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.

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

The 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.

STRIDULATION AND ASSOCIATED BEHAVIOR OF THE NATIVE ELM BARK BEETLE HYLURGOPINUS RUFIPES (EICHHOFF) (COLEOPTERA: SCOLYTIDAE)

Male native elm bark beetles, Hylurgopinus rufipes (Eichhoff), had distinctive simple multipulse stress and rivalry chirps, and a bimodally patterned premating stridulation at the gallery site. Males were strongly arrested at attractive female galleries. Not all female galleries were attractive to males. For a short period after the arrival of the first (resident) male, conspecific males often contested the resident male. Stridulation by females was not detected.

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

Field 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.

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

The 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.