Tomicus piniperda (L.)

(Synonym: Blastophaga piniperda L.)

Taxonomic position: Insecta, Holometabola, Coleoptera, Curculionidae.

Common name: Common pine shoot beetle.

Geographic distribution: Europe, Africa, northern Asia and North America (since 1992).

Host plants: The primary hosts are several pine (Pinus) species, more rarely spruce (Picea) and larch (Larix).

Morphology: The body of the adults is 3.5–5.0 mm in length, cylindrical, dark brown to black, with a rounded head.

Life history: Tomicus piniperda overwinters as adults, sheltering in hollowed twigs or in galleries of host trees, and laying ca 70 eggs/female. The larvae develop there and in early spring the young beetles invade one (or more) young branches for maturation feeding. Such feeding damages the branches and might even kill them. Later the beetles seek weakened, stressed or dead pine trees (or their stumps) in which they excavate breeding galleries, often at the base of the trunk, and lay some eggs. More than one tree site (or host) is invaded, in which more eggs are laid; the emergence of the beetle’s progeny thus lasts for several weeks. Development to adulthood requires about 3-4 months, the threshold of development is at around 10ºC. There is only a single annual generation, but due to their prolonged oviposition, beetles of various ages co-occur. Adults may fly for some distances to find suitable hosts, being attracted by volatiles (like alpha-pinene) emitted, and the resin produced, by damaged trees or their stumps. The beetles are very suseptible to high temperatures (>40ºC). During rainy seasons the eggs, and the very young larvae within healthy trees, may be killed by becoming immersed in the resin.

Economic importance: Tomicus piniperda is a serious pest of pines in Europe and the United States. It attacks the trunks and growing shoots of pines, especially Scotch pine (Pinus sylvestris L.), occasionally also spruce (Abies sp.) and larch (Larix sp.). Weakened, stressed, or dying trees are especially vulnerable, but healthy trees may also be attacked and sometimes killed, the damage being compounded by subsequent attacks of secondary pests. In some cases pest infestations do not kill the trees, but affect their growth and stem straightness, reducing the value of the timber. The worst damage is due to feeding on the growing points, resulting in growth malformations and reductions of crop value, especially in Christmas tree plantations. In China the pest killed many apparently healthy Pinus yunnanensis L. trees, causing great economic losses. Outbreaks of this pest may be associated with epidemics caused by shoot-disease fungi.

Management

Monitoring: Circular exit and entrance holes next to the broken ends of small branches indicate the entrance or exit holes of the beetles. Drooping shoots whose needles turn yellow or red in early summer likewise suggest the pest’s presence. In pine stands funnel traps baited with alpha-pinene can be used to follow beetle phenology.

Horticultural methods: Precise timing of cutting operations and the debarking of cut timber.

Host plant resistance and effects: Beetles infesting vigorous P. sylvestris trees may become embalmed within resinous lesions, whereas less vigorous trees cannot defend themselves. Several parasitoids attack the pest in North America, and in one case more were recorded on Pinus banksiana Lamb trees than on other pines.

Biological control: Various Pteromalidae (including, in Israel, Metacolus unifasciatus) and Braconidae parasitize the pest. In addition, some beetles, including Thanasimus formicarius L., eat several pine shoot beetles daily. These predators disperse along with their prey (T. piniperda and other bark beetles), being attracted to volatiles from the damaged and fallen trees, wait there and feed on the arriving pests. In France the predatory beetles arrive in spring; their effect on pest numbers is later strengthened by the parasites and other predators. This sequential arrival of the natural enemies suggests that the interactions among the natural enemy guild are complementary.

References

Haack, R.A. and. Poland, T.M. 2001. Evolving management strategies for a recently discovered exotic forest pest: the pine shoot beetle, Tomicus piniperda (Coleoptera). Biological Invasions 3: 307–322.

Halperin. J. 1978. Blastophagus piniperda in Israel. La – Yaaran 28: 20-28, 45 (in Hebrew with an English Abstract).

Hanson S. 1940. The prevention of outbreaks of the pine beetles under war-time conditions. Bulletin of Entomological Research 31: 247-251.

Herard, F. and Mercadier, G. 1996. Natural enemies of Tomicus Piniperda and Ips acuminatus (Col., Scolytidae) on Pinus sylvestris near Orleans, France: temporal occurrence and relative abundance, and notes on eight predatory species. Entomophaga 41: 183–210.

Hui Y. 1991. On the bionomy of Tomicus piniperda (L.) (Col., Scolytidae) in the Kunming region of China. Journal of Applied Entomology 112: 366-369.

Kaitera, J. and Jalkanen, R. 1994. The history of shoot damage by Tomicus spp. (Col., Scolytidae) in a Pinus sylvestris L. stand damaged by the shoot-disease fungus Gremmeniella abietina (Lagerb.) Morelet. Journal of Applied Entomology 117: 307-313.

Kennedy, A.A. and McCullough, D.G. 2002. Phenology of the larger European pine shoot beetle Tomicus piniperda (L.) (Coleoptera: Scolytidae) in relation to native bark beetles and natural enemies in pine stands. Environmental Entomology 31: 261-272.

Långström, B., Hellqvist, C., Ericsson, A. and Gref, R. 1992. Induced defence reaction in Scots pine following stem attacks by Tomicus piniperda. Ecography 15: 318-327.

Ryall, K.L. and Smith, S.M. 2000. Reproductive success of the introduced pine shoot beetle, Tomicus piniperda (L.) (Coleoptera, Scolytidae) on selected North American and European conifers. Proceedings of the Entomological Society of Ontario 131: 113-121.

Thomas, M.C., Dixon, W.N. and Fasulo, T.R. 2014. Pine Shoot Beetle, Tomicus piniperda (Linnaeus) (Insecta: Coleoptera: Curculionidae: Scolytinae). University of Florida IFAS Extension, EENY-321.

Website

https://entnemdept.ifas.ufl.edu/creatures/trees/beetles/pine_shoot_beetle.htm