Where have all the insects gone?

Vogel, Gretchen

doi:10.1126/science.aal1160

Cited by 49 publications

(53 citation statements)

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“…A species may be at low risk of extinction yet functionally extinct, which may be the case for species whose current populations are extremely low relative to historical baselines (e.g., marine species [Jackson et al. ]; insects [Vogel ]).…”

Section: Defining and Quantifying Recoverymentioning

confidence: 99%

Quantifying species recovery and conservation success to develop an IUCN Green List of Species

Akçakaya

Bennett

Brooks

et al. 2018

Conservation Biology

184

201

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Stopping declines in biodiversity is critically important, but it is only a first step toward achieving more ambitious conservation goals. The absence of an objective and practical definition of species recovery that is applicable across taxonomic groups leads to inconsistent targets in recovery plans and frustrates reporting and maximization of conservation impact. We devised a framework for comprehensively assessing species recovery and conservation success. We propose a definition of a fully recovered species that emphasizes viability, ecological functionality, and representation; and use counterfactual approaches to quantify degree of recovery. This allowed us to calculate a set of 4 conservation metrics that demonstrate impacts of conservation efforts to date (conservation legacy); identify dependence of a species on conservation actions (conservation dependence); quantify expected gains resulting from conservation action in the medium term (conservation gain); and specify requirements to achieve maximum plausible recovery over the long term (recovery potential). These metrics can incentivize the establishment and achievement of ambitious conservation targets. We illustrate their use by applying the framework to a vertebrate, an invertebrate, and a woody and an herbaceous plant. Our approach is a preliminary framework for an International Union for Conservation of Nature (IUCN) Green List of Species, which was mandated by a resolution of IUCN members in 2012. Although there are several challenges in applying our proposed framework to a wide range of species, we believe its further development, implementation, and integration with the IUCN Red List of Threatened Species will help catalyze a positive and ambitious vision for conservation that will drive sustained conservation action.

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Section: Defining and Quantifying Recoverymentioning

confidence: 99%

Quantifying species recovery and conservation success to develop an IUCN Green List of Species

Akçakaya

Bennett

Brooks

et al. 2018

Conservation Biology

184

201

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“…Insects constitute most species (May, ), and they hence play important roles as decomposers, pollinators, and herbivores acting as prey for higher trophic levels (Gullan, ). A number of studies have recently shown dramatic reductions in the biomass and the abundance of insects (Fox et al, ; Hallmann et al, ; Vogel, ). The abundance of flying insects has been reduced by more than 75% since 1990 even within nature reserves in Germany (Hallmann et al, ; Vogel, ).…”

Section: Introductionmentioning

confidence: 99%

Parallel declines in abundance of insects and insectivorous birds in Denmark over 22 years

Møller

2019

Ecology and Evolution

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Farmers in most western countries have increased use of fertilizer and pesticides with impact on wild animals and plants, including the abundance of insects and their predators. I used 1,375 surveys of insects killed on car windscreens as a measure of insect abundance during 1997–2017 at two transects in Denmark. I cross‐validated this method against three other methods for sampling insect abundance, and I investigated the effects of this measure of insect abundance on the abundance of breeding insectivorous birds. The abundance of flying insects was quantified using a windscreen resulting in reductions of 80% and 97% at two transects of 1.2 km and 25 km, respectively, according to general additive mixed model. Insect abundance increased with time of day, temperature, and June date, but decreased with wind resulting in a reduction by 54%. The abundance of insects killed on a car windscreen was strongly positively correlated with the abundance of insects caught in sweep nets and on sticky plates in the same study areas and at the same time as when insects were sampled using windscreens. The decline in abundance of insects on windscreens predicted the rate at which barn swallows Hirundo rustica fed their nestlings, even when controlling statistically for time of day, weather, and age and number of nestlings. The abundance of breeding pairs of three species of aerially insectivorous birds was positively correlated with the abundance of insects killed on windscreens at the same time in the same study area. This suggests a link between two trophic levels as affected by the temporal reduction in the abundance of flying insects. These findings are consistent with recent dramatic declines in insect abundance in Europe and North America with consequences for the rate of food provisioning of barn swallow offspring, the abundance of aerially insectivorous birds and bottom‐up trophic cascades.

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“…The here documented abundance decline of this once so abundant spider in the Swiss midland is evidently revealing a bottom-up trophic cascade in response to prey scarcity recently documented in the Swiss midland and across vast areas of western Europe [1,2,24,25]. The hypothesis that the availability of flying insect prey in the study area had drastically declined over the past decades is confirmed by the "windshield phenomenon" noticed throghout the Swiss midland (i.e., nowadays many times less flying insects are killed on the front windshields of cars compared to previous decades; [9,34]. This is in sharp contrast to the situation a few decades ago, when fairly frequently "wasteful killing" (and coupled with it "partial consumption") of insects in Araneus diadematus webs at favorable web sites could be witnessed (with capture rates of sometimes up to 1000 prey web -1 day -1 ; [35]).…”

Section: Discussionmentioning

confidence: 67%

Where have all the spiders gone? Observations of a dramatic population density decline in the once very abundant garden spider,Araneus diadematus(Araneae: Araneidae), in the Swiss midland

Nyffeler

Bonte

2020

Preprint

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AbstractAerial web-spinning spiders (including large orb-weavers) depend, as a group of insectivores, completely on flying insects as a food source. The recent widespread loss of flying insects across large parts of western Europe, both in terms of diversity and biomass, can therefore be anticipated to have a drastic negative impact on survival and abundance of this type of spiders. To test the putative importance of such a to date neglected trophic cascade, a survey of population densities of the European garden spider Araneus diadematus – a large orb-weaving spider – was conducted in late summer 2019 on twenty sites of the Swiss midland. The data from this survey were compared with published population densities for this species from the previous century. The study verifies above-mentioned hypothesis that this spider’s present-day overall mean population density has declined alarmly to densities much lower than can be expected from normal population fluctuations (0.7% of the historical densities). Review of other available records suggests this pattern is widespread and not restricted to this region. In conclusion, the here documented abundance decline of this once so abundant spider in the Swiss midland is evidently revealing a bottom-up trophic cascade in response to the widespread loss of flying insect prey in recent decades.

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Where have all the insects gone?

Cited by 49 publications

References 0 publications

Quantifying species recovery and conservation success to develop an IUCN Green List of Species

Quantifying species recovery and conservation success to develop an IUCN Green List of Species

Parallel declines in abundance of insects and insectivorous birds in Denmark over 22 years

Where have all the spiders gone? Observations of a dramatic population density decline in the once very abundant garden spider,Araneus diadematus(Araneae: Araneidae), in the Swiss midland

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