Adelges Cooleyi Research Articles

Whole-genome sequence of the Cooley spruce gall adelgid, Adelges cooleyi (Hemiptera: Sternorrhyncha: Adelgidae).

The adelgids (Adelgidae) are a small family of sap-feeding insects, which, together with true aphids (Aphididae) and phylloxerans (Phylloxeridae), make up the infraorder Aphidomorpha. Some adelgid species are highly destructive to forest ecosystems such as Adelges tsugae, Adelges piceae, Adelges laricis, Pineus pini, and Pineus boerneri. Despite this, there are no high-quality genomic resources for adelgids, hindering advanced genomic analyses within Adelgidae and among Aphidomorpha. Here, we used PacBio continuous long-read and Illumina RNA-sequencing to construct a high-quality draft genome assembly for the Cooley spruce gall adelgid, Adelges cooleyi (Gillette), a gall-forming species endemic to North America. The assembled genome is 270.2 Mb in total size and has scaffold and contig N50 statistics of 14.87 and 7.18 Mb, respectively. There are 24,967 predicted coding sequences, and the assembly completeness is estimated at 98.1 and 99.6% with core BUSCO gene sets of Arthropoda and Hemiptera, respectively. Phylogenomic analysis using the A. cooleyi genome, 3 publicly available adelgid transcriptomes, 4 phylloxera transcriptomes, the Daktulosphaira vitifoliae (grape phylloxera) genome, 4 aphid genomes, and 2 outgroup coccoid genomes fully resolves adelgids and phylloxerans as sister taxa. The mitochondrial genome is 24 kb, among the largest in insects sampled to date, with 39.4% composed of noncoding regions. This genome assembly is currently the only genome-scale, annotated assembly for adelgids and will be a valuable resource for understanding the ecology and evolution of Aphidomorpha.

Adelges cooleyi

This datasheet on Adelges cooleyi covers Identity, Hosts/Species Affected, Further Information.

Do birds help trees grow? An experimental study of the effects of land-use intensification on avian trophic cascades.

By regulating populations of herbivores, predators can indirectly influence plant production. However, the factors influencing the strength of this type of trophic cascade are still unclear. We hypothesized that changes to plant community structure would affect the number of avian predators, thereby mediating cascade strength. Using a 4-yr, blocked, split-plot experiment, we independently manipulated both predators (birds) and plants in an early seral managed forest system in western Oregon, USA, and measured abundance across three trophic levels. We applied herbicides, as a surrogate for land-use intensification, to recently clear-cut stands to establish an experimental gradient in plant abundance and species richness, and excluded birds using 28, 225 m2 exclosures. In total, we counted and identified 94,738 arthropods of 141 families in paired control and bird exclosure plots. On average, insectivorous birds reduced arthropod abundance by 16% and plant damage by 14%, and some well-known pests (e.g., Adelges cooleyi) of crop trees (mostly Pseudotsuga menziesii) in our system were reduced by as much as 30%. However, this effect did not translate into a trophic cascade that increased crop-tree growth in the presence of birds. We experimentally reduced plant abundance and diversity by 67% and 55%, respectively, in the most intensive herbicide treatment in relation to untreated controls, but reduced vegetative resources did not change the strength of the direct effect of birds on arthropods or the indirect effect of birds on plants.

Predators collected from balsam woolly adelgid and Cooley spruce gall adelgid in western Oregon and Washington, U.S.A., with reference to biological control of hemlock woolly adelgid (Hemiptera: Adelgidae)

As part of a comprehensive study to survey predators associated with hemlock woolly adelgid, Adelges tsugae Annand, 1928 in the Pacific Northwest (PNW), U.S.A. (Kohler et al. 2008), predators of balsam woolly adelgid, Adelges piceae (Ratzeburg, 1844) and Cooley spruce gall adelgid, Adelges cooleyi (Gillette, 1907) (all Hemiptera: Adelgidae) were sampled on nine dates from June 2005 to October 2006 on a small number of trees. Samples were collected every 6–8 weeks. Predators were collected from two A. piceae infested grand fir, Abies grandis (Douglas ex David Don) Lindley, and one A. cooleyi infested Engelmann spruce, Piceae engelmanii Parry ex Engelmann, on the Oregon State University campus in Corvallis, Oregon, and two A. cooleyi infested Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco (all Pinaceae). One Douglas-fir was an ornamental tree in Corvallis, Oregon and the other was in a seed orchard on Whidbey Island, Washington. Adelges cooleyi predators were collected by striking an infested branch four times over a plastic tub with an area of 0.16 m2. Adelges piceae predators were collected by brushing adelgid wool on the bole of infested trees with a 2-inch wide paintbrush over a beat sheet. Predators were collected from the tub and beat sheet with an aspirator. Adult insects were killed in a sealed 9-dram plastic vial containing a small piece of Hot Shot No-Pest Insecticide Strip (Spectrum Brands Inc., Atlanta, Georgia). Immature insects were killed in KAAD mixture (10 parts 95% ethanol, 1 part kerosene, 2 parts glacial acetic acid, and 1 part dioxane) and preserved in 70% ethanol (Borrer et al. 1989). Adult specimens were identifi ed either by taxonomic specialists or by comparison to previously identified museum specimens. Voucher specimens were deposited in the Oregon State Arthropod Collection, Department of Zoology, Oregon State University, Corvallis, Oregon.

Prey Suitability and Phenology of Leucopis spp. (Diptera: Chamaemyiidae) Associated With Hemlock Woolly Adelgid (Hemiptera: Adelgidae) in the Pacific Northwest

Leucopis spp. (Diptera: Chamaemyiidae) from the Pacific Northwest previously were identified as potential biological control agents for the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), in the eastern United States. We collected Leucopis spp. larvae from A. tsugae infested western hemlocks in Oregon and Washington and reared them on an unidentified Pineus spp., Pineus strobi (Hartig), Adelges cooleyi (Gillette), Adelges piceae (Ratzeburg), and A. tsugae in three no-choice tests. Leucopis spp. survival on A. tsugae was significantly higher than on A. piceae during the 2010 progrediens generation test and significantly higher than on P. strobi and A. cooleyi during the 2010 sistens generation test. However, across all three tests, some larvae completed development to adult on all four of the alternative adelgid species. Larvae that survived to the adult stage were identified as Leucopis argenticollis Zetterstedt and Leucopis piniperda Malloch. These results suggest that populations of L. argenticollis and L. piniperda in the Pacific Northwest may not be specific to A. tsugae. We also studied the phenology of Leucopis spp. on fourteen A. tsugae infested western hemlock trees in Oregon and Washington over a period of 14 mo. Leucopis spp. larvae were collected year-round, but highest densities coincided with the presence of progrediens and sistens eggs and adults of A. tsugae. There was a positive correlation between Leucopis spp. and A. tsugae abundance.

Sampling plan for Adelges cooleyi (Hemiptera: Adelgidae) in spruce seed orchards

AbstractWithin-plant and between-plants distributions of the Cooley spruce gall adelgid, Adelges cooleyi (Gillette), fundatrices were measured in “interior spruce”, Picea glauca × P. engelmannii (Moench) Voss. & Parry (Pinaceae), seed orchards in central British Columbia to develop a quantitative sampling plan. Adelgids (number of fundatrices per shoot) were abundant at the lower and middle crown heights of the tree crowns but scarce at the upper crown height, and more abundant on the ends and central one-third of branches than on the inner portions. The northern and eastern aspects of trees had slightly but significantly more adelgids than did the southern and western aspects, and terminal shoots had more adelgids than did distolateral shoots. Variance was much greater between than within trees. These data were used to create a sampling plan with a sample unit consisting of a single 1-year-old shoot selected from the ends or central area of main branches in the lower or middle portion of each sample tree. Collecting 104 samples required 69 min, and yielded an estimate of the mean number of fundatrices per shoot with a standard error of 10% of the mean.

Phylogeography of a specialist insect, Adelges cooleyi: historical and contemporary processes shape the distribution of population genetic variation

Adelges cooleyi is a host-alternating, gall-making insect native to the Rocky Mountains and Cascade Mountains in western North America. The insect's primary hosts are Picea (spruce) species, and its secondary host is Pseudotsuga menziesii, Douglas fir. To determine whether there are large-scale patterns of genetic variation in this specialist insect, we created molecular phylogenies of geographically separate samples of A. cooleyi using sequence data from two mitochondrial (mtDNA) genes and amplified fragment length polymorphisms (AFLPs). Three divergent mtDNA lineages were identified. Analysis of mtDNA and AFLP genetic variation revealed that samples from southeastern Arizona are genetically isolated from all other samples. AFLP data identified possible gene flow between individuals from divergent mtDNA lineages in an area in the central Rocky Mountains. Factors that likely affected divergence within A. cooleyi were identified by comparing our conclusions with well-known changes in the distribution of vegetation in response to glaciations and previous phylogeographical work conducted on this specialist insect's host-plants. In addition to documenting previously unknown patterns of genetic variation in A. cooleyi, our work provides the basis for a testable hypothesis regarding the extent to which the distribution of variation in Picea and Pseudotsuga hosts mediates the distribution of genetic variation for this specialist insect.

Founder effects and phenotypic variation in Adelges cooleyi, an insect pest introduced to the eastern United States

Introduced organisms experience founder effects including genetic bottlenecks that result in significant reductions in genetic variation. Genetic bottlenecks may constrain the evolution of phenotypic traits that facilitate success in novel habitats. We examined the effect of introduction into novel environments on genetic diversity of an insect pest, Adelges cooleyi, which was introduced into the eastern United States during the mid nineteenth century. We compared variation in mitochondrial and nuclear genomes in native and introduced samples to determine the effect of introduction on genetic variation experienced by this insect. We also measured an ecologically important phenotype, variation in host preference, in both native and introduced samples to compare variation in that trait with molecular genetic variation. To further investigate the relationship between genetic and phenotypic variation, we examined the degree to which mtDNA haplotypes provide information about host preference. Adelges cooleyi in eastern North America has significantly reduced genetic and phenotypic variation, but this low variation does not appear to have prevented persistence in a novel environment. Introduced insects appear to have retained host preference phenotypes similar to those of insects found where introductions likely originated.

Feeding Preference of Three Lady Beetle Predators of the Hemlock Woolly Adelgid (Homoptera: Adelgidae)

In a laboratory study, we tested the feeding preferences of three coccinellid predators of hemlock woolly adelgid, Adelges tsugae Annand, an introduced pest of hemlock in the eastern United States. The species tested were Sasajiscymnus tsugae Sasaji & McClure (formerly Pseudoscymnus tsugae) from Japan, Scymnus ningshanensis Yu & Yao from China, and Harmonia axyridis (Pallas), a generalist species introduced from Asia that is currently widespread in eastern hemlock, Tsuga canadensis Carriere, forests. We measured the feeding preference of each beetle species when given the choice of A. tsugae and either 1) Pineus strobi (Hartig) on Pinus strobus L.; 2) Adelges laricis Vallot on Larix decidua Mill.; 3) Adelges cooleyi (Gillette) on Pseudotsuga menziesii (Mirb.) Franco; or 3) Paraprociphilus tessellatus (Fitch) on Alnus serrulata (Ait.) Willd. We evaluated beetle preference for adults, nymphs, and eggs of each prey species. Generally, when adult or nymphal prey stages were compared, S. tsugae preferred A. tsugae adults to P. strobi, A. cooleyi, A. laricis, and P. tessellatus. S. ningshanensis showed less preference between adelgid species, but it did not prefer P. tessellatus nymphs. When preferences for adelgid eggs were assayed, S. tsugae and S. ningshanensis showed no preference between A. tsugae and A. cooleyi or P. strobi, but S. tsugae did prefer A. tsugae to A. laricis. Larvae of S. tsugae were unable to survive on P. tessellatus nymphs. H. axyridis adults readily consumed both A. tsugae and P. tessellatus, but H. axyridis larvae did not complete their life cycle on A. tsugae. Our host range tests suggest that S. ningshanensis and S. tsugae may feed on several species of Adelgidae and that A. tsugae is often preferred.

Evidence for long‐distance, chemical gall induction by an insect

AbstractWe report that a chemical stimulus from a herbivore, a galling insect, changes plant morphology and physiology to benefit the herbivore. Previous studies could not determine whether insect galls are induced by mechanical or chemical stimuli because feeding and oviposition both occurred at the site of gall formation. We report that the mouthparts of a spruce‐galling insect,Adelges cooleyi, were inserted in stem phloem cells far from induced galls, that tissues between mouthparts and galls appeared normal, and that the ability to initiate galls was inversely correlated with distance from buds (potential gall sites). Thus the effects of chemical stimuli were unambiguously separated from any mechanical influence of probing stylets or ovipositors. Our results strongly suggest that galls were induced by a chemical stimulus transported to buds via vascular tissue and that its efficacy was dose‐dependent.

Is gall size a good indicator of adelgid fitness?

sects emerging from a gall. Furthermore, fecundity of emerging adelgids was positively related to body size. We expect the fitness of other galling adelgids to also be positively related to gall size because: i) there are no known predators or parasitoids of these insects while within the galls; and ii) fecundity of the only two other adelgids investigated was positively related to body size (Sopow & Quiring, 1998). Here we test the prediction that insect fitness is positively related to gall size for three species of spruce-galling adelgids, Adelges cooleyi, Pineus pinifoliae ,a ndP. similis.

Within‐plant distribution of a galling adelgid (Homoptera: Adelgidae): the consequences of conflicting survivorship, growth, and reproduction

Abstract. 1. Adelges cooleyi (Gil.) was rarely found in the top‐most whorl of shoots in its host plant Engelmann spruce.2. The survivorship of the few Adelges fundatrices which did colonize the top whorl was at or near zero for the 3 years in which survivorship was assessed, while survivorship in the bottom whorls was at least 60%.3. In contrast, when an Adelges fundatrix did survive in the top whorl, her growth and reproductive output, and the growth of her progeny, the gallicolae, were at least double that of bottom whorl fundatrices.4. The distribution of fundatrices within spruce trees was strongly correlated (R2=0.934) with fundatrix fitness (=survivorship × fecundity × growth).5. We hypothesize that the vigorous growth of top whorl shoots promotes Adelges growth and fecundity, but the earlier growth of these shoots results in low temperature mortality of fundatrices.

Patterns of Gall Formation by the Cooley Spruce Gall Adelgid on Colorado Blue Spruce

Observations were made of galling patterns by the Cooley spruce gall adelgid (Adelges cooleyi) on landscape and nursery plantings of Colorado blue spruce from 1985-1988. Overall incidence of galling varied widely between seasons, and appeared to be related to late winter and early spring weather conditions. Strong orientation of galls occurred with highest numbers of galls occurring along the north (37%) and east (34%) sides of the trees. Galling was also found to be consistently correlated on individual trees, suggesting a possible genetic basis for resistance. Galling was associated with tree color, being greatest on trees with greener coloration, but was not correlated with onset of spring bud break. The implication of these findings in tree siting and in identifying resistant genotypes is discussed.

Comparison of the potential of organophosphorous insecticides and soaps in conifer aphid control

A comparison of the toxicity to two aphids, Elatobium abietinum and Adelges cooleyi, and a coccinellid predator, A. obliterata, of dimethoate, fenitrothion and malathion with Safer's insecticidal soap (SIS) and saponified corn oil and sunflower oil confirmed that the organophosphates were more toxic. This did not detract from the effectiveness of the soaps under field conditions provided that appropriately higher concentrations were applied. SIS was not more toxic to the insects than the saponified oils with corn oil soap, which is rich in oleic and linoleic acid, frequently producing higher insect mortality levels. In E. abietinum a linear relationship was demonstrated between insecticide susceptibility and aphid instar, with late instars apparently becoming progressively more susceptible. This relationship disappeared when LC 50 values were corrected for size differences. Larval Aphidecta obliterata were more susceptible than adults and field applications of these chemicals should be timed to avoid the larval feeding period. Phytotoxic symptoms appeared on Sitka spruce needles after application of sunflower oil soap, current year needles being particularly susceptible to damage. Corn oil soap or SIS could be substituted during this susceptible period.

Douglas Fir Seed Sources Tested for Christmas Trees in Connecticut

Douglas fir, Pseudotsuga Menziesii (Mirb.) Franco, is a popular Christmas tree in the Northeast. In 1976 trees from 11 geographic sources ranging from British Columbia to southern Arizona and New Mexico were planted in a replicated design and managed as a commercial plantation. Information was also obtained on 10 seed sources grown on a commercial tree farm. All sources were hardy in the Connecticut plantings. In general, trees from southern Rocky Mountain sources were bluer, and grew faster than those from northern sources, but they were also more susceptible to attack by Cooley gall aphid, Adelges cooleyi (Gill), and rhabdocline needle cast fungus, Rhabdocline pseudotsugae (Syd.)

Adelges cooleyi (Homoptera: Phylloxeridae) Control on Douglas-Fir Christmas Trees1

Endosulfan and Baygon® ( o -isopropoxyphenyl methyl-carbamate) high-volume sprays and ultra-low-volume applications of Baygon controlld the Cooley spruce gall aphid, Adelges cooleyi (Gillette), on plantation sand Douglas-fir Christmas trees. One application sufficed for a growing season.

The Biology of Adelges cooleyi (Gill.) (Homoptera: Phylloxeridae)

Adelges cooleyi (Gill.) causes galls on spruce in the forests and on shelter-belt and shade-tree plantings in Alberta. The alternate host is Douglas fir, on which the injury is less conspicuous. The tree species affected are white spruce, Picea glauca (Moench) Voss, Engelmann spruce, P. engelmanni Parry, and blue Douglas fir, Pseudotsuga menziesii (Mirb.) Franco. A. cooleyi is indigenous to North America.

ADELGES COOLEY1 GILLETTE (HEMIPTERA, ADELGIDAE) OF THE DOUGLAS FIR IN BRITAIN: COMPLETION OF ITS LIFE CYCLE

SUMMARY Adelges cooleyi is a pest of Sitka spruce, the primary host, and Douglas fir, the secondary host, on the latter of which it has been known in Britain since 1913. Hitherto its life cycle in Britain has been regarded as incomplete because of the non‐viability of generation I (sexuales) on Sitka spruce and consequent absence of the subsequent generation II (fundatrix vera) and generation III (gallicolae). Both of these generations have been discovered for the first time in Britain and their development followed. The investigation began with the finding of the dead galls of A. cooleyi on Sitka spruce at Glen Tress in February 1935. Subsequently, dead galls were also found at Stobs, Melrose, Dreghorn and Murthly. At Melrose they were found on a new secondary host, the white spruce, Picea alba. Later the fundatrix vera of generation I was found. The growth of the galls was followed on cut twigs in the laboratory and on growing shoots in the field; galls of the current season were found at Glen Tress, Dreghorn and Murthly. The winged gallicolae of generation II were observed migrating to Douglas fir, where they settled and oviposited. From the eggs there hatched typical hibernating first‐instar nymphs (sistentes). Generation III (colonici) was determined to be triple‐brooded, and this character has recently been noted in Adelges cooleyi in British Columbia. The population of the sistentes on Douglas fir during any one winter was found to be composed of four categories, which hav* been designated. The migration of generation IV (sexuparae) to Sitka spruce and white spruce was observed at Glen Tress and Melrose respectively. It was also verified in the laboratory. Generation V (sexuales), for some cause or causes yet unknown, was practically exterminated during development. Only a few adults were observed. The solitary egg laid by the female of this generation was not discovered. Further investigation is required concerning: The causes of mortality of the sexuales. The oviposition of the sexual female, and the sexually produced egg. The extent of the distribution and establishment of the spruce generations in Britain. The prospective status of A. cooleyi as a pest of Sitka spruce in Britain. With regard to status, it would be unsafe, at the present juncture, to speculate, especially as the investigation has been conducted for only one year. I have, therefore, refrained from discussing possibilities of damage to the spruce host until more evidence is available.The writer is indebted to Mr R. Carrick, B.Sc, Research Student in the Department of Entomology, for the photograph of the winged gallicollae reproduced in PI. XXV, fig. 4. Part of the expenses incurred in conducting the investigation were met by a grant from the Earl of Moray Endowment of the University of Edinburgh, and it is a pleasure to acknowledge this assistance.