Adelges Piceae Research Articles

NITROGEN FERTILIZATION OF THE HOST TREE AND POPULATION GROWTH OF THE BALSAM WOOLLY APHID, ADELGES PICEAE (HOMOPTERA: ADELGIDAE)

AbstractThe relationship between nutrition of the host tree, Abies amabilis (Dougl.) Forbes, as influenced by nitrogen fertilizers, and the growth of populations of the balsam woolly aphid, Adelges piceae (Ratz.), was investigated. Sixty trees, growing in a greenhouse in two soil types, a nutrient-deficient mineral soil and an enriched humic soil, were infested with woolly aphid larvae. Subsequently, groups of 10 trees received foliar treatments of various concentrations of ammonium nitrate and urea. The following year, 32 young trees in Seymour Valley, B.C., were studied to determine the effect of fertilization of uninfested trees on establishment of aphid larvae.In the greenhouse, foliar sprays of 1% ammonium nitrate solution resulted in a 23% decrease in population in 10 weeks, as contrasted with a 31% increase in the control population. In the field, larval establishment was 31% to 37% lower on the ammonium nitrate-treated trees than on the control trees. Inasmuch as there was no evidence of increased mortality of aphids in situ, we infer that the fertilizer acts primarily by inhibiting initial settling of larvae on the host trees.

Tanglefoot Traps for Detection of the Balsam Woolly Aphid

Microscope slides and wire screens coated with a thin layer of Tree Tanglefoot® were evaluated as a means of collecting wind-dispersed nymphs of the balsam woolly aphid, Adelges piceae (Ratzburg) thus enabling survey entomologists to detect localized infestations of this insect before widespread fir mortality occurs. Peak nymph collections were made in June and September, coinciding with occurrence of peak numbers of this life stage in the southern Appalachians. More nymphs were collected on horizontal than on vertical traps.

Foreign Predator Introductions for Control of the Balsam Woolly Aphid in the Pacific Northwest

The balsam woolly aphid, Adelges piceae (Ratzeburg), an import from Europe, causes major damage to true fir forests in North America. A program has been underway since 1957 to control the pest in Oregon and Washington by introducing insect predators. Twenty-three species have been introduced from 7 countries throughout the world. They include 15 species of beetles, 4 of flies, 3 of lacewings, and 1 bug. Three species of flies, Aphidoletes thompsoni Möhn, Cremifania nigrocellulata Czerny, and Leucopis obscura Haliday and 2 species of beetles, Laricobius erichsonii Rosenhauer and Pullus impexus (Mulsant), are successfully established. They prey on the aphid but so far have not sufficiently reduced populations to prevent tree killing. Reasons for their failure include poor synchronization of predator-prey seasonal habits, inadequate searching ability of the predators, and inability of the host trees to withstand even light populations of the aphid. Search for more effective predators is continuing. The aphid problem is expected to decrease as the present virgin old forests are converted, under management, to less susceptible young forests. Aphid predators may become relatively more effective under such forest conditions.

Hormonal Action in Production of Tumours and Compression Wood by an Aphid

Barnes and Newton1 described tumours in alfalfa caused by a leaf-hopper. They concluded that these were induced by a substance in the insect's saliva, “probably some growth regulator rather than a virus”, and that individual plants vary in their sensitivity to this substance. Examinations of the balsam woolly aphid, Adelges piceae (Ratz.), have led to similar conclusions2.

Observations on the Effectiveness and Biology of the European Predator Laricobius erichsonii Rosen. (Coleoptera: Derodontidae) in Oregon and Washington

In 1957, a program of introducing insect predators for control of the balsam woolly aphid, Chermes (= Adelges) piceae Ratz., was begun in Oregon and Washington. This program was made possible through the generous cooperation of the Canadian Department of Agriculture, which provided many of the predators. Eighteen predator species from Europe, Asia, and Australia were liberated from 1957 through 1960. Four of the species are known to have survived one or more winters and show promise of becoming permanently established.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae) X. Field Identification of Laricobius erichsonii Rosen. (Coleoptera: Derodontidae)

Over the past ten years a number of exotic predators have been introduced into New Brunswick and other parts of North America as part of a biological control program against the balsam woolly aphid, Adelges piceae (Ratz.). Several of these have become established and others show considerable promise. As introductions continue it becomes exceedingly important that field workers be able to distinguish rapidly all stages of introduced and native predators. Field identification characters for some species (Chamaemyiidae and Syrphidae) have been published in previous papers in this series (Brown and Clark, 1956, 1960; Clark and Brown, 1957) and have been found to be very useful.

Studies of Predators of the Balsam Woolly Aphid Adelges piceae (Ratz.) (Homoptera: Adelgidae): IX. Pullus impexus (Muls.) (Coleoptera: Coccinellidae), An Introduced Predator in Eastern Canada,

Pullus impexus (Muls.) is one of many species of predators that have been introduced into Eastern Canada since 1933 as part of a biological control program against the balsam woolly aphid, Adelges piceae (Ratz.) Delucchi (1954) has published many details of the systematics, biology, and natural control of this species in Europe where he found it to be associated with all A. piceae infestations. According to Pschorn-Walcher and Zwölfer (1960), it is one of a group of predators that are usually associated with lower population densities of A. piceae and other related adelgids, rhan are Aphidoletes thompsoni Möhn and Laricobius erichsonii Rosen. Because it is common on adelgid infestations in Europe and because it can easily be reared en masse, large numbers have been released in North America. The purpose of the present paper is to bring together available information on releases, life-history and natural control, and control value of this species, obtained from studies carried out over the past nine years in New Brunswick.

An Improved Container for Shipping Live Insects

Live insects have been shipped from the Belleville laboratory for many years by rail in wooden chests insulated with cork, lined with metal and cooled with natural ice. These chests were cumbersome and had to be re-iced en route or heavy mortality resulted. In 1959, a more reliable method was developed for shipping adult Aphidoletes thompsoni Moehn (Diptera: Cecidomyjidae), a predator of the balsam woolly aphid, Adelges piceae (Ratz.) (Homoptera: Aphididae) by air express. It incorporates the use of a lightweight container and a patented coolant in cans. Although it was developed specifically for A. thompsoni it was also used successfully for shipping other species.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae) VIII. Syrphidae (Diptera),

Several species of native syrphids have been found to prey upon the introduced balsam woolly aphid, Adelges piceae (Ratz.), in New Brunswick and three of these, Syrphus torvus O. S., Metasyrphus lapponicus (Zett.), and Neocnemodon coxalis (Curr.), are sometimes very common. As part of a long-term study of the biological control of the balsam woolly aphid by native and introduced predators, the life histories, natural control, population fluctuations and control value of these native syrphids have been investigated.

A REVIEW OF THE BALSAM WOOLLY APHID IN NEWFOUNDLAND

The balsam woolly aphid, Adelges piceae (Ratz.), first recorded in Newfoundland in 1949, is now the most serious forest insect pest in the Province, having spread over an area of more than 1,600 square miles. Its host is balsam fir, Abies balsamea (L.) Mill. There are three separate infestations, the largest and most important being in southwestern Newfoundland. The aphid has two generations a year. A biological control program was initiated in 1952 and seven species of predators have been released, three of which are established. Silvicultural and climatic control factors are discussed and the possibilities for the extension of outbreaks are considered.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae), VII. Laricobius rubidus Lec. (Coleoptera: Derodontidae), a Predator of Pineus strobi (Htg.) (Homoptera: Adelgidae)

Although Laricobius rubidus LeConte (1861, 1866) is not a common predator of the balsam woolly aphid, Adelges piceae (Ratz.), this paper is included in the series because of the close taxonomic similarities of L. rubidus in all stages to the recently introduced L. erichsonii Rosenh. In the past there has been confusion in the literature because the majority of records of rubidus have been erroneously attributed to erichsonii. These records have been discussed in detail in a paper on L. erichsonii, a species which has been introduced into North America as part of a biological control program against A. piceae (Clark and Brown, 1958).

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae) VI. Aphidecta obliterata (L.) (Coleoptera: Coccinellidae), an Introduced Predator in Eastern Canada,

Aphidecta obliterata (L.) is a common predator on conifer-infesting adelgids and aphids in Western Europe, including Scandinavia and the British Isles (Wylie, 1958b). The life cycle in Europe and descriptions of the various stages have been published (Weise, 1892; Portevin, 1931; Van Emden, 1949; Van Dinther, 1951; Wylie, 1958a). Beginning in 1941 several attempts have been made to introduce this species into Eastern Canada against the balsam woolly aphid, Adelges piceae (Ratz.). The initial liberations from England and Germany were apparently unsuccessful due to the inability of the insect to survive the Canadian winter conditions. Later collections were made in Sweden, Czechoslovakia, and Switzerland (Table I) from areas where the winter conditions more closely resemble those in Canada. These liberations also proved unsuccessful. The present paper brings together all available information on the liberations and related experiments olbtained during the liberation years.

Observations on the Life-Cycle of the Balsam Woolly Aphid, Adelges piceae (Ratz.), in the Willamette Valley of Oregon

The balsam woolly aphid, Adelges piceae (Ratz.) (Adelgidae, Homoptera), originally introduced from Europe, was reported on grand fir, Abies grandis (Doug.) Lindl., in the Willamette Valley by Keen (5) around 1930. Serious outbreaks of this insect were first recorded on subalpine fir, A. lasiocarpa (Hook.) Nutt., in Oregon and Pacific silver fir, A. amabilis (Doug].) Forb., in Washington in 1954 ( 3 ) . At present about 600,000 acres of subalpine and Pacific silver firs are heavily infested in the Pacific Northwest.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae): V. Laricobius erichsonii Rosen. (Coleoptera: Derodontidae), an Introduced Predator in Eastern Canada,

Laricobius erichsonii Rosen. is one of several species that have been introduced into the Atlantic Provinces since 1933 for the biological control of the balsam woolly aphid, Adelges piceae (Ratz.). This small beetle occurs commonly on A. piceae infestations in Europe where it is one of the more numerous predators of the adelgid (Mesnil, 1950:). Franz (1953) described its range in Europe as from the Italian Alps to near southern Denmark and from Normandy almost to the Carpathian Mountains, srating that its distribution is bound to that of the Coniferae on which its prey live. Franz also described the morphology of all stages in detail and discussed the bionomics and ecology in Europe. Prior to these studies the biology of thc insect was unknown.

Observations on Aphidecta obliterata (L.) (Coleoptera: Coccinellidae), a Predator of Conifer-Infesting Aphidoidea

During 1950 and 1951 the writer collaborated with officers of the Commonwealth Institute of Biological Control in studies of the predators of Adelges (Dreyfusia) piceae (Ratz.) and Adelges (Dreyfusia) nüsslini (Börner) in Europe. These studies preceded the importation of the more important predacious species into Canada and their release against A. piceae. Observations on one of these predators, Aphidecta obliterata (L.) (Coleoptera: Coccinellidae), are given in this paper.

Development, Feeding Habits, and Predator-Prey Relations of Insect Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae), Recently Introduced into Canada

Smith and Coppel (in preparation) listed the releases and reviewed the bionomics in Europe of insect predators of the balsam woolly aphid, Adelges piceae (Ratz.), recently introduced into Canada. The most promising species released since 1951 are Aphidecta obliterata (L.) and Pullus impexus (Muls.) (Coleoptera: Coccinellidae) ,Cremifania nigrocellulata Cz.(Diptera: Chamaemyiidae), and Laricobius erichsonii Rosenh. (Coleoptera: Derodontidae). All these species, with the possible exception of A. obliterata, are established near Fredericton, New Brunswick. Investigations in co-operation with the Forest Biology Laboratory, Fredericton, were begun in 1951 on the behaviour and initial establishment of the introduced predators (Clark, Brown, and Smith, 1954). The present paper contains field and laboratory observations on the development, feeding habits, and predator-prey relations of the four promising species.

Responses to Light and Influence of Light and Temperature on Locomotion of the Crawler of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Phylloxeridae), and of Insect Predators of this Species

This is a report on observations made in the field and in the laboratory in 1954 and 1955 at Fredericton, New Brunswick, on the responses to light and influences of light and temperature on the locomotory activities of introduced insect predators and the motile first-instar larva, or crawler, of the balsam woolly aphid, Adelges piceae (Ratz.). Adults and larvae of the predators were observed in the field and tests were conducted with adults in the laboratory. The species studied were Aphidecta obliterata (L.) and Pullus impexus (Muls.) (Coleoptera: Coccinellidae), Cremifania nigrocellulata Cz. and Neoleucopis obscura (Hal.) (Diptera: Chamaemyiidae) , and Laricobius erichsonii Rosenh. (Coleoptera: Derodontidae). The work is part of an investigation on factors influencing the searching abilities of the predators.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae): IV. Neoleucopis obscura (Hal.) (Diptera: Chamaemyiidae), an Introduced Predator in Eastern Canada

Early in the present century the balsam woolly aphid, Adelges piceae (Ratz.), was introduced accidentally into North America. The history of its development and spread in the United States and Canada has been described by Balch (1952). At the present time, the adelgid occurs in eastern Canada over approximately the southern half of New Brunswick with an extension of the range in the extreme northeastern part of the Province, throughout Nova Scotia and Prince Edward Island, and in some areas of the southwestern and southeastern parts of Newfoundland.

Releases in North America and Reviews of Bionomics in Europe of Insect Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae)

The balsam woolly aphid, Adelges piceae (Ratz.), causes serious damage to balsam fir, Abies balsamea (L.) Mill., in Eastern Canada. It was introduced from Europe before 1900 (Balch, 1952) and has also become established in the northeastern United States. In continental Europe A. piceae is common on Abies alba Mill. but is not so serious a pest as in Canada. It has an extensive complex of insect predators in both Canada (Balch, 1934) and Europe (Delucchi, 1954). Balch (1934, 1952) found those in Canada inadequate as control agents. Some of the predators of Pineus pini Koch and Pineus strobi (Htg.) studied by Wilson (1938) in England, and recommended for introduction to new areas, were imported to Canada and released against A. piceae. Predators were first introdnced from Ensland in 1933 and later from continental Europe beginning in 1951.

Studies of Predators of the Balsam Woolly Aphid,Adelges piceae(Ratz.) (Homoptera: Adelgidae): III. Field Identification and some Notes on the Biology ofNeoleucopis pinicolaMall. (Diptera: Chamaemyiidae)

Neoleucopis pinicolaMall. is a common predator on the pine bark aphid,Pineus strobi(Htg.) in New Brunswick. The host adelgid occurs throughout most of the United States and southern Canada on white pine,Pinus strobus, L., Scots pine,Pinus sylvestrisL., and Austrian pine,Pinus nigraArnold (Craighead, 1950). It is also an occasional predator on the balsam woolly aphid,Adelges piceae(Ratz.) (Brown and Clark, 1956b). No reference toN. pinicolawas found in the literature other than Malloch's (1921) description.