?Cooley Spruce Adelgid
nymph stage of Cooley Spruce Adelgid, Whitney Cranshaw, Colorado State University
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Homoptera Superfamily: Aphidiodea Family: Phylloxeroidea Subfamily: Adelgidae Genus: Adelges Species: A. cooleyi
Binomial name
Adelges cooleyi (authority unknown)

Gall Adelgid refers to adelgid species that produce Galls in spruce trees, conifer species. Such Galls can be produced by an infection by Adelges cooleyi (Adelges is the Genus, and Adelgidae is the Subfamily), a species of aphid-like woolly adelgids (order Homoptera). These infect the new buds of native spruce trees (Cooley Spruce Gall Adelgid) in the foothills of the Rocky Mountains in the spring. They also attack blue spruce to a lesser degree. The parasite completes two generations within the year. The parasite requires two different trees for its life cycle, the second being the Rocky Mountain Douglas Fir. They may also attack Sitka, Engelmann, or white spruce. There are many different species of adelgids that produce different gales on different spruce species. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Subphyla and Classes Arthropods (phylum Arthropoda) (from Greek ἀρθρον, meaning joint and πούς/ποδός, meaning foot) are the largest phylum of animals and include the insects, arachnids, crustaceans, and others. ... Classes & Orders See taxonomy Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely-distributed taxon within the phylum Arthropoda. ... Suborders Heteroptera Homoptera Hemiptera is an order of insects, comprising some 67,500 known species in two suborders, Heteroptera and Homoptera. ... In biology, binomial nomenclature is the formal method of naming species. ... Kalanchoë infected with crown-gall using Agrobacterium tumefaciens. ... Species About 35; see text. ... Orders & Families Cordaitales† Pinales   Pinaceae- Pine family   Araucariaceae- Araucaria family   Podocarpaceae- Yellow-wood family   Sciadopityaceae- Umbrella-pine family   Cupressaceae- Cypress family   Cephalotaxaceae- Plum-yew family   Taxaceae- Yew family Vojnovskyales† Voltziales† The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... An infection is the detrimental colonization of a host organism by a foreign species. ... In biology, a genus (plural genera) is a taxonomic grouping. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Families There are 10 families: Adelgidae - adelgids, conifer aphids, Adelges cooleyi, Hemlock Wolly Adelgid, Adelges piceae Anoeciidae Aphididae Drepanosiphidae Homomasagymibutae Greenideidae Hormaphididae Lachnidae Mindaridae Pemphigidae Phloeomyzidae Phylloxeridae Thelaxidae Aphids, also known as greenfly/blackfly or plant lice, are minute plant-feeding insects in the superfamily Aphidoidea in the homopterous division... Wooly aphid on new growth blackberry, red objects unknown, possibly parasitic mites Wooly aphids (family: Eriostomatidae) are sucking insects that live on plant fluids, and produces a filamentous waxy white covering which resembles cotton or wool. ... Suborders Heteroptera Homoptera Hemiptera is an order of insects, comprising some 67,500 known species in two suborders, Heteroptera and Homoptera. ... Flower buds have not yet bloomed into a full-size flower. ... Foothills are geographically defined as gradual increases in hilly areas at the base of a mountain range. ... Wilcox Pass The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. ... Binomial name Picea pungens Engelm. ... Parasitism is an interaction between two organisms, in which one organism (the parasite) benefits and the other (the host) is harmed, though usually without killing the host. ... Generation (From the Greek γιγνομαι), also known as procreation, is the act of producing offspring. ... A life cycle includes the major sexual stages of a species, especially in regard to its ploidy. ... Pseudotsuga menziesii var. ... Species See text. ... Binomial name Picea sitchensis (Bong. ... Binomial name Picea engelmannii Parry ex Engelm. ... Binomial name Picea glauca (Moench) Voss The White Spruce (Picea glauca) is a medium-sized evergreen tree growing to 15-30 m tall, rarely to 40 m tall, and with a trunk diameter of up to 1 m. ...

Male sex organ of the Cooley Spruce. Pollen is released by this structure and is carried by the wind.

Identification

The infection is most noticeable on Cooley Spruce in the spring, May to June, when the galls appear. This infection may be mistakingly diagnosed to as caused by worms, grubs, or even as a sex organ of the spruce. Spruce pollen, however is released from a smaller structure that lacks needles. The galls are characterized by this pineapple-like form, with a length of 0.5 cm to 8 cm depending on the growth capacity of the tree. Most galls take on a pink, red or even deep purple colour while the needles usually remain green. The segments of the new bud that have this gall form will die after the apids leave in the summer. Once on Douglas-Fir, the adelgids consume the needles but do not form galls.

Diversity of colour of galls. Can be green to red, and to deep-purple.

The end of a gall where infection was complete. The tissue has since become necrotic on this hardened remnant.

The end of a gall that had partial infection. Growth continues but it is convoluted.

Infection

In the fall, the immature female adelgid, small, globular, and wingless (1.2-1.7 mm), finds a spruce to over-winter on. In the spring when the winter thaw occurs, the female matures and lays some eggs in what resemble sacks (totalling several hundred eggs) on the branches near the developing buds. These in fact are not sacks, but individual tufts of white waxy threads that protect the eggs. The females prefer areas on the spruce where they have greater protection from the elements, especially wind. These female individuals have an obvious patch of white wax wool as a covering. Their mouthparts consist of thread-like stylets which are used to penetrate into vascular bundles for feeding. Classes & Orders See taxonomy Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely-distributed taxon within the phylum Arthropoda. ... The stylet or stomatostyle, is the primitive mouth-parts of the nematode. ...

A healthy bud where infection did not occur, but where a tuff of eggs is attached.

Once hatched, the young nymphs begin feeding around the base of the needles in a new bud. The nymphs's saliva introduced into the plant trigger the changes in development of the plant, distinguished by the thickening and expansion of the basal portion of needles towards the characteristic gall form. When there are incomplete infections, the side of the bud facing the ground will be infected first. Only partially afflicted buds can support new growth after the affected tissue has died. In biology, a nymph is the immature form of some insect species (e. ... Saliva, often informally known as spit, is the moist, clear, and usually somewhat frothy substance produced in the mouths of some animals, including humans. ...

Large contrast box showing an infected bud (gall) beside healthy buds. Two egg tufts are visible to the left of the gall (infected bud).

Cross-section of gall in June. Nymphs are very small, but can be seen with the naked eye. The white part is a waxy excretion by the nymph.

The chamber at the base of each needle is not connected with any other chamber in the gall. This differentiates this infection from that caused by the woolly adelgid genus Pineus, where in that case the chambers are interconnected.

Cross-sectional difference between cooley spruce gall adelgid (left) and Pineus (right).¹

The nymphs are light brown when first hatched, becoming black when settled in gall chamber; they are flattened oval in shape and secrete a fringe of white wax. If a gall is opened in June, this white wax will be easily visible.

Life Cycle

The life cycle of the gall adelgid requires six generations to complete, only two of which cause damage (nymph stages) and has two migration phases between the spruce and the Douglas-Fir. On Douglas-Fir, adults are about 0.1 cm long, oval, and light to dark brown in colour. At maturity they are completely covered with white, waxy wool and appear, from spring to fall, as stationary wool tufts on the underside of needles.¹

Non-tufted and tufted cooley spruce gall adelgids on Douglas-fir foliage. Tufts are destinguished by wool-like appearance.¹

Life cycle of the Cooley spruce gall adelgid. Research indicates that the adelgids leaving spruce must develop on Douglas-fir before returning to spruce. Observations in Colorado suggest that spruce to spruce movement also may occur.²

While the chambers of the galls are closed, the nymphs actively feed and increase in size. By midsummer (August to September), the galls begin to dry out, the chambers open and winged forms of the adelgids emerge. These winged adult females have dark red-brown colour, with a heavily sclerotized thorax.³,⁴ The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. ...

Alate stage emerged from gall. Whitney Cranshaw, Colorado State University.

These leave the original tree and most migrate to Douglas-Fir trees. The abandoned galls continue to dry out and harden as the plant tissue dies. These dead galls are remenants that are never used again. The gall portion of partial infections dies, while the uninfected segment can continue growth, resulting in curved and convoluted shapes.

Egg tufts on needles of Douglas-Fir.³

Close up of an egg cluster, and the waxy strands, of the Cooley spruce gall adelgid on a needle of Douglas-Fir.⁶

On Douglas-Fir, eggs are laid on the needles and several generations of woolly adelgids are produced. Yellow spots and bent needles result from feeding damage.² The needles of light to moderately infested trees exhibit chlorotic mottling where individual adults have fed. Attacked needles may also be twisted. Severely infested foliage may be completely chlorotic and drop prematurely.¹ Late in the summer, some of the woolly adelgids develop wings and fly back to spruce to deposit eggs, which produce the overwintering population. Others are wingless and remain on Douglas-Fir trees, where they produce other overwintering forms.²

Predation and Control

Natural predators, such as ladybirds/ladybugs, hoverfly and lacewing larvae, spiders and mites do reduce adelgid and aphid populations to some degree.⁴ Subfamilies Chilocorinae Coccidulinae Coccinellinae Epilachninae Scymininae Sticholotidinae etc. ... Subfamilies Eristalinae Microdontinae Syrphinae 200 genera about 5,000 species The flower-flies or hover-flies are a family of flies (Diptera), scientifically termed the Syrphidae. ... Suborders Megaloptera Raphidiodea Planipennia The insect order Neuroptera, or net-winged insects, includes the fishflies, snakeflies, lacewings and antlions. ... A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... Suborders Araneomorphae Mesothelae Mygalomorphae See the taxonomy section for families Spiders are predatory invertebrate animals that produce silk, and have two tagma, eight legs, no chewing mouth parts and no wings. ... Families Tetranychidae - Spider mites Eriophyidae - Gall mites Sarcoptidae - Sarcoptic Mange mites The mites and ticks, order Acarina or Acari, belong to the Arachnida and are among the most diverse and successful of all the invertebrate groups, although some way behind the insects. ...

Spraying againsts these adelgids with chemicals is possible, and can be done in either the fall or the early spring. Foliar treatments of carbaryl (Sevin) and permethrin have been most effective in Colorado State University trials. Horticultural oils, which have also been very effective, can cause temporary discoloration of spruce needles.²

Conifer Aphids

Young trees that are large enough or having enough shade are most vulnerable to infection by aphids, such as Adelges cooleyi. Mature trees are more resistant.

The most commonly occurring aphids locally, in the canadian Rocky Mountains, are several species of giant conifer aphids of the genus Cinara, and the Cooley spruce gall aphid Adelges cooleyi. Other aphids that have been pests are the green spruce aphid, Elatobium abietinum; the primitive woolly aphid, Mindarus obliquus; and two conifer root aphids, Pachypappa tremulae and Prociphilus xyloster. The balsam woolly aphid, Adelges piceae (also known as the balsam woolly adelgid), although a concern because of quarantine regulations, has not been reported at any local nurseries.⁵

True fir showing balsam woolly aphid damage. Note stunted needles and galled buds.⁵

Green spruce aphids: a serious pest of spruce species along coastal British Columbia - particularly of Sitka spruce - and may occur on pine and Douglas-Fir. Adults are green, 1 mm long with long cornicles. Note mottled spruce needles (courtesy of Forest Insect and Disease Survey, P.F.C., Victoria, B.C.)⁵

The coniferous root aphid, Pachypappa tremulae, previously called Rhizomaria piceae, has been a pest at several British Columbia nurseries, particularly near Prince George. This aphid has taken advantage of potted seedlings.⁵

The balsam woolly aphid has become established in British Columbia and can seriously damage all true firs. Quarantines have to be respected to prevent its spread.

See also

Hemlock Wolly Adelgid: Another disease caused by a woolly adelgid species. Hemlock Woolly Adelgid or HWA: Hemlock Woolly Adelgid or HWA is a destructive introduced pest that poses a major threat to eastern and Carolina hemlock trees throughout their range. ...

Balsam wooly adelgid: another species of woolly adelgid. Binomial name Adelges piceae (Ratzeburg, 1844) Balsam woolly adelgids are small wingless insects that infest and kill firs, especially Balsam Fir and Fraser Fir. ...

More on the invasive woolly aphid species: The term invasive species refers to a subset of those species defined as introduced species or non-indigenous species. ...

• Forest Pests. (2005). Balsam woolly aphid Adelges piceae (Ratzeburg). (World Wide Web page). Available: http://www.forestpests.org/southern/balsamwoollyadelgid.html (Dec. 1, 2005)

A University of Minnesota Panflet with image of mature woolly adelgid female: [1] and related pests

References

• Note 1: Ebata, Tim. March 12, 2002. Cooley Spruce Gall adelgid - Pest Guide BC Ministry of Forests, Victoria, BC, Canada. Part of:[2]

• Note 2: Cranshaw, W.S. June 23, 2005. Cooley Spruce Galls Colorado State University.

• Note 3: UBC Faculty of Forestry, Vancouver, B.C., Canada. Insects Studied in Forestry 308

• Note 4: Cooley spruce gall aphid. 1977. Wood, C. Government of Canada. Department of the Environment. Canadian Forest Service, Pacific Forest Research Centre, Victoria, BC. Forest Pest Leaflet 06. 4 p. PDF form

• Note 5: Canadian Forestry Service,2002-12-23. Online publication about Aphids

• Note 6: Childs, R. University of Massachusetts Amherst, Massachusetts, 01003. Cooley Spruce Gall Adelgid - Landscape Nursery and Urban Forestry - UMass Extension