Scolytus multistriatus (Marsham, 1802)

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 21-23

Taxon classification Animalia Coleoptera Curculionidae

Scolytus multistriatus (Marsham, 1802) Fig. 12

Ips multistriatus Marsham, 1802: 54.

Scolytus multistriatus (Marsham, 1802). Chapuis and Candeze 1853: 577.

Scolytus javanus Chapuis, 1869: 56. Schedl 1954: 137.

Scolytus multistriatus For complete taxonomic history see Wood and Bright (1992).

Diagnosis.

Both sexes of the species are distinguished by the presence of lateral teeth on the apical margins of ventrites 2-4 and by a median conical spine on the basal margin of ventrite 2.

Description (male).

2.2-3.9 mm long (mean = 2.81 mm; n = 20); 2.0-2.6 times as long as wide. Head, pronotum, and abdominal venter dark red-brown, legs light brown, antennae yellow-brown, elytra usually dark red-brown but may be brown. Color not uniform and pronotal and elytral surfaces frequently contain patches of red-brown mixed with dark red-brown. Pronotum typically darker than elytra.

Head. Epistoma weakly, broadly emarginate; epistomal process absent; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons appearing flattened when viewed laterally; moderately, coarsely, longitudinally aciculate-punctate; aciculations converging at epistoma; punctures small, coarse; smoderately, uniformly covered by long, fine, yellow erect hair-like setae, these longer than width of midpoint of eye. Antennal scape short, elongate; club flattened, thinner on apical half, irregularly ovoid, setose with partial septum, two sharply arcuate sutures visible.

Pronotum wider than long; apical margin broadly rounded, median area between eyes lined with scales; sides distinctly arcuate, strongly constricted near apex, forming a weak transverse impression near apical margin; surface smooth, shining, punctures on disc fine, shallow, moderately abundant, larger and more abundant laterally and on apical constriction; apical and anterolateral margins bearing sparse, erect, yellow, hair-like setae; base weakly bisinuate.

Elytra with sides sub-parallel on apical half, narrowing to subquadrate, smooth apex; apex entire at suture. Margin of apical edge bearing small, fine punctures. Disc smooth, shining; interstriae weakly impressed, more than twice width of striae, interstrial punctures uniseriate, smaller than those of striae, bearing sparse, long, semi-erect yellow hair-like setae (may be abraded); striae weakly impressed. Declivity bearing sparse, short, erect yellow setae. Metepimeron greater than half-length of metanepisternum.

Venter. Apical margin of ventrite 1 weakly elevated above base of ventrite 2. Ventrite 2 nearly perpendicular to ventrite 1; surface smooth, shining, finely punctate, punctures small, coarse; surface flattened; basal margin armed with a long, smooth, conical spine with it’s base extending from basal margin to half length of segment; lateral margins of ventrites 2-4 armed with lateral tooth. Ventrite 5 carinate ridge closer to apical margin of segment; length of ventrite 5 greater than combined lengths of ventrites 3 and 4; setal patch and median depression absent.

Female.

2.4-3.3 mm long (mean = 2.95 mm; n = 20); 2.2-2.7 times as long as wide. Similar to male except epistoma feebly entire, frons strongly convex when viewed laterally, weakly aciculate, setae sparser, shorter, less than the width of eye.

Specimens examined.

165.

Type material.

Holotype Scolytus javanus Chapuis: male, labeled "Java, Solier, Dejean" (ISNB).

Non-type material.

CANADA: ALBERTA: Calgary, 19.VII.[19]94, T. Reichardt, ex. pheromone trap no. EBB XI (CNCI-2). ONTARIO: St. Catherines, 22.VI.1961, Kelton, Brumpton (CNCI-1). Toronto, 1970, ex. reared on elm [= Ulmus sp.] (CNCI-1). Queenston, 26.VI.[19]50, ex. elm [= Ulmus sp.] (CNCI-1). QUEBEC: Montreal, 14.VII.1977, E.J. Kiteley (CNCI-1); Île de Montreal, Île de Sainte Hélène, 12.VIII.1985, L. Lariviere (CNCI-1). MEXICO:Chihuahua: Cuidad Juarez, II.1987, I.C. Rodriguez (CNCI-2). UNITED STATES:CALIFORNIA: [Alameda Co.]: Berkeley, 23.V.1962, ex. elm [= Ulmus sp.] (EMEC-2). Contra Costa Co.: Antioch [Dunes] National Wildlife Refuge, 10.X.[19]91, J.A. Powell (EMEC-1). Fresno Co.: 11.I.1950, N.J. Smith (SBMN-2). Inyo Co.: Big Pine, 4000 ft, V.1971, D. Guiliani, ex. black light (CASC-1), VII.1971 (CASC-1). COLORADO:Mesa Co.: Grand Junction, X.1979, D. Leatherman, ex. European ash [= Fraxinus sp.] (CSUC-1). Weed Co.: Briggsdale, 1.IX.198[sic!], D. Leatherman (CSUC-1). GEORGIA:Clarke Co.: Whitehall forest, 17-24.IX.1976, R. Turnbow, ex. window trap F-8 (CNCI-1). ILLINOIS:Alexander Co.: Horseshoe Lake, 28.IX.1968, T.E. Brooks (CNCI-4). KENTUCKY:Green Co.: 9.VII.1941, C. Cook (MSUC-1). MASSACHUSETTS: [Hampshire Co.]: Northampton, 10.VIII.1974, E.J. Kiteley (MSUC-1). [Suffolk Co.]: Forest Hills [= Boston], 3.VI.[?], W.M. Mann (USNM-1). MICHIGAN:Antrim Co.: Eastport, ca. 3 mi N., N45°08'30", W85°22'50", 3-5.VII.2003, F.W. Stehr, ex. UV light (MSUC-1). Cass Co.: Cassopolis, 2.VI.2007, A.D. Smith (MSUC-3). Genesee Co.: Richfield County Park, N43.100610°, W-83.55810°, ex. Lindgren with EtOH (MSUC-1). Ingham Co.: Lansing, 2 mi N., E. State Rd, N42.7842°, W84.5361°, 261 m, 16-30.VII.2007, PI A.I. Cognato (MSUC-1); G.L. Parsons, ex. UV light. & white lights (MSUC-1). East Lansing, 1.X.1957, R.C. Fox (MSUC-1), 2.X.1957 (MSUC-5), 3.X.1957 (MSUC-7), 4.X.1957 (MSUC-1), 5.X.1957 (MSUC-3), 6.X.1957 (MSUC-4), 10.X.1957 (MSUC-1), 15.X.1957 (MSUC-5); 25.VI.1981, R. Fischer (MSUC-1); N42°11.320', W84°27.867', 258 m, 16.IX.2011, S.M. Smith, A.I. Cognato, I.A. Cognato, ex. Ulmus sp. (MSUC-7); Michigan State University campus, 17.VI.2011, D.G. McCullough (MSUC-3). Kalamazoo Co.: Gourdneck Lake State Game Area, 19.VI.2011, A.I. Cognato, ex. Ulmus sp. (MSUC-21). Kalkaska Co.: T27N R7W S18, 28.XII.1986, P. Waclawski, ex. basement wood (MSUC-1), 20.XII.1987 (MSUC-1), 3.I.1987 (MSUC-5). Lapeer Co.: Potter Lake, 19.VI.1967, Brivio (MSUC-2). Macomb Co.: East of Memphis, 3.V.1964, C. Brivio (MSUC-1), 17.VI.1965 (MSUC-1), 21.VIII.[19]66 (MSUC-2), 23.VIII.1969 (MSUC-1), 30.VIII.1969 (MSUC-1). Saginaw Co.: St. Charles, 30.V.1969, J.H. Truchan, ex. rotary trap at 6 ft height level (MSUC-2), 11.VI.1969, ex. rotary trap at 12 ft height level (MSUC-1), 16.VI.1969 (MSUC-3). Sanilac Co.: Port Sanilac, 20.VI.1986, Brivio (MSUC-1). MONTANA:Choteau Co.: Great Falls, VII-VIII.1977, S. Kohler, ex. caught in flight, sticky trap, multilure bait (CNCI-1). Gallatin Co.: Bozeman, VII-VIII.1977, S. Kohler, ex. caught in flight, sticky trap, multilure bait (CNCI-1). NEW YORK: [Westchester Co.]: Yonkers, VIII.1935, H. Dietrich, ex. elm [= Ulmus sp.] (CNCI-3). OKLAHOMA: [Oklahoma Co.]: Jones, 13.VI.1957, D. Alexander (USNM-1). TEXAS: [El Paso Co.]: El Paso, 045483, 17.VII.[19]94, lot 94 07975, ex. Mexico–in log of Prunus sp. (USNM-10). WYOMING:Carbon Co.: Medicine Bow National Forest, VI-VIII.1999, ex. Polyphorus volvatus [= Cryptoporus volvatus (Peck) Shear] (CSUC-1). Additional specimens:Czech Republic (MSUC-2), Italy (MSUC-8) and Russia (MSUC-22).

Distribution.

CANADA: Alberta, Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan. MEXICO: Aguascalientes, Chihuahua. UNITED STATES: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, D.C., West Virginia, Wisconsin, Wyoming (Fig. 13).

Hosts.

All native and introduced Ulmus spp. including Ulmus americana L. (American elm) and Zelkova serrata (Thunb.) Makino.

Common names.

Smaller European elm bark beetle and the European elm bark beetle.

Biology.

Scolytus multistriatus colonizes cut, stressed, weakened and diseased elm trees ( Ulmus spp.) ( Wood 1982). It seldom attacks healthy and vigorous trees ( Bright 1976). Scolytus multistriatus females produce an aggregation pheromone to aggregate conspecifics to host trees. The pheromone bouquet is composed of three components: (-)-4-methyl-3-heptanol, (-)-2,4-dimethyl-5-ethyl-6,8-dioxabicylo[3.2.1]octane (α)-multistriatin and (-)-α-cubebene ( Pearce et al. 1975).

Mating can occur either as the female is undergoing maturation feeding in twig crotches or within the gallery as described for the genus ( Svihra and Clark 1980). The adult gallery is excavated parallel to the grain of the wood and consists of a single egg gallery; a nuptial chamber is not constructed. The adult gallery ranges in size from 2.5-5.0 cm in length. Egg niches are constructed along the gallery and score the sap wood. Twenty-four to 96 eggs may be laid singly along the egg gallery. Larval mines lightly score the sapwood and radiate perpendicular to the egg gallery. Larval galleries later meander often at an oblique angle to the grain of wood, forming a fan shaped pattern. Larvae construct pupal chambers in the bark ( Bright 1976).

There are one to one-half generations per year in Canada and three in the southern US ( Furniss and Johnson 2002). In Canada, adults emerge in June and July and feed at twig crotches of healthy trees for 7-10 days before selecting host material ( Chamberlin 1958; Baker 1972; Svihra and Clark 1980). The brood from these adults either emerges in August or September or overwinters as larvae.

Scolytus multistriatus is the principal vector of the Dutch elm disease fungus Ophiostoma ulmi (Buisman) Melin & Nannf in North America. This beetle vectored disease killed 50-75% of the elms population in northeastern North America prior to the 1930s ( Bloomfield 1979). Adults become covered in fungal spores upon emergence from brood material. Adults inoculate elms with the Dutch elm disease fungus as they feed in twig crotches ( Svihra and Clark 1980). This feeding activity leaves wounds in the bark that allow spores to be transferred from the beetle’s cuticle to the tree tissues ( Bright 1976).

Remarks.

This species is native to the Palearctic region and is primarily distributed throughout Europe but also occurs in Iran and Algeria ( Knížek 2011). Scolytus multistriatus was first detected in North America in 1909 from elm trees on the Harvard University campus in Massachusetts ( Chapman 1910).