Smaller European Elm Bark Beetle Research Articles

Biology and Feeding Habits of the Smaller European Elm Bark Beetle on American Elm Trees Treated with Bidrin®1

Feeding of Scolytus multistiatus (Marsham) on branches of American elm trees, Ulmus Americana L., that were injected with Bidrin® (3-hydroxy- N, N -di-methyl- cis -crotonamide dimethyl phosphate) was similar to that of untreated trees. Evidence of nonuniform translocation of the chemical throughout the tree crown, the girdling effect of Bidrin on the tree at the injection site, and the scattered phytotoxicity to the foliage, all were considered detrimental. Three complete generations and a partial emergence of a 4th generation of the beetles occurred in Oklahoma during 1967.

Emergence of Entedon leucogramma from Smaller European Elm Bark Beetle Larvae Reared on Artificial Media

Emergence of Entedon leucogramma from Smaller European Elm Bark Beetle Larvae Reared on Artificial Media

A Technique for Rearing Larvae of the Smaller European Elm Bark Beetle on an Artificial Medium

A Technique for Rearing Larvae of the Smaller European Elm Bark Beetle on an Artificial Medium

Phenological Events Associated with the Spring Emergence of the Smaller European Elm Bark Beetle in Dubuque, Iowa

Spring emergence of the smaller European elm bark beetle, Scolytus multistriatus (Marsham), was studied in 1964, 1965, and 1966 in Dubuque, Iowa, in relation to other spring phenomena influenced by weather. The time of blooming of common trees and shrubs was observed and beetle emergence was determined by observing both standing elm trees within the city and caged infested elm material. From this, a flowering sequence of 4 plants which bloom prior to S. multistriatus emergence was established. In 1964 and 1966 S. multistriatus emergence began between the time of initial full bloom of the purple lilac, Syringa vulgaris L., and bridal wreath, Spiraea Vanhouttei (Briot) Zab., and in 1965 it coincided with the first day of full bloom of bridal wreath. Emergence of S. multistriatus began 10 days later in 1966 than in 1964, but the sequence of events remained unchanged.

Seasonal Development of the Smaller European Elm Bark Beetle in Southern California

Since its initial California find in San Jose in March 1951, the smaller European elm bark beetle, Scolytus multistriatus (Marsham), has spread rapidly to most of the elm-growing areas of this State. Owing to the many drought-weakened elm trees, it has become a particularly serious pest in southern California on both native and imported elms. To be able to suggest to spray-operators appropriate times to spray for the beetles, it was essential to learn something of its development under southern California conditions. It was reasoned that the number of generations of beetles might be more here, and consequently spraying dates might vary considerably, as our winters are mild and the growing season longer, compared with the Northeastern United States, where this well-known insect has been studied thoroughly.

Twig Feeding by the Smaller European Elm Bark Beetle on Different Kinds of Trees1

Compared with the number of cambial punctures chewed by the smaller European elm bark beetle, Scolytus multistriatus (Marsham), on cut twigs of American elm, Ulmus americana L., in a series of twig-feeding tests conducted under variable temperature conditions in laboratory, there was relatively little to no significant increase or decrease in the number of such punctures on the following trees: Siberian elm, Ulmus pumila L.; Vanhoutte' English elm, U. procera Vanhouttei (Schelle) Rehd.; Japanese elm, U. japonica (Rehd.) Sarg.; Buisman selection smoothleaved elm, U. carpinifolia Gleditsch; Augustine ascending elm, U. americana ascendens Slavin F.; slippery elm, U. fulva Micheux; or on Japanese zelkova, Zelkova serrata (Thunb.) Mak. On David hemiptelea, Hemiptelea Davidii (Hance) Planch., there were significantly fewer cambial punctures while on native hackberry, Celtis occidentalis L., and white oak, Quercus alba L., no such punctures occurred.

Residual Effectiveness of DDT Emulsion Sprays with and without Horticultural Oil Against the Smaller European Elm Bark Beetle1

Prior to World War II, Dutch elm disease control in Eastern United States was based entirely on sanitation. Funds and manpower were available through such government programs as WPA. Bromley (1948) reported sprays containing lead arsenate effective against elm bark beetles. Whitten (1945) reported that DDT controlled the smaller European elm bark beetle, Scolytus multistriatus (Marsham). Plumb (1950) and Matthysse et al. (1954) reported effective control of elm bark beetles and Dutch elm disease by dormant mist-blown applications of concentrated DDT-xylene emulsions. Following World War II, DDT became available and its use increased.

Evaluation of Insecticides for Control of the Smaller European Elm Bark Beetle

Evaluation of Insecticides for Control of the Smaller European Elm Bark Beetle

An Evaluation of Certain Compounds as Feeding Deterrents Against the Smaller European Elm Bark Beetle, Scolytus multistriatus1

The smaller European elm bark beetle, Scolytus multistriatus , was reared in elm logs in culture chambers fashioned from 55-gallon lever-lock drums. Feeding cages were designed and 42 compounds were tested as feeding deterrents against the beetle. None were as effective in reducing feeding at concentrations of 20,000 p.p.m. as was DDT. Four chemicals (decanoic acid, N,N-diethyl-m-toluamide, 3,4-diethoxybenzaldehyde and dimethyl phthalate) proved to be very effective in combination with DDT. Concentrations of 10,000 p.p.m. of the deterrent together with a similar amount of DDT were in each case equal or superior to 20,000 p.p.m. DDT in effectiveness. The same compounds at 5,000 p.p.m., in combination with DDT at 5,000 p.p.m. each, were also equal to 20.000 p.p.m. DDT in reducing feeding.

Beauveria Bassiana as a Pathogen of Scolytus Multistriatus

This muscardine fungus was the organism most frequently encountered in a survey for pathogens of the smaller European elm bark beetle, Scolytus multistriatus Marsh., and was found in larvae from five widely separated areas in Connecticut. Up to 6.5% of overwintering larvae in trees cut from city streets were infected, but under certain environmental conditions the fungus may be much more effective in killing the beetles. In one epizootic caused by this fungus, 97% of larvae were killed in the bark of trees in a shady grove, less than 4% in nearby trees standing in the open. In controlled laboratory experiments the fungus killed up to 99% of the larvae in 5 days. Pupae and adults were also susceptible, though adults were slightly less so than larvae.

Insecticides to Prevent the Emergence of Scolytus multistriatus

Emulsions of four insecticides were tested for their effectiveness in preventing emergence of the smaller European elm bark beetle, Scolytus multistriatus (Marsh.). Emulsions of 12% DDT, 6% dieldrin and 6% lindane were applied to bark brought into the laboratory. The bark surface was only slightly moistened during spraying. Lindane was most effective, followed by dieldrin and DDT in reducing emergence by 97%, 51% and 22%, respectively. Daily readings of the treatments with lindane, dieldrin, and DDT showed that 1%, 5% and 41%, respectively of the beetles were alive 24 hours after emerging. Beetles were in the larval stage at time of treatment and none of the insecticides prevented them from reaching the adult stage. Two replicated field tests were run using 0.25% to 2% sprays of DDT, dieldrin, lindane and malathion in amounts that wetted the bark of the infested elm logs. The beetles were in the larval or pupal stage when treated and again the sprays did not kill the insects until they reached the adult form. All sprays penetrated better when the bark was thoroughly wetted whereas only lindane penetrated well in the laboratory test. Lindane and dieldrin sprays at either 0.5% or 1% were very effective in reducing emergence. DDT sprays were less effective while 0.5% or 1% malathion sprays were least efficient.

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