Species distribution models for crop pollination: a modelling framework applied to Great Britain

Insect pollination benefits over three quarters of the world's major crops. There is growing concern that observed declines in pollinators may impact on production and revenues from animal pollinated crops. Knowing the distribution of pollinators is therefore crucial for estimating their availability to pollinate crops; however, in general, we have an incomplete knowledge of where these pollinators occur. We propose a method to predict geographical patterns of pollination service to crops, novel in two elements: the use of pollinator records rather than expert knowledge to predict pollinator occurrence, and the inclusion of the managed pollinator supply. We integrated a maximum entropy species distribution model (SDM) with an existing pollination service model (PSM) to derive the availability of pollinators for crop pollination. We used nation-wide records of wild and managed pollinators (honey bees) as well as agricultural data from Great Britain. We first calibrated the SDM on a representative sample of bee and hoverfly crop pollinator species, evaluating the effects of different settings on model performance and on its capacity to identify the most important predictors. The importance of the different predictors was better resolved by SDM derived from simpler functions, with consistent results for bees and hoverflies. We then used the species distributions from the calibrated model to predict pollination service of wild and managed pollinators, using field beans as a test case. The PSM allowed us to spatially characterize the contribution of wild and managed pollinators and also identify areas potentially vulnerable to low pollination service provision, which can help direct local scale interventions. This approach can be extended to investigate geographical mismatches between crop pollination demand and the availability of pollinators, resulting from environmental change or policy scenarios

Climate-driven spatial mismatches between British orchards and their pollinators: increased risks of pollination deficits

Understanding how climate change can affect crop-pollinator systems helps predict potential geographical mismatches between a crop and its pollinators, and therefore identify areas vulnerable to loss of pollination services. We examined the distribution of orchard species (apples, pears, plums and other top fruits) and their pollinators in Great Britain, for present and future climatic conditions projected for 2050 under the SRES A1B Emissions Scenario. We used a relative index of pollinator availability as a proxy for pollination service. At present there is a large spatial overlap between orchards and their pollinators, but predictions for 2050 revealed that the most suitable areas for orchards corresponded to low pollinator availability. However, we found that pollinator availability may persist in areas currently used for fruit production, but which are predicted to provide sub-optimal environmental suitability for orchard species in the future. Our results may be used to identify mitigation options to safeguard orchard production against the risk of pollination failure in Great Britain over the next 50 years; for instance choosing fruit tree varieties that are adapted to future climatic conditions, or boosting wild pollinators through improving landscape resources. Our approach can be readily applied to other regions and crop systems, and expanded to include different climatic scenarios

Protecting an ecosystem service: approaches to understanding and mitigating threats to wild insect pollinators

Insect pollination constitutes an ecosystem service of global importance, providing significant economic and aesthetic benefits as well as cultural value to human society, alongside vital ecological processes in terrestrial ecosystems. It is therefore important to understand how insect pollinator populations and communities respond to rapidly changing environments if we are to maintain healthy and effective pollinator services. This paper considers the importance of conserving pollinator diversity to maintain a suite of functional traits to provide a diverse set of pollinator services. We explore how we can better understand and mitigate the factors that threaten insect pollinator richness, placing our discussion within the context of populations in predominantly agricultural landscapes in addition to urban environments. We highlight a selection of important evidence gaps, with a number of complementary research steps that can be taken to better understand: i) the stability of pollinator communities in different landscapes in order to provide diverse pollinator services; ii) how we can study the drivers of population change to mitigate the effects and support stable sources of pollinator services; and, iii) how we can manage habitats in complex landscapes to support insect pollinators and provide sustainable pollinator services for the future. We advocate a collaborative effort to gain higher quality abundance data to understand the stability of pollinator populations and predict future trends. In addition, for effective mitigation strategies to be adopted, researchers need to conduct rigorous field-testing of outcomes under different landscape settings, acknowledge the needs of end-users when developing research proposals and consider effective methods of knowledge transfer to ensure effective uptake of actions

The effect of the herbicide glyphosate on non-target spiders: Part II. Indirect effects on Lepthyphantes tenuis in field margins

We have examined the indirect effect of the herbicide glyphosate on the spider Lepthyphantes tenuis in field margins. Glyphosate was applied to a randomised block design field experiment comprising 360, 720 and 1440 g glyphosate AE ha−1 treatments and an unsprayed control. Spiders were sampled in each month from June to October 1998. Spider abundance was significantly lower in all the treatments than in the unsprayed control. Abundance was also significantly lower in the 720 and 1440 g treatments than in the 360 g treatment. No significant difference could be detected between the 720 and 1440 g treatments. Poisson regression models showed that patterns of decline in L tenuis were related to increasing dead vegetation and decreasing vegetation height. Glyphosate applications only had a within-season indirect habitat effect on L tenuis as field margins sprayed 16 months after an application of 360 g glyphosate ha−1 showed no detrimental effect

The effect of the herbicide glyphosate on non-target spiders: Part I. Direct effects on Lepthyphantes tenuis under laboratory conditions

We examined the toxic effects of glyphosate to adult female Lepthyphantes tenuis (Araneae, Linyphiidae), a common spider of agricultural habitats. The overspray technique was used to investigate the effect of the herbicide on forty individuals in each of six glyphosate treatments (2160, 1440, 1080, 720, 360 and 180 g ha−1) and a distilled water control. Spiders collected from the wild were individually placed in exposure chambers and checked every 24 h over a 72-h experimental period. Mortality of L tenuis remained at less than 10% in all treatments at 24 and 48 h after spray application, and only increased marginally (to 13%) after 72 h. These results support other limited data which suggest that glyphosate is ‘harmless’ to non-target arthropods. More extended laboratory testing to investigate any side-effects of glyphosate on the life history of L tenuis and other non-beneficial invertebrates is required

The Effects of Different Rates of the Herbicide Glyphosate on Spiders in Arable Field Margins

Volume: 27Start Page: 249End Page: 25

Pollination service to field beans, from <i>Bombus pascuorum</i>.

<p>The potential pollination service is represented using geometric intervals, with the exclusion of the zero class which was manually defined. Areas evaluated as 0 indicate crop fields outside the foraging distance of <i>B. pascuorum</i> (i.e. no pollination service). Map projection: BNG.</p