Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Pineus pini
(pine woolly aphid)

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Datasheet

Pineus pini (pine woolly aphid)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Natural Enemy
  • Preferred Scientific Name
  • Pineus pini
  • Preferred Common Name
  • pine woolly aphid
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • P. pini (sensu lato) can cause problems on exotic species of two-needled pines (subgenus Haploxylon) even within its native range, as reported for P. pini from Germany by
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    Wallingford
    Oxfordshire
    OX10 8DE
    UK
    compend@cabi.org
  • Distribution map More information

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Pictures

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PictureTitleCaptionCopyright
Pineus boerneri adult progredientes and egg, with wax filaments removed.
TitleAdults and egg
CaptionPineus boerneri adult progredientes and egg, with wax filaments removed.
CopyrightGillian W. Watson
Pineus boerneri adult progredientes and egg, with wax filaments removed.
Adults and eggPineus boerneri adult progredientes and egg, with wax filaments removed.Gillian W. Watson
Pineus boerneri adult progredientes and earlier instar, with wax filaments removed.
TitleAdults and earlier instars
CaptionPineus boerneri adult progredientes and earlier instar, with wax filaments removed.
CopyrightGillian W. Watson
Pineus boerneri adult progredientes and earlier instar, with wax filaments removed.
Adults and earlier instarsPineus boerneri adult progredientes and earlier instar, with wax filaments removed.Gillian W. Watson
Needlebases of Pinus oocarpa from Muguga, Kenya, infested by Pineus boerneri.
TitleInfestation
CaptionNeedlebases of Pinus oocarpa from Muguga, Kenya, infested by Pineus boerneri.
CopyrightGillian W. Watson
Needlebases of Pinus oocarpa from Muguga, Kenya, infested by Pineus boerneri.
InfestationNeedlebases of Pinus oocarpa from Muguga, Kenya, infested by Pineus boerneri.Gillian W. Watson
Pinus oocarpa sapling in Muguga, Kenya, heavily infested by Pineus boerneri.
TitleInfested sapling
CaptionPinus oocarpa sapling in Muguga, Kenya, heavily infested by Pineus boerneri.
CopyrightGillian W. Watson
Pinus oocarpa sapling in Muguga, Kenya, heavily infested by Pineus boerneri.
Infested saplingPinus oocarpa sapling in Muguga, Kenya, heavily infested by Pineus boerneri.Gillian W. Watson
Pinus kesiya in the Viphya Plateau, Malawi, damaged by two alien aphid pests, Pineus boerneri and Eulachnus rileyi.
TitleDamage symptoms
CaptionPinus kesiya in the Viphya Plateau, Malawi, damaged by two alien aphid pests, Pineus boerneri and Eulachnus rileyi.
CopyrightGillian W. Watson
Pinus kesiya in the Viphya Plateau, Malawi, damaged by two alien aphid pests, Pineus boerneri and Eulachnus rileyi.
Damage symptomsPinus kesiya in the Viphya Plateau, Malawi, damaged by two alien aphid pests, Pineus boerneri and Eulachnus rileyi.Gillian W. Watson

Identity

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Preferred Scientific Name

  • Pineus pini sensu lato

Preferred Common Name

  • pine woolly aphid

Other Scientific Names

  • Anisophleba pini Koch, 1857
  • Aphis pini Gmelin, 1790
  • Kermaphis pini var. laevis Maskell, 1885
  • Kermes pini Macquart, 1819
  • Pineus boerneri Annand, 1928
  • Pineus havrylenkoi Blanchard, 1944
  • Pineus laevis (Maskell, 1885) Börner, 1907
  • Pineus pini (Macquart, 1819) Börner, 1907
  • Pineus simmondsi Yaseen & Ghani, 1971
  • Pineus sylvestris Annand, 1928

International Common Names

  • English: pine, adelgid; pine, aphid, common; pine, aphid, eurasian; pine, woolly, aphid; scots pine, adelges

Local Common Names

  • Australia: pine adelgid
  • Denmark: fyrrestammelus
  • Finland: mäntykirva
  • Germany: Wollaus, Europaeische Kiefern-; Wollaus, Kieferntrieb-
  • New Zealand: pine adelgid; pine twig chermes
  • Norway: furubarlus
  • Sweden: tall-lus

EPPO code

  • PINEPI (Pineus pini)

Summary of Invasiveness

Top of page P. pini (sensu lato) can cause problems on exotic species of two-needled pines (subgenus Haploxylon) even within its native range, as reported for P. pini from Germany by Steffan (1970b), from France by Gaumont (1978) and from Italy by Covassi and Binazzi (1981).

Infestation by P. pini (sensu lato) causes premature needle shedding and reduction in the length of infested needles, reducing productivity and leading to up to 50% loss of growth increment (Day et al., 2003) and up to 20% tree mortality (Odera, 1974). Stress can make pine trees more vulnerable to attack (Madoffe and Austara, 1993; Day et al., 2003). Damage to trees is most severe under warm, dry conditions (Mailu et al., 1978a).

Wind can facilitate the spread of Pineus (McClure, 1989a), but transmission between countries and between continents is mainly by human transport of infested planting material of two-needled pines (Barnes et al., 1976). The cryptic habit of these insects make them very difficult to detect at plant quarantine inspection, and after introduction they may be overlooked for years because the attention of forest entomologists is often focused on more easily detected pests. In Zimbabwe, the pest was accidentally introduced in 1962 but was not noticed until 1968 (Barnes et al., 1976).

Once introduced and established, alien P. pini (sensu lato) can spread at an average rate of spread of 15 km per year (McClure, 1989b). In Zimbabwe it spread rapidly and reached all the important areas of afforestation within 12 years of its introduction; nearly all the hard pines were attacked with varying degrees of severity, whereas introduced species of soft pine were not (Barnes et al., 1976).

P. pini (sensu lato) has been recorded outcompeting native insects on pines in Kyrgyzstan (Ponomareva and Gabrid, 1981) and in north-eastern North America (McClure 1984a, 1989b).

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Hemiptera
  •                         Suborder: Sternorrhyncha
  •                             Unknown: Aphidoidea
  •                                 Family: Adelgidae
  •                                     Genus: Pineus
  •                                         Species: Pineus pini

Notes on Taxonomy and Nomenclature

Top of page Damaging populations of asexually-reproducing adelgid aphids belonging to the genus Pineus have been recorded from many temperate and tropical countries around the world in the literature, some under the name Pineus pini, others as P. laevis or P. boerneri, or as one of the other names given in the list of 'non-preferred scientific names'. It should be noted that, in this datasheet, the names in this list are not necessarily taxonomic synonyms. At present there is no completely reliable method for identifying each of the taxa within this complex, at least some of which are taxonomically distinct from each other. P. boerneri is distinct from P. pini, but these species are difficult to differentiate by morphology alone (Blackman and Eastop, 1994). P. havrylenkoi and P. sylvestris are thought to be synonyms of P. boerneri; P. simmondsi Yaseen & Ghani, 1971, recorded from Pinus roxburghii in Pakistan, may also be (Blackman and Eastop, 1994). P. pini (Gmelin) and P. pini (Linnaeus) are synonyms of P. pini (Macquart); Gmelin's names are not regarded as taxonomically valid because he often used trinomials. P. laevis is currently regarded as a synonym of P. pini (Macquart) (Blackman and Eastop, 1994).

Pineus cladogenous Fang & Sun (1985) and Pineus harukawai Inouye (1953), known from Japan, are not regarded as part of the Pineus pini sensu lato complex (Blackman and Eastop, 1994).

Description

Top of page The following is based on Carter (1971). Pineus are such small insects that they are normally prepared as slide mounts so that morphological details can be studied at high magnification. The dorsum bears a regular arrangement of segmental chitinous plates ornamented with wax glands, whose relative sizes and arrangement are of taxonomic importance. In life, the reddish-brown body is usually concealed within a tangle of white wax threads.

Wingless (apterous) adult females are each 0.9-2.3 mm long, the body being ovoid to turbinate; the heavily sclerotized sistens is easier to study than the lightly sclerotized summer form (progrediens); Carter (1971) provides an illustration of the dorsum. Adults are similar to the immature instars, being ovoid with dorsal segmentally arranged sclerotized plates ornamented with wax glands, and short legs and antennae concealed beneath the body. However, the adult females each possess an ovipositor, which is lacking in the immature stages, and the antennae are proportionally very short, with only 1-3 segments that are often partly or completely fused together. There is greater fusion of dorsal plates in adults than in immature Pineus, especially on the head and anterior parts of the thorax.

Winged adult female Pineus resemble other winged aphids in having the body clearly divided into head, thorax and abdomen, and in possessing well-developed legs and antennae; Carter (1971) provides an illustration of the dorsum. The body length is 1.0-1.9 mm. They differ from alate Aphididae in each possessing an ovipositor like that of the apterous female. There are five antennal segments, with each of segments III, IV and V often bearing a single, large sensorium. Compound eyes are present. The shape and venation of the wings is sometimes taxonomically useful.

P. pini (sensu lato) eggs are laid in a nest of white wax fibres secreted by the wax pores of the adult female. Each egg is fairly elongate-ovoid, about 0.2 mm long, and yellow when laid but gradually changes colour to brownish-red as the embryo develops.

First-instar crawlers of Pineus species are very small (each 0.2-0.4 mm long), reddish-brown, ovoid and wingless, with three pairs of legs and small, three-segmented setae; the last antennal segment bears a long apical seta. Eyes are represented only by three oscelli on each side of the head.

Distribution

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P. pini is native to western and Central Europe (Blackman and Eastop, 1994) and P. boerneri may be of eastern Asian origin (Blackman and Eastop, 1994). Records of these species from other parts of the world represent introduced populations.

The geographical records listed for P. pini sensu lato can be tentatively assigned to the following species:

P. pini: Western and Central Europe, Australia, New Zealand.

P. boerneri: China, Taiwan, Hawaii, California, north-eastern USA, Chile and Argentina, eastern and southern Africa, Australia, New Zealand and probably Malaysia; also possibly Pakistan.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

ChinaPresentPresent based on regional distribution.
-JiangsuPresentMcClure, 1984b
-LiaoningPresentMcClure, 1984b
-ZhejiangPresentMcClure, 1984b
Georgia (Republic of)PresentNative Invasive Saradzhishvili, 1985
IsraelPresentIntroduced Invasive Mendel et al., 1994
JordanPresentIntroduced Invasive Mendel et al., 1994
KyrgyzstanPresentIntroduced Invasive Ponomareva and Gabrid, 1981; Gabrid, 1982
LebanonPresentIntroduced Invasive Mendel et al., 1994
MalaysiaPresentPresent based on regional distribution.
-Peninsular MalaysiaPresentIntroducedNHM, 1943
PakistanPresentIntroducedAnon., 2001; NHM, 1970
TaiwanPresentIntroduced Invasive Anon., 2001; McClure, 1984b
TurkeyPresentNHM, 1970; Canakcioglu, 1972

Africa

EthiopiaPresentIntroducedNHM, 1973
KenyaPresentIntroduced1969 Invasive Blackman et al., 1995; Odera, 1974; Karanja and Aloo, 1990
MalawiPresentIntroduced Invasive Blackman et al., 1995; Chilima, 1991; Chilima and Leather, 2001
MoroccoPresentNative Invasive Questienne, 1979
South AfricaPresentIntroduced1978 Invasive Zwolinski, 1989
TanzaniaPresentIntroduced Invasive Madoffe and Austara, 1993
ZambiaPresentIntroduced Invasive Skakachite & Chenduauka, 1991
ZimbabwePresentIntroduced1962 Invasive Blackman et al., 1995; Anon, 1971; Barnes et al., 1976

North America

USAPresentPresent based on regional distribution.
-ConnecticutPresentIntroduced Invasive McClure, 1982
-HawaiiPresentIntroducedpre-1972 Invasive Nakao et al., 1981; Anon, 1978
-MainePresentIntroduced Invasive McClure, 1982
-MassachusettsPresentIntroduced Invasive McClure, 1982
-New HampshirePresentIntroduced Invasive McClure, 1982
-Rhode IslandPresentIntroduced Invasive McClure, 1982
-UtahPresentIntroducedNHM, 1924
-VermontPresentIntroduced Invasive McClure, 1982

South America

ArgentinaPresentIntroduced Invasive Fiorentino & Diodato de Medina, 1991
ChilePresentIntroduced Invasive Anon., 2001

Europe

Czechoslovakia (former)PresentNative Not invasive Hochmut, 1969
FinlandPresentNative Not invasive Heliovaara and Vaisanen, 1989
FrancePresentNative Invasive Carter, 1971; Gaumont, 1978
GermanyPresentNative Not invasive Steffan, 1970b
IrelandWidespreadNative Not invasive NHM, 1984
ItalyWidespreadNative Invasive Covassi & Binnazzi, 1981; Toccafondi et al., 1991
LithuaniaPresentNative Not invasive Yuronis & Ionaitis, 1984
NetherlandsWidespreadNative Not invasive Ravensberg, 1954
PolandPresentJaskiewicz and Sawinska, 2005; Wojtan et al., 2006
PolandPresentJaskiewicz and Sawinska, 2005; Wojtan et al., 2006
SpainPresentNative Not invasive NHM, 1990
SwedenPresentNative Invasive NHM, 1990; Zambonelli, 2002
UKWidespreadNative Not invasive Carter, 1971
-England and WalesWidespreadNative Not invasive Carter and Barson, 1973
-ScotlandWidespreadNative Not invasive Murray & Parry, 1969

Oceania

AustraliaPresentIntroduced Invasive Blackman et al., 1995; Simpson and Ades, 1990a
-New South WalesPresentIntroduced Invasive Simpson and Ades, 1990b
-South AustraliaPresentIntroduced Invasive NHM, 1963
-TasmaniaPresentIntroduced Invasive Anon., 2001
-VictoriaPresentIntroduced Invasive Minko, 1959
-Western AustraliaPresentIntroduced Invasive NHM, 1965
New ZealandWidespreadIntroducedbefore 1884 Invasive Blackman et al., 1995; McClure, 1984b; Zondag, 1977

History of Introduction and Spread

Top of page Pineus boerneri (as P. pini) was first recorded from Africa (Zimbabwe) in 1962 (Barnes et al., 1976), and from South Africa in 1978 (Zwolinski, 1989). It was probably introduced to Africa accidentally on pine scions from Australia (Barnes et al., 1976).

Risk of Introduction

Top of page P. pini (sensu lato) are very small, cryptic insects that are easily overlooked. They have already been accidentally introduced to a number of countries on infested planting material of two-needled pines, and have subsequently become pests. Cuttings and seedlings of two-needled pines should be subject to very close examination before being exported/imported to a country where P. pini (sensu lato) does not occur.

Habitat

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Pineus boerneri has been recorded preferentially attacking the 3-year-old growth of the lower canopy of Pinus resinosa in the north-eastern USA, feeding beneath bark flakes or at the base of the needle sheaths (McClure, 1982).

Habitat List

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CategoryHabitatPresenceStatus
Littoral
Coastal areas Present, no further details Harmful (pest or invasive)
Terrestrial-managed
Cultivated / agricultural land Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Harmful (pest or invasive)
Managed forests, plantations and orchards Present, no further details Harmful (pest or invasive)
Managed grasslands (grazing systems) Present, no further details Harmful (pest or invasive)
Protected agriculture (e.g. glasshouse production) Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Harmful (pest or invasive)
Urban / peri-urban areas Present, no further details Harmful (pest or invasive)
Terrestrial-natural
semi-natural/Cold lands / tundra Present, no further details Harmful (pest or invasive)
semi-natural/Natural forests Present, no further details Harmful (pest or invasive)
semi-natural/Natural grasslands Present, no further details Harmful (pest or invasive)
semi-natural/Riverbanks Present, no further details Harmful (pest or invasive)
semi-natural/Wetlands Present, no further details Harmful (pest or invasive)

Hosts/Species Affected

Top of page All the recorded host plants of P. pini sensu lato are members of the subgenus Diploxylon (two-needled pines), not subgenus Haploxylon (pines with needles occurring in groups of more than two) (Anon., 1971). In former Czechoslovakia, with only one exception, infestations of Pineus found on members of Hapoxylon were always Pineus cembrae or P. strobi, not P. pini (Hochmut, 1969).

Pineus boerneri was recorded attacking 39 species of Pinus in Kenya (Odera, 1974), including all the species listed in this datasheet. Host plants that have evolved together with an aphid species have usually evolved defences against aphid infestation that result in slower aphid reproduction on that host.

McClure (1990) suggested that the native host of P. boerneri was Pinus thunbergii; the aphid had significantly greater survival and fecundity on Pinus resinosa (native to America) than on P. thunbergii (native to China).

Growth Stages

Top of page Flowering stage, Fruiting stage, Seedling stage, Vegetative growing stage

Symptoms

Top of page Injury to Pinus resinosa caused by Pineus boerneri in the north-eastern USA included discoloration of foliage, distortion, resinosis, death of branches and death of trees (McClure, 1982). In Africa, other symptoms observed include reduction in the length of infested needles (Day et al., 2003). In Kenya, Mailu et al. (1982b) found that a highly significant negative relationship between needle length and aphid numbers suggested that measurements of needle lengths alone might be adequate to estimate the intensity of infestation by P. boerneri. Damage to trees is most severe under warm, dry conditions (Mailu et al., 1978a).

List of Symptoms/Signs

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SignLife StagesType
Fruit / abnormal shape
Fruit / external feeding
Fruit / gummosis
Fruit / lesions: on pods
Growing point / dieback
Growing point / dwarfing; stunting
Growing point / external feeding
Inflorescence / external feeding
Leaves / abnormal leaf fall
Leaves / yellowed or dead
Stems / dead heart
Stems / dieback
Stems / distortion
Stems / external feeding
Stems / gummosis or resinosis
Stems / stunting or rosetting
Whole plant / early senescence
Whole plant / external feeding
Whole plant / plant dead; dieback

Biology and Ecology

Top of page Genetics

Steffan (1970a) discussed the evolution of asexual lines in species of adelgids including P. pini, and remarked that the asexual strain often had a different number of chromosomes to the sexual strain. P. pini may have arisen as an asexual strain of P. orientalis (Marchal, 1911; Carter, 1969, 1971).

Blackman et al. (1995) found that different populations of Pineus ?boerneri varied in their chromosome number, as might be expected of an asexual species. Specimens with 2n=16 were recorded from Hawaii and California, USA; samples with 2n=17 were recorded from California, Africa, Australia and New Zealand. Some samples from Australia and New Zealand had 2n=19 and 2n=21. Blackman et al. (1995) postulated that the 17-chromosome form of P. boerneri could have arisen from the 16-chromosome form through a single dissociation of one of the longest pair of chromosomes. Such dissociations are common in permanently parthenogenetic populations of aphids (Blackman, 1980).

Physiology and Phenology

In North America, Pineus boerneri is parthenogenetic, trivoltine and passes through six stages of development (McClure, 1989b); however, the generation overlap was so pronounced that all the developmental stages were present at almost all times of the year.

The following is based on Carter (1971). The life cycle of P. pini (sensu lato) differs from that of most adelgids by its simplicity. There may be a partial migration of alatae (sexuparae) to Picea (the ancestral primary host) each year, but males are never produced and sexual reproduction and gall formation on Picea does not occur.

In the absence of sexual reproduction, gall-forming females (gallicolae) do not occur, and asexual reproduction by wingless and winged (alate) females continues throughout the year. There are at least three overlapping generations annually. Clutches of eggs are laid (one egg at a time) over a period of several weeks, resulting in considerable differences between the hatching times of the first and last eggs laid. There are five immature instars before an adult is produced. Overwintering is as wingless adult females (hiemosistentes) that are heavily sclerotized, and as second- and third-instar larvae. In spring, the larvae develop into apterous progredientes (the summer form of the adult female, which is lightly sclerotized) and alate (winged) females.

Reproductive Biology

Reproduction is asexual all year, by the parthenogenetic production of eggs.

Environmental Requirements

Stress can make pine trees more vulnerable to attack by P. boerneri (Madoffe and Austara, 1993; Day et al., 2003). Air pollution was found to make pines more susceptible to attack by P. pini in Finland, possibly due to a resultant reduction in predatory mite populations (Heliovaara and Vaisanen, 1989).

In the north-eastern USA, survival of P. boerneri was higher on branches than on needles during winter, but was higher on needles than on branches in spring and summer (McClure, 1984a). Wind facilitated the spread of P. boerneri in north-eastern North America, and extremes of summer and winter temperatures determined the ultimate limits of its latitudinal distribution; heavy rain reduced its abundance (McClure, 1989a).

In Malawi, the biological performance and pest status of P. boerneri is influenced by external factors especially the within-tree and seasonal fluctuations in the level of nitrogen, total rainfall and canopy structure (Chilima and Leather, 2001). Prolonged, heavy rainfall reduced population levels significantly, mainly through eggs and crawlers being washed off the tree, whereas numbers increased in hot, dry weather; other causes of mortality were found to be excessive heat and crawler dispersion (Mailu et al., 1980).

In the UK, Carter and Barson (1973) found that the threshold temperature for flight by winged Pineus was 16°C, and at least 64% of the catch was taken in the afternoon; fluctuations in the mean date of flight each year were probably related to the phonological condition of the food plant.

Associations

In Scotland, UK, P. pini is sometimes associated with a covering of the fungus Cucurbitaria pithyophila [Curreya pityophila] on the lower branches of Pinus sylvestris, occasionally killing the bark (Murray and Parry, 1969).

In north-eastern America, where the introduced P. boerneri and the native P. coloradensis occur together on Pinus resinosa, P. boerneri was found to maintain numerical dominance over P. coloradensis (McClure, 1984a) and displaced P. coloradensis in the majority of stands over a 5-year period (McClure, 1989b). However, where P. boerneri and Matsucoccus resinosae (an introduced scale insect) occurred together, the presence of M. resinosae on the branches resulted in significantly reduced numbers of P. boerneri on both branches and needles, whereas the presence of P. boerneri had no significant effect on numbers of M. resinosae. In one-third of the affected stands, P. boerneri was excluded by the scale insect within 3 years (McClure, 1990).

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Cheilomenes aurora Predator Adults/Eggs/Larvae/Nymphs/Pupae
Diomus pumilio Predator Adults/Eggs/Larvae/Nymphs/Pupae
Exochomus flavipes Predator Adults/Eggs/Larvae/Nymphs/Pupae
Exochomus quadripustulatus Predator Adults/Eggs/Larvae/Nymphs/Pupae
Leucopis argenticollis Predator Adults/Nymphs Kenya Pinus
Leucopis atrifacies Predator Adults/Eggs/Larvae/Nymphs/Pupae
Leucopis manii Predator Adults/Eggs/Larvae/Nymphs/Pupae
Leucopis nigraluna Predator Adults/Eggs/Larvae/Nymphs/Pupae
Leucopis obscura Predator Adults/Nymphs Australia; Hawaii; USA; Hawaii Pinopsida; Pinus; Pinus pinaster
Leucopis praecox Predator Adults/Nymphs Australia Pinus
Leucopis tapiae Predator Adults/Eggs/Larvae/Nymphs/Pupae
Rhyzobius chrysomeloides Predator Adults/Nymphs
Scymnus nigrinus Predator Adults/Eggs/Larvae/Nymphs/Pupae
Scymnus suturalis Predator Adults/Eggs/Larvae/Nymphs/Pupae
Tetraphleps raoi Predator Adults/Eggs/Larvae/Nymphs/Pupae
Wesmaelius concinnus Predator Australia Pinus

Notes on Natural Enemies

Top of page Introduced populations of P. boerneri have been successfully controlled by the introduction of predatory species of Leucopis. The most effective control agent recorded is L. tapiae in Hawaii, where Leucopis tapiae (as L. obscura, on Maui, Molokai and Kauai islands) and L. nigraluna (on Hawaii island) were found to maintain P. boerneri (as P. pini) populations below economically significant levels (Nakao et al., 1978; Culliney et al., 1988).

In Kenya, predatory Exochomus spp. were found to remove 12% of the Pineus boerneri population (Mailu et al., 1980). In Zimbabwe, coccinellid beetles were responsible for a marked decline in the infestation (Anon., 1971).

Biological control attempts have also been made in Australia (Waterhouse and Sands, 2001). Only Exochomus quadripustulatus, imported from the UK, became established there. The native predator Diomus pumilo is considered an important predator.

Means of Movement and Dispersal

Top of page Natural Dispersal

Dispersal of P. pini (sensu lato) is mainly achieved by the tiny first-instar larvae, which walk actively and seek new feeding sites. They are capable of walking a few metres only, but can be picked up and carried over longer distances by the wind. Wind facilitated the spread of P. boerneri in north-eastern North America (McClure, 1989a). Transmission between countries and between continents is by human transport of infested planting material (Barnes et al., 1976).

Crawlers of P. boerneri were found to be positively phototactic in some circumstances, but were negatively phototactic and positively thigmotactic when seeking to settle and feed, therefore colonizing tight crevices; branch undersides were settled much more often than better-lit branch upper surfaces (Mailu et al., 1982a).

Occasionally, in crowded conditions, P. pini (sensu lato) produce winged females that fly to seek new host trees. In the UK, winged Pineus were recorded mainly in late May and June each year; the threshold temperature for flight by winged Pineus was 16°C, and at least 64% of the catch was taken in the afternoon; fluctuations in the mean date of flight each year was probably related to the phenological condition of the food plant (Carter and Barson, 1973).

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Clothing, footwear and possessionsAir Yes
Plants or parts of plants Yes

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Bark adults; eggs; nymphs Yes Pest or symptoms usually invisible
Flowers/Inflorescences/Cones/Calyx adults; eggs; nymphs Yes Pest or symptoms usually invisible
Leaves adults; eggs; nymphs Yes Pest or symptoms usually invisible
Seedlings/Micropropagated plants adults; eggs; nymphs Yes Pest or symptoms usually invisible
Stems (above ground)/Shoots/Trunks/Branches adults; eggs; nymphs Yes Pest or symptoms usually invisible

Impact Summary

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CategoryImpact
Animal/plant collections Negative
Animal/plant products Negative
Biodiversity (generally) None
Crop production None
Environment (generally) None
Fisheries / aquaculture None
Forestry production Negative
Human health None
Livestock production None
Native fauna None
Native flora None
Rare/protected species None
Tourism None
Trade/international relations Negative
Transport/travel None

Economic Impact

Top of page Pineus boerneri

In sub-Saharan Africa pine trees are widely grown, both commercially and by small-scale farmers; they are an important source of building material and fuelwood. Infestation by Pineus boerneri causes premature needle shedding and reduction in the length of infested needles, reducing productivity and leading to up to 50% loss of growth increment (Day et al., 2003) and up to 20% tree mortality (Odera, 1974). In South Africa, Zwolinski (1990) recorded loss of increment at breast height, and overall height, in Pinus pinaster trees at 63 and 65%, respectively. Madoffe and Austara (1990) recorded P. boerneri (as P. pini) causing over 20% loss of dry matter in seedlings of Pinus patula in Tanzania. Similarly, infestation of developing cones of P. pinaster in South Africa reduced overall seed yield by 23%, not counting those cones that failed to reach maturity (Zwolinski et al., 1989). Murphy (1996) estimated that P. boerneri and another introduced pine aphid (Eulachnus rileyi) together were causing a growth increment loss of US $1.5 million annually. Damage to trees is most severe under warm, dry conditions (Mailu et al., 1978a). Survey procedures and criteria for assessment of damage by P. boerneri were given by Mailu et al. (1980).

P. boerneri was recorded injuring and killing trees at all of the infested sites studied in Connecticut and Massachusetts (north-eastern USA) (McClure, 1989b). It is listed (as P. havrylenkoi) as one of the main pests of pine trees in Argentina (Fiorentino and Diodato de Medina, 1991).

Mendel et al. (1994) recorded P. pini from Jordan for the first time, causing severe damage to young stands of Aleppo and stone pines. It is not clear whether this record referred to P. boerneri or P. pini.

In Australia (Victoria), Minko (1962) mentioned P. pini causing damage to Pinus radiata in nurseries; this may actually have referred to P. boerneri.

Pineus pini (sensu lato)

In response to problems with adelgids (including P. pini) on exotic conifers grown in the numerous tree nurseries east of Oldenburg, Germany, Steffan (1970b) recommended that these tree species should not be planted in shelter belts, parks or forests within the growing region.

In Sweden, infestation by P. pini of pine tree hosts in glasshouse cultures of chanterelle mushrooms limited long-term cultivation of this crop (Zambonelli, 2002).

Covassi and Binazzi (1981) mentioned that, in Italy, P. pini is injurious to young pine trees in nurseries, new plantations, parks and gardens in several parts of Italy.

In the Republic of Georgia, a study of damage caused by P. pini (sensu lato) found that infestation could result in a 32% reduction in annual height increment, and various other signs of damage, and concluded that the adelgid was a serious threat to pine trees in that zone (Saradzhishvili, 1985).

In Kyrgyzstan, P. pini (sensu lato) (as P. pini) outcompeted the native Oligonychus piceae in the same ecological niche; local natural enemies were ineffective against it, suggesting it was an introduction, and Pineus numbers were only reduced after Leucopis spp. were released (Ponomareva and Gabrid, 1981).

Canakcioglu (1972) listed P. pini as one of the most important forest pests in Turkey.

Diagnosis

Top of page Pineus are such small insects that they are normally prepared as slide mounts so that morphological detail can be studied at high magnification. Carter (1971) provides a method for the preparation of slide mounts and keys to identify the genus Pineus and to more-or-less separate the four species that occur in the UK; the key covers P. pini and P. orientalis, but not P. boerneri.

Detection and Inspection

Top of page Strong light and magnification are required, and the bark and needle sheaths need to be destructively examined. P. pini (sensu lato) occur as brownish-red ovoids in nests of white wax fibres beneath bark flakes and bud scales, and concealed within the needle sheaths. Clusters of yellow or brownish-red eggs may also be present in the wax nests; the eggs are not attached to the host plant.

Similarities to Other Species/Conditions

Top of page P. pini is morphologically indistinguishable from P. orientalis, a species that reproduces sexually and alternates between Picea (the primary host) and Pinus sylvestris. At present, P. boerneri is not reliably morphologically distinguishable from P. pini and P. orientalis because morphological variation in these species has not been sufficiently well analysed and no identification key is available.

Prevention and Control

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Phytosanitary Measures

Restricted movement and thorough inspection of planting material of Haploxylon pines is the most effective way to prevent P. pini (sensu lato) entering a country.

Cultural Control and Sanitary Methods

Stress can make pine trees more vulnerable to attack by P. boerneri (Madoffe and Austara, 1993); avoidance of marginal growing conditions through more attention to the selection of suitable planting sites can avoid problems with Pineus infestation (Day et al., 2003).

Possible management of P. boerneri in Malawi, through the regulation of nitrogen nutrition and canopy structure, was discussed by Chilima and Leather (2001).

In response to problems with adelgids (including P. pini) on exotic conifers grown in the numerous tree nurseries east of Oldenburg, Germany, Steffan (1970b) recommended that these tree species should not be planted in shelter belts, parks or forests within the growing region.

Host-Plant Resistance

Different species of pine tree, and different provenances of any one pine species, vary in their susceptibility to attack by P. pini (sensu lato) (Simpson and Ades, 1990b; Falkenhagen, 1991a, b). The level of susceptibility of a particular pine species may vary also between one locality and another, reflecting different levels of environmental stress between sites. Simpson and Ades (1990b) called for more research on the planting of multi-clonal mixtures and the pattern in which they are planted, to minimize losses.

Replanting with species or provenances of pines less susceptible to attack is an option for the control of P. pini (sensu lato), but is a long-term and possibly expensive solution that may incur hidden costs in reduced yield or quality, e.g. Pinus radiata has been replaced with the less susceptible P. patula in East Africa, but the latter species is inferior in fibre quality (Day et al., 2003).

Odera (1974) mentioned that Pinus ayacahuite and P. strobes var. chiapensis are resistant to attack by Pineus boerneri (as Pineus pini) in Kenya.

Biological Control

Where members of P. pini (sensu lato) have been accidentally introduced, they are good candidates for classical biological control (Mills, 1990). Pineus boerneri has been controlled successfully by introduced natural enemies in Hawaii, New Zealand and Chile.

Introduced populations of P. boerneri have been successfully controlled by the introduction of predatory species of Leucopis. The most effective control agent recorded is L. tapiae in Hawaii, where Leucopis tapiae (as L. obscura, on Maui, Molokai and Kauai islands) and L. nigraluna (on Hawaii island) were found to maintain P. boerneri (as P. pini) populations below economically significant levels (Nakao et al., 1978; Culliney et al., 1988).

In 1991 L. tapiae was also found to have accidentally entered Malawi, but has not provided such effective control there as in Hawaii (Greathead, 1995; Day et al., 2003). An account of various (mostly unsuccessful) introductions of alien predator species to East Africa against P. boerneri is given by Day et al. (2003).

In Kyrgyzstan, P. pini (sensu lato) (as P. pini) outcompeted the native Oligonychus piceae in the same ecological niche; local natural enemies were ineffective against it, suggesting it was an introduction, and Pineus numbers were only reduced after Leucopis spp. were released (Ponomareva and Gabrid, 1981).

Introduction of the predatory bug Tetraphleps raoi to Kenya in 1975 resulted in some reduction in P. boerneri populations, but not sufficient to prevent reduction of tree growth and occasional tree mortality (Karanja and Aloo, 1990).

References

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