Are insects declining and at what rate? An analysis of standardised, systematic catches of aphid and moth abundances across Great Britain

1. Although we have known anecdotally that insects have been declining in Great Britain for more than 100 years, insect declines have only been statistically estimated over the last 20 years. Estimation of the rate of those declines is still hotly debated,fuelled by a lack of standardised, systematically collected data. 2. More than 24 million individual moths and aphids collected from 112 light traps and 25 12.2 m suction-traps, respectively, were analysed using mixed models. Our objective was to estimate the long-term trends in both groups based on annual totals recorded every year between 1969 and 2016. 3. The models showed that two paradigms existed: Over 47 years, long-term linear trends showed that moths had declined significantly by −31%, but short-term trends indicated that there were periods of significant decline and recovery in most decades since the 1960s. Conversely, despite aphid annual totals fluctuating widely, this group was in a steady state over the long-term, with a non-significant decline of −7.6%. Sensitivity analysis revealed that moth trends were not driven by a group of abundant species, but the sign of the overall aphid trends may have been driven by three of the most abundant species. 4. The spatial extent of moth trends suggests that they are extremely heterogeneous.Uniquely, moth declines were different among several habitat types, with robust significant declines found in coastal, urban and woodland habitats, but notably not in agricultural,parkland and scrubland habitats. Conversely, aphid trends showed spatial synchrony extending to 338 km, albeit with local variation

Large-scale migration synchrony between parasitoids and their host

1. Parasitoids are a valuable group for conservation biological control. In their role as regulators of aphid pests, it is critical that their lifecycle is synchronised with their hosts in both space and time. This is because a synchronised parasitoid community is more likely to strengthen the overall conservation biological control effect, thus damping aphid numbers and preventing potential outbreaks. One component of this host-parasitoid system was examined, that of migration, and the hypothesis that peak summer parasitoid and host migrations are synchronised in time was tested. 2. Sitobion avenae Fabricius and six associated parasitoids were sampled from 1976 to 2013 using 12.2-m suction-traps from two sites in Southern England. The relationship between peak weekly S. avenae counts and their parasitoids was quantified. 3. Simple regression models showed that the response of the peak parasitoids to the host was positive: generally, more parasitoids migrated with increasing numbers of aphids. Further, when averaged over time, the parasitoid migration peak date corresponded with the aphid migration peak. The co-occurrence of the peaks was between 51% and 64%. However, the summer peak in aphid migration is not steadily shifting forward with time unlike spring first flights of aphids. Cross-correlation analysis showed that there were no between-year lagged effects of aphids on parasitoids. 4. These results demonstrate that the peak in migration phenology between host and parasitoid is broadly synchronised within a season. Because the threshold temperature for flight (>12 degrees C) was almost always exceeded in summer, the synchronising agent is likely to be crop senescence, not temperature. Studies are needed to assess the effects of climate change on the mismatch potential between parasitoids and their hosts

Long‐term trends in migrating Brassicogethes aeneus in the UK

BACKGROUND The pollen beetle (Brassicogethes aeneus) causes significant yield loss in oilseed rape (Brassica napus). Predicting population changes remains a scientific challenge, especially since its phenology and abundance varies dramatically over space and time. We used generalized additive models to investigate the long-term trends in pollen beetle annual, seasonal and monthly counts from Rothamsted 12.2 m suction-traps. We hypothesised that the beetle's abundance is positively related to the area of oilseed rape at a national and regional level. We used random forest models to investigate the inter-generational relationship within years. RESULTS Although B. aeneus annual counts and area of oilseed rape grown in the UK both increased by 162% and 113%, respectively, over the time period, they were not significantly related. The size of the immigrating pollen beetle population (up to June 1st) can be explained both by the size of the population in the previous summer and prevailing winter temperatures, indicating a positive feedback mechanism. CONCLUSION Currently, pollen beetle numbers continue to increase in the UK, meaning that control issues may persist, however the relationship between counts in spring, during the susceptible phase of the crop, and counts in the previous summer indicates that it may be possible to forecast the counts of the spring migration of B. aeneus a few months in advance using suction-trap samples, which could aid decisions on control options

Bucking the trend: the diversity of Anthropocene ‘winners’ among British moths

An appreciation of how some species are becoming more common despite unprecedented anthropogenic pressures could offer key insights for mitigating the global biodiversity crisis.  Research to date has largely focused on declining species, while species that are becoming more common have received relatively little attention. Macro-moths in Great Britain are well-studied and species-rich, making them an ideal group for addressing this knowledge gap. Here, we examine changes in 51 successful species between 1968 and 2016 using 4.5 million occurrence records and a systematic monitoring dataset. We employ 3D graphical analysis to visualise long-term multidimensional trends in prevalence (abundance and range) and use vector autoregression models to test whether past values of local abundance are useful for predicting changes in the extent of occurrence. The responses of Anthropocene winners are heterogeneous, suggesting multiple drivers are responsible. Changes in range and local abundance frequently occur intermittently through time, demonstrating the value of long-term, continuous monitoring. There is significant diversity among the winners themselves, which include widespread generalists, habitat specialists, and recent colonists. We offer brief discussion of possible causal factors and the wider ecosystem implications of these trends

A review of selected neighbourhood sustainability assessment frameworks using the Bellagio STAMP

Purpose The neighbourhood sustainability assessment frameworks through which a proposed neighbourhood development can be evaluated against an array of sustainability indicators began to gain prominence in the first decade of the twenty-first century. However, how these frameworks align with the Bellagio STAMP is an area yet to be examined by existing studies to inform their better development and usage in the delivery of sustainable neighbourhoods. The purpose of this paper is to review selected neighbourhood sustainability assessment frameworks using the Bellagio STAMP with the aim of identifying areas for improvement, while also exploring the possibilities of adopting the Bellagio STAMP as a consensus approach and reference to sustainability assessment at the neighbourhood level. Design/methodology/approach Adopting document analysis as a data collection method, the paper reviews BREEAM communities, LEED Neighbourhood Development, Pearl community rating system and Green Star communities using the Bellagio STAMP. Findings Findings from the study revealed that some of the selected assessment frameworks align partially with the Bellagio STAMP in their development, while areas for improvement were identified. Research limitations/implications The study recommends that the Bellagio STAMP could offer helpful guidelines and procedure in conceptualising sustainability assessment at the neighbourhood level especially in developing countries where such a framework is yet to be conceived. Originality/value This study adds to the sustainability assessment literature by operationalising the Bellagio STAMP leading to its better understanding and application in sustainability assessment either in practice or in theory

Is the Insect Apocalypse upon us? How to Find Out

In recent decades, entomologists have documented alarming declines in occurrence, taxonomic richness, and geographic range of insects around the world. Additionally, some recent studies have reported that insect abundance and biomass, often of common species, are rapidly declining, which has led some to dub the phenomenon an “Insect Apocalypse”. Recent reports are sufficiently robust to justify immediate actions to protect insect biodiversity worldwide. We caution, however, that we do not yet have the data to assess large-scale spatial patterns in the severity of insect trends. Most documented collapses are from geographically restricted studies and, alone, do not allow us to draw conclusions about insect declines on continental or global scales, especially with regards to future projections of total insect biomass, abundance, and extinction. There are many challenges to understanding insect declines: only a small fraction of insect species have had any substantial population monitoring, millions of species remain unstudied, and most of the long-term population data for insects come from human-dominated landscapes in western and northern Europe. But there are still concrete steps we can take to improve our understanding of potential declines. Here, we review the challenges scientists face in documenting insect population and diversity trends, including communicating their findings, and recommend research approaches needed to address these challenges

Long-term trends in migrating Brassicogethes aeneus in the UK

Background The pollen beetle (Brassicogethes aeneus) causes significant yield loss in oilseed rape (Brassica napus). Predicting population changes remains a scientific challenge, especially since its phenology and abundance varies dramatically over space and time. We used generalized additive models to investigate the long-term trends in pollen beetle annual, seasonal and monthly counts from Rothamsted 12.2 m suction-traps. We hypothesised that the beetle's abundance is positively related to the area of oilseed rape at a national and regional level. We used random forest models to investigate the inter-generational relationship within years. Results Although B. aeneus annual counts and area of oilseed rape grown in the UK both increased by 162% and 113%, respectively, over the time period, they were not significantly related. The size of the immigrating pollen beetle population (up to June 1st) can be explained both by the size of the population in the previous summer and prevailing winter temperatures, indicating a positive feedback mechanism. Conclusion Currently, pollen beetle numbers continue to increase in the UK, meaning that control issues may persist, however the relationship between counts in spring, during the susceptible phase of the crop, and counts in the previous summer indicates that it may be possible to forecast the counts of the spring migration of B. aeneus a few months in advance using suction-trap samples, which could aid decisions on control options

The long-term population dynamics of common wasps in their native and invaded range

Summary 1. Populations of introduced species are often thought to perform differently, or experience different population dynamics, in their introduced range compared to their native habitat. Differences between habitats in climate, competition or natural enemies may result in populations with varying density dependence and population dynamics. 2. We examined the long‐term population dynamics of the invasive common wasp, Vespula vulgaris, in its native range in England and its invaded range in New Zealand. We used 39 years of wasp density data from four sites in England, and 23 years of data from six sites in New Zealand. Wasp population time series was examined using partial rate correlation functions. Gompertz population models and multivariate autoregressive state‐space (MARSS) models were fitted, incorporating climatic variation. 3. Gompertz models successfully explained 59–66% of the variation in wasp abundance between years. Density dependence in wasp populations appeared to act similarly in both the native and invaded range, with wasp abundance in the previous year as the most important variable in predicting intrinsic rate of increase (r). No evidence of cyclic population dynamics was observed. 4. Both the Gompertz and MARSS models highlighted the role of weather conditions in each country as significant predictors of annual wasp abundance. The temporal evolution of wasp populations at all sites was best modelled jointly using a single latent dynamic factor for local trends, with the inclusion of a latent spring weather covariate. That same parsimonious multivariate model structure was optimal in both the native and invaded range. 5. Density dependence is overwhelmingly important in predicting wasp densities and ‘wasp years’ in both the native and invaded range. Spring weather conditions in both countries have a major influence, probably through their impact on wasp colony initiation and early development. The population dynamics in the native range and invaded range show no evidence of cyclic boom‐and‐bust dynamics. Invasive species may not exhibit different population dynamics despite considerable variation in abundances throughout their distribution

Where and why are species' range shifts hampered by unsuitable landscapes?

There is widespread concern that species will fail to track climate change if habitat is too scarce or insufficiently connected. Targeted restoration has been advocated to help species adapt, and a “conductance” metric has been proposed, based on simulation studies, to predict effective habitat configurations. However, until now there is very little empirical evidence on how the configuration of habitat is affecting expansion at species' cool range margins. We analysed the colonisation events that have occurred in continuously monitored trap locations for 54 species of southerly distributed moths in Britain between 1985 and 2011. We tested whether the time until colonisation was affected by attributes of each species, and of intervening landcover and climate between the trap and the baseline distribution (1965–1985). For woodland species, the time until colonisation of new locations was predicted by the “conductance” of woodland habitat, and this relationship was general, regardless of species' exact dispersal distances and habitat needs. This shows that contemporary range shifts are being influenced by habitat configuration as well as simple habitat extent. For species associated with farmland or suburban habitats, colonisation was significantly slower through landscapes with a high variance in elevation and/or temperature. Therefore, it is not safe to assume that such relatively tolerant species face no geographical barriers to range expansion. We thus elucidate how species' attributes interact with landscape characteristics to create highly heterogeneous patterns of shifting at cool range margins. Conductance, and other predictors of range shifts, can provide a foundation for developing coherent conservation strategies to manage range shifts for entire communities