''Pissodes strobi'', known as the white pine weevil or Engelmann spruce weevil, is the primary

weevil Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than in length – and herbivorous. Approximately 97,000 species of weevils are known. They belong to several fa ...

attacking and destroying white pines. It was described in 1817 by William Dandridge Peck, professor of natural history and botany at

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

. The weevil is dark brown with white spots and is native to North America. The eggs are laid inside a tree, usually white pine,

Sitka spruce ''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to just over tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth- ...

white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to: * '' Picea engelmannii'', native to the Rocky Mountains and Cascade Mountains of the United States and Canada * ''Picea glauca ''Picea glauca'', the whi ...

Engelmann spruce ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is highly prized for producing distinctive tone wood for acoustic guitars ...

, or other

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

, and the offspring feed on this tree until the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

is killed. Terminals or shoots, as well as needles from pine or spruce, is what the diet of adult white pine weevils consists of.

Distribution

White pine weevils, native to North America, can be found in a number of different tree species. More than 20 species of tree have the potential to be infested by white pine weevils, mainly affecting eastern white pines. Other species that can be affected include Colorado blue,

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

, and Serbian spruces, as well as Scots,

red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–750 nanometres. It is a primary color in the RGB color model and a seconda ...

, pitch, jack, and Austrian pines.

Diet

The diet of adult white pine weevils consists of the needles and shoots of both pine and spruce trees. Holes in the bark of a tree as a result of this feeding habit are evident as a white pine weevils will eat through the bark in order to reach the terminals. Feeding occurs in the spring, when white pine weevils emerge from overwintering.

Behavior

White pine weevils will emerge in spring, waiting out the winter. This is the period in which females will lay their eggs in targeted trees. It takes until late summer for these larvae to become adults, and after winter passes in the following spring the next generation adult white pine weevils will reproduce and females will continue laying eggs in host trees. Storage of fertilized eggs through the winter season is an observed ability of female white pine weevils. Meaning that in following egg-laying seasons occurring in spring, female white pine weevils do not necessarily have to breed within that period.

Damage to white spruce and white pine

Severe damage to

and white pine can be created by the white pine weevil.Kiss, G.K. 1989. Genetic improvement of white and Engelmann spruce. p. 132 ''in'' Magnussen, S.; Boyle, T.J.B. (Eds.). Proc. Part 1, 22nd Meet. Can. Tree Improv. Assoc., Edmonton AB, Aug. 1989. Damage is caused due to reproduction of white pine weevils in host trees. When white pine weevils lay eggs they typically do so on the apical shoot. In around a week, or seven days, larvae will hatch from the eggs. The

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is ...

of the shoot is what the larvae will feed on once they hatch. As a result of larvae feeding on the phloem, recent growth of the infected tree will begin to wilt or droop. Feeding can even cause death of recent growth. Weevil resistance is a trait found in some trees and might be heritable. A study showed that the

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

(sap) released from wounds in white spruce leaders (tips) susceptible to the white pine weevil showed a different terpenoid composition than wounds induced in resistant white pine leaders. (Tomlin et al. 2000).Tomlin, E.S.; Antonejevic, E.; Alfaro, R.I.; Borden, J.H. 2000. Changes in volatile terpene and diterpene resin acid composition of resistant and susceptible white spruce leaders exposed to simulated white pine weevil damage. Tree Physiol. 20:1087–1095. While certain trees may have resistance to an attack by white pine weevils, this does not mean they will not be attacked. This involves factors that aid in weevil resistance, and factors that could encourage white pine weevils to initiate an attack on more resistant trees, like food scarcity. In coastal British Columbia, Sitka spruce trees developed a resistance against the white pine weevils which includes disruptions in egg & larvae development, deters host selection & mating, and delays the development of ovaries in female white pine weevils.Robert, et al. Behavioral and Reproductive Response of White Pine Weevil (Pissodes Strobi) to Resistant and Susceptible Sitka Spruce (Picea Sitchensis). MDPI, Molecular Diversity Preservation International, 19 Aug. 2010.

References

* {{Taxonbar, from=Q7198435 Molytinae Insect vectors of plant pathogens Taxa named by William Dandridge Peck Beetles described in 1817