Moths, the often-overlooked nighttime pollinators, are facing the pressures of urbanization, and their resilience is being tested to its limits.

You may be surprised to learn that moths account for one-third of all pollinator visits to crops, flowers, and trees in urban areas. Recent studies have revealed that moths carry more pollen and visit a greater variety of plant and fruit crops than previously believed.

However, their population has declined by a staggering 33 percent in the past 50 years. This decline poses a significant threat to the plants and crops that depend on these insects for pollination.

As we strive to protect our natural ecosystems, the new findings underscore the vital role moths play in urban environments and the need for action to protect the vital insects.

The delicate balance of pollination

Pollination is a vital process that sustains the biodiversity and ecological balance of our planet. While bees have garnered significant attention for their pollination services, moths have been unjustly overlooked.

A new study conducted by the University of Sheffield has shed light on the intricate relationships between urbanization, bees, and moths.

The study revealed that bees and moths have distinct preferences when it comes to the plants they interact with. This means that urban environments need to foster the growth of plant species that are not only bee-friendly but also moth-friendly.

Bees are generally more resilient to urbanization due to their ability to feed on floral resources both as adults and larvae. In contrast, moths have more specific requirements, as they rely on nectar as adults and particular leaves to nourish their caterpillars and complete their life cycles.

Urban green spaces rich in flowers may be suitable for bees, but moths may require a diverse array of plants, such as nettles, to sustain their caterpillars.

As urbanization continues to reshape our landscapes, the repercussions on both bee and moth populations are becoming increasingly evident. Such disruptions threaten the delicate balance of these ecosystems.

The crucial role of moths

Despite their nocturnal nature, moths play a vital role in supporting urban plant communities. Accounting for a third of all pollination in flowering plants, crops, and trees, moths are key contributors to the health and vitality of urban ecosystems.

Their long proboscises — specialized mouthparts that allow them to reach deep into flowers — enable moths to access nectar from flowers with long floral tubes that other insects may not be able to reach.

Dr. Emilie Ellis, the lead author of the study, emphasizes the urgent need for greater awareness and protection of moths. She asserts that while bees have rightfully well-received attention in conservation efforts, moths have been left in the shadows.

“This research is important because it sheds light on the crucial role of moths as pollinators in urban environments. By recognizing their significance, we can better understand and conserve these often overlooked insects. Additionally, the decline of pollination networks due to urbanization has broader implications for ecosystem health, agriculture, and the maintenance of biodiversity,” she told ZME Science.

With moth populations facing drastic declines in recent decades, it is imperative that urban planners, policymakers, and gardening initiatives consider the specific needs of moths.

Incorporating diverse and moth-friendly plant species into our urban landscapes, for instance, can boost the resilience of both plants and insects in the face of the climate crisis and further losses owed to human encroachment.

Dr. Stuart Campbell, a senior author of the study, notes that pollination can be a tangled web of dependencies — and there’s so much we don’t know.

“Most plants depend on insects for pollination, but knowing which insects do the pollinating is actually a really difficult question to answer,” he said.

With approximately 2,500 moth species visiting flowers mostly at night, compared to around 250 bee and 59 butterfly species in the UK, the role of moths in pollination remains largely unexplored despite their huge potential.

The researchers used DNA sequencing on pollen stuck to night-flying moths after they visit flowers. They found moths are pollinating a range of plant species, many of which are unlikely to be pollinated by bees — but also vice versa, highlighting the two ecological engineers’ complementary pollination strategies.

This was no easy task though. A huge amount of sampling data had to be processed and the DNA metabarcoding techniques used to identify plant pollen involved a lot of cumbersome and painstaking lab work.

There were also many logistical hurdles that the researchers had to overcome.

“Identifying suitable sites for sampling that represented a range of urbanization gradients was a tricky task – especially when most allotment holders do not use email or even text! There were some frustrations when conducting fieldwork and having to time site visits in a precise order so that a specific allotment plot holder was around to give us access,” said Ellis.

Yet despite these setbacks, the effort paid off. And even though some community members weren’t as responsive as the team had wished, the researchers were generally well welcomed and the community was highly supportive overall.

“Working so close to the allotment holders was extremely rewarding. It involved countless cups of tea and easy chatting. My favorite moment was when we conducted our first nocturnal sampling for moths,” Ellis said.

“We set up light traps in the allotments and when we returned the next morning, we were able to show the allotment gardeners the diverse array of moths we had captured.”

“This was the first time many of them had seen the diversity of moths, of all different sizes, shapes, and colors representing a fascinating part of the urban biodiversity.”

Urban planning and moths

Urban planners have a crucial role to play in supporting the conservation of moths and other pollinators in urban environments, the researchers say.

By incorporating moth-friendly plants and habitats into urban landscapes, they can create welcoming spaces for these important insects.

“To date, only diurnal pollinators have been considered when testing the effectiveness of urban wildflower planting but we found that several common garden plants frequently planted for diurnal insects were also visited by moths, e.g., borage (Borago officinalis), nasturtium (Tropaeolum spp.) and comfrey (Symphytum spp.),” Ellis told ZME Science.

“Importantly, we find that both bees and moths were primarily visiting wild plants rather than crops, despite sampling in urban horticultural sites. Allowing the natural regeneration of wild species is important for urban bees, but our results show the importance of these plants for moths.”

Urban planners can consider the following measures:

1. Plant Diversity: Introduce a diverse range of flowering plant species that cater to the specific needs of moths. This includes plants with night-blooming flowers and fragrances that attract moths. By offering a variety of nectar sources, urban planners can provide a stable food supply for moths throughout their life cycles.
2. Native Plants: Prioritize the use of native plant species in urban green spaces. Native plants are well-adapted to the local environment and provide essential resources for native pollinators, including moths. They also promote biodiversity and support the overall health of urban ecosystems.
3. Reduce Light Pollution: Artificial lights at night can disrupt the behavior of moths, affecting their navigation and feeding patterns. Urban planners can work towards reducing light pollution by using low-intensity lighting, directing lights downward, and implementing lighting curfews in certain areas. This allows moths to navigate more effectively and carry out their pollination duties undisturbed.
4. Create Habitats: Design urban spaces that include moth-friendly habitats such as meadows, hedgerows, and wildflower strips. These areas provide shelter, breeding sites, and food sources for moths. Including diverse vegetation structures, such as tall grasses and shrubs, can offer different niches for moths to inhabit.
5. Avoid Pesticide Use: Minimize or eliminate the use of pesticides in urban landscapes. Pesticides can have detrimental effects on pollinators, including moths. Instead, encourage sustainable pest management practices that focus on integrated pest management, which uses a combination of biological control, cultural practices, and targeted pesticide applications only when necessary.
6. Public Awareness and Education: Raise awareness among the public about the importance of moths and other pollinators in urban ecosystems. Educate communities about the role they can play in conserving and creating habitats for these insects, such as by planting moth-friendly gardens and avoiding the use of harmful chemicals.
7. Collaborate with Conservation Organizations: Work together with local conservation organizations and researchers to gather data on moth populations and their habitat requirements. Collaborative efforts can lead to more effective conservation strategies and better-informed urban planning decisions.
   
   

By implementing these measures, urban planners can contribute significantly to the conservation of moths and other pollinators in urban environments.

This proactive approach not only benefits the insects but also helps to maintain the health and resilience of urban ecosystems, ultimately improving the quality of life for humans as well.

The findings appeared in the journal Ecology Letters.