Ips typographus

Ips typographus

The European spruce bark beetle (Ips typographus Linnaeus, 1758) is an insect belonging to the Curculionidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Animalia,
Subkingdom Eumetazoa,
Bilateria branch,
Phylum Arthropoda,
Subphylum Tracheata,
Superclass Hexapoda,
Class Insecta,
Subclass Pterygota,
Endopterygota cohort,
Superorder Oligoneoptera,
Coleopteroid section,
Order Coleoptera,
Suborder Polyphaga,
Infraorder Cucujiformia,
Superfamily Curculionoidea,
Family Curculionidae,
Subfamily Scolytinae,
Ipini tribe,
Genre Ips,
Species I. typographus.
The terms are synonyms:
– Bostrichus 8dentatus G.J.Billberg, 1820;
– Bostrichus octo-dentatus L.Gyllenhal, 1813;
– Bostrichus octodentatus Paykull & G.de, 1800;
– Bostrichus typographus (C.Linnaeus, 1758);
– Dermestes typographus C.Linnaeus, 1758;
– Tomicus typographus (C.Linnaeus, 1758).

Geographic Distribution and Habitat –
The Ips typographus is a beetle native to the coniferous forests of northern Asia and Europe; from this area of origin it subsequently spread also in fir plantations in western Europe, in the United States and also in Japan.
Its presence is reported in the following countries: France, Switzerland, Sweden, Norway, Estonia, Germany, Finland, Poland, Belgium, Austria, Russia, Japan, Czech Republic, Netherlands, Italy, Denmark, Luxembourg, United Kingdom, Lithuania, Slovakia, Korea, Latvia, Slovenia, Mexico, Ukraine, Bulgaria, Belarus, Spain, Portugal, Romania and the United States.
It is an insect considered very dangerous, which mainly affects spruce trees (Picea abies), but also attacks Picea orientalis, Picea jezoensis, and species of the genera Pinus and Abies.
Serious infestations have occurred in several countries, including Italy, Germany, the Czech Republic, Poland, Slovakia, Sweden and Norway.

Morphology –
Ips typographus is a beetle which in the adult stage is characterized by a short body, between 4.2 and 5.5 mm long, approximately cylindrical in shape, which has serrations on the back, the color varies from black to brown or reddish and the body is covered with yellowish hairs on the sides and front.
The larvae have a whitish body and an orange head; they are apodous and 5 mm long before pupating. They are also endophytic and xylophagous.
The pupae are a waxy white color and about 4mm long.

Attitude and biological cycle –
Ips typographus is able to fly up to 4 km to find suitable wood to reproduce. The reproduction period begins at the beginning of spring, in any case depending on the climatic conditions, and the males build a “nuptial chamber” under the bark of the host trees, thus proceeding to emit pheromones which attract up to four females. As soon as they arrive, the females begin to dig tunnels that branch off from the chamber, in each of which about 50 eggs are laid.
The spawning period can last even for three weeks, and the first ones hatch even before the last ones are laid.
As soon as they are born, the larvae begin to feed on the wood, digging further tunnels (always under the bark) which branch off from the original one, forming a pattern from which the name of this xylophagous insect derives.
When the larvae reach maturity, they pupate in the terminal area of the galleries:
The young adults, which emerge from the pupal casing, continue to feed on the wood for a certain period, getting out of the bark through 2-3 mm wide holes. this insect normally completes two generations a year; if the second generation fails to mature before winter arrives, it can finish the process the following spring; the adults also overwinter, generally taking refuge in the organic debris near the tree, or even under the bark of the tree itself.

Ecological role –
The Ips typographus, during its biological cycle, digs typical tunnels in the wood, with a characteristic architecture and visible on the wood under the bark.
In conditions of high infestations the needles of the affected plants become yellowish and then reddish-brownish in color, to then fall off within a few weeks, starting from the highest ones; moreover, the presence of this beetle can be detected by the presence of the excrements it leaves in the ravines of the bark, by the exit holes of the adult and by accumulations of resin expelled from the bark.
This bark beetle normally reproduces in diseased or already dead wood, for example fallen trees, stumps or cut trunks; however during a high infestation it also affects healthy trees, and in the most severe cases, or in conjunction with other types of pre-existing damage (such as fires, storms and wars), this insect can lead to the death of entire forests. Furthermore, together with other xylophagous insects that feed on the bark, it is a vector of the fungus Ceratocystis polonica and of fungi of the Ophiostoma genus, which contribute, in turn, to the deterioration of the wood.
In general, when the infestations are high, the damage is caused by both the adults and the larvae and in some cases it can even be very serious. The affected plants show evident deterioration with chlorosis, redness and desiccation of part of the top.
The containment and fight against this beetle is based on careful and effective measures of removal of affected trees and cleaning of reproductive material consisting of weak or fallen trees, trunks with bark, etc., before the new generation of adults emerges from the bark.
Among the defense techniques against the Ips typographus, those based on the biological fight are recommended which can be carried out by mass trapping, using special Theyson type window traps, activated with the sexual aggregation pheromone.
Furthermore, among the products allowed in organic farming, the entomopathogenic fungus Beauveria bassiana is effective, which however is difficult to apply over large areas and due to the difficulty of reaching the parasite inside the trunks.
Techniques for strengthening trees are also functional, as well as pheromone traps or so-called “trap trees”.
Furthermore, it should be remembered that the Thanasimus formicarius is one of the natural predators of this beetle.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Russo G., 1976. Agricultural entomology. Special Part. Liguori Publisher, Naples.
– Pollini A., 2002. Handbook of applied entomology. Edagricole, Bologna.
– Tremblay E., 1997. Applied entomology. Liguori Publisher, Naples.

Photo source:
– https://www.artportalen.se/MediaLibrary/2022/6/30aa5fad-6297-4b07-b7d9-32de42daa6bd_image.jpg