Leiden University Scholarly Publications

Musters, C.J.M.; Honkoop, H.P.; Snoo, G.R. de 2024

Well known indicator groups do not predict the decline of insects

Article / Letter to editor

open access

n decision making for insect conservation, one depends largely on knowledge of the relationship between changes in environmental factors and abundance of a very limited number of species. The... Show moren decision making for insect conservation, one depends largely on knowledge of the relationship between changes in environmental factors and abundance of a very limited number of species. The species we have knowledge on cannot be regarded as a representative sample of all insects. How accurately do changes in the abundance of these species predict the changes in other species? To answer this question, we studied 373 insect species belonging to the Apidae (bees), Lepidoptera (butterflies), Orthoptera (grasshoppers), Ephemeroptera (mayflies), Trichoptera (caddisflies), Odonata (dragonflies), and Plecoptera (stoneflies), with known population trends and attributes in the Netherlands. The 78 attributes included morphological and demographic trait values, as well as habitat requirements of species. We trained Random Forests (RFs) with random samples and with taxonomic groups to predict the decline of the species based on their attributes. Then we used the trained RFs to predict the decline of the species outside the training groups and checked the accuracy of the predictions. The results showed that accuracy of the predictions of the RFs trained by the random samples increased from 0 to 0.20 (maximum 0.40, on a scale of 0 to 1) with sample size increasing from 10 to 90% of the insects. Moreover, we found that the accuracy of the predictions by the RFs trained with the taxonomic groups were zero in case of butterflies and grasshoppers, and low in other groups (maximum 0.37, in case of bees predicting terrestrial insects). Accuracy depended significantly on the size of the taxonomic group. Large over- or underestimation of number of declining species occurred in all cases. Further, we found that the taxonomic groups had few attributes important for predicting in common. The attribute ‘Active dispersion’ had the highest importance when all insects were used for training the RF. Using ‘indicator groups’ for predicting the decline of insects has a high risk of over- or underestimating the actual number of declining species and should therefore be advised against unless the indicator group is sure to be representative. Show less

Snoo, G.R. de; Dijk, J. van; Vletter, W.; Musters, C.J.M. 2023

People’s appreciation of colorful field margins in intensively used arable landscapes and the conservation of plants and invertebrates

Article / Letter to editor

open access

2024-05-27T00:00:00Z

Sown field margins can improve the conservation of biodiversity in rural areas and can contribute to the aesthetics of rural landscapes, thereby potentially increasing public support for agri... Show moreSown field margins can improve the conservation of biodiversity in rural areas and can contribute to the aesthetics of rural landscapes, thereby potentially increasing public support for agri-environmental measures. However, these two functions do not necessarily coincide. This raises the question whether field margins that are appreciated for their contribution to landscape aesthetics also deliver on the conservation of biodiversity. We conducted choice experiments with different groups of citizens and collected biodiversity data in the Netherlands, to investigate if the number of colors and vegetation cover in field margins increased respondents’ appreciation for them, and how these visual cues correlated with taxonomic diversity and abundance of plants and invertebrates in those field margins. Using manipulated photos, we also assessed whether the presence of colorful field margins in a range of different rural landscapes increased respondents’ appreciation of those landscapes. Respondents preferred colorful margins with high vegetation cover and showed a preference for green rural landscapes with colorful field margins. The presence of colorful field margins increased landscape aesthetics most in the least appreciated landscapes. The number of colors correlated positively with the diversity of sown and spontaneous plant species, and overall invertebrate abundance and abundance of predatory invertebrates, but was not related to invertebrate diversity. Our results show for the first time that colorful field margins support both public appreciation and diversity of plants and abundance of ground-dwelling invertebrates, with potential advantages to farmers in terms of natural pest control, at least in intensively used agricultural landscapes. However, management practices to maintain a high number of colors over time may be detrimental for invertebrate diversity. To optimize the different functions, we recommend that field margin layouts should consist of a perennial part that is allowed to develop over time, in combination with a part that is managed for its colorfulness. Show less

Musters, C.J.M.; Wiggers, J.M.R.; Snoo, G.R. de 2022

Distribution of ground-dwelling arthropods across landscapes with intensive agriculture in temperate areas

Article / Letter to editor

open access

The idea that land use in the surroundings may affect the abundance of arthropods on a location plays an important role in the argument that agriculture is the prime cause of the recently... Show moreThe idea that land use in the surroundings may affect the abundance of arthropods on a location plays an important role in the argument that agriculture is the prime cause of the recently discovered general decline of insects. We studied the abundance of ground-dwelling arthropods in agricultural fields along a gradient of increasing distance from (semi)natural areas and in relation to landscape complexity in both the North America (Illinois, USA) and Europe (The Netherlands) using pitfalls. Our results showed that the total abundance did not change with distance when we controlled for vegetation height and landscape complexity around the sample locations. Vegetation height affected abundance positively in crop land and negatively in grassland. Landscape complexity only affected abundance when it was measured in a 6000 m radius around sample location, not at lower levels of scale. We conclude that an effect of increasing landscape complexity may be expected when that is done on a large enough scale. Show less

Musters, C.J.M.; Evans, T.R.; Wiggers, J.M.R.; Zelfde, M. van 't; Snoo, G.R. de 2021

Distribution of flying insects across landscapes with intensive agriculture in temperate areas

Article / Letter to editor

open access

Yuan, R.; Musters, C.J.M.; Zhu, Y.; Evans, T.R.; Sun, Y.J.; Chesler, E.J.; ... ; Bartke, A. 2020

Genetic differences and longevity-related phenotypes influence lifespan and lifespan variation in a sex-specific manner in mice

Article / Letter to editor

open access

Epidemiological studies of human longevity found two interesting features, robust advantage of female lifespan and consistent reduction of lifespan variation. To help understand the genetic aspects... Show moreEpidemiological studies of human longevity found two interesting features, robust advantage of female lifespan and consistent reduction of lifespan variation. To help understand the genetic aspects of these phenomena, the current study examined sex differences and variation of longevity using previously published mouse data sets including data on lifespan, age of puberty, and circulating insulin-like growth factor 1 (IGF1) levels in 31 inbred strains, data from colonies of nuclear-receptor-interacting protein 1 (Nrip1) knockout mice, and a congenic strain, B6.C3H-Igf1. Looking at the overall data for all inbred strains, the results show no significant difference in lifespan and lifespan variation between sexes; however, considerable differences were found among and within strains. Across strains, lifespan variations of female and male mice are significantly correlated. Strikingly, between sexes, IGF1 levels correlate with the lifespan variation and maximum lifespan in different directions. Female mice with low IGF1 levels have higher variation and extended maximum lifespan. The opposite is detected in males. Compared to domesticated inbred strains, wild-derived inbred strains have elevated lifespan variation due to increased early deaths in both sexes and extended maximum lifespan in female mice. Intriguingly, the sex differences in survival curves of inbred strains negatively associated with age of female puberty, which is significantly accelerated in domesticated inbred strains compared to wild-derived strains. In conclusion, this study suggests that genetic factors are involved in the regulation of sexual disparities in lifespan and lifespan variation, and dissecting the mouse genome may provide novel insight into the underlying genetic mechanisms. Show less

Musters, C.J.M.; Ieromina, O.; Barmentlo, S.H.; Hunting, E.R.; Schrama, M.J.J.; Cieraad, E.; ... ; Bodegom, P.M. van 2019

Partitioning the impact of environmental drivers and species interactions in dynamic aquatic communities

Article / Letter to editor

open access

Temperate aquatic communities are highly diverse and seasonally variable, due to internal biotic processes and environmental drivers, including human‐induced stressors. The impact of drivers on... Show moreTemperate aquatic communities are highly diverse and seasonally variable, due to internal biotic processes and environmental drivers, including human‐induced stressors. The impact of drivers on species abundance is supposed to differ fundamentally depending on whether populations are experiencing limitations, which may shift over the season. However, an integrated understanding of how drivers structure communities seasonally is currently lacking. In order to partition the effect of drivers, we used random forests to quantify interactions between all taxa and environmental factors using macrofaunal data from 18 agricultural ditches sampled over two years. We found that, over the agricultural season, taxon abundance became increasingly better predicted by the abundances of co‐occurring taxa and nutrients compared to other abiotic factors, including pesticides. Our approach provides fundamental insights in community dynamics and highlights the need to consider changes in species interactions to understand the effects of anthropogenic stressors. Show less

Barmentlo, S.H.; Schrama, M.J.J.; Bodegom, P.M. van; Snoo, G.R. de; Musters, C.J.M.; Vijver, M.G. 2019

Neonicotinoids and fertilizers jointly structure naturally assembled freshwater macroinvertebrate communities

Article / Letter to editor

open access

Although it is widely acknowledged that a decline of freshwater biodiversity jeopardizes the functioning of freshwater ecosystems, the large number of (human-induced) pressures jointly acting on... Show moreAlthough it is widely acknowledged that a decline of freshwater biodiversity jeopardizes the functioning of freshwater ecosystems, the large number of (human-induced) pressures jointly acting on these systems hampers managing its biodiversity. To disentangle the magnitude and the temporal effects of these single and interacting pressures, experiments are required that study how these pressures affect the structuring of natural communities. We performed experiments with naturally assembled invertebrate communities in 36 experimental ditches to assess the single and joint effects of environmentally relevant concentrations of two commonly co-occurring stressors: fertilizer inputs and neonicotinoid insecticides, in this case thiacloprid. Specifically, we explored whether these agrochemicals result in sustained changes in community structure by inspecting divergence, convergence and short- /long-lived dissimilarity of communities, when compared to a control treatment. Our results indicate strong impacts on the abundance of different taxa by exposure to the agrochemicals. However, we found no effect of any treatment on total abundance, taxon richness or convergence/divergence (measured as beta dispersion) of the communities. Moreover, we found contrasting responses when both joint stressors were present: when considering abundance of different taxa, we observed that fertilizer additions reduced some of the thiacloprid toxicity. But when assessing the community structure, we found that exposure to both stressors consistently resulted in a more dissimilar community compared to the control. This dissimilarity was persistent up to four months after applying the agrochemicals, even though there was a turnover in taxa explaining this dissimilarity. This turnover indicates that the persistent dissimilarity can potentially be attributed to a rippling effect in the community rather than continued toxicity. Such shifts in natural freshwater invertebrate communities, months after the actual exposure, suggests that stressors may have important long-term repercussions for which may subsequently lead to changes in ecosystem functioning. Show less

Barmentlo, S.H.; Schrama, M.J.J.; Bodegom, P.M. van; Snoo, G.R. de; Musters, C.J.M.; Vijver, M.G. 2019

Neonicotinoids and fertilizers jointly structure naturally assembled freshwater macroinvertebrate communities

Article / Letter to editor

open access

Although it is widely acknowledged that a decline of freshwater biodiversity jeopardizes the functioning of freshwater ecosystems, the large number of (human-induced) pressures jointly acting on... Show moreAlthough it is widely acknowledged that a decline of freshwater biodiversity jeopardizes the functioning of freshwater ecosystems, the large number of (human-induced) pressures jointly acting on these systems hampers managing its biodiversity. To disentangle the magnitude and the temporal effects of these single and interacting pressures, experiments are required that study how these pressures affect the structuring of natural communities. We performed experiments with naturally assembled invertebrate communities in 36 experimental ditches to assess the single and joint effects of environmentally relevant concentrations of two commonly co-occurring stressors: fertilizer inputs and neonicotinoid insecticides, in this case thiacloprid. Specifically, we explored whether these agrochemicals result in sustained changes in community structure by inspecting divergence, convergence and short- /long-lived dissimilarity of communities, when compared to a control treatment. Our results indicate strong impacts on the abundance of different taxa by exposure to the agrochemicals. However, we found no effect of any treatment on total abundance, taxon richness or convergence/divergence (measured as beta dispersion) of the communities. Moreover, we found contrasting responses when both joint stressors were present: when considering abundance of different taxa, we observed that fertilizer additions reduced some of the thiacloprid toxicity. But when assessing the community structure, we found that exposure to both stressors consistently resulted in a more dissimilar community compared to the control. This dissimilarity was persistent up to four months after applying the agrochemicals, even though there was a turnover in taxa explaining this dissimilarity. This turnover indicates that the persistent dissimilarity can potentially be attributed to a rippling effect in the community rather than continued toxicity. Such shifts in natural freshwater invertebrate communities, months after the actual exposure, suggests that stressors may have important long-term repercussions for which may subsequently lead to changes in ecosystem functioning. Show less

Upadhyaya, S.K.; Musters, C.J.M.; Lamichhane, B.R.; Snoo, G.R. de; Thapa, P.; Dhakal, M.; ... ; Iongh, H.H. de 2018

An Insight Into the Diet and Prey Preference of Tigers in Bardia National Park, Nepal

Article / Letter to editor

open access

Musters, C.J.M.; Bodegom, P.M. van 2018

Analysis of species attributes to determine dominant environmental drivers, illustrated by species decline in the Netherlands since the 1950s

Article / Letter to editor

open access

2019-05-29T00:00:00Z

The relative impact of climate change and land use change on biodiversity loss is still under discussion. To alleviate drawbacks related to the use of observed species distributions, we introduce a... Show moreThe relative impact of climate change and land use change on biodiversity loss is still under discussion. To alleviate drawbacks related to the use of observed species distributions, we introduce a novel approach to separate the effects of climate change and land use change, the latter split into fragmentation, agricultural intensification and reforestation. This approach, coined the Attribute Importance Analysis (AIA), uses the ability of species attributes to explain population declines. Through the a priori association between attributes and individual drivers, the relative importance of the drivers in causing the species decline can be assessed. We tested this approach on the population decline of vertebrate, insect, vascular plant, and fungi species in the Netherlands since the 1950s. Fragmentation was clearly the strongest driver of species decline for vertebrates and plants, and this may also be true for insects. For fungi, climate change seems the only driver. We found a weak signal of the importance of agricultural intensification for the decline of vertebrates only. We ascribe this unexpected low importance of agricultural intensification to our partitioning of agricultural effects into fragmentation and intensification. Our generic approach can offer valuable quantitative information on the relative importance of drivers that change local community composition without the need for spatial explicit information. Without data on temporal trends in drivers, including local climate and land use change, accurate information on species decline, species attribute values and association of attributes with drivers can give insights into the causes of species decline, which, in turn, can be used to adapt nature management accordingly. Show less