The capacity of conophthorin to enhance the attraction of two Xylosandrus species (Coleoptera: Curculionidae: Scolytinae) to ethanol and the efficacy of verbenone as a deterrent

相似文献   

Interruption of aggregation pheromone in Ips typographus (L.) (Col. Scolytidae) by non-host bark volatiles

Abstract 1 The antennally active nonhost bark volatiles (NHVs): trans‐conophthorin (tC), C₆‐alcohols (green leaf volatiles; GLVs) and C₈‐alcohols, were tested for their ability to reduce attraction of the spruce bark beetle Ips typographus (L) (Col. Scolytidae) to its pheromone sources in both laboratory walking bioassy and field trapping experiments. 2 In the walking bioassay with I. typographus females, individual NHVs such as tC, 3‐octanol and 1‐octen‐3‐ol, and the unsuitable host signal, verbenone (Vn), were inactive at the doses tested. However, the blend of C₆‐alcohols (3GLVs) and all the binary, ternary, or quarternary blends significantly reduced the female attraction to the pheromone sources. 3 In the field trapping experiments, individual NHV signals (tC, C6‐alcohols and C₈‐alcohols) all reduced catch of I. typographus in pheromone‐baited traps, with their inhibitory effects similar to that of the known inhibitor, Vn. The binary, ternary or quarternary combinations of these NHV signals or Vn, all caused significantly stronger reductions in trap catches than the individual signals. The blends showed similar levels of interruption, except the binary blend of C₈‐alcohols (2C8OH) and Vn. 4 Difference in trapping mechanism between pipe traps (attraction and landing) and Lindgren funnel traps (attraction) did not affect the pattern of inhibition of these active NHV signals and Vn. 5 These behaviourally active nonhost volatiles and Vn might be used effectively to protect spruce trees or stands against attacks by I. typographus.     

Interactions among intraspecific competition, emergence patterns, and host selection behaviour in Ips pini (Coleoptera: Scolytinae)

Abstract.  1. Variations in developmental conditions of bark beetles, particularly intraspecific competition, can induce morphological and physiological modifications in the offspring. It is hypothesised that intraspecific competition could also affect host selection behaviour. Such behavioural changes might be manifested in response to host (alpha-pinene) or beetle (verbenone) compounds.
2.  Ips pini were bred at different densities. The offspring were measured for size, weight, and lipid concentration, and then subjected to tunnelling bioassays in agar media amended with varying amounts of alpha-pinene or verbenone.
3. High parental colonisation densities reduced emergence time of parents and offspring. Increasing colonisation density and emergence time had a negative influence on offspring vigour, resulting in a reduction of the distance tunnelled by the beetles.
4. Both alpha-pinene and verbenone were repellent. Surprisingly, verbenone was also toxic at high concentrations, with its effect being greater on beetles arising from high densities. The repellent effect of these compounds did not vary according to colonisation density, but for both compounds, at a 1.5 mg g^–1 concentration, it increased with emergence time.
5. The consequences of varying vigour and behaviour in relation to developmental conditions and emergence patterns on population dynamics of I. pini are discussed.     

An operative kairomonal lure for managing pine sawyer beetle Monochamus galloprovincialis (Coleoptera: Cerymbycidae)

Abstract:  Monochamus galloprovincialis Olivier (Col., Cerambycidae) is a vector of the pine wood nematode, Bursaphelenchus xylophilus , causing the destructive pine wilt disease. An effective lure for monitoring and/or mass-trapping would be of great interest in the management of this pine sawyer. Males and females of this species show an attractive kairomonal response to blends composed of four pheromone compounds used by Ips spp. bark beetles and two host volatiles from pines. This six-component lure is highly attractive but may to be too complex and costly for practical use as each component is released from a separate lure. The role of each component, ipsdienol, ipsenol, cis -verbenol, methyl butenol, α -pinene and ethanol as attractants for M. galloprovincialis was field tested in Spain to obtain a simpler but equally effective bait. Ipsenol was confirmed as the strongest kairomonal signal to M. galloprovincialis synergizing response to α -pinene by 95 times. The addition of methyl butenol to this blend doubled the number of males and females trapped. On the other hand, neither ipsdienol, cis -verbenol nor ethanol improved the results when incorporated into the above three-component blend. A lure consisting of ipsenol, methyl butenol and α -pinene may be very cost-efficient in operational monitoring or mass trapping of M. galloprovincialis . Three potentially repellent candidates, (−)verbenone, methyl cyclohexenone and trans -conophthorin, were also tested against the attractive three-component bait. trans -Conophthorin significantly reduced male catches of M. galloprovincialis ; methyl cyclohexenone had no effect. Verbenone significantly enhanced the response of females to the attractive combination of α -pinene, ipsenol and methyl butenol.     

Can Ips typographus (L.) (Col., Scolytidae) smell the carrion odours of the dead beetles in pheromone traps? Electrophysiological analysis

Abstract:   Head-space samples of Ips typographus dead beetles taken from pheromone traps were tested by combined gas chromatography and electroantennographic detection (GC–EAD) on the antennae of the same species, and identified by GC-mass spectroscopy (MS). The GC-EAD analysis showed that antennae of both sexes responded to 1-hexanol and verbenone from the aeration samples, while the typical and strong carrion odours from the dead beetles such as dimethyl disulphide, 3-methyl-1-butenol (isoamyl alcohol), 2,5-dimethyl pyrazine and isovaleric acid elicited no antennal responses. The EAD active compounds, 1-hexanol and verbenone, have been shown in earlier studies to be inhibitory on attraction of I. typographus to pheromone traps. Thus, the decreased catching efficacy of pheromone traps with many dead beetles might be the result of the release of 1-hexanol and verbenone from the dead beetles, but not to the typical carrion smells which are strongly detected by the human nose.     

Semiochemical diversity diverts bark beetle attacks from Norway spruce edges

The semiochemical diversity hypothesis (SDH) states that interference with host‐selection from non‐host volatiles (NHV) is an important mechanism for associational resistance. Inhibition of bark beetle attraction to point sources by non‐host volatiles (NHV) is well established and might be a signal serving in host‐selection also at the habitat scale. In forests dominated by Norway spruce in middle and northern Europe (N Slovakia 2006 & 2007, SE Sweden 2007), we applied a blend of NHV and verbenone, released from dispensers fixed at 2 and 6 m height at forest edges with high Ips typographus populations. In Slovakia, three different doses (0.2–0.7 dispensers/m forest edge) were tested in 20‐tree zones of spruce stand edges. The Swedish experiments used only the middle dose. In Slovakia, there was high tree mortality but dispensers with the anti‐attractants reduced killed trees in a dose‐dependent manner. The reduction in tree killing ranged from 35 to 76% compared to untreated zones. Regression analysis of relative tree kill on log dispenser density was highly significant ( = 0.34, corresponding effect size d≈ 0.98). In Sweden, with lower beetle populations, most attacks (99%) were found outside the experimental areas, with high attack rates (15 trees/ha) in a range of 15–30 m from treated groups, indicating an active inhibitory radius exceeding the previous estimates. The SDH as a functional aspect of biodiversity was tested by converting spruce monocultures into an artificial semiochemically mixed forests. The use of NHV provides the only non‐insecticidal method of direct protection of conifer forests. The demonstrated principle of protection is still too expensive for area‐wide use, but viable for high‐value areas (nature reserves). Further development of push–pull strategies or area‐wide applications may prove more cost efficient. In the long‐term, the only sustainable approach is a forest landscape of mixed habitats.     

Influence of sex,maturity and host substances on pheromones in the guts of the bark beetles, Ips paraconfusus and Dendroctonus brevicomis

Pheromones and metabolites of host (ponderosa pine) compounds were found in association with the hindgut of both naturally fed and of non-fed, host vapour-exposed bark beetles, Ips paraconfusus and Dendroctonus brevicomis. Much smaller amounts were found in the corresponding heads and mid guts. Sex-specific differences in content of pheromones were observed as in earlier studies. Exposure of I. paraconfusus to vapours of a pheromone component, ipsenol and other monoterpene alcohols resulted in their accumulation in the hindgut but relatively very low amounts in the head. The possible sites of pheromone biosynthesis are discussed. Exposure of male I. paraconfusus to vapours of host compounds, myrcene and α-pinene, revealed that immature adults do not produce the pheromone components, ipsenol and ipsdienol, as mature adults do while both immature and mature sexes produced another pheromone component, cis-verbenol, as well as trans-verbenol and myrtenol. Immature D. brevicomis adults did not contain pheromones until their exposure to vapours of (?)-α-pinene which caused production of trans-verbenol but only about 10% that of mature adults treated similarly. Verbenone, a male-produced inhibitory pheromone of D. brevicomis, apparently was not synthesized from (?)-α-pinene in females nor was its synthesis in males enhanced by exposure to this host compound.     

Integrating repellent and attractant semiochemicals into a push–pull strategy for ambrosia beetles (Coleoptera: Curculionidae)

Non‐native ambrosia beetles (Coleoptera: Curculionidae), especially Xylosandrus compactus (Eichhoff), Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford), are destructive wood‐boring pests of trees in ornamental nurseries and tree fruit orchards. Previous studies have demonstrated the adults are repelled by verbenone and strongly attracted to ethanol. We tested a “push–pull” semiochemical strategy in Ohio, Virginia and Mississippi using verbenone emitters to “push” beetles away from vulnerable trees and ethanol lures to “pull” them into annihilative traps. Container‐grown trees were flood‐stressed to induce ambrosia beetle attacks and then deployed in the presence or absence of verbenone emitters and a perimeter of ethanol‐baited interception traps to achieve the following treatment combinations: (a) untreated control, (b) verbenone only, (c) ethanol only, and (d) verbenone plus ethanol. Verbenone and ethanol did not interact to reduce attacks on the flooded trees, nor did verbenone alone reduce attacks. The ethanol‐baited traps intercepted enough beetles to reduce attacks on trees deployed in Virginia and Mississippi in 2016, but not in 2017, or in Ohio in 2016. Xylosandrus germanus, X. crassiusculus and both Hypothenemus dissimilis Zimmermann and X. crassiusculus were among the predominant species collected in ethanol‐baited traps deployed in Ohio, Virginia and Mississippi, respectively. Xylosandrus germanus and X. crassiusculus were also the predominant species dissected from trees deployed in Ohio and Virginia, respectively. While the ethanol‐baited traps showed promise for helping to protect trees by intercepting ambrosia beetles, the repellent “push” component (i.e., verbenone) and attractant “pull” component (i.e., ethanol) will need to be further optimized in order to implement a “push–pull” semiochemical strategy.     

Evaluation of repellents for the redbay ambrosia beetle,Xyleborus glabratus,vector of the laurel wilt pathogen

The redbay ambrosia beetle, Xyleborus glabratus, is the vector of the laurel wilt disease fungal pathogen, Raffaelea lauricola. Since the vector's initial detection in the USA in the early 2000s, laurel wilt has killed millions of redbay, Persea borbonia, trees and other members of the plant family Lauraceae. To protect host trees from beetle attack and laurel wilt infection, we tested the efficacy of host‐ and non‐host‐derived and commercial compounds as X. glabratus repellents in field experiments. In our first trial, the major constituents of the non‐host tree, longleaf pine, Pinus palustris, and SPLAT Verb (verbenone 10%) were paired with manuka oil attractants and beetle captures were counted. Verbenone and a 1 : 1 blend of myrcene and camphene were intermediate to both the manuka positive and blank negative controls. Subsequently, we tested different blends of methyl salicylate (MeSA), a host defence and signalling compound, and verbenone in SPLAT dispensers using freshly cut redbay bolts as an attractant. All treatments reduced X. glabratus captures and boring holes as compared to the redbay (‐) repellent positive control; however, SPLAT Verb and SPLAT MeSA‐Verb (5% each) achieved the highest repellency, with results comparable to that of the non‐host (laurel oak). These trials establish that host‐derived and commercially available repellent compounds can reduce X. glabratus attacks and therefore have potential as part of an integrated management strategy against laurel wilt and its vector.