Smaller European Elm Bark Beetle Research Articles

Scolytus multistriatus associated with Dutch elm disease on the island of Gotland: phenology and communities of vectored fungi

Scolytus multistriatus Marsham, the smaller European elm bark beetle, is a vector for Dutch elm disease (DED) that in the year 2005 invaded the island of Gotland (Sweden). The island possesses the largest population of elm (mainly Ulmus minor Mill.) in northern Europe. The aim of this study was to monitor flying periods of S. multistriatus during three consecutive years and by using high-throughput sequencing to assess communities of vectored fungi. Sampling of the beetles was carried out at two different sites in Gotland in 2012, 2013, and 2014. In total, 50 pheromone traps were placed at each site and checked weekly during June-August each year. From all sites and years, 177 beetles were trapped. Among these, 6.2 % were trapped in June, 76.8 % in July, and 16.9 % in August (difference significant at p<0.007). Sequencing of ITS rDNA from the beetles revealed the presence of 1589 fungal taxa, among which virulent DED pathogen Ophiostoma novo-ulmi Brasier was the second most common species (9.0 % of all fungal sequences). O. ulmi Buisman, the less virulent DED pathogen, was also detected but only in a single beetle, which was sampled in 2012 (0.04 % of sequences). There were 13.0 % of the beetles infested with O. novo-ulmi in 2012, 4.0 % in 2013, and 27.7 % in 2014. O. novo-ulmi comprised 0.8 % of fungal sequences in 2012, 0.002 % in 2013, and 8.2 % in 2014. The study showed that the proportion of S. multistriatus vectoring O. novo-ulmi has increased in recent years.

Dutch elm disease pathogen transmission by the banded elm bark beetle Scolytus schevyrewi

SummaryDutch Elm Disease (DED) is a vascular wilt disease of Ulmus species (elms) incited in North America primarily by the exotic fungus Ophiostoma novo‐ulmi. The pathogen is transmitted via root grafts and elm bark beetle vectors, including the native North American elm bark beetle, Hylurgopinus rufipes and the exotic smaller European elm bark beetle, Scolytus multistriatus. The banded elm bark beetle, Scolytus schevyrewi, is an exotic Asian bark beetle that is now apparently the dominant elm bark beetle in the Rocky Mountain region of the USA. It is not known if S. schevyrewi will have an equivalent vector competence or if management recommendations need to be updated. Thus the study objectives were to: (i) determine the type and size of wounds made by adult S. schevyrewi on branches of Ulmus americana and (ii) determine if adult S. schevyrewi can transfer the pathogen to American elms during maturation feeding. To determine the DED vectoring capability of S. schevyrewi, newly emerged adults were infested with spores of Ophiostoma novo‐ulmi and then placed with either in‐vivo or in‐vitro branches of American elm trees. The inoculation of trees via feeding wounds was successful 30% of the time for in‐vivo trials and 33% for in‐vitro trials. Although the infection rate of DED has declined in Colorado over the past 10 years, the disease is still present in urban elms. While it appears that S. schevyrewi is another vector of the DED pathogens, it appears that S. schevyrewi is no more efficient than S. multistriatus. Thus, management programs that remove elm bark beetle breeding sites, rapidly remove DED‐infected elms and include the planting of DED‐resistant elms should continue to be effective management tactics.

Characterization of two non-native invasive bark beetles, Scolytus schevyrewi and Scolytus multistriatus (Coleoptera: Curculionidae: Scolytinae)

AbstractScolytus schevyrewi Semenov, the banded elm bark beetle, and S. multistriatus Marsham, the smaller European elm bark beetle, are morphologically similar. Reliance on adult external morphological characters for identification can be problematic because of wide within-species variability and the need for good-quality specimens. The inability to identify developmental stages can also hamper early-detection programs. Using two character identification systems, genitalic (aedeagus) morphology, and DNA markers (random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR)) to distinguish S. schevyrewi from S. multistriatus, we examined specimens from geographically distinct populations of both species collected from infested host trees or semiochemical-baited funnel traps. We found that aedeagus morphology can be used to identify the two species. The use of two oligonucleotide primers in the RAPD-PCR analysis yielded distinct DNA banding patterns for the two species. Species identification using RAPD-PCR analysis was validated by a blind test and used to make species identifications of larval specimens. These tools improve the ability to differentiate between S. schevyrewi and S. multistriatus at immature and adult stages, and could be developed and used for other scolytines as well.

Association of Ophiostoma novo-ulmi with Scolytus schevyrewi (Scolytidae) in Colorado.

The smaller European elm bark beetle, Scolytus multistriatus, has been the primary vector of the Dutch elm disease fungus, Ophiostoma novo-ulmi, in elm trees in Colorado since 1948. An exotic from Asia, the banded elm bark beetle, Scolytus schevyrewi, was found in Siberian elm, Ulmus pumila, in Colorado in April of 2003; this was the first report of S. schevyrewi in North America. S. schevyrewi is now found throughout much of Colorado and in at least 21 other states. The similarities in breeding and feeding habits between S. schevyrewi and S. multistriatus have raised concerns about the ability of S. schevyrewi to serve as a vector for O. novo-ulmi. The objective of this preliminary study was to determine if O. novo-ulmi could be isolated from adult S. schevyrewi emerging from diseased elm trees. S. schevyrewi and S. multistriatus were allowed to infest diseased stem segments of American elm, Ulmus americana. The infested stem segments were caged and isolations were made from the adult brood that emerged. O. novo-ulmi was isolated from most of the adults of both beetle species, showing that S. schevyrewi could acquire the pathogen as effectively as S. multistriatus. Future studies are needed to determine if S. schevyrewi can effectively transmit the pathogen to healthy trees.

The Banded Elm Bark Beetle: A New Threat to the Elms in North America

An exotic bark beetle from Asia, the banded elm bark beetle, Scolytus schevyrewi, has been discovered in 21 states of the United States. Although its point of entry is not known, a survey of museum specimens suggests that it has been in the US for at least 10 years. It is most abundant in western states, attacks primarily American and Siberian elms, and carries spores of the fungal pathogen for Dutch elm disease. In Colorado, S. schevyrewi appears to compete successfully with the more familiar smaller European elm bark beetle, Scolytus multistriatus. The host range, chemical ecology, and impact of S. schevyrewi are under investigation. The insect will likely have a significant deleterious effect on elms in the urban and peri-urban landscapes of North America.

Altered Elm Resistance to Smaller European Elm Bark Beetle (Coleoptera: Scolytidae) and Forest Tent Caterpillar (Lepidoptera: Lasiocampidae)

N-ethylmaleimide in paraffin oil as a stem band and an inoculated heat-killed microbial suspension each altered Siberian and American elms regarding preference for herbivory by the forest tent caterpillar, Malacosoma disstria Hubner, and for cortical feeding by the smaller European elm bark beetle, Scolytus multistriatus Marsham. Such alteration was affected by the time after treatment, sample height in the plant, and the N-ethylmaleimide concentration.

A new synthesis of (-)-α-multistriatin, the pheromone of the smaller european elm bark beetle

-(-)-α-Multistriatin[(1 S , 2 R ,4 S ,5 R )-2,4-dimethyl-5-ethyl-6,8-dioxabicyclo-[3.2.1]octane] was synthesized from ( Z )-2-butene-1,4-diol monobenzyl ether by employing the Sharpless asymmetric epoxidation and the regioselective epoxide cleavage with Me 3Al as the key-steps.

Colonization., Emergence, and Survival of Hylurgopinus rufipes and Scolytus multistriatus (Coleoptera: Scolytidae) in Insecticide-treated Elm Wood

Application of 0.1, 0.25, 0.5% (AI) chlorpyrifos, 2.0% (AI) carbaryl, or 0.1% (AI) permethrin to cut elm, either before or after gallery formation, significantly reduced brood production of Scolytus multistriatus (Marsham), the smaller European elm bark beetle, and Hylurgopinus rufipes (Eichhoff), the native elm bark beetle. Bioassays and residue analyses of treated elm, Ulmus americana L., showed that 0.5% (AI) chlorpyrifos was present and active for at least 11 months, thus providing ample time for cut elm to reach a point at which it was no longer suitable for beetle breeding. Application of 0.5% (AI) chlorpyrifos makes possible the long-term storage of undebarked, cut elm in a manner that is compatible with ongoing Dutch elm disease control programs.

Seasonal Detection of Visible Dutch Elm Disease Symptoms

Most of the lightly diseased American elms (10% or less crown wilt) that were suitable candidates for fungicide injection and/or pruning therapy for Dutch elm disease were discovered in surveys during June and early July. More treatable elms were found in areas where diseased elms were removed promptly (up to 20 work days after discovery) than where removal was delayed until fall and winter, and in areas where the smaller European elm bark beetle is the primary vector of Dutch elm disease rather than where the native elm bark beetle is the primary vector.

Elm Bark Beetle Control on American Elm, 1979, 1980

Abstract American elms were sprayed hydraulically with methoxychlor to determine efficacy against twig-crotch feeding by the smaller European elm bark beetle, a vector of Dutch elm disease (DED). Experiments were conducted in each of 3 cities (Denver, CO; Warren, MI; Shaker Heights, OH). Treatment factors, replicated 3 times, were concentration (1, 2, 4%), sticker (Nu-Film-17, Vapor Gard, Rhoplex Ac-33, none), and season sprayed (fall, spring). Spray equipment and conditions were John Bean 785 gun, no. 14 disc, 39 kg/cm2 pressure,ca. 150 liters/tree, temperature 4.4° to 10°C, wind 0 to 12 km/hr, stickers at 1:800 final mix, and trees dormant. Forty twigs were collected at each tree level (top, middle, bottom) for bioassay. Fall-sprayed trees were sampled at 14 days postspray and at 12 months postspray. Spring-sprayed trees were sampled at 14 days postspray and at 6 months postspray. Beetles were caged in small cylinders on twig crotches and allowed to feed for 24 h at 30 ± 1°C and 88 ± 2% RH. Percentage of beetles that failed to feed to the xylem of twigs was used to measure effects of the treatments.

Residues of Insecticides on American Elm, Cuyahoga, Co., Ohio, 1983

Abstract The crowns of street–lawn American elms, Ulmus americana L., (avg 64.0 cm in dbh; 20.1 m in height) were sampled at 16 weeks postspray to determine chemical residue. These trees were previously sprayed at bud break with candidate insecticides for evaluation against twig-crotch feeding by the smaller European elm bark beetle. Treatments were 4 insecticides applied at 2 concentrations and methoxychlor applied at 1 concentration. Each treatment was applied to 3 single tree replicates. Sevin 4-Oil was mixed in diesel fuel; all others were mixed in water. A John Bean 300G Rotomist mist blower equipped with 3 DC-5 nozzles with no. 45 cores was used. Each tree received an average of 24.6 liters of finished spray except methoxychlor-treated trees averaged 9.5 liters. When trees were sprayed on 5 May, the ambient temperature was 2–10°C, the sky was clear, and the wind was 0-5 kph. Between treatment and assay, the mean temperature was 20.6°C and the total rainfall was 37.9 cm. For assay, 5 twigs were collected from each of the 12 sectors (3 vertical levels and 4 quadrants) in each tree crown. A circular bark sample (4.5 mm2) was cut from the crotch of each twig. Samples from each vertical level were combined for assay and were analyzed on a Varian Aerograph chromatograph equipped with a 63 Ni electron capture detector. For Sevin assay, phenol conversion by the microscale derivatization technique was used. Aliquots were injected on a 0.64 cm (O.D.) by 0.6 m column packed with 2% OV-225 on 60/80 Gas Chrom Q (AW; DMCS treated). Nitrogen exit flow was 40 to 60 ml/min. Pydrin was extracted by soaking samples in hexane overnight. Aliquots were injected on a 2 mm (I.D.) by 1.2 m column packed with 3% Dexsel-300 on 100/120 Gas Chrom Q. Nitrogen exit flow was 20 to 25 ml/min. Methoxychlor extracts were prepared by soaking samples in hexane overnight. The column, 0.64 cm (O.D.) by 1.8 m, was packed with 5% DC-11 on 70/80 Aeropack 30. Nitrogen exit flow was 30 to 35 ml/min.

Control of Elm Bark Beetle on American Elm, Bioassay Tests, Cuyahoga, Co., Ohio, 1983

Abstract In Shaker Heights, Ohio, the crowns of street-lawn American elms, Ulmus americana L., (avg 64.0 cm in dbh; 20.1 m in height) were sprayed at bud break with candidate insecticides for evaluation as alternatives to the standard methoxychlor emulsion used to control twig-crotch feeding by the smaller European elm bark beetle. Treatments included 4 insecticides at 2 concentrations and methoxychlor at 1 concentration. Each treatment was applied to 3 single tree replicates. Sevin 4-Oil was mixed in diesel fuel; all others in water. A John Bean 300G Rotomist mist blower equipped with 3 DC-5 nozzles with no. 45 cores was used. Each tree received an average of 24.6 liters of finished spray except methoxychlor-treated trees averaged 9.5 liters. When trees were sprayed on 5 May, the ambient temperature was 2-10°C, the sky was clear, and the wind was 0-5 kph. Between treatment and bioassay, the mean temperature was 20.6°C and the total rainfall was 37.9 cm. At 16 wks postspray, 10 twigs were collected for bioassay from each of 12 sectors (3 vertical levels and 4 quadrants) in each tree crown. Twigs from each vertical level were combined for bioassay. Bioassays were made by confining 1-day old adult beetles on twigs in small cages. The mean percentage of beetles that failed to penetrate the twig xylem, after feeding for 24 h at 30 ± 1°C and 92 ± 2% RH, was used as a measure of treatment effectiveness.

Numbers of Scolytus multistriatus (Coleoptera: Scolytidae) Caught on Multilure-Baited Sticky Traps Increase with Methoxychlor1

Multilure-baited sticky traps were attached to various methoxychlor-sprayed and unsprayed trap sites to determine the effect of the insecticide treatments on catches of the smaller European elm bark beetle, Scolytus multistriatus (Marsham). Significantly more bark beetles were captured by baited sticky traps attached to the boles of sprayed healthy American elms, Ulmus americana L., and also by traps attached to the boles of sprayed elms infected with the Dutch elm disease fungus, than were captured by traps on comparable unsprayed elms. Bark beetle catches on traps attached to sprayed and unsprayed utility poles and tree trap sites other than elms were not significantly different. These tests suggest that other beetle attractants associated with healthy and diseased elms and the presence of methoxychlor on the trap sites significantly affected trap catches.

SEASONAL FLIGHT ACTIVITY OF THE SMALLER EUROPEAN ELM BARK BEETLE, SCOLYTUS MULTISTRIATUS (COLEOPTERA: SCOLYTIDAE), AND ASSOCIATES IN GEORGIA

AbstractThe smaller European elm bark beetle, Scolytus multistriatus (Marsham), had three distinct periods of adult flight annually in Georgia. Adults of the associated native elm bark beetle, Hylurgopinus rufipes Eichhoff, were trapped on elm logs during only one period in the spring, but some adults were reared from infested bolts in the fall. Seasonal abundance of the S. multistriatus parasite Spathius benefactor Matthews (Braconidae) showed little temporal relationship to its host. However, Entedon leucogramma Ratzeburg (Eulophidae) emergence was highly synchronized with S. multistriatus emergence. Scolytus multistriatus overwintered as fully developed larvae as in other parts of its range.

Evaluation of Hydraulically Applied Methoxychlor to Protect American Elms from Feeding by the Smaller European Elm Bark Beetle (Coleoptera: Scolytidae)1

American elm trees, Ulmus americana L., were sprayed by hydraulic sprayer with various concentrations of methoxychlor, with and without stickers, in different seasons and cities to determine chemical deposit and efficacy against Scolytus multistriatus (Marsham), a vector of the Dutch elm disease fungus. Gas-liquid chromatography assays and beetle bioassays were used to quantify methoxychlor deposits. Methoxychlor deposit was unaffected by the addition of spray sticker, but concentration, residual period, season sprayed, and skill of the spray crew significantly affected deposit.

TRAPPING ELM BARK BEETLES IN THE CITY OF WINNIPEG, WITH A NEW RECORD FOR SCOLYTUS MULTISTRIATUS, (COLEOPTERA: SCOLYTIDAE) IN MANITOBA

The first outbreak of Dutch elm disease in Manitoba was recorded in 1975 in Brandon, Selkirk, and Winnipeg (Hildahl 1977). The primary vector of the disease in Canada is the native elm bark beetle, Hylurgopinus rufipes (Eichh.). The smaller European elm bark beetle, Scolytus multistriatus (Marsh.), is considered the primary vector in most of the United States. In Canada, the latter species occurs throughout most of southern Ontario, parts of south-central Quebec, and has been recorded in New Bmnswick (Sterner et al. 1976).

Attraction of Elm Bark Beetles to Cut Limbs on Elm

The smaller European elm bark beetle, Scolytus multistriatus, vector of the Dutch elm disease fungus, is attracted to pruned limbs of European and Siberian elm compared to healthy, non-pruned limbs. To minimize the spread of Dutch elm disease it is suggested that pruning of elm limbs be undertaken during the fall and winter when bark beetle activity is reduced or absent.

Preparation of the both enantiomers of threo-2-amino-3-methylhexanoic acid by enzymatic resolution and their conversion to optically active forms of threo-4-methylheptan-3-ol, a pheromone component of the smaller european elm bark beetle

The both enantiomers of threo-2-amino-3-methylhexanoic acid were prepared by resolving its racemic N-acetate with Aspergillus acylase. The amino acid enantiomers were converted to optically active forms of threo-4-methylheptan-3-ol, a pheromone component of Scolytus multistriatus.

Stereospezifische Synthese von (+)‐(3R, 4R)‐4‐Methyl‐3‐heptanol, das Enantiomere eines Pheromons des kleinen Ulmensplintkäfers (Scolytus multistriatus)

Stereospecific Synthesis of (+)‐(3R, 4R)‐4‐Methyl‐3‐heptanol, the Enantiomer of a Pheromone of the Smaller European Elm Bark Beetle (Scolytus multistriatus)Reduction of 2 with actively fermenting baker's yeast gave (−)‐3. Stereospecific alkylation [3] of (−)‐3 with propyl iodide furnished ethyl (+)‐(2R, 3R)‐2‐propyl‐3‐hydroxypentanoate ((+)‐4, 58%) which was converted to the tetrahydropyranyl ether (−)‐5, then the alcohol 6, the p‐toluenesulfonate 7 and the thiophenyl ether 8 to give the title compound (+)‐1. The latter consisted of 97% of the threo‐ and 3% of the erythro‐isomer. The above synthesis also correlates the absolute configuration of (−)‐(R)‐3 with that of (+)‐(R)‐citronellic acid (see [2]).

Landing Times on Various Surfaces for Scolytus multistriatus after Responding to the Pheromone Multilure12

Tests were conducted to determine the length of time that the smaller European elm bark beetle remained on various surfaces (landing time) after responding to baits of Multilure, a 3-component pheromone system containing α-cubebene, 4-methyl-3-heptanol, and 2-4-di-methyl-5-ethyl-6, 8-dioxabicyclo (3.2.1) octane (multistriatin). Results showed that landing times of beetles on plywood were not affected by the presence of lindane. Beetles remained longer on the boles of American elm, Ulmus Americana L., than on nonelm boles.