Aspects of the biology, survey and control of the introduced smaller European bark beetle, Scolytus multistriatus, a potential carrier of Dutch elm disease in Victoria.  F. G. Neumann and G. Minko.  May 1985.  21 pp. (unpubl.)

SUMMARY

Scolytus multistriatus Marsham (Coleoptera: Scolytidae) (smaller European elm bark beetle), discovered in Australia in 1974 near Melbourne, was found widely established within bark of Ulmus procera (English elm) trees in North-eastern, Central, South-western and South-eastern Victoria, though not in East Gippsland. Except for short-term maturation feeding immediately after emergence, on phloem and xylem tissues of young branchlets of healthy elm, the insect has behaved as a secondary phloeophagous (phloem-feeding) bark beetle in wind-fractured limbs or felled material. In Victoria, this insect is ecologically significant to urban forestry because of its potential as a vector of Ceratocystis ulmi (Buism.) C. Moreau (Dutch elm disease) (DED); this has killed millions of elms in Western Europe and North America since the 1920s.

Near Myrtleford (approximately 650 m a.s.l.), two generations were produced between late November 1977 and early April 1978, and a third (GIII) between then and early December, whereas on Mt Hotham (1862 m a.s.1.), only one generation developed. The slow development of GIII near Myrtleford was due to final instar larvae (instar III) undergoing quiescence (temperature-induced temporary cessation of development). Flight activity commenced in late October and practically ceased by late May, with peaks occurring during November, January and March. Each peak was associated with a mean daily temperature of 16-21°C, and the appearance of a new generation. Dispersal flights up to a distance of 10 km were recorded. Fecundity averaged 52 eggs per female, the proportion of females in trapped populations was 0.5, and the annual reproductive potential per female exceeded 17 570 females.

In the absence of DED, the insect is economically unimportant. The following control measures would immediately be recommended should DED be discovered: (1) strict adherence to a sanitation program, and (2) where elms have a special significance, a low volume application during September and December of 1% emulsion of methoxychlor insecticide to the crowns of healthy elms, supplemented by mass-trapping of beetles using synthetic pheromone (MULTILURE^†)-baited traps in areas where beetle population levels are low.

^†Registered Trade Name. Use of trade names is for the information and convenience of the reader. Such use does not constitute official endorsement or approval by the State Forests and Lands Service of any product to the exclusion of others that may be equally suitable.

Also published:

Kassaby, F.Y. (1985)  Solar heating soil for control of damping-off diseases.  Soil Biol. and Biochem. 17 (4): 429-34.