Native Elm Bark Beetle Research Articles

A Mark-recapture Technique for the Dutch Elm Disease Vector the Native Elm Bark Beetle, Hylurgopinus rufipes (Coleoptera: Scolytidae)

Six mark-recapture experiments were conducted in Manitoba, Canada, to determine the effectiveness of fluorescent powder to mark emerging native elm bark beetle adults, Hylurgopinus rufipes (Eichoff) (Coleoptera: Scolytidae), the vector of Dutch elm disease, Ophiostoma novo-ulmi (Brazier), after departure from overwintering sites in spring and emergence from broodwood in summer. Native elm bark beetles marked themselves on emergence from overwintering sites and summer trap logs. The spring and summer periods of flight activity for unmarked and marked beetles were similar. Marked beetles were captured over 1 month after peak emergence in the spring and 2 months after emergence from trap logs in the summer. Marked beetles were captured up to 1 km (0.6 mi) from release sites. Where integrated Dutch elm disease management activities are implemented in buffer zones to minimize the number of elm bark beetles entering community urban forests, buffer zones should be a minimum of 1 km (0.6 mi) in width.

The pathogen causing Dutch elm disease makes host trees attract insect vectors

Dutch elm disease is caused by the fungal pathogen Ophiostoma novo-ulmi which is transmitted by the native elm bark beetle, Hylurgopinus rufipes. We have found that four semiochemicals (the monoterpene (-)-beta-pinene and the sesquiterpenes (-)-alpha-cubebene, (+)-spiroaxa-5,7-diene and (+)-delta-cadinene) from diseased American elms, Ulmus americana, synergistically attract H. rufipes, and that sesquiterpene emission is upregulated in elm trees inoculated with O. novo-ulmi. The fungus thus manipulates host trees to enhance their apparency to foraging beetles, a strategy that increases the probability of transportation of the pathogen to new hosts.

Persistence, Penetration, and Surface Availability of Cypermethrin and Its Major Degradation Products in Elm Bark

The initial residues of cis-A, trans-C, cis-B, and trans-D cypermethrin in elm bark treated with a 400× aqueous dilution of Ripcord 40 EC (1.0 g of active ingredient/L) to runoff ranged from 29 to 58, from 24 to 53, from 25 to 35, and from 17 to 25 μg/g, respectively. These residues dissipated quickly with half-lives of 1.60−12.0 days for the faster dissipation phase. The dissipation of cypermethrin during the later period became much slower, with dissipation half-lives of 209−365 days. Cypermethrin residues in elm bark remained 100% effective against the native elm bark beetle for ∼60 days after application. Laboratory tests indicated that cypermethrin residues in the bark were 100% effective in preventing elm bark beetles from making overwintering tunnels for up to 627 days (fall application) and 433 days (spring application). No penetration of cypermethrin to the cambium layer or wood tissue was detected during the experimental period of 791 days. Total cypermethrin residue absorbed from treated elm bark during a 1 min contact period did not exceed the acceptable daily intake for humans. Keywords: Cypermethrin; degradation products; elm bark; elm bark beetle; residue; effectiveness; penetration; contact availability

The Native Elm Bark Beetle: Primary Vector of Dutch Elm Disease in Saskatchewan

The Native Elm Bark Beetle: Primary Vector of Dutch Elm Disease in Saskatchewan

An elm bark beetle bioassay for residual efficacy of chlorpyrifos and cypermethrin used for the control of Dutch elm disease in Manitoba

Abstract The basal 1 m of the elm trunks were treated with 0.48% (active ingredient, Al) Dursban aqueous solution (chlorpyrifos) or 0.1% (Al) Ripcord aqueous solution (cypermethrin) for control of overwintering native elm bark beetle, Hylurgopinus rufipes, the vector of Dutch elm disease, Ophiostoma (Ceratocystis) ulmi, at Beaudry Provincial Park, near Winnipeg, Manitoba, Canada. A simple and effective bioassay method was developed to determine insecticidal persistence against the native elm bark beetle. Beetles reared in naturally infested elm logs were confined to the surface of elm bark circles taken from the treated trees. Bark circles were cut at various times after treatment using a cordless hole saw and stored at ‐ 32°C until the beetles were available. Mortality/morbidity data for the two treatments were suitable for use in the comparison of the action of the two insecticides over a two‐year period.

EVALUATION OF MONOSODIUM METHANE ARSENATE FOR THE SUPPRESSION OF NATIVE ELM BARK BEETLES, HYLURGOPINUS RUFIPES (EICHHOFF) (COLEOPTERA: SCOLYTIDAE)

AbstractThe native elm bark beetle, Hylurgopinus rufipes (Eichhoff), is the major vector of Dutch elm disease, Ophiostoma ulmi (Buisman) Nannf., in Manitoba. The herbicide Glowon™, monosodium methane arsenate (MSMA), was applied to a chainsaw cut in American elm, Ulmus americana L., tree stems to determine if the treated elms would become effective trap trees for H. rufipes. Three treatments were compared: treated with herbicide and girdled, girdled, and control. All herbicide-treated elms died within 18 days after application. Significantly higher numbers (P < 0.01) of native elm bark beetles were attracted to the herbicided elms, compared with the other treatments. Beetles bred only in the elms treated with herbicide. Of the total brood galleries constructed, 72% had no egg hatch while the remaining 28% had larval tunnels. Progeny adults emerged from less than 1% of the larval tunnels. MSMA application could supplement the Dutch elm disease management program in Manitoba.

HYLURGOPINUS RUFIPES (EICHHOFF) (COLEOPTERA: SCOLYTIDAE): ATTRACTION TO BROODWOOD, HOST COLONIZATION BEHAVIOR, AND SEASONAL ACTIVITY IN CENTRAL MINNESOTA

AbstractField tests, using bolts of American elm trees either uninfested or infested with laboratory-reared or feral Hylurgopinus rufipes (Eichhoff), the native elm bark beetle, were conducted to evaluate colonization behavior of the beetle. The data confirm that (1) colonization of elm by H. rufipes can be accounted for by host attractants alone; (2) overwintered adult H. rufipes are attracted to broodwood (moribund or recently cut elm) in the spring, but summer-emergent adults are attracted to healthy elm; and (3) H. rufipes attacks broodwood primarily during evening beetle flights, and females initiate the gallery. A beetle-produced sex pheromone may be involved in the male–female pairing on broodwood.

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.

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.

Attraction of the Native Elm Bark Beetle to American Elm After the Pruning of Branches12

During May and June more overwintering adults of Hylurgopinus rufipes (Eichhoff) were caught on American elms, Ulmus americana L., that had been pruned than on those that were not pruned. Fewer beetles were caught on pruned elms whose wounds were treated with dressing compound than on pruned elms with no wound dressing. The number of H. rufipes that were caught also varied with height above the ground; more beetles were caught at 3 m on elm trunks than at 2 or 4 m. After mid-July, there was no significant difference in the number of summer-emerging H. rufipes caught on pruned elms compared with that on unpruned elms.

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).

Seasonal development of Dutch elm disease on white elms in central Ontario, Canada. II. Following feeding by the North American native elm bark beetle

Adults of the North American native elm bark beetle, Hylurgopinus rufipes, naturally infested with Dutch elm disease fungus, Ceratocystis ulmi, were caged on trunks of white elms (Ulmus americana) so that infection could be studied. In surveys made in 1971, expression of external symptoms of Dutch elm disease was observed on elms which had been caged with beetles during the period May 26 to July 9, 1971. Vascular discoloration (internal symptom expression), fungus spread, fungus contamination of beetles, and transmission of fungus to the host by beetles were pronounced on elms caged with beetles from June 3 to July 2. Ceratocystis ulmi was recovered from leaves of trees caged during the period May 26 to July 2. Until May 31, 1972, dieback and death resulting from infection were restricted to trees caged with beetles during June. Corresponding development of vascular discoloration and fungus spread in the host also occurred, mostly during the caging period in June. There was no appreciable change in beetle activity in xylem tissue during the period of experiment. These results suggest that the period of highest susceptibility of white elm to Dutch elm disease in 1971 in central Ontario was June 3 to July 2.Inoculation through feeding by caged beetles carrying C. ulmi is probably the method that most closely approximates natural infection.

Feeding Responses by Hylurgopinus rufipes1 to Combined Chemical and Physical Stimuli2

Feeding responses by adults of the native elm bark beetle, Hylurgopinus rufipes (Eichhoff) (Coleoptera: Scolytidae), on 1-mm-thick pith discs soaked in 10 mg of an 80% ethanol extract of trunk bark of Ulmus americana were significantly different (0.01 level) from the controls. The beetle fed only on chemically treated 1-mm-thick discs. Thus, the thigmotactic stimulus of such discs was a required component of the total stimulus for feeding by this insect. Feeding on a benzene extract of U. americana bark, or on p -hydroxybenzaldehyde, was not significantly different (0.05 level) from the control.

Measurement of Gas Exchange in Woody Plants

METHODS of controlling Dutch elm disease have been investigated at this laboratory for the past four years. Emphasis has been placed on two approaches to the problem of control. One approach has been the search for a suitable chemotherapeutant to control the causal agent, the fungus Ceratocystis ulmi (Buism) C. Moreau. The other approach has been the screening of systemic insecticides to control its vectors, the European elm bark beetle, Scolytus multistriatus (Marsham), and the native elm bark beetle, Hylurgopinus rufipes (Eich). A difficulty was found in methods of measuring the effects of chemotherapeutants and pesticides on diseased and healthy American elms, Ulmus americana L., in the laboratory under controlled conditions. A careful survey of existing literature showed that no device existed for measuring the effects of chemotherapeutants, pesticides and disease. Indeed, other workers in these fields have expressed and emphasized the lack of methods of measuring disease in woody plants1,2. This led us to investigate respiration as a means of studying the effects of chemotherapeutants and pesticides on woody plants.

Scolytid Vectors of the Dutch Elm Disease in Ontario

Although many possible vectors of the Dutch elm disease, Ceratocystis ulmi (Buism.) C. Moreau, have been listed by Collins et al. (1936) and others, only two, Scolytus multistriatus (Marsh.), the European elm bark beetle, and Hylurgopinus rufipes (Eichh.), the native elm bark beetle, are known to transmit the disease with any regularity. In this capacity alone thcse two species of beetles are important pests of elm. The persistent spread of the Dutch elm disease in southern Ontario (Hord and Quirke, 1955) made it imperative that adequate surveys be maintained to indicate yearly changes in the occurrence of the introduced vector, and to ascertain more precisely the distribution of the native vector relative to the distribution of elm in Ontario. Consequently the Forest Insect Survey of the Forest Insect Laboratory, Sault Ste. Marie, intensified its elm bark beetle program in 1956, and from then to 1959, 138 positive samples of these two scolytid beetles have been received. An analvsis of these records and their relationihip to the current incidence of the Dutch elm disease in Ontario are presented in this paper.

Effects on Wildlife of DDT Used for Control of Dutch Elm Disease

Dutch elm disease, the causal agent of which is a fungus, Ceratostomella ulmi, is spread from tree to tree by certain bark beetles of the family Scolytidae. In eastern United States two important carriers are the native elm bark beetle (Hylurgopinus rufipes) and the smaller European elm bark beetle (Scolytus multistriatus). In the area of this study the latter is of greater importance. Control of the disease involves control of the beetle vectors which introduce spores of the fungus at the time of feeding. Spraying programs are based on the application of sufficient DDT to elm trees to kill the bark beetles before feeding takes place. Since adult beetles emerge and fly to new trees during several spring and summer months, it is necessary to make two applications of spray in order to provide residual amounts during this period. The first is put on before the leaves are developed in the spring and the residual DDT is presumed to remain effective until the time of the second application in July. Preliminary investigations by the Bureau of Entomology and Plant Quarantine indicated that this procedure was an effective means of safeguarding valuable shade elms. However, frequent reports of bird mortality were received and it appeared advisable to review the program in terms of its effect on songbirds and other wildlife. This report summarizes results of the first summer's work on the problem. While the information was obtained from investigations in Princeton, New Jersey, the results would appear to be applicable to the Dutch elm disease problem as it exists elsewhere in the nation and

Studies on the Larvae of the Native Elm Bark Beetle

Studies on the Larvae of the Native Elm Bark Beetle