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Local and landscape effect of maize cultivation on bee biodiversity and abundance - Using field trials of the engineered crop MON810 to study bees in the agricultural landscape

Lariviere, Delphine (2017) BIOM24 20142
Degree Projects in Biology
Abstract
Agricultural intensification has led to the homogenization of the landscape and the disappearance of diverse habitats with rich flower resources that are important for pollinating insects. The main insect pollinators, by far, are bees. And while honey bees (Apis mellifera) are the best known, there are also hundreds of other species of bees that contribute to pollination services. Due to their foraging behaviour, bees are exposed to many agricultural practices that are likely to influence their abundance and/or diversity. I studied bee diversity, abundance and temporal trends in maize in southern Sweden for three years as part of the EU FP7 research project AMIGA, “Assessing and Monitoring the Impacts of Genetically modified plants on... (More)
Agricultural intensification has led to the homogenization of the landscape and the disappearance of diverse habitats with rich flower resources that are important for pollinating insects. The main insect pollinators, by far, are bees. And while honey bees (Apis mellifera) are the best known, there are also hundreds of other species of bees that contribute to pollination services. Due to their foraging behaviour, bees are exposed to many agricultural practices that are likely to influence their abundance and/or diversity. I studied bee diversity, abundance and temporal trends in maize in southern Sweden for three years as part of the EU FP7 research project AMIGA, “Assessing and Monitoring the Impacts of Genetically modified plants on Agro-ecosystems”. Few studies have addressed bee utilization of maize fields and my study is the first large-scale bee inventory of its kind in Sweden. Honey bees, bumble bees, and solitary bees have been analysed separately. My study quantifies the influence of landscape effects on bee abundance and diversity and possible effects of local management practice exemplified by use of the engineered crop MON810. I found no effect of the genetically modified maize on bee abundance and diversity in any of the three groups, which is in accordance with previous studies. There was a significant positive effect of the percentage of surrounding non-agricultural area on bumble bee and solitary bee abundance as well as on solitary bee species diversity. This effect was greater during certain months of the sampling. Bumble bee abundance and diversity were greater with increasing non-agricultural area in June. Solitary bee abundance was greater with increasing non-agricultural area especially in July. These results illustrate the importance of surrounding non-agricultural land for bee diversity and abundance spatially and temporally. The presence of bees in maize fields throughout the entire season suggest that bees might use these crop fields for other purposes than pollen collection, for instance passing through them on their way to other areas. But further studies need to address this topic and provide behavioural data throughout the entire season to confirm any other form of interaction. The discussion highlights the importance of diversifying landscapes and natural habitats for bees that are foraging in the surroundings of cultivated maize fields. (Less)
Popular Abstract
Bees in maize fields: quantity, timing, and species diversity - Surrounding landscape and genetically modified crop effects

Demands in food are increasing and the agricultural systems need to adapt and increase yields. Nowadays, agricultural landscape look like large fields of identical crop. This change is not without consequences. By homogenizing the landscape, the living organisms have less and less habitats and resources to live on. Some insects are sensitive to such changes because they rely on specific plants. Bees for examples are relying on pollen and nectar from cultivated and wild flowers. And while honey bees (Apis mellifera) are the best known, there are also hundreds of other bee species that rely on specific plants in the... (More)
Bees in maize fields: quantity, timing, and species diversity - Surrounding landscape and genetically modified crop effects

Demands in food are increasing and the agricultural systems need to adapt and increase yields. Nowadays, agricultural landscape look like large fields of identical crop. This change is not without consequences. By homogenizing the landscape, the living organisms have less and less habitats and resources to live on. Some insects are sensitive to such changes because they rely on specific plants. Bees for examples are relying on pollen and nectar from cultivated and wild flowers. And while honey bees (Apis mellifera) are the best known, there are also hundreds of other bee species that rely on specific plants in the landscape. Bees are important pollinators and contribute to the reproduction of many plants. The pollination service they provide is valued to > $200 billion/year worldwide. Therefore, the monitoring and conservation of the bee fauna is important in a current context of agricultural intensification.

I caught bees in maize fields during 3 summers (2012 to 2014) with special traps. Fields were either conventional maize fields in the countryside or experimental fields where controlled trials of genetically modified (GM) and non-GM maize were being run by the EU AMIGA research project. GM maize produces a ‘built-in’ insecticide against a moth larvae that causes significant yield losses in maize cultivation. After each season, I counted and identified all bees caught. I then analysed the collected data together with landscape and maize type information. 892 bees were caught from June to October with a peak of presence in July. I separated the bees I caught in 3 groups: bumble bees, honey bees and solitary bees.

GM crop effect? I studied the effect of genetically modified maize with a plot experiment. After analysis, no differences were found in the amount of bee and bee species caught between both type of maize. My results are in accordance with previous research on the absence of direct effects of the toxin on bees. However, recent research from Portugal has highlighted possible side effects of the GM maize toxin on honey bee behaviour. To detect such results, further research needs to be conducted with larger fields, and measure the impact on bee foraging behaviour at a landscape level.

The importance of surrounding landscape? Surrounding non- agricultural land such as water bodies, forest patches or meadows may shelter suitable nesting habitats and beneficial resources for bee communities. I statistically tested the matter and found a positive effect of non-agricultural land on bumble bee and solitary bee. The more non-agricultural land in a radius of 500 meters from maize fields, the more bees. The effect differed in strength between months and was most pronounced in July. I also found a positive effect of non-agricultural land on the number of solitary bee species. The more non-agricultural land in a radius of 500 meters from maize fields, the more solitary bee species. My findings support results from other research on the negative effect of agricultural intensification. My discussion stresses the importance of knowing when bees are present in maize fields and more precisely what they are doing there. My study concludes that bees are present in maize fields from June to October, before, during and after pollen release. The reasons for their presence remain unknown and further studies need to address this topic. The interaction between bees and maize is important; pollinators may rely on surrounding crops that are not traditionally thought to be of interest for bees. Management needs to adapt to this new knowledge.


Advisor: Lars Pettersson and Tina D’Hertefeldt
Master’s Degree Project in Biology 30 credits. 2017
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Lariviere, Delphine
supervisor
organization
course
BIOM24 20142
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8903267
date added to LUP
2017-02-15 14:09:21
date last changed
2017-02-15 14:09:21
@misc{8903267,
  abstract     = {Agricultural intensification has led to the homogenization of the landscape and the disappearance of diverse habitats with rich flower resources that are important for pollinating insects. The main insect pollinators, by far, are bees. And while honey bees (Apis mellifera) are the best known, there are also hundreds of other species of bees that contribute to pollination services. Due to their foraging behaviour, bees are exposed to many agricultural practices that are likely to influence their abundance and/or diversity. I studied bee diversity, abundance and temporal trends in maize in southern Sweden for three years as part of the EU FP7 research project AMIGA, “Assessing and Monitoring the Impacts of Genetically modified plants on Agro-ecosystems”. Few studies have addressed bee utilization of maize fields and my study is the first large-scale bee inventory of its kind in Sweden. Honey bees, bumble bees, and solitary bees have been analysed separately. My study quantifies the influence of landscape effects on bee abundance and diversity and possible effects of local management practice exemplified by use of the engineered crop MON810. I found no effect of the genetically modified maize on bee abundance and diversity in any of the three groups, which is in accordance with previous studies. There was a significant positive effect of the percentage of surrounding non-agricultural area on bumble bee and solitary bee abundance as well as on solitary bee species diversity. This effect was greater during certain months of the sampling. Bumble bee abundance and diversity were greater with increasing non-agricultural area in June. Solitary bee abundance was greater with increasing non-agricultural area especially in July. These results illustrate the importance of surrounding non-agricultural land for bee diversity and abundance spatially and temporally. The presence of bees in maize fields throughout the entire season suggest that bees might use these crop fields for other purposes than pollen collection, for instance passing through them on their way to other areas. But further studies need to address this topic and provide behavioural data throughout the entire season to confirm any other form of interaction. The discussion highlights the importance of diversifying landscapes and natural habitats for bees that are foraging in the surroundings of cultivated maize fields.},
  author       = {Lariviere, Delphine},
  language     = {eng},
  note         = {Student Paper},
  title        = {Local and landscape effect of maize cultivation on bee biodiversity and abundance - Using field trials of the engineered crop MON810 to study bees in the agricultural landscape},
  year         = {2017},
}