Adult Feeding Preference and Fecundity in the Large Pine Weevil, Hylobius abietis (Coleoptera: Curculionidae)

Adult feeding preferences of Hylobius abietis on Picea abies, Larix decidua, Pinus sylvestris, Pseudotsuga menziesii, Abies alba and Betula pendula were tested in outdoor conditions. The preferred food source was P. menziesii, and the mean bark area consumed per seedling was 440.8 ± 147.9 mm2. The second most preferred host was P. abies. The coniferous species that suffered the least damage was A. alba (76.8 ± 62.56 mm2 per seedling). B. pendula was the least preferred source of food, and it caused mortality of 60% of weevils that fed on it. Weevils exhibited large differences in fecundity when fed with different tree species in a laboratory experiment. The largest number of eggs was laid by females fed with P. abies. Mean egg numbers reached 26.4 ± 24.89 eggs per experiment for P. abies. Similar fecundity was observed in weevils fed with twigs of P. sylvestris. Oviposition was approximately six times lower in females fed with L. decidua and P. menziesii. The maximum number of eggs laid by a single female during a one-month experiment was 90. The results are discussed in relation to management of H. abietis.

Ecology, management and damage by the large pine weevil (Hylobius abietis) (Coleoptera: Curculionidae) in coniferous forests within Europe

Coniferous forests in Europe have a considerable number of pests that attack trees of all ages from youngest up to oldest ones. One of them is the large pine weevil Hylobius abietis. This species is widespread in Europe and occurs from warm southern areas (Spain) up to northern countries (Sweden, Finland). Larvae of this species do not cause damage, they help in the decomposition process of stumps and roots. Adults are harmful as they consume bark of young coniferous seedlings, above all of spruce and pine. One adult can consume on average 75 mm2 of bark per day. Individuals can live up to 4 years, and during their lives they can damage and kill several tens of coniferous seedlings. Traditional chemical protection of seedlings against this pest is and will gradually be more and more restricted or forbidden. In this review, we describe this method as well as all other alternative methods including biological protection. We estimate that H. abietis causes annual damages in Europe of almost 120 million € and damages several tens of thousands of hectares of young forest stands.

Emissions of biogenic volatile organic compounds (BVOCs) from the rhizosphere of Scots pine (Pinus sylvestris) seedlings exposed to warming, moderate N addition and bark herbivory by large pine weevil (Hylobius abietis)

Aims Biogenic volatile organic compound (BVOC) research has been mostly focused on foliar emissions. In this experiment, the main focus was on rhizosphere BVOC emissions of Scots pine seedlings under changing growth conditions. Methods Soil-growing Scots pines were exposed to increased air (0.5°C) and soil (4.0°C) temperature and N addition (30 kg N ha− 1 yr− 1) for three growing seasons in a field experiment. In addition to these factors, seedlings were exposed to bark herbivory by large pine weevils in two last seasons. Gas-chromatography and mass-spectrometry was used for analyzing the BVOC samples collected from pine rhizosphere. Results Almost 98 % of BVOCs were non-oxygenated monoterpenes (nMTs), 1 % oxygenated monoterpenes (oMTs), 0.5 % sesquiterpenes (SQTs), and 1 % other BVOCs. In both years, there was an interaction of warming, N addition and bark herbivory on rhizosphere BVOC emissions. In 2015, warming and N addition in single exposures decreased oMT emissions, while herbivory in single exposure increased oMT emissions. In 2016, the three-way interaction showed that the effects of warming, N addition and herbivory on BVOCs were mainly detected in single exposures. In 2016, warming decreased nMT, oMT, SQT and other BVOC emissions; N addition decreased oMT and SQT emissions; and herbivory decreased SQT and other BVOC emissions. Conclusions Warming and N addition in single exposures decreased the rhizosphere BVOC emissions. The effect of bark herbivory on BVOC emissions varied between the years from increase to decrease. It seems that under altered growth conditions Scots pine seedlings may reduce carbon investment to rhizosphere BVOCs.

Forest management practices in reduction of damage caused by Pine weevil (Hylobius abietis L.) and Cervidae animals in newly planted Scots pine forests.

<p><strong>Key words</strong>: forest regeneration, Conniflex, Trico, mechanical site preparation</p><p>Forest regeneration is crucial stage in commercial forest management because actions during this stage impact future forest productivity and value. Scots pine is one of the main tree species in forestry of the northern part of Europe. Foresters have to overcome different risk factors during regeneration process and two of them are seedling damage by Pine weevil (<em>Hylobius abietis</em> L) and browsing by herbivores of <em>Cervidae</em> family. Pine weevil is one of the main forest pests in Europe that damage regenerated coniferous stands. Damage caused by this pest can produce 70% mortality of planted seedlings. Another significant risk factor is browsing. With increase of deer <em>(Cervidae)</em> population the damaged forest area also increases to the extent that foresters choose other tree species for regeneration. The mitigation of these risks is possible with appliance of forest management practices.  There are used different repelents against Cervidae animals.  Regarding Pine weevil, due to restrictions on insecticide use in EU, different protective coating materials have been developed, and several studies show that soil preparation before planting reduce amount of damaged Pine seedlings and increase possibility of successful regeneration.  We evaluated if and how forest management methods - soil preparation techniques (spot mounding, disc trenching) in combination with different plant protection products (Conniflex, Trico) - affects the degree of damage caused by pine weevil and <em>Cervidae</em> animals to Scots pine seedlings one and two years after outplanting in four forest stands in Latvia. The results from this study shows that application of Conniflex reduce number of damaged trees by 16.8% first and 20.3% second year after outplanting compared to untreated seedlings. Soil preparation has significant impact on reduction of pine weevil damage. The best results have been achieved by planting with Conniflex treated seedlings on spot mounds (2.4% damaged trees compared to 48.9% in unprepared soil without treatment). Repellent Trico do not provide additional protection against Pine weevil and do not have long term protection effect against browsing. Overall conclusion is that combination of soil preparation and use of appropriate coating material (Conniflex) can provide sufficient protection without usage of insecticides, and Trico has to be applied before winter season to achieve effect of protection.</p>

Spatio-temporal distribution of Hylobius abietis in Scots pine stands – implications for pest monitoring

The protection of reforested areas against the large pine weevil Hylobius abietis is one of the greatest forest management challenges in many European countries. No information exists on the spatial distribution of this pest, which is necessary to assess its abundance and, consequently, to precisely estimate its threat to reforested sites. The aim of this study was to assess the spatio-temporal changes in the number of H. abietis beetles in reforested clear-cut areas (reforestations) and neighbouring Pinus sylvestris stands, from which these beetles are assumed to migrate to the reforestations. In this two-year study, baited traps were used to catch H. abietis beetles in the reforestations and neighbouring stands. The results revealed significantly more beetles in the neighbouring old stands (61–69 years) than in the young stands (5–11 years). The distribution of the beetles in both the old and young stands was inversely dependent on the distance from the stand edge. The large pine weevil migration to the reforestations was most intense in mid-May and early June. In May, most beetles were collected along the edges of the reforestations; in June, their distribution was more regular; and in July, the beetles were more abundant in the central part of the reforestations. These results allow H. abietis monitoring improvement, which is an important element of integrated forest protection.

Liparus (Liparus) glabrirostris Küst. and Hylobius (Callirus) abietis (L.) (Coleoptera: Curculionidae) first records for Serbia

This paper presents a survey of data on two weevil species not recorded for the fauna of Serbia till now. Despite their large size, Liparus (Liparus) glabrirostris Küster, 1849 and Hylobius (Callirus) abietis (Linnaeus, 1758) have not been recorded for Serbia in the newest Palaearctic weevil catalogue (Alonso-Zarazaga et al., 2017) or in the Fauna Europaea (Alonso-Zarazaga et al., 2013, https://fauna-eu.org/). In this paper L. glabrirostris, found in a single locality on Mt Goč, is registered as the third representative of the genus Liparus Olivier, 1807 in Serbia. Hylobius abietis is a serious, widely distributed conifer pest, but was not faunistically registered for Serbia till now. Some ecological data and distribution maps with Serbian locations are given for both species.