.. This 'semiochemical-diversity hypothesis' provides new support to the general 'stability-diversity hypothesis'.
Aggregation pheromones of almond bark beetle Scolytus amygdali (Coleoptera: Scolytidae)
The almond bark beetle (ABB), Scolytus amygdali (Coleoptera: Scolytidae), is a pest of stone fruits in the Mediterranean region and southern Europe. Adults feeding on buds cause most of the damage. Applications of non-selective insecticides, burning of dead trees and pruning slash are environmentally unsafe and are often ineffective for ABB control. Preliminary experiments with ABB colonizing branches indicated the existence of an aggregation pheromone, and prompted us to identify it. Volatiles emitted by female ABB boring into plum branches were collected on Porapak Q and eluted with hexane. GC-EAD analyses of volatile extracts, using female antennae as an electroantennographic detector, revealed four EAD-active candidate pheromone components, as follows: (3S,4S)-4-methyl-3-heptanol (SS-I), most abundant and EAD-active component; (3S,4S)-4-methyl-3hexanol (SS-II); (5S,7S)-7-methyl-1,6-dioxaspiro[4,5]decane (III); and 7-methyl-1,6-dioxaspiro [4,5]dec-8-ene [IV], the first unsaturated spiroaketal found in insects. In field experiments (1994)(1995)(1996)(1997)(1998) using funnel traps baited with polyethylene pheromone dispensers, SS-I unlike SS-II was attractive by itself, while SS-I plus SS-II at a ratio of 2:1 was optimally attractive. Addition of stereoisomeric mixtures of III and/or IV did not affect trap captures. Candidate kairomones ethanol and propanol did not affect total trap catches. Methanol, in contrast, strongly inhibited attraction of beetles to pheromone-baited traps and prevented colonization of cut branches. It failed, however, to reduce damage to tree buds caused by ABB maturation feeding. Although SS-I plus SS-II was twice as attractive as the stereoisomeric mixtures of 4-methyl-3-heptanol plus 4-methyl-3-hexanol, these readily obtainable stereoisomeric mixtures can be used for both pheromone-based monitoring and control of ABB populations.
Identification and Field Evaluation of Attractants for the Cranberry Weevil, Anthonomus musculus Say
Journal of Chemical Ecology, 2011
Studies were conducted to develop an attractant for the cranberry weevil, Anthonomus musculus, a pest of blueberry and cranberry flower buds and flowers in the northeastern United States. In previous studies, we showed that cinnamyl alcohol, the most abundant blueberry floral volatile, and the green leaf volatiles (Z)-3-hexenyl acetate and hexyl acetate, emitted from both flowers and flower buds, elicit strong antennal responses from A. musculus. Here, we found that cinnamyl alcohol did not increase capture of A. musculus adults on yellow sticky traps compared with unbaited controls; however, weevils were highly attracted to traps baited with the Anthonomus eugenii Cano aggregation pheromone, indicating that these congeners share common pheromone components. To identify the A. musculus aggregation pheromone, headspace volatiles were collected from adults feeding on blueberry or cranberry flower buds and analyzed by gas chromatographymass spectrometry. Three male-specific compounds were identified: (Z)-2-(3,3-dimethyl-cyclohexylidene) ethanol (Z grandlure II); (Z)-(3,3-dimethylcyclohexylidene) acetaldehyde (grandlure III); and (E)-(3,3-dimethylcyclohexylidene) acetaldehyde (grandlure IV). A fourth component, (E)-3,7dimethyl-2,6-octadien-1-ol (geraniol), was emitted in similar quantities by males and females. The emission rates of these volatiles were about 2.8, 1.8, 1.3, and 0.9 ng/adult/d, respectively. Field experiments in highbush blueberry (New Jersey) and cranberry (Massachusetts) examined the attraction of A. musculus to traps baited with the male-produced compounds and geraniol presented alone and combined with (Z)-3-hexenyl acetate and hexyl acetate, and to traps baited with the pheromones of A. eugenii and A. grandis. In both states and crops, traps baited with the A. musculus maleproduced compounds attracted the highest number of adults. Addition of the green leaf volatiles did not affect A. musculus attraction to its pheromone but skewed the sex ratio of the captured adults towards females. Although the role of plant volatiles in host-plant location by A. musculus is still unclear, our studies provide the first identification of the primary A. musculus aggregation pheromone components that can be used to monitor this pest in blueberry and cranberry pest management programs.
2001
Non-host volatiles (NHV) were tested on antennae of Ips sexdentatus with coupled gas chromatographicelectroantennographic detection (GC-EAD). Significant antennal responses were found to aggregation pheromone components, ipsdienol and amitinol, an attraction inhibitor, verbenone, and non-host bark volatiles extracted from Betula pendula, including trans-conophthorin (tC) and alcohols. The tC, a blend of three green leaf alcohols (C6alcohols), and a blend of two bark alcohols (C8-alcohols) were tested in combination for their ability to disrupt the attraction of the stenographer bark beetle to pheromone-baited traps, unbaited and pheromone-baited maritime pine logs. The strongest disruptive effect resulted from the addition of the tC combined with the blends of NHV alcohols at high release rate, achieving an 83% reduction in trap catches, 89% reduction of attacks on unbaited pine logs, and 60% on baited logs. It is proposed that the two types of NHV have an additive effect, tC playing a major role in pheromone disruption while the alcohols would interrupt host specific signals. The results suggest that I. sexdentatus uses both bark and green leaf volatiles from non-host tree species in the host selection process. These NHV are promising disruptants, which could be used to prevent stenographer bark beetle attacks on log piles or standing trees in forest. A mixture of conifers and broad-leaved species would also disturb olfactory guided host selection supporting the assumption that more diverse forests are less prone to pest insect outbreaks.
Arthropod-Plant Interactions, 2008
The Canadian Entomologist 32: 965 -981 Leaf and bark volatiles from non-host birches, Betula pendula Roth. and Betula pubescens Ehrh. (Betulaceae), and aspen, Populus tremula L. (Salicaceae), were tested on spring-dispersing Tomicus piniperda (L.) and Tomicus minor (Hart.) by gas chromatographicelectroantennographic detection (GC-EAD) and by attractantbaited traps in southern Sweden. GC-EAD analysis of the head-space volatiles from fresh bark chips of B. pendula revealed two green leaf alcohols, I-hexanol and (273hexen-1-01, that consistently elicited antennal responses by T. piniperda and T. minor.
Journal of Chemical Ecology, 1990
Capillary gas chromatography with columns of different polarity and two-dimensional fractionation of effluents were used with novel subtractive-combination bioassays to rigorously isolate host-and insect-produced pheromone synergists of the bark beetle Pityogenes chalcographus (Coleoptera: Scolytidae). Methyl (E,Z)-2,4-decadienoate (E,Z-MD) and the previously identified chalcogran were found to be synergistically attractive to both sexes. E,Z-MD was produced sex-specifically in males, and only when they had fed on host-plant tissue. A Norway spruce monoterpene fraction (including c~-pinene, /3-pinene, and camphene) increased the attractive response to the pheromone components. Dose-response curves for E,Z-MD and chalcogran in the laboratory bioassay indicated the two components are highly synergistic. The isolation methods are important for further progress in identifying certain semiochemical synergists found in trace amounts in complex chemical mixtures, such as when insects must feed in host plants in order to produce pheromone.
The boll weevil, Anthonomus grandis, has been monitored through deployment of traps baited with aggregation pheromone components. However, field studies have shown that the number of insects caught in these traps is significantly reduced during cotton squaring, suggesting that volatiles produced by plants at this phenological stage may be involved in attraction. Here, we evaluated the chemical profile of volatile organic compounds (VOCs) emitted by undamaged or damaged cotton plants at different phenological stages, under different infestation conditions, and determined the attractiveness of these VOCs to adults of A. grandis. In addition, we investigated whether or not VOCs released by cotton plants enhanced the attractiveness of the aggregation pheromone emitted by male boll weevils. Behavioral responses of A.
Chemoecology, 1993
The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm (Helicoverpa zea) and the codling moth (Cydia pomonella), is enhanced or synergized by a certain group of host-plant volatiles, the "green-leaf volatiles" (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent leaf volatiles of certain H. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture of H. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome of C. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps.