Dendrolimus pini

 
IDENTITY
Name:   Dendrolimus pini
Pest Authorities:  (Linneaus)
Taxonomic Position:  Insecta: Lepidoptera: Lasiocampidae
Sub-specific Taxon:  
Pest Type:   Insect
Common Name(s):
   Bombyx du pin (French)
   Fyrrespinner (Norwegian)
   Grosse Kiefernglucke (German)
   Hoja muerta del pino (Spanish)
   Kiefernspinner (German)
   Lasiocampa del pino (Spanish)
   Mäntykehrääjä (Finnish)
   Pine lappet (English)
   Pine moth (English)
   Tallspinnare (Swedish)
Synonym(s):
   Phalaena pini Linneaus
 
RISK RATING SUMMARY
Numerical Score:  6
Relative Risk Rating:  High Risk
Uncertainty:   Very Uncertain
Uncertainty in this assessment results from: The ability of Dendrolimus pini to adapt to North American tree species is not known.

RISK RATING DETAILS
Establishment Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Suitable climatic conditions and suitable host material coincide with ports of entry or major destinations.
  • Organism has demonstrated ability to utilize new hosts
  • Organism has active, directed host searching capability or is vectored by an organism with directed, host searching capability.
  • Organism has high inoculum potential or high likelihood of reproducing after entry.
Justification: Suitable climatic conditions and, provided that Dendrolimus pini can adapt to North American conifers, potential hosts occur at many ports of entry in Canada and the U.S. This insect is expected to have a high likelihood of reproducing after entry.

Spread Potential Is Moderate Risk
The relevant criteria chosen for this organism are:  
  • Organism is capable of dispersing more than several km per year through its own movement or by abiotic factors (such as wind, water or vectors).
  • Organism has a high reproductive potential
  • Potential hosts have contiguous distribution.
  • Organism has broad host range.
Justification: Females do not fly until some of their egg compliment is deposited. Therefore adult flight may not be an important means of dispersal. Early instar larvae, however, are subject to dispersal by air currents. Late instar larvae are able to migrate short distances to neighboring stands of trees. Since eggs and pupae could occur in the bark crevasses of host trees, these stages are potentially subject to human assisted dispersal via international trade in unprocessed logs. This insect has a high reproductive potential and potential hosts (conifers) have contiguous distributions in many parts of North America.

Economic Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism attacks hosts or products with significant commercial value (such as for timber, pulp, or wood products.
  • Organism directly causes tree mortality or predisposes host to mortality by other organisms.
  • Damage by organism causes a decrease in value of the host affected, for instance, by lowering its market price, increasing cost of production, maintenance, or mitigation, or reducing value of property where it is located.
  • Organism may cause loss of markets (domestic or foreign) due to presence and quarantine significant status.
Justification: Dendrolimus pini is a major defoliator of pines and other conifers over much of its natural range. Outbreaks can occur over large areas and last for 7-8 years. Defoliation can cause growth loss, dieback and tree mortality of conifers, many of which are of vital economic importance. Moreover defoliated trees are susceptible to attacks by bark beetles and wood boring insects.

Environmental Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism is expected to cause significant direct environmental effects, such as extensive ecological disruption or large scale reduction of biodiversity.
  • Introduction of the organism would likely result in control/eradication programs that may have potential adverse environmental affects.
Justification: Should this insect be capable of developing into outbreaks in North America, it could cause major ecological disruptions including extensive tree mortality, changes in species composition and increased fuel levels resulting in wildfires of increased severity. Moreover, eradication or control efforts with chemical or biological insecticides could cause undesireble side effects to non-target organisms.

 
HOSTS
Dendrolimus pini feeds on the foliage of a number of conifers. The favorite host is Scotch pine, Pinus slyvestris. Other host trees include Swiss stone pine, Pinus cembra; Sitka spruce, Picea sitchensis, Siberian larch, Larix siberica; silver fir, Abies alba; Douglas-fir, Pseudotsuga menzeisii and common juniper, Juniperus communis (Bistimmungensüben an Insekten 2002, FUNET n.d.)

 
GEOGRAPHICAL DISTRIBUTION
Africa:
      Dendrolimus pini is reported from North Africa (FUNET n.d.).
Asia:
     This insect is found in Asian Russia, where it generally follows the natural range of its favorite host, Pinus sylvestris, and occurs in the southern regions of Western and Middle Siberia to the Lake Baikal Region (Isaev and Shvidenko 2002). It also occurs in pine regions of several Near Eastern countries that border the Mediterranean Sea (FUNET n.d.).
Europe:
     This insect is widely distributed in Europe from the British Isles, Portugal and Spain east to the Ural Mountains of Russia (FUNET n.d.). It apparently is rare in the British Isles with only four collections in recent years (Kimber 1999).
 
BIOLOGY
The genus Dendrolimus consists of about 30 species of conifer feeding Lepidoptera, several of which periodically reach epidemic levels and can cause severe defoliation over large areas. Two examples are the pine caterpillar, D. punctatus in China and Southeast Asia and the Siberian silk moth, D. sibirica in eastern Russia, Mongolia and northern China. D. pini is the only species not confined to Asia. This genus is not represented in North America.

Moths emerge in midsummer and live for 9-10 days. Adult flight occurs from early July to mid August. Females do not fly before they mate but remain at rest on the lower boles of pines. Mating begins at night and continues for several hours. Females can fly after they have deposited some of their eggs. Females deposit between 150-250 eggs in groups of 20-100 on twigs, needles and the bark of host trees.

Eggs hatch within 16-25 days after they are deposited. Larval hatching begins in early September. Hatching larvae immediately begin to feed on pine needles. At first they feed only on the needle margins and later they consume the entire needle. Larvae molt 2-3 times before winter. The period of autumn feeding continues until the first frost (November). The larvae then move down the tree boles to overwintering sites between the litter and mineral soil. About 85% of the larvae overwinter in the immediate vicinity of tree boles.

Between March and April, when the soil temperature reaches 3 degrees C, the larvae begin to return to the tree crowns. Spring feeding consumes 3-5 times the volume of foliage consumed during the previous autumn. Larvae may also feed on the bark of young pine shoots. Larvae prefer to feed on one-year old needles. Mature larvae can crawl for distances of several hundred meters to neighboring pine stands.

Pupation begins in May and June and lasts for 4-5 weeks. Pupae are formed inside loose, partially transparent cocoons, which can be found in tree crowns, bark crevasses and understory vegetation (Sierpinska 1998).

Natural enemies include several entomogenous bacteria and fungi, parasitoids and predators. Three species of egg parasitoids, 21 larval parasitoids and one pupal parasitoid are known from Poland. In addition, 10 species of predaceous insects have been reported (Sierpinska 1998).

 
PEST SIGNIFICANCE
Economic Impact:    Dendrolimus pini is capable of developing into outbreaks that cover thousands of hectares of pine forests, resulting in heavy defoliation. Defoliation can result in growth loss and tree mortality. Moreover, trees weakened by defoliation have increased susceptibility to attack by bark beetles and woodborers. In Poland, periodic outbreaks have been reported since 1791-92. Between 1946 and 1995, 233,000 ha of Polish forests required direct control to reduce damage. There are indications in Poland that the frequency of outbreaks has increased (Sierpinska 1998). In northern Germany, outbreaks between 1782-1792 and 1869-1872 damaged over 170,000 ha and caused extensive tree mortality (Bistimmungensüben an Insekten 2002). More recently, an outbreak in northeastern Germany occurred between 1993 and 1996 and peaked in 1995 with 83,700 ha defoliated. During this outbreak, trees with a needle loss of 80% or more suffered dieback. A buprestid, Phaenops cyanae, was associated with the dieback (Moeller et al. 1998). In eastern Russia, outbreaks reportedly occur in pine forests of medium and older age classes, are associated with periods of warm, dry weather and last for 7-8 years (Isaev and Shivdenko 2002). In Poland, on the other hand, young stands appear to be more susceptible to outbreaks (Sierpinska 1998).

Environmental Impact:   Extensive defoliation of conifer forests can result in widespread mortality of host trees, increased fuel levels, which can increase the intensity of wildfire, and changes in tree species composition. In addition, use of chemical and biological insecticides during eradication/control programs could result in undesireable side effects to non-target organisms.

Control:    Direct control involves ground and/or aerial applications of either chemical or biological insecticides. Extensive conifer monocultures are especially susceptible to outbreaks (Sierpinska 1998). Therefore increasing the species diversity in forest plantation programs should reduce the extent, intensity and frequency of outbreaks.

 
DETECTION AND IDENTIFICATION
Symptoms:    Symptoms include defoliation of pines and other conifers and presence of insect life stages.

Morphology:    Eggs are about 2 mm long, blue green in color when first deposited, later turning to gray.

Mature larvae range in size from 50-80 mm and are covered with soft gray or brownish hairs. Thoracic segments 2 and 3 have thick bands of hairs of alternating steel blue and black. The dorsal surface of each abdominal segment contains a black mark flanked by irregular white lines.

Pupae range from 30-35 mm in length, are brown to black in color with both ends rounded. They are enclosed in a yellow-brown spindle shaped cocoon, which also contains remnants of the steel blue thoracic hairs.

Adults are covered with thick scales on both the wings and body. Males have a wingspan of 50-70 mm and females a wingspan of 70-90 mm. The forewings are gray-brown to brown in color. They contain a reddish brown lateral band, edged on both sides with an irregular dark-brown to black stripe. The hind wings are red brown to gray brown in color. Body color is brown. Coloring of the males is typically darker than the females (Bistimmungensüben an Insekten 2002).

Testing Methods for Identification:    Examination of adults by a taxonomist with expertise in the family Lasiocampidae is required for positive identification.

 
MEANS OF MOVEMENT AND DISPERSAL
Since females do not fly until they have deposited some of their eggs, adult flight may not be an important means of dispersal. First instar larvae are subject to dispersal by air currents and mature larvae are capable of crawling several hundred meters to undamaged stands of host trees. Although Dendrolimus pini does not have a demonstrated capacity for human assisted dispersal, eggs and pupae hidden in the bark crevasses of unprocessed pine logs could be moved via international trade.

 
BIBLIOGRAPHY
Bistimmungensüben an Insekten 2002. Dendrolimus pini L. Kiefernspinner, Grosse Kiefernglucke (Lepidoptera, Lasiocampidae). On line: http://www.faunistik.net/detinvert/lepidoptera/ lasiocampidae/dendrolimus_pini (In German).
FUNET (Finnish University and Research Information Network) n.d.. Dendolimus Germar, 1821. On line: http://www.funet.fi/pub/sci/bio/life/ insecta/lepidoptera/ditrysia/bombycoidea/lasiocampidae/
Issaev, A.; Shividenko, A. 2002. Forest-Description. In: Land Resources of Russia. IIASA and RAS. On line: http://www.iiasa.as.at/Research/FOR/russia_cd/for_des.htm
Kimber, I. 1999. 1639 Pine-tree lappet, Dendrolimus pini (Linneaus, 1758), UK Moths, On line: http://cgi.ukmoths.force9.co.uk/show.php?bf=1639
Moeller, K.; Haeussler, D.; Majunke, C; Apel,K.H.; Loeffler, S. Heydeck, P.; Wenk, M. 1998. About the current outbreak of the European pine moth (Dendrolimus pini L.) in the northeast German lowlands. In: Proceedings: Population Dynamics, Impacts, and Integrated Pest Management of Forest Defoliating Insects. USDA Forest Service General Technical Report NE –247, pp. 353.
Sierpinska, A. 1998. Towards integrated pest management of Denrolimus pini. In: Proceedings: Population Dynamics, Impacts, and Integrated Pest Management of Forest Defoliating Insects. USDA Forest Service General Technical Report NE –247, pp. 129-142.
 
AUTHOR(s)
Name(s):
William M. Ciesla
 
 
Name and Address of the First Author:
William M. Ciesla
Forest Health Management International
2248 Shawnee Court
Fort Collins, CO
USA 80525
 
CREATION DATE:        06/27/03
MODIFICATION DATE:        05/06/04

    
Selected images from Forestry Images (www.forestryimages.org)
View all images

1260053
1260053

Adult(s)
Resting male. Sachsen, Germany
Photo by Hannes Lemme,
Sächsische Landesanstalt für Forsten

1258047
1258047

Cocoon(s)
Photo by Stanislaw Kinelski,



1258049
1258049

Larva(e)
Photo by Stanislaw Kinelski,


1220020
1220020

Larva(e)
a few days before pupation
Photo by Hannes Lemme,
Sächsische Landesanstalt für Forsten


1258048
1258048

Egg(s)
Photo by Stanislaw Kinelski,


1220023
1220023

Egg(s)
eggs and hatched larvae
Photo by Hannes Lemme,
Sächsische Landesanstalt für Forsten