Karsten Mody

Although the biodiversity crisis and insect decline have received increasing scientific and public attention, they persist. Measures to stop biodiversity loss do not yet appear to be effective. A key step forward is to bridge science and practice, with digital tools and data‐driven environmental education playing a crucial role. To provide an evidence‐based tool that shows the negative effects of mowing on insects and spiders, we developed the ‘Insect Calculator’ ( insektentaschenrechner.de/en ). Using a large, comprehensive dataset from suction sampling across various grassland types and urban green spaces in Germany and Switzerland, the Insect Calculator models, visualises and communicates the effects of different detailed mowing regimes and other parameters, such as urban isolation surrounding grasslands, on arthropod density and species richness. Two different modes of the Insect Calculator, which require different levels of knowledge, are available to users: the ‘Walking mode’ for interested laypersons and the ‘Expert mode’ mainly for grassland management practitioners. For example, the tool shows that 73% more arthropods can be found in unmown meadows than in mown ones. It also highlights that, compared to bar mowers, mulchers cause a greater decline in insect populations, as well as the influence of other factors, including cutting height, width and frequency. One particular benefit of the Insect Calculator is that it shows how arthropods are affected by these various factors applied in conjunction. Solution . The Insect Calculator is an informative and user‐friendly tool designed to enhance environmental education by illustrating the severe effects of mowing on insects and spiders. Users themselves can answer questions about how to support arthropods. The proposed tool aims to inspire the development of similar tools that bridge the gap between science and practice in biodiversity conservation while also addressing other biodiversity threats.

Ivermectin, an anthelmintic used in livestock, is excreted in faeces and can therefore affect non-target organisms. While its effects on coprophagous insects have been well studied, recent research suggests that it can be taken up by plants, raising the possibility that it may affect a much wider range of invertebrates than previously known. Our study investigated the effects of ivermectin on insects from different feeding guilds. First, we tested its effects on the larvae of the noctuid moths Spodoptera frugiperda and Helicoverpa armigera (chewing herbivores) using an artificial diet. Secondly, we investigated the effects of its presence in the soil of pea plants Pisum sativum on the pea-feeding aphid Acyrthosiphon pisum (phloem-feeding herbivore). Thirdly, we tested ivermectin in an artificial diet for Drosophila melanogaster used as a host for the parasitoid Pachycrepoideus vindemmiae. Our results showed that ivermectin reduced pupal weight and survival in moth larvae, inhibited aphid colony establishment and reduced parasitoid emergence rates from ivermectin-exposed Drosophila pupae. These results highlight the potential of ivermectin to affect multiple trophic levels and emphasise the need for sustainable veterinary practices in the use of anthelmintics in free-ranging livestock and companion animals.

The abandonment of traditional agricultural practices and subsequent succession are major threats to many open-adapted species and species-rich ecosystems. Viticulture on steep slopes has recently suffered from strong declines due to insufficient profitability, thus increasing the area of fallow land considerably. Changing cultivation systems from vertically oriented to modern vineyard terraces offers an opportunity to maintain management economically viable and thus reduces further abandonment. Hillside parallel terraces favor mechanization, and their embankments offer large undisturbed areas that could provide valuable habitats. We investigated the effects of vineyard abandonment, different vineyard management types (vertically oriented vs. terraced), and local parameters on Orthoptera diversity in 45 study sites along the Upper Middle Rhine Valley in Germany. Our results show that woody structures and vineyard abandonment reduced Orthoptera diversity at the local and landscape scale due to decreased habitat quality, especially for open-adapted species. In contrast, open inter-rows of actively managed vineyard types supported heat-adapted Caelifera species. On terrace embankments, extensive management and taller vegetation benefited Ensifera species, while short and mulched vegetation in vertically oriented vineyards favored the dominance of one single Caelifera species. Our results highlight the significance of maintaining viticultural management on steep slopes for the preservation of both open-adapted Orthoptera species and the cultural landscape.

In the course of global climate change, central Europe is experiencing more frequent and prolonged periods of drought. The drought years 2018 and 2019 affected European beeches ( Fagus sylvatica L.) differently: even in the same stand, drought damaged trees neighboured healthy trees, suggesting that the genotype rather than the environment was responsible for this conspicuous pattern. We used this natural experiment to study the genomic basis of drought resistance with Pool-GWAS. Contrasting the extreme phenotypes identified 106 significantly associated SNPs throughout the genome. Most annotated genes with associated SNPs (>70%) were previously implicated in the drought reaction of plants. Non-synonymous substitutions led either to a functional amino acid exchange or premature termination. A SNP-assay with 70 loci allowed predicting drought phenotype in 98.6% of a validation sample of 92 trees. Drought resistance in European beech is a moderately polygenic trait that should respond well to natural selection, selective management, and breeding. Impact Statement: European beech harbours substantial genetic variation at genomic loci associated with drought resistance and the loci identified in this study can help to accelerate and monitor adaptation to climate change.

Massive declines in insect biodiversity and biomass are reported from many regions and habitats. In urban areas, creation of native wildflower meadows is one option to support insects and reduce maintenance costs of urban green spaces. However, benefits for insect conservation may depend on previous land use, and the size and location of new wildflower meadows. We show effects of conversion of roadside plantings–from exotic shrubs into wildflower meadows–on (1) the abundance of 13 arthropod taxa–Opiliones, Araneae, Isopoda, Collembola, Orthoptera, Aphidoidea, Auchenorrhyncha, Heteroptera, Coleoptera, Nematocera, Brachycera, Apocrita, Formicidae–and (2) changes in maintenance costs. We assessed the influence of vegetation type (meadow vs. woody), meadow age, size, location (distance to city boundary), and mowing regime. We found many, but not all, arthropod taxa profiting from meadows in terms of arthropod activity abundance in pitfall traps and arthropod density in standardized suction samples. Arthropod number in meadows was 212% higher in pitfall traps and 260% higher in suction samples compared to woody vegetation. The increased arthropod number in meadows was independent of the size and isolation of green spaces for most taxa. However, mowing regime strongly affected several arthropod taxa, with an increase of 63% of total arthropod density in unmown compared to mown meadow spots. Costs of green space maintenance were fivefold lower for meadows than for woody vegetation. Our study shows that (1) many different arthropod taxa occur in roadside vegetation in urban areas, (2) replacement of exotic woody vegetation by native wildflower meadows can significantly increase arthropod abundance, especially if meadow management permits temporarily unmown areas, and (3) maintenance costs can be considerably reduced by converting woody plantings into wildflower meadows. Considering many groups of arthropods, our study provides new insights into possible measures to support arthropods in urban environments.

Most forests are exposed to anthropogenic management activities that affect tree species composition and natural ecosystem processes. Changes in ecosystem processes such as herbivory depend on management intensity, and on regional environmental conditions and species pools. Whereas influences of specific forest management measures have already been addressed for different herbivore taxa on a local scale, studies considering effects of different aspects of forest management across different regions are rare. We assessed the influence of tree species composition and intensity of harvesting activities on arthropod herbivores and herbivore-related damage to beech trees, Fagus sylvatica, in 48 forest plots in three regions of Germany. We found that herbivore abundance and damage to beech trees differed between regions and that – despite the regional differences - density of tree-associated arthropod taxa and herbivore damage were consistently affected by tree species composition and harvest intensity. Specifically, overall herbivore damage to beech trees increased with increasing dominance of beech trees – suggesting the action of associational resistance processes – and decreased with harvest intensity. The density of leaf chewers and mines was positively related to leaf damage, and several arthropod groups responded to beech dominance and harvest intensity. The distribution of damage patterns was consistent with a vertical shift of herbivores to higher crown layers during the season and with higher beech dominance. By linking quantitative data on arthropod herbivore abundance and herbivory with tree species composition and harvesting activity in a wide variety of beech forests, our study helps to better understand the influence of forest management on interactions between a naturally dominant deciduous forest tree and arthropod herbivores.

Plant resistance strongly depends on plant characteristics that affect herbivore preference or performance. Different plant genotypes may express specific characteristics that lead to differential resistance to herbivores. Few studies have investigated these aspects for weevils, a particularly speciose taxon of insect herbivores, on fruit tree cultivars, which are vegetatively propagated. We studied the influence of apple cultivar on preference and performance of a fruit tree herbivore, the flower‐feeding apple blossom weevil Anthonomus pomorum (Coleoptera: Curculionidae). We quantified field infestation of five different apple genotypes by the weevil at different collection dates as measure of preference, as well as the mass and emergence time of weevils developing on these cultivars as measures of performance. Infestation of apple flower buds by A. pomorum differed significantly between cultivars. The collection date affected the number of infested flowers in a cultivar‐specific way. Weevil mass differed significantly between apple cultivars. The average mass of weevils from Ariwa, the cultivar producing the heaviest weevils, was 40% higher than the mass of weevils from Rewena, the cultivar producing the lightest weevils. Weevil emergence time from infested flowers differed significantly between cultivars. Weevils emerged earliest from cultivars Ariwa and Retina, at an intermediate time from Discovery and Florina, and latest from Rewena. The present study demonstrates that preference and performance of florivores feeding on fruit trees can strongly differ between apple cultivars representing specific tree genotypes. These differences may directly and indirectly affect herbivore and antagonist populations and can be considered for pest management.

Successful reforestation of tropical pastures can be facilitated or impeded depending on the interactions between native timber trees and arthropod communities. We assessed arthropod abundance on Tabebuia rosea (Bignoniaceae), a Central American extrafloral nectary‐bearing timber tree, in a plantation of native trees on former pasture in Panama, and we excluded ants from branches of T. rosea to determine ant impact on arthropod assemblages and on leaf damage. The trees' ant fauna was dominated by ground‐nesting species and ants were scarce in tree crowns, constituting only 2% of all arthropods collected by branch beating. Leaf damage was principally caused by caterpillars (mainly the pyralid Eulepte gastralis) and by beetles (mainly the chrysomelid Walterianella inscripta). Sugar baits at tree trunks revealed that rewarding food resources recruited high ant numbers to some tree individuals. Activity of the dominant ant, Ectatomma ruidum, at baits was negatively related to leaf damage by E. gastralis, suggesting that trees might be better protected from this herbivore when ant abundance is high. Exclusion of ants resulted in increased beetle diversity. The key herbivore W. inscripta was significantly more abundant on ant‐exclusion branches at the beginning, but not towards the end of the rainy season, when beetle density increased. Overall leaf damage and arthropod abundance were not significantly affected by ant exclusion. In conclusion, ant abundance on native timber trees in plantations recently established on former pasture can be low, and ant assemblages may be dominated by ground‐nesting generalist species, as shown in this study. This may explain the lacking protection of the timber trees from insect herbivory by ants. Increased protection of establishing timber trees by ants probably requires plantation management measures that increase the abundance of more specialized tree‐visiting and tree‐nesting ants.