The seed predator Argyresthia conjugella Zeller has rowan as its preferred host plant. In years of poor fruiting in rowan, it oviposits on apples. To improve the knowledge of this apple pest, rowanberries were collected from localities all over Norway from 1971 to 1985, and seed predators and their parasitoids were allowed to emerge for up to five years. Two species of seed predators, A. conjugella and Megastimus brevicaudis Ratzeburg, and seven species of parasitic Hymenoptera were common. The distribution of these species is shown on EIS (European Invertebrate Survey) maps of Norway. The biology of the parasitoids is summarized based on the published literature and their behavior during emergence. The tendency for delayed emergence, which is an indication of prolonged diapause, was more pronounced in M. brevicaudis than in A. conjugella, the former appearing in all five years. Five of the parasitoids also delayed their emergence, and three of them to a high degree, up to five years. Prolonged diapause must be taken into account in studies of rowanberry insect guilds.

AbstractAccording to the plant stress hypothesis, population peaks of herbivores such as moths are caused by plant stress factors that force plants to reallocate stored defensive proteins to transportable and easily digestive N‐compounds. A suggested plant stress factor is ionization caused by cosmic ray muons, which are modulated by the 9.3‐year lunar nodal phase cycle, solar activity, and atmospheric pressure. Vascular plants are more sensitive to ionization than are bryophytes, and woody plants are more sensitive than are herbaceous plants, but the difference may be less during dormancy in winter. We selected the 14 most common moth species from a 30‐year light‐trapping study in southern Norway to test whether the fluctuation patterns of species from three different feeding guilds were correlated with lunar/solar cycles, or with atmospheric pressure in winter, when muon fluxes are higher than in other seasons. The population indices of three species feeding on deciduous woody plants were positively correlated with the lunar nodal phase index, and there was a similar tendency for the remaining three species. No positive correlations with the lunar index were found for species feeding on herbs or mosses. For nine species, that is, from all three guilds, there was a significant negative correlation between the population index and winter atmospheric pressure in the previous year. The results are in accordance with predictions deduced from the cosmic ray hypothesis, but thorough investigations of the proposed physiological mechanisms are needed for the hypothesis to be widely accepted.

Thrips are a major pest in protected strawberry production. Knowledge of thrips species composition could be instrumental for improved thrips management, but very little is known about which species are present in strawberries grown in high-tunnels in Denmark. Thrips (adults and larvae) were sampled in two strawberry tunnels of the cultivars Murano and Furore from May to August 2018, in the middle and in the edges of the tunnels. The most abundant thrips species found in the tunnels were Frankliniella intonsa and Thrips tabaci adults. Frankliniella intonsa were also the most frequently found species of the immatures sampled, followed by T. tabaci larvae, and other species. The number of thrips differed between the two cultivars, sampling times and location in the tunnel. Frankliniella intonsa was more abundant in the middle of the tunnels, while T. tabaci was more abundant in the edge of the tunnels adjacent to the field margins. The number of thrips peaked by the end of July. Both chemical and biological control should consider species composition and occurrence; hence, a fundamental first step for thrips management is to identify the species present on the target crop.

Insects are reported to be in decline around the globe, but long-term datasets are rare. The causes of these trends are elusive, with changes in land use and climate among the top candidates. Yet if species traits can predict rates of population change, this can help identify underlying mechanisms. If climate change is important, for example, high-latitude species may decline as temperate species expand. Land use changes, however, may impact species that rely on certain habitats. We present 30 years of moth captures (comprising 97,032 individuals of 808 species) from a site in southeast Norway to test for population trends that are correlated with species traits. We use time series analyses and joint species distribution models combined with local climate and habitat data. Species richness declined by 8.2% per decade and total abundance appeared to decline as well (−9.4%, p = 0.14) but inter-annual variability was high. One-fifth of species declined, although 6% increased. Winter and summer weather were correlated with annual rates of abundance change for many species. Opposite to general expectation, many species responded negatively to higher summer and winter temperatures. Surprisingly, species’ northern range limits and the habitat in which their food plants grew were not strong predictors of their time trends or their responses to climatic variation. Complex and indirect effects of both land use and climate change may play a role in these declines. Our results provide additional evidence for long-term declines in insect abundance. The multifaceted causes of population changes may limit the ability of species traits to reveal which species are most at risk.

(1) We document the invertebrate fauna collected from 24 oak canopies in east and west Norway as a contribution to the Norwegian Biodiversity Information Centre’s ‘The Norwegian Taxonomy Initiative’. (2) A snap-shot inventory of the canopies was recorded by means of emitting a mist of natural pyrethrum into the canopies at night using a petrol-driven fogger and collecting the specimens in butterfly nets spread on the ground under the canopy. (3) Almost the entire catch of more than 6800 specimens was identified to 722 species. Out of 92 species new to the Norwegian fauna, 21 were new to science and, additionally, 15 were new to the Nordic fauna. Diptera alone constituted nearly half of the species represented, with 61 new records (18 new species). Additionally, 24 Hymenoptera (one new species), six oribatid mites (two new species) and one Thysanoptera were new to the Norwegian fauna. (4) Our study emphasizes the importance of the oak tree as a habitat both for a specific fauna and occasional visitors, and it demonstrates that the canopy fogging technique is an efficient way to find the ‘hidden fauna’ of Norwegian forests. The low number of red listed species found reflects how poor the Norwegian insect fauna is still studied. Moreover, the implication of the IUCN red list criteria for newly described or newly observed species is discussed.

Despite more than 250 years of taxonomic research, we still have only a vague idea about the true size and composition of the faunas and floras of the planet. Many biodiversity inventories provide limited insight because they focus on a small taxonomic subsample or a tiny geographic area. Here, we report on the size and composition of the Swedish insect fauna, thought to represent roughly half of the diversity of multicellular life in one of the largest European countries. Our results are based on more than a decade of data from the Swedish Taxonomy Initiative and its massive inventory of the country's insect fauna, the Swedish Malaise Trap Project The fauna is considered one of the best known in the world, but the initiative has nevertheless revealed a surprising amount of hidden diversity: more than 3,000 new species (301 new to science) have been documented so far. Here, we use three independent methods to analyze the true size and composition of the fauna at the family or subfamily level: (1) assessments by experts who have been working on the most poorly known groups in the fauna; (2) estimates based on the proportion of new species discovered in the Malaise trap inventory; and (3) extrapolations based on species abundance and incidence data from the inventory. For the last method, we develop a new estimator, the combined non-parametric estimator, which we show is less sensitive to poor coverage of the species pool than other popular estimators. The three methods converge on similar estimates of the size and composition of the fauna, suggesting that it comprises around 33,000 species. Of those, 8,600 (26%) were unknown at the start of the inventory and 5,000 (15%) still await discovery. We analyze the taxonomic and ecological composition of the estimated fauna, and show that most of the new species belong to Hymenoptera and Diptera groups that are decomposers or parasitoids. Thus, current knowledge of the Swedish insect fauna is strongly biased taxonomically and ecologically, and we show that similar but even stronger biases have distorted our understanding of the fauna in the past. We analyze latitudinal gradients in the size and composition of known European insect faunas and show that several of the patterns contradict the Swedish data, presumably due to similar knowledge biases. Addressing these biases is critical in understanding insect biomes and the ecosystem services they provide. Our results emphasize the need to broaden the taxonomic scope of current insect monitoring efforts, a task that is all the more urgent as recent studies indicate a possible worldwide decline in insect faunas.

Trophic interaction hypotheses for multiannual population fluctuations of herbivores include the predation hypothesis, the induction hypothesis and the plant stress hypothesis. Spatial synchrony is best explained by plant stress, such as high reproduction, because weather may synchronize resource allocation in plants over large areas. We used a 29‐yr time series on moth light trapping (6 selected species) and small rodent snap trapping (2 selected species) from southern Norway to test whether herbivore population fluctuations can be related to sexual reproduction of their host plants. The fluctuation pattern of the moths Parashwammerdamia lutarea and Yponomeuta padella, feeding on leaves of rowan (Sorbus aucuparia), could be explained by fluctuations in an annual index of rowanberry production, whereas the fluctuation pattern of Yponomeuta evonymella, feeding on leaves of bird cherry (Prunus padus), could not. The moth Eulithis populata, feeding on bilberry (Vaccinium myrtillus) leaves, fluctuated in synchrony with the bank vole (Myodes clethrionomys), which feeds on bilberry twigs in winter. E. populata and the bank vole also fluctuated in synchrony with a shorter index on bilberry seed crops. Finally, two moths feeding on mosses, Eudonia truncicolella and Catoptria falsella, fluctuated in synchrony with the moss‐feeding wood lemming (Myopus schisticolor). The observed patterns could be caused by a positive effect of the supply of highly nutritious reproductive plant tissue, but the one‐year delayed response by the rodents, which to a large extent feed on the plant species in question during winter, suggests that feeding deterrents are involved.

Grouse and vole numbers may peak after peaks in the seed crop of bilberry (Vaccinium myrtillus) because of reduced levels of feeding deterrents in bilberry plants. We predicted that grouse reproduction depends also on summer (June–September) temperatures in the 2 previous years, because bilberry plants will be less exhausted after a high seed crop in or after warm summers, and thus rebuild their chemical defence more quickly. After berry peak years, population indices of capercaillie (Tetrao urogallus) and bank vole (Myodes glareolus) in southern Norway were negatively related to summer temperatures in the previous year or previous 2 years. Willow grouse (Lagopus lagopus) chick production in five areas in Norway was negatively related to summer temperatures in the 2 previous years when controlling for vole density. A similar pattern was found for the bilberry-feeding moth (Eulithis populata), an important prey for grouse chicks. In eastern Norway, autumn densities of capercaillie and black grouse (Tetrao tetrix) were more likely to peak in vole peak years at high altitudes, where summer temperatures are low. We conclude that high summer temperatures may limit grouse reproduction through the effect on bilberry plants and that a warm climate thus adversely affects population levels of grouse.

A checklist of species of Thysanoptera from each of the Nordic countries is presented. The list is based on published data, unpublished data (personal communication) and own results. 194 species from 69 genera are recorded till now. The number of species and genera from Norway, Sweden, Finland, Denmark and Iceland respectively, are 162/63, 131/54, 148/59, 111/45 and 12/7. New species, with detailed information, from Norway and Sweden are 12 and 3 respectively.

Autumn Northern Bullfinch abundance at bird observatories around the Baltic Sea confirmed periodic irruptive behaviour outside of its normal wintering range, but age-ratio data suggested dispersal was not linked to reproductive success. Rowan berries are important food of Fennoscandian Northern Bullfinches and show synchronised masting in annual fruit production over large spatial scales. Norwegian and Finnish annual berry abundance indices from 1972-2004 were used to test the hypothesis that poor rowanberry production in normal wintering areas was responsible for efflux of birds to other areas. Annual Finnish wintering bird surveys and catches at local bird observatories correlated with rowanberry abundance indices, supporting the prediction that highest Bullfinch abundance would occur in normal wintering areas in years with heavy rowanberry crops. Northern Bullfinch autumn abundance at Danish and Swedish bird observatories (outside the normal winter range) showed inverse correlations with Norwegian rowanberry crops, supporting the prediction of highest irruptions in years of lowest rowanberry abundance from the normal wintering range. These data suggest that at large spatial scales, berry masting can have profound effects on the annual distribution and migratory behaviour of birds consuming the crop.

In 1984 a study was begun to describe variations in abundance over a long period of time for common, phototactic Lepidoptera and other insects at a single locality (Kobro 1991). Preliminary results on abundance of Neuroptera and Raphidioptera for the period 1988–1996 were discussed by Greve & Kobro (1998). 32 species of Neuroptera and 2 species of Raphidioptera were collected by the light trap. The light-trapping has continued all years up to present time. The presence of one species Micromus variegatus (Fabricius, 1793), not included by Greve & Kobro (1990) is discussed here.

Apple fruit moth, Argyresthia conjugella Zell. (Lepidoptera: Argyresthiidae), is the most important pest of apples in Scandinavia. In years when its primary host, rowan (Sorbus aucuparia L.), has little or no berries for egglaying, female A. conjugella fly into apple orchards to lay their eggs. In some years the entire apple crop can be destroyed. Volatiles from apples and rowan have been collected and identified. In GC-EAD tests females have responded to several compounds found in both rowan and apple. Some of these compounds were used in field trapping tests during 2002, and a mixture of two compounds trapped significantly more females and males compared to control traps. However, field trapping results from 2003 indicate that the two-compound blend seem to trap insects too late in the season to prevent egglaying in apples. Several new compounds were also tested in 2003, and some of these gave promising results. The results will be discussed in relation to use attractive plant volatiles as a control method against A. conjugella females.

In Norway, a positive relationship between spring numbers of lesser spotted woodpecker (Dendrocopos minor) and previous June temperatures has been interpreted as an effect of temperatures on woodpecker survival and reproduction during the breeding season. This article considers the possibility that woodpecker numbers are related to the abundance of the moth Argyresthia goedartella in the current year. Larvae and pupae of A. goedartella are important food for lesser spotted woodpeckers in early spring when few other surface-living invertebrates are available. The occurrence of this moth depends on the flowering of birch (Betula spp.) and alder (Alnus glutinosa), which in turn is influenced by June temperatures in the preceding year. Spring numbers of the lesser spotted woodpecker in two regions of Norway were compared with a trapping index of A. goedartella and weather variables assumed to influence the woodpeckers' breeding success and adult survival. The best multiple regression model included December temperatures and moth indices, supporting the hypothesis of a strong impact of A. goedartella on spring survival. Conservation strategies for the lesser spotted woodpecker should therefore focus not only on minimum areas of deciduous forests with decaying wood, but also on the availability of the moths' host trees, birch and alder.

The presence of multiple phenological forms has previously made adults of Hoplothrips species difficult to identify. We present a set of diagnostic metric characters by which the 8 species recorded from Norway can be recognised. Some biological interpretations are also given.

Plant volatiles mediate host finding in insect herbivores and lead to host fidelity and habitat‐specific mating, generating premating reproductive isolation and facilitating sympatric divergence. The apple fruit moth, Argyresthia conjugella Zeller (Lepidoptera: Argyresthiidae), is a particularly suitable species to study the cues and behavioural mechanisms leading to colonization of a new host: it recurrently oviposits on the non‐host plant, apple Malus domestica Borkh. (Rosaceae), where the larvae cannot complete their development. The larval host of the apple fruit moth (Lepidoptera, Argyresthiidae), is rowan Sorbus aucuparia L. (Rosaceae). Fruit setting in rowan, however, fluctuates strongly over large areas in Scandinavia. Every 2–4 years, when too few rowanberries are available for egg laying in forests, apple fruit moth females oviposit instead on apple in nearby orchards, but not on other fruits, such as pear or plum. This poses the question of which cues mediate attraction to rowan and apple, and how apple fruit moth discriminates rowan from apple. Chemical analysis and antennal recordings showed that 11 out of 15 rowan volatiles eliciting an antennal response in A. conjugella females co‐occur in rowan and apple headspace, in a different proportion. In the field, A. conjugella was attracted to several of these plant volatiles, especially to 2‐phenyl ethanol, methyl salicylate, and decanal. Addition of anethole to 2‐phenyl ethanol had a strong synergistic effect, the 1 : 1 blend is a powerful attractant for A. conjugella males and females. These results confirm that volatiles common to both plants may account for a host switch in A. conjugella from rowan to apple. Some of the most attractive compounds, including 2‐phenyl ethanol, anethole, and decanal, which have been found in several apple cultivars, were not present in the headspace of the apple cultivar, Aroma, which is also susceptible to attack by A. conjugella. This supports the idea that the odour signal from apple is suboptimal for attraction of A. conjugella, but is nonetheless sufficient for attraction, during times when rowan is not available for egg laying.

Entomologia Experimentalis et ApplicataVolume 115, Issue 2 p. 351-353 When does the apple fruit moth (Argyresthia conjugella) fly and oviposit? Gunnhild Jaastad, Corresponding Author Gunnhild Jaastad The Norwegian Crop Research Institute, Ullensvang Research Centre, Lofthus, Norway; *Correspondence: Dr Gunnhild Jaastad, The Norwegian Crop Research Institute, Ullensvang Research Centre, N-5781 Lofthus, Norway. Tel.: +47 53 67 12 22; Fax: +47 53 67 12 01; E-mail: [email protected]Search for more papers by this authorGeir K. Knudsen, Geir K. Knudsen The Norwegian Crop Research Institute, Plant Protection Centre, Ås, Norway;Search for more papers by this authorSverre Kobro, Sverre Kobro The Norwegian Crop Research Institute, Plant Protection Centre, Ås, Norway;Search for more papers by this authorPeter Witzgall, Peter Witzgall Swedish University of Agricultural sciences, Department of Crop Science, Alnarp, SwedenSearch for more papers by this author Gunnhild Jaastad, Corresponding Author Gunnhild Jaastad The Norwegian Crop Research Institute, Ullensvang Research Centre, Lofthus, Norway; *Correspondence: Dr Gunnhild Jaastad, The Norwegian Crop Research Institute, Ullensvang Research Centre, N-5781 Lofthus, Norway. Tel.: +47 53 67 12 22; Fax: +47 53 67 12 01; E-mail: [email protected]Search for more papers by this authorGeir K. Knudsen, Geir K. Knudsen The Norwegian Crop Research Institute, Plant Protection Centre, Ås, Norway;Search for more papers by this authorSverre Kobro, Sverre Kobro The Norwegian Crop Research Institute, Plant Protection Centre, Ås, Norway;Search for more papers by this authorPeter Witzgall, Peter Witzgall Swedish University of Agricultural sciences, Department of Crop Science, Alnarp, SwedenSearch for more papers by this author First published: 03 May 2005 https://doi.org/10.1111/j.1570-7458.2005.00283.xCitations: 2Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume115, Issue2May 2005Pages 351-353 RelatedInformation