Course:CONS200/2023/Course: CONS 200; The Impacts of Light Pollution on Nocturnal Agricultural Pollinators in Canadian Praries

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The Importance of the Canadian Prairies Ecosystems

A map demonstrating the extent of the Canadian Prairie Ecozone.

The Canadian Prairie ecosystem in Canada is a temperate grassland that covers over 465km^2 and 4.7% of land area in Canada[1]. It is concentrated in central and Western Canada including Manitoba, Saskatchewan, and Alberta[1]. The prairies are made up of glacial deposits because the ecozone was glaciated during the last ice age resulting in clay soils[1]. The climate of the prairies is currently semi-arid to sub-humid, with mean precipitation ranging from 280 mm/yr to 540 mm/yr, increasing Eastward[1]. The mean winter average temperature is between -6 to -17 degrees Celsius, and the mean summer average temperature is between 15 to 19 degrees Celsius[1].

Currently, most of the land of the prairies is agricultural, but before European colonization in the 18th century, the land was home to more than twelve Indigenous groups[1]. Furthermore, there are upwards to 4.5 million people living in the prairies and the economy is reliant on the exports of agriculture, natural gas, oil, and potash[1].

It is uncertain exactly how climate change will affect the prairies; however, it is known that there will be changes species composition, crop types, water availability, seeding dates, and diseases[2].

The Importance of Agricultural Production in the Canadian Prairies

A map showing the land use in the Canadian Prairie Ecozone.

The prairies are largely agricultural with 88% of the prairies being agricultural land and 55% being cropland[1].

Between 2005 and 2009, the Canadian Prairies exported 21 billion dollars worth of agriculture[2]. This was about 51% of Canadian agricultural production[2]. Additionally, the biggest production of agriculture in Canada is produced in the Canadian Prairies, and 80% of the wheat grown in the prairies is exported[3].

Nocturnal Pollinators in the Canadian Prairies

Nocturnal pollinators are animals and insects that activate during the night and sleep during the day. It is estimated that around 30% of all vertebrates and 60% of invertebrates are nocturnal[4]. There are numerous examples of nocturnal pollinators in the Canadian prairies, which are typically crucial to individual species and populations. In Canada, the most common nighttime pollinators are insects, with moths and bees in particular.

Among insects, some of the most recognized species inhabiting the Canadian prairies are a number of nocturnal Diptera (an order that includes but is not limited to mosquitoes, midges, and sand flies) and Lepidoptera (an order of insects that includes butterflies and moths). Moths are important nocturnal pollinators; in particular, nectarivorous species from the families Sphingidae, Noctuidae, and Geometridae and probably also the newly defined Erebidae[5]. Moths are pollinators with patterned, frequently vividly coloured wings. Moths prefer white flowers, as they are easier to see in the faint moonlight as they are primarily active at night. Chironomidae, known as “non-biting midges”, as well as two other families of flies, Cecidomyiidae and Ceratopogonidae, are also abundant in Canadian prairies and have been observed pollinating a wide range of plants [6]. The only legally protected insects in Canada are butterflies and moths, of which about 10% of butterflies (18 species) and 9% of macromoths (119 species) are found nowhere else in Canada[7].

Agricultural Significance of Nocturnal Pollinators

Nocturnal pollinating insects play an important role in ecosystem stability and food security. The stability of the populations of nocturnal pollinators is linked to pollination services to plants, which maintains the sustainability of ecosystems and agriculture[8]. Nocturnal pollinators such as moths, bees, and other more well-known pollinating insects, play an important role in pollinating many flowering plants, including species that diurnal pollinators such as bees do not visit.

Special Adaptations

Nocturnal moths, like their diurnal relatives, fly from flower to flower during the night to feed on nectar. However, moths have advantages over diurnal pollinators, as they are better-adapted to the lower temperatures and light conditions that a nocturnal period in the Canadian prairies provides [9]. Moth scale hairiness acts as an insulator, reducing heat loss and playing an important role in thermoregulation. Hairiness is thought to be a crucial characteristic for pollination because the greater area of surface and electrostatic pull enable pollen to stick to the moths' bodies[9].

Crop Pollination

Lepidoptera spp., a nocturnal moth that pollinates Brassica napus L. (canola)

Nocturnal insects (particularly moths) contribute to the pollination of select commercially important crops[10]. Nocturnal Lepidoptera (moths) play an important role in crop pollination in the Canadian Prairies, particularly in pollination of canola, one of the common crops grown in the Canadian Prairies[11]. Some of the apples grown in the Canadian prairies that may be pollinated by moths include Prairie Sun, Prairie Sensation and Autumn Delight[12]. Other crop plants that are pollinated exclusively at night include Bauhinia forficate which belongs to the family of Fabaceae that includes important agricultural crops such as Glycine max (soybean), Phaseolus (beans), and Pisum sativum (pea). Bauhinia forficate is pollinated primarily by a nocturnal moth, hawkmoth Manduca sexta[13]. Saponaria officinalis (Caryophyllaceae) is solely pollinated at night by moths and hawkmoths[14].

Asclepias speciosa, commonly referred to as milkweed, grows throughout the Canadian prairies and serves as a vital supply of nectar for bees and other nectar-seeking insects as well as a food source for monarch butterflies and their relatives' larvae[15]. Moths (both Sphingidae and other families) tend to pollinate Asclepias spp[16]. The moths provide benefits including higher quality pollination, causing equal or greater seed set in spite of transferring fewer pollinia[16]. As a result, moth-pollinated plants perhaps invest fewer resources into producing pollen without compromising reproductive success[17].

Non-Crop Pollination

Another important plant species that is pollinated by hawkmoths (Sphingidae) is the Western Prairie Fringed Orchid[18]. The Western Prairie Fringed Orchid has been a catalyst for the acquisition of tall grass prairie land and a focus plant for ecotourism opportunities in the Manitoba Tall Grass Prairie Preserve promoting education and public outreach for tall grass prairie habitats[18] . Overall, nocturnal pollination can be important for many plant families, including plants not just of ecological, but also agricultural importance.

World map of light pollution from artificial light sources

What is Artificial Light at Night (ALAN)?

ALAN stands for Artificial Light At Night, which is comprised of “street lighting, advertising lighting, architectural lighting, security lighting, domestic lighting and vehicle lighting” that is turned on at night [19].

Due to ALAN, natural patterns of darkness are disrupted[19]. This is due to the “direct effects of illumination” from light sources turned on at night, and “skyglow,” which is “scattering [of light] by atmospheric molecules of aerosols in the atmosphere”[19]. Due to rapidly growing urbanization, approximately 18.7% of “global land area” is affected by ALAN, and this percentage is expected to grow by 6% annually [19]. Not only does ALAN result in light occurrence at unnatural times, the light spectrum of ALAN varies from “sunlight, moonlight, or starlight”[19]. For this reason, it is expected that there will be impacts on living organisms by ALAN[19].

The Effect of Artificial Light on Nocturnal Pollinator Abundance, Reproduction, Feeding habits, Population Dynamics, Behavior and how this affects the Canadian Prairies:

Streetlights are common sources of ALAN

Nocturnal pollinators' rhythm has been disrupted by humans and the widespread production of artificial light at night[4]. Artificial light at night (ALAN) can have significant impacts on nocturnal pollinators, such as moths and bats[4]. A disruption in the efficacy of nocturnal pollinators will be likely to cause problems in the future crop production. Over one-third of the world’s production of crops are dependent on animal pollination[20]. Additionally, 88% of angiosperms depend on some sort of animal pollination. With an increase in light pollution, we will see changes in how these pollinators act, reproduce, and interact with other organisms[21], as light pollution changes the natural behaviours of nocturnal pollinators and their fitness[20].


There are roughly 140,000 species of moths, a very large nocturnal group, that are often attracted to artificial light sources[22]. A street lamp can attract a moth from 25 yards away[4]. This causes swarms of moths and acts as an effective lure for moth predators such as bats and spiders to exploit the increased moth concentration under the light. This exploitation has caused moth abundance at ground level decreased by >25% at lit sites compared to unlit sites[4]. According to research conducted by the charity Butterfly Conservation in Great Britain, two-thirds of populations of larger moth species have declined over a 40-year period[23]. Streetlights have significant effects on the overall moth abundance.


Artificial light at night has significant effects on moth reproduction[22]. It was found that the effects of artificial night lights with different spectral compositions effect the amount of sex pheromone produced by M. brassicae females[22]. The pheromone biosynthesis activation neuropeptide regulates the moth's sex pheromone production which is produced during the night, and the release of PBAN is regulated by light[22]. The production of sex pheromones was reduced by artificial lighting exposure and affected the processes involved in moth reproduction, indicating that ALAN has a negative impact on reproductive processes (CITATION?). The sex pheromone produced is essential to attract potential mates, and its reduced production from ALAN could lead to reduced mating success, having major implications for moth populations[22]


Artificial light can have detrimental effects on a moth's ability to feed and forage. Moths exposed to different types of article light were found to decrease feeding activity by 63-82% compared to being in the dark [24]. In both female and male moths, reduced feeding due to artificial light results in increased mortality and therefore a decrease in the moth populations. It was also found that starvation of female moths lead to reduced fertility, as females that were able to feed properly laid more eggs than those affected by artificial light [24].  Pollinators such as moths that are subjected to artificial night lighting compared to darkness are found to spend significant less time feeding, which in the long run will have damaging effects on the moth pollinator populations. Additionally, it was found that ALAN can disrupt navigation, leading to a reduction in foraging efficiency and an increase in energy spent by pollinators[21]. Navigation disruption that leads to decreased foraging results in increased mortality due to insufficient amounts of food, and therefore moth populations decrease.

Population Dynamics

Hawk moth larvae, a nocturnal moth species whose abundance is decreased by ALAN.

Artificial light changes the behavior, physiology, and survival of species through acts of reproduction and behavior which then affect species interactions and ecosystem functioning[25]. For example, increased artificial light can result in nocturnal and daytime species increasing their interactions with one another[25]. Interactions between species that would not normally interact can cause competition and affect reproduction and abundance of all species[25]. Additionally, it was found that there was a 62% reduction in nocturnal pollinator visits between dark areas and artificially lighted areas which caused a 13% reduction in fruit set[26]. This has potential to cascade into greater effects on the ecosystem as seed production and plant composition could be altered[21].

How Disruptions to Nocturnal Pollinators May Affect the Canadian Prairies:

In the Canadian prairies, excess light pollution will bring a decrease in insect abundance and biomass[20]. It is clear that plants that depend on nocturnal pollinators for their reproduction processes will see a decline in pollination rates[18]. Additionally, artificial light can decrease feeding activity having consequences of reduced fertility and death[24]. This reduction in fertility and increase in starvation deaths will result in smaller populations of nocturnal pollinators[24]. Changes in the behavior, physiology, and survival of pollinators will adversely affect species interactions and ecosystem functioning[25].

The reduction in abundance and productivity of nocturnal pollinators in the Canadian prairies will negatively affect not only ecosystem functioning but the Canadian economy. This is because agricultural output may be stunted as is already being seen in some native plants grown like Platanthera praeclara in Manitoba[18]. Decreases in crop yields can create supply chain issues as supply of goods produced in the prairies may decrease, and Canadian GDP may decrease. The risk of food insecurity arises in both Canada and countries which rely on Canadian agricultural exports. Canadians whose livelihoods depend on the success of the agricultural industry in the prairies may suffer financially.

More research is required to fully understand the implications of increased light pollution and understand how it will specifically affect the Canadian Prairie ecosystem. Due to limited research, there is insufficient evidence to determine the long-term implications of light pollution on nocturnal pollinators in the Canadian Prairies. However, it is evident that nocturnal pollinators play a crucial role in the ecosystem health of the Canadian prairies and the success of the agricultural industry, and that the impacts of ALAN on nocturnal pollinators must be better researched.


LED lighting to replace mercury vapour lamps.

Due to the negative impacts of light pollution on nocturnal pollinators in the prairies, it is critical that new approaches to artificial lighting be taken. “Saving dark areas” is the most effective measure currently available[27]. However, in areas that require lighting, light-emitting diodes (LED) lamps with longer wavelengths and without blue light should replace “mercury vapour lamps,” as insects are less disturbed[27]. Furthermore, increases in both “formal or informal green spaces”[27] that contain “shade islands” which protect “areas against light scatter”[27]. However, this still requires further study[27].

Rather than focusing on shielding light or altering light bulb types, reducing lighting to only where and when it is needed is the most researched and effective solution[28]. This can be achieved in part by setting “motion activation and/or automatic timers” on lighting[28]. Furthermore, limiting light pollution during mating and courtship seasons of various species could “greatly improve insect survivorship”[28].

Lastly, if lighting cannot be avoided, limiting its intensity will reduce adverse ecological effects by “reducing the trespass of direct and reflected light into unlit areas and reducing sky glow” [29]. This method would additionally “reduce energy consumption and carbon emissions,” offering a multitude of environmental benefits[29]. However, research needs to be done regarding the specific impacts of ALAN on species[29]. “Wavelengths,” “thresholds,” “timing,” duration,”“spatial extent” and the “social and economic requirements” for ALAN are not well understood[29]. Before proper solutions can be determined for limiting the impacts of ALAN on ecosystems, ALAN and its effect on species itself must be understood[29]. How specific species react to light pollution is not well-researched, including nocturnal pollinators. For this reason, it is clear that concrete, evidence-based solutions beyond limiting light pollution itself cannot be recommended with confidence. More research on this topic is urgently required as ecosystems continue to be degraded by artificial lighting and urbanization continues on an uphill trajectory.


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Seekiefer (Pinus halepensis) 9months-fromtop.jpg
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