Aggregation attractant of the European elm bark beetle,Scolytus multistriatus

The three components of theScolytus Multistriatus aggregation attractant-4-methyl-3-heptanol (1), -multistriatin (2), and -cubebene (3)-were collected from beetles and elm wood by aeration, solvent extraction of host tissue, or solvent extraction of beetles and beetle parts. Bioassays and analysis of extracts demonstrated that (a) compounds 1 and 2 are produced by virgin females and 3 is host-produced, (b) cessation of the production of 1 is coincident with diminished attractiveness of females after they have been joined by males, (c) the release of 3 from elm wood is augmented by attacking beetles, and (d) the level of 3 is related to the condition of the wood, and fungal growth (particularlyceratocystis ulmi) may lead to increased levels of 3. Compound 1 was concentrated in the upper abdominal area and 2 in the abdomen tips, but neither component was in the hindgut. A gland opening through the vaginal palpi (a pair of sclerotized conical structures) was circumstantially associated with the release of 2. Compounds 1, 2, and 3 are regulatory agents that contribute to the initiation and maintenance of the beetle-elm-microorganism biosystem.Coleoptera:Scolytidae.     

Response of the european elm bark beetle,Scolytus multistriatus,to host bacterial isolates

The response of the European elm bark beetle,Scolytus multistriatus, to host bacterial isolates was studied qualitatively under field conditions. Initial experiments indicated that such isolates were attractive to in-flight beetles. These isolates, identified asBacillus subtilis (five strains),B. pumilus, andEnterobacter cloacae, were grown on nutrient agar in glass vials and attached to sticky traps in elm woods. Although beetles were caught on the bacterial isolate-baited traps, the catches were variable, inconsistent, and often contradictory from one experiment to another. High numbers ofS. multistriatus were caught on traps baited with three strains ofB. subtilis, but in addition to thesubtilis strains, there were also aerial contaminants in the treatments, namelyE. aerogenes, Corynebacterium sp., andFlavobacterium sp. Also, relatively high catches were recorded on nutrient agar controls. When elm wood-bark plugs, sterilized (by gamma irradiation) and unsterilized, were placed in vials with the host bacterial isolates, the presence or absence of fresh elm, gamma irradiated or not, had no noticeable effect on beetle attractancy.Coleoptera: Scolytidae.     

Attraction of European elm bark beetles,Scolytus multistriatus,to pheromone-baited traps

Newly emergedScolytus mullistriatus reared in the laboratory were marked, released in the field, and recaptured on sticky pheromone-baited traps at various distances. Four groups of beetles were conditioned before release by providing food, flight exercise, both food and flight, or by withholding food and flight for 24 hr to determine effect of treatment on pheromone response. Average catches per trap for untreated beetles and the respective treatments were 5.5, 2.1, 1.1, 1.0, and 0.6. Overall recovery ranged from 3 to 8% of 58,421 marked beetles released in four experiments. Combined feeding and flight exercise resulted in low trap response but flight to distant traps increased. Beetles held with no food or flight showed the lowest response. EndemicS. multistriatus responded to all traps with catches ranging from 13 to 17 times the number of marked beetles recaptured.Coleoptera: ScolytidaeThe use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture or the Forest Service of any product or service to the exclusion of others that may be suitable.     

Response of the European elm bark beetle,Scolytus multistriatus (Coleoptera: Scolytidae), to isomers and components of its pheromone

Laboratory bioassays (two methods) and field tests demonstrated synergistic action of the three components [(–)-4-methyl-3-heptanol (I); (–)-2,4-dimethyl-5-ethyl-6,8-dioxabicylo[3.2.1]octane (-multistriatin) (II); and (–)--cubebene (III)] of the pheromone bouquet ofScolytus multistriatus. Individually and in pairs the components were slightly attractive; I+II was clearly the most active doublet. Indirect evidence indicates that only one of the four enantiomers of I is active. Of the , , and isomers of II, only the is active. With the addition of compound I, slightly attractive extract from mated females became nearly as active as extract from virgin females.     

Response of the elm bark beetle,Scolytus multistriatus (Coleoptera: Scolytidae), to component mixtures and doses of the pheromone,multilure

The response of the elm bark beetle,Scolytus multistriatus (Marsham), was measured to various doses and mixtures of the three components of its aggregation pheromone. The ratio of the components released, particularly heptanol to multistriatin, strongly influenced the number, but not the sex ratio, of beetles that responded. We concluded that a bait that released about 400 100 800 g/day of heptanol-multistriatin-cubebene would be effective in mass-trapping beetles.The use of a trade, firm, or corporation name in this paper is for the information and convenience of the reader. It does not constitute an official endorsement or approval by the Forest Service or the U.S. Department of Agriculture.     

Structure-activity correlations among analogs of 4-methyl-3-heptanol,a pheromone component of the european elm bark beetle (Scolytus multistriatus)

A number of analogs of the title compound (1), with several different functional groups in place of the 3-OH and with a variety of substituents, were tested for biological acitivity by a laboratory walking-beetle assay. The electroantennogram (EAG) response was determined for many of these, as well. Field tests with baited sticky traps were carried out on compounds with activity in the walking-beetle assay and/or that gave a high EAG response. Structure-activity correlations with parameters reflecting hydrophobic, steric, electronic, and van der Waals interactions with olfactory receptors were examined primarily on the basis of the behavioral tests. Electronic substituent effects on the 3-position functional group and steric effects were found to correlate best. It is suggested that the strength of a hydrogen bond to the 3-oxygen or 3-nitrogen (as proton acceptor) is important in chemoreception by receptors that are involved in the behavioral response.     

Components of moribund American elm trees as attractants to elm bark beetles,Hylurgopinus rufipes andScolytus multistriatus

Hylurgopinus rufipes male and female beetles were attracted to American elms infected with Dutch elm disease, and to American elms killed by injection of cacodylic acid.H. rufipes was also attracted to solvent extracts of elm, or to Porapak Q-trapped volatiles from elm. The major components of attractive fractions of Porapak Q-trapped volatiles were isolated, identified, and tested in field bioassays. Several artificially compounded mixtures of sesquiterpenes were attractive toH. rufipes, although no bait tested was as attractive as diseased tree controls. Laboratory bioassays withH. rufipes were marginally successful. In laboratory bioassays, nine of 14 sequiterpenes identified from active fractions of Porapak extracts elicited significant response fromScolytus multistriatus male and female beetles: - and -cadinene, -cubebene, -muurolene, and -elemene were most active. However, in field tests, none of the sesquiterpenes alone or in combination significantly attractedS. multistriatus, nor did they significantly enhance the attraction ofS. multistriatus to female-produced pheromone components (4-methyl-3-heptanol [H] and -multistriatin [M]). In other field tests, -cubebene (C) significantly enhanced response ofS. multistriatus to H plus M, but foliage, logs, or chips of healthy elm did not enhance trap catch to HMC.Coleoptera: Scolytidae.     

Chemical attractants for the smaller european elm bark beetleScolytus multistriatus (Coleoptera: Scolytidae)

The secondary attractant for the smaller European elm bark beetleScolytus multistriatus is a mixture of three compounds: (-)4-methyl-3-heptanol(I); 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo(3.2.1) octane (II); and (–)-cubebene (III). The novel structure assigned to compound II was confirmed by synthesis. All three compounds were isolated from the volatile compounds collected on Porapak Q by aerating elm bolts infested with virgin female beetles. The GLC fractionations were monitored by two laboratory bioassays. Individually, each compound was inactive in the laboratory bioassays, but a mixture of all three showed activity nearly equivalent to that of the of the original Porapak extract. A mixture of synthetic I and II plus natural III (from cubeb oil) was highly attractive to beetles in preliminary field tests.Supported in part by a cooperative research grant to the State University of New York College of Environmental Science and Forestry, State University of New York, Syracuse, New York, from the USDA Forest Service, Northeastern Forest Experiment Station, Upper Darby, Pennsylvania, and from the Elm Research Institute, Harrisville, New Hampshire.     

Effects of multilure components on twig-crotch feeding by European elm bark beetles

The three components of the European elm bark beetle pheromone dispensed from polyethylene vials attached to the boles of healthy juvenile elms affected the rates of beetles landing and twig feeding on the baited trees. Maximum attraction to the tree occurred when all three pheromone components were presented together in a ratio of 118 for 4-methyl-3-heptanol (H), -multistriatin (M), and -cubebene (C). M released either alone or in excess of its natural ratio with H and C induced twig-crotch feeding. H presented alone had no effect on attraction or twig-crotch feeding, but in combination with M it induced landing on and boring into the tree bole. We concluded that the ratio of M and H being released influenced incoming beetles either to land on and colonize the bole or to feed in twig crotches. M in excess of H, known to occur when most females are mated, terminates colonization and deflects incoming beetles to crowns of elms. Scolytus multistriatus (Coleoptera: Scolytidae).     

Individual variation in aggregation pheromone content of the bark beetle,Ips typographus

The total amounts of, and proportions among, components of the aggregation pheromone produced byIps typographus were found to vary considerably among individuals excised from attacks on standing spruce trees. Chemical analyses of 392 individual male beetles were made by GC-MS. Both unmated and mated males had log-normal frequency distributions in their content of the pheromone components 2-methyl-3-buten-2-ol (MB) andcis-verbenol (cV), since a large fraction of males had a low content. The amount of MB in male hindguts varied independently of cV and the other oxygenated monoterpenes, while the amount of cV covaried with the other pinene alcohols and showed a variation between beetles from different spruce trees. Mated males had, on average, lower amounts of MB than unmated, while the average content of cV in mated males varied with the resin content of their host trees. Ipsdienol and ipsenol were only found in mated males, but in less than 40% and 10%, respectively, of these mated males. Even-aged males exposed to -pinene in the laboratory showed slightly less variation in the amounts of verbenols, and the variations in ratio between cV and tV were similar to those among males attacking the same spruce tree.Coleoptera, Scolytidae.This study was made within the Swedish project Odour Signals for Control of Pest Insects.     

Field response of spruce bark beetle,Ips typographus,to aggregation pheromone candidates

Six compounds previously identified from hindguts of unmated maleIps typographus (L.) during host colonization: 2-methyl-3-buten-2-ol (MB),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt),trans-myrtanol (tM), and 2-phenylethanol (PE), were tested for their attractivity in the field with a subtractive method. The amounts of MB and cV released from a pipe trap were similar to those given off from the commercial bait Ipslure as well as that from a Norway spruce tree,Picea abies (L.) Karst., under mass attack. The blend of the compounds became nonattractive when either MB or cV was subtracted, while subtraction of any of the other four compounds had no effect. Addition of ipsdienol (Id) to the blend did not significantly increase the attraction. In a second comparative test, the addition of three compounds as a group (tV + Mt + PE) to MB + cV again had no effect on the attraction, but the addition of Id increased the catch somewhat. Addition of host logs to a bait releasing MB + cV at a rate lower than in previous experiments did not influence the attraction to pipe traps. Sticky traps containing natural pheromone sources (50 males in a log), which released 1–5 mg/day of MB as determined by aerations with deuterated MB as internal standard, were less attractive than a synthetic source releasing similar amounts of MB.Coleoptera: Scolytidae.This study was made within the Swedish project Odour Signals for Control of Pest Insects.     

Effect of mating on terminating aggregation during host colonization in the bark beetle,Ips paraconfusus

Attraction of maleIps paraconfusus to male-infested ponderosa pine logs was inhibited by volatiles from logs infested with mated males and females over an 8-day period in the field. The response of females during this time was not significantly inhibited by these volatiles. Synthesis of the male-specific pheromones, ipsenol and ipsdienol, appeared negligible after 8 days in males allowed to mate with 3 females in these logs while males alone contained levels of these pheromones at about half their maximum rate. The decline in pheromone production in mated males appears to result, at least in part, from a reduction in the activity of the biosynthetic system that converts the host monoterpene, myrcene, to ipsenol and ipsdienol. Mating and feeding have apparently no effect on the biosynthetic system that converts the host monoterpene, (–)--pinene, to the pheromone,cis-verbenol in either males or females. The reduced production and release of pheromones by males after mating appears to play a major function in the process of terminating the aggregation phase of host colonization.     

Pheromone production by the bark beetle,Ips paraconfusus,in the nonhost,white fir

MaleI. paraconfusus confined to artificial entrance tunnels in white fir logs produced the pheromone compounds ipsenol and ipsdienol in their hindguts. The hindguts were attractive to females in a laboratory olfactometer and the male infested logs were attractive in field bioassay. The amount of pheromones produced and the amount of feeding and boring activity is much less in white fir than in ponderosa pine. There were no pheromones detected in the hindguts of recently emerged, unfed males.Coleoptera; Scolytidae.Research supported by the Rockefeller Foundation, an NIH training grant, USDA/SEA Regional Research Project W-110, and the USDA Forest Service.From a thesis submitted by J.S. Elkinton in partial satisfaction of the requirements for the PhD degree, University of California, Berkeley, California, 1979.     

Field response of the dutch elm disease vectors,Scolytus multistriatus (Marsham) andS. scolytus (F.) (Coleoptera: Scolytidae) to 4-methyl-3-heptanol baits containing α-, β-,δ-, or δ-multistriatin

The field responses of English populations of the Dutch elm disease vectors,Scolytus multistriatus andS. scolytus to baits containing 4-methyl-3-heptanol, a host synergist [(?)-α-cubebene or (?)-limonene] and (±)-α-, (+)-β-, (?)-β-, (±)-γ-, or (±)-δ-multistriatin were examined. (±)-α-Multistriatin, released at 5–10 μg/day, enhanced the response ofS. multistriatus to baits containing 4-methyl-3-heptanol and either of the host synergists but had no effect on the capture ofS. scolytus. The release of larger amounts (57 or 365 μg/day) of (±)-α-multistriatin interrupted the response of both species to the 4-methyl-3-heptanol baits. It appears that α-multistriatin has multiple functions as a behavior-modifying substance for the two beetles. The (+)-β-, (?)-β-, (±)-γ-, and (±)-δ-multistriatins were inactive when released at 5–10 μg/day. The results of these field experiments suggest that one bait can be formulated to capture both species.     

榆树皮胶粉制备改性天然高分子絮凝剂

在乙醇-水体系中以榆树皮胶粉、氯乙酸、丙烯酰胺为原料合成改性天然高分子絮凝剂,以产物黏度和模拟水浊度去除率为目标,研究了碱投加量、氯乙酸投加量、单体质量比、接枝共聚温度对产品性能的影响,得到了最佳合成工艺条件,并采用红外光谱对改性产物进行了分析。结果表明:当m(榆树皮胶粉)∶m(氢氧化钠)∶m(氯乙酸)∶m(丙烯酰胺)=5∶1∶1.2∶3,聚合温度为75℃时,产品具有最佳的絮凝效果和最高黏度,其他反应条件为碱化时间3 h、碱化温度70℃、聚合时间5 h。红外光谱表明,榆树皮胶粉发生了接枝共聚。     

Behavioral responses of elm bark beetles to baited and unbaited elms killed by cacodylic acid

Diseased elms, treated with various doses of cacodylic acid in northwest England, became attractive to elm bark beetles (Coleoptera: Scolytidae). This attraction seemed to be independent of pheromone baits. However attractive the trees became, they were unsuitable to the beetles as breeding sites since significantly more beetles visited the trees than were stimulated to penetrate and attempt to breed. It seems as if colonization of trap trees by the bark saprophytePhomopsis oblonga following cacodylic acid treatment made the trees unsuitable to beetles for breeding.     

Oviposition stimulants for the beetle,Monochamus alternatus hope,in inner bark of pine

Field and laboratory ovipositional responses ofMonochamus alternatus Hope, respectively, to methanol and water extracts from pine inner bark were examined in comparison with those to pine inner bark, especially using a laboratory-built apparatus for the latter bioassay. Irrespective of the existence of volatiles from paraquat-induced lightwood, pine inner bark and its methanol and water extracts stimulated ovipositional response only in the presence of free moisture.     

Collection on Porapak Q of the aggregation pheromone ofScolytus multistriatus (Coleoptera: Scolytidae)

The attractive volatiles in the air around the virgin female of the smaller European elm bark beetle,Scolytus multistriatus (Marsham), tunneling in elm logs can be collected by passing the air through a column of Porapak Q. These volatiles can be removed from the Porapak by Soxhlet extraction with hexane, yielding an extract that is attractive to in-flight beetles in the field. GLC analyses of this extract and an extract of virgin female frass indicate that the aeration extract contains active chemicals that are not in the extract of frass.     

Semiochemicals produced by western balsam bark beetle,Dryocoetes confusus Swaine (Coleoptera: Scolytidae)

The most prominent beetle-produced volatiles identified in the abdominal extracts of maleDryocoetes confusus Swaine after they had bored for 24 hr in logs of subalpine fir,Abies lasiocarpa (Hook.) Nutt. were:exo andendo-brevicomin,trans-verbenol, verbenone, myrtenol,trans-pinocarveol,cis- andtrans-p-menthen-7-ol, 3-caren-10-ol, and several monoterpenes and sesquiterpenes. Myrtenol was the only conspicuous compound in extracts from males that had been exposed toA.lasiocarpa resin volatiles for 24 hr. Laboratory bioassays indicated that both (–)- and (+)-exo-brevicomin were attractive to femaleD. confusus, and that the (–) enantiomer did not inhibit response to its antipode. Results from field trapping experiments indicated that bothero-brevicomin and myrtenol are aggregation pheromones forD. confusus.exo-Brevicomin baits were effective in causing attack byD. confusus on baited and surrounding trees, suggesting that this pheromone may have utility in manipulating populations of the beetle.Research supported by the Natural Sciences and Engineering Research Council of Canada, Operating Grants A3881 and A3706 and Strategic Grant G1039.     

Interactions between components of the aggregation pheromone during chemotaxis by the bark beetleIps paraconfusus

The male-produced aggregation pheromone inIps paraconfusus is composed of three compounds. Female bark beetles were exposed to combinations of these compounds, presented as point sources in an enclosed, circular arena. By itself,cis-verbenol (cV) had no effect on the number of beetles that reached the source. Either ipsenol (Ip) alone or ipsdienol (Id) alone strongly increased the number that reached the source, with Id producing a dose-response curve with a much steeper slope. cV moved the onset of the response to Id to higher doses of Id, but the response rose more rapidly after onset than when cV was absent. Overall, cV inhibited the effect of Id except at the highest dose. cV affected the onset of the response to Ip little or none, but strongly increased the slope of the response, synergizing the effect of Ip. The responses to combinations of Id and Ip were related to the log of a linear combination of their doses. The results are consistent with a model where Id and Ip act at a single site of action, but with different potencies, while cV appears to modify the effects of Id and Ip, rather than affecting the site of action directly.