Author:Anahi – Maryland Grows

Use De-Icing Salts With a Grain of Salt

January 10, 2025January 14, 2025Maryland GrowsLeave a comment

Winter Wonderlands are pretty to watch and enjoy with a lot of waterproof and warm clothes, but they also have their little challenges. For example, lots of snow can lead to a lot of compacted snow, that turns into ice, making Winter Wonderlands turn into Winter Slipperylands with all the accidents and issues that ensue. A common practice to reduce ice and its dangers is the use of de-icing salts. In this post, I want to talk about de-icing salts and how their excessive use can lead to unwanted consequences in our natural spaces and the organisms that inhabit them.

What are de-icing salts?

De-icing salts are most commonly sodium chloride salts, a non-food-grade version of the salts we use in our kitchens. Because high concentrations of sodium chloride in the soil lead to many environmental issues, alternatives exist, including potassium chloride, calcium chloride, magnesium chloride, and calcium magnesium acetate (CMA). Note, however, that although these alternatives are considered more environmentally friendly, they are just less environmentally harmful than sodium chloride.

All these salts generally reduce the freezing temperature of water, leading to water (ice) melting at temperatures at which it would have been frozen in the absence of the salt. Although this is a very simple and effective way of reducing or preventing ice formation, the intense use of salts leads to accumulation in the soil and water table, which is worrisome in many ways.

Photo of a large bag of de-icing salt on a walkway ready to be applied. — De-icing salts can degrade ecosystems when misapplied or applied unnecessarily. Photo: J. Jönsson (CC).

What happens if salts accumulate in the soil and water?

As we apply salts, they eventually dissolve in the water we are trying to de-ice, in moisture in the soil, and/or with precipitation. This salt then accumulates in the soil and in the water bodies into which the area drains. Both these processes can have strong effects on the health of the environment and the survival of many species.

Soils with high salt content are generally more toxic for plants (herbaceous and woody) that are not otherwise adapted to salty environments, leading to a negative effect on plant health and survival in regions where salts are applied intensely and regularly. For example, high salt content in the soil reduces the ability of plants to capture water and other nutrients and to tolerate low temperatures and drought. Further, when exposed to these high concentrations, plant tissues can also become enriched in salts, which can lead to cell dehydration and an inability to perform photosynthesis.

Reductions in plant diversity and health can also lead to other, more indirect effects. They can affect the ability of insects or other animals to find appropriate host plants to develop on and nest in and can lead to an increase in pest outbreaks, which are associated with reductions in the general diversity of the plant communities.

Besides accumulating in the soil, salts can also dissolve in the water and end up in the water bodies close to where the salts were applied. When salt use is very intense, it can lead to a significant accumulation of salts in lakes, streams, and rivers, which has demonstrated negative impacts on their organisms. Fishes, amphibians, insects, aquatic plants, and microorganisms display specific ranges of salt tolerance, and given that freshwater is not normally enriched in salts, the rise in its concentration leads to an inability for these organisms to survive under those conditions. Further, because some of the de-icing salts have phosphates, their runoff into the Chesapeake Bay can increase phosphate pollution and its negative effects on the survival of Bay ecosystems. Finally, it has been shown that high salt concentrations in water promote the survival of salt-tolerant organisms, one of which is mosquitoes. This can lead to larger mosquito populations in areas where there is intense and regular use of de-icing salts.

Does this mean that I can’t use de-icing salts anymore?

No, this means that because salts are not neutral to our environment, we should use them thoughtfully and cautiously. For example, shoveling or plowing snow before it becomes packed and icy is a great way to maintain ice- and salt-free spaces. Also, only applying salts when you’re sure that a storm will arrive is another way to reduce salt applications and its negative effects on the environment. Finally, if salts are needed, a good strategy is to apply them lightly and only to high-traffic areas. Don’t treat areas where there is no traffic. It has been shown that de-icing salt grains spaced 3 inches apart can readily and efficiently remove ice. Applying salts more heavily does not improve the de-icing action but increases salt concentration in the soil and water bodies.

Image: Lake Superior Streams Regional Stormwater Protection Team.

Finally, if you do need to use salts on a regular basis, consider planting native salt-tolerant plants. For ideas, refer to this Salt-Tolerant Native Plants page from Virginia Cooperative Extension Master Gardeners in Northern VA. These plants will grow in Maryland, increase the biodiversity of your green space, and, in some cases, capture some of the salts in the soil, further reducing salt runoff.

To learn more:

Maryland Department of the Environment: learn other strategies to reduce salt use.
U. of Minnesota Extension: learn how to prevent or adapt to high salt concentration in soils.
Chesapeake Bay Program: learn how de-icing salts affect the health of the Chesapeake Bay.

By Anahí Espíndola, Associate Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

How to Pay for a Pollinator or Native Plant Garden?

December 9, 2024Maryland GrowsLeave a comment

We hear a lot about the importance of establishing native and pollinator gardens. Indeed, these spaces provide many ecological services, from providing food resources and shelter for biodiversity to improving the quality of our soils and reducing water runoff. However, establishing these spaces requires at least some funds, which may or may not be available to many. In this post, I want to share some resources that can provide either funding or materials to establish such spaces in our properties.

Grants and rebates for native gardens and more

In our region, several grants exist that can provide funding to partially or completely cover expenses associated with the establishment of pollinator and native gardens. Some of these are state- or region-wide, while others are county or city-based. Below I share some of these, but because many of these grants are local, if you don’t happen to be in the regions where these are active, do a quick search on your favorite web search engine and I am pretty sure you’ll find one that applies to you relatively easily.

State-wide grant:

The Chesapeake Bay Trust has a state-wide program of mini grants which can be used to fund pollinator and rain gardens, among others. These grants provide up to $5,000 of funding for projects of different sizes, and the submission deadline is on a rolling basis. Applicants can be many different types of organizations, but it’s best is to check their current guidelines to know all the specifics about each year’s rules (these can be found directly on the grant website).

County-based programs:

Log for Prince George's County. It says Prince George's County Maryland Proud. Get to Know Us.

The Rain Check Rebate Program is offered by Prince George’s County and includes monetary support to establish rain gardens (which can also act as pollinator gardens) and other features (e.g., rain barrels, permeable driveways) that will increase water retention and reduce water runoff. Through this program, private property owners receive up to $6,000, and commercial properties, associations, and non-profits receive up to $20,000. The application process is relatively straightforward and simple, and the reimbursements are processed relatively quickly.

The non-profit Unity Gardens provides grants to fund the planting of native gardens (including rain and pollinator gardens) in Anne Arundel County. These grants are open to the public and range from $1,000 to $3,000 (depending on the type of project). Applications open in the fall and spring, but the documentation and guidelines for applications are accessible all year round. Check the website to learn more.

City-based grants:

The city of Ocean City, MD offers mini-grants for local property owners. These grants aim to support the establishment of pollinator gardens and other native plant gardens within the boundaries of the city. The grants provide up to $5,000 of funding, and applications for some of these projects are open year-round, while others have specific deadlines. Check the grants website to learn the specifics about each of these programs.

Free plants to establish gardens

Not every organization or institution has funds to establish grants such as those presented above. However, many cities and other non-profits give away plants at different times of the year. Generally, these giveaways happen in the spring and the fall, when plantings are the most likely to succeed. Below, I’ve included some examples for you. However, note that many local events happen everywhere, so if you’re interested in these giveaways, I strongly recommend that you search or keep an eye out for announcements in your area by the end of the winter or the summer.

Free native garden kits and plants:

The organization Nature Forward provides free native garden kits which include garden designs and the actual plants that go with them! Because this is directly associated with the Anacostia watershed, the geographical range of this program is restricted (check the map on their website). The sign-up is currently full, but you can still add yourself to the waitlist.

Sometimes, native plant nurseries decide to organize such giveaways. This is the case of Bona Terra in Friendship, MD, which created a “plant grant,” basically a registration-based plant giveaway. The giveaway can be for individuals or groups, and registration is required to receive either individual plants or trays. Check out their website to learn more and access the forms.

City-based plant giveaways:
Several cities provide free plants to their residents. An example is the City of College Park, which has been giving away native plants that support pollinators throughout the year at markets and public events. Check with your city or local government to see if such programs are available to you… and if they are not, you can always ask for them to be established!!

Leave the Leaves, All While Not Making Your Neighbors Mad

November 13, 2024Maryland Grows4 Comments

With the fall season we are starting to see a lot of articles talking about the massive ecological and soil quality benefits of leaving leaves, stems, and sticks in our green spaces. As a biologist, I understand why doing so is indeed the right thing to do, but I often face pushback on this topic from people I mention this to through my Extension work or just in my neighborhood. There are of course many barriers to adopting such practices that I have heard people mention, but one that comes up often is the one that involves social or peer pressure. In other words, how to adopt this without making your neighbors mad? In today’s blog, I want to give some pointers to avoid conflict with (and maybe even convince) neighbors who may be less convinced than you on these practices.

Some fall practices that we know are good for biodiversity and your soil

I do not want to talk yet again in depth about these practices (you can read more about it in these other articles if you want to know more):

But I want to just quickly state some of them, so you know what I am referring to throughout this article. I feel that there are three major types of practices that can be adopted for protecting pollinators and other insects during the winter: leaving the fallen leaves on the ground, not pruning certain pithy stems to the ground until the Spring, and making branches and stick piles in sections of your green spaces.

For all these practices, common sense should be used when deciding whether to adopt them or not (e.g., if you are in a fire-prone area, perhaps making huge wood piles is not a good idea), remembering that these are indeed all practices that have been shown to improve biodiversity in our green spaces.

Fallen tree leaves have been spread about fours inches deep in a wide circle around the base of a very large tree in a backyard. Stones are used to create the circular perimeter and contain the leaves. — Piling the leaves around trees is a good way to retain them in the green space, all while giving an impression of “tidiness” to the yard. Photo: D. Mizejewski.

How to avoid “leaving the leaves” look messy?

So, you want to participate in the ”leave the leaves” action, but you still want to make clear that somebody is actually taking care of it. What to do?

If you have the option to ignore others’ opinions, you can just leave the leaves where they fell and go on with your life. 😊 That said, this may or not apply to most people.
You can pick certain areas of your green space to leave the leaves, but rake other areas. Perhaps you want to have the areas that are less exposed to people’s eyes be those selected for leaving the leaves. This will show that your leaving the leaves is purposeful and not just a lack of care.
If you have trees on your space, you can also decide to pile up the leaves around trees. This will provide shelter to insects and other small critters, provide mulch for the tree, and sign active care of your space.
A problem I sometimes hear about is leaves blowing over to another person’s yard or space. To avoid this, you can use plants to line/fence your green space. These plantings will have the positive effects of both allowing your leaves to stay on the ground, while minimizing “spill overs”.
Explain what you are doing. You can tell your neighbors about what is going on, and even put a sign up to clarify what is happening (if you want to go “fancy”, the Xerces Society has a neat one).
A thing NOT to do if you would like to retain arthropod diversity but also make the leaves look “tidier”, is mow them over. This has been shown to kill the insects that were preparing to overwinter in them. ☹

A "Pollinator Habitat" sign is visible in this part of the landscape where fallen tree leaves are spread about four inches deep in a garden bed. The sign explains that the leaves help overwintering pollinators survive the winter. — Displaying a sign that explains that some activities in our green spaces are creating pollinator habitat can go a long way. Photo: C. Corner.

How to leave the stems without issues

Another practice shown to support stem-nesting insects (including several bees) is not trimming pithy stems all the way down during the fall.

If you have the option to ignore others’ opinions, you can just leave the stems and go on with your life. 😊 That said, this may or not apply to most people.
As for the leaves, you can select sections of your space where you decide to implement this. An extension of this idea is that perhaps you can reconsider where your plantings are, so you have the pithy plants (e.g., brambles) in areas that you know are not going to be looked at all the time.
You can also decide to trim the plants down to some extent (about 2-3 ft from the ground) but not completely. This will show that you are taking care of the plants, but that you actively decided not to trim them all the way down.
Letting people know what is going on is always a good thing. You can add a little sign to tell people about what you’re doing and why, and/or you can talk to your neighbors to let them know.

2 foot to 3 foot lengths of tree branches and sticks are piled together in an out-of-the way spot in the yard to provide habitat for insects and other small critters. The pile is surrounded and held up four medium-size sticks stuck in the ground vertically at the corners of the pile. — Make your wood and stick piles look “organized” by defining spaces in your yard that you allocate to creating those biodiversity habitats. Photo: Natural History Museum.

Making a pile of sticks and wood without scaring people

Making stick piles is a very good practice to retain biodiversity in green spaces. That said, people can feel like a pile can look untidy, and even some cities may have some regulations about what type of pile may be OK versus not.

If you have the option to ignore others’ opinions, you can just make a pile and go on with your life. 😊 That said, this may or not apply to most people.
You can restrict the pile clearly to a specific area of your space, and make clear that you have actively decided to make one and are taking care of it. This is to sign that this is not just some brush you left around after you trimmed some plants, but actually a specific green space feature you are trying to build.
You can make it look cute. Check out this other blog, A Brilliant Fall Banquet, where some ideas are given.
Information, information, information. Let people know what this is and why you are doing it. And also, if there are some afraid of snakes or fires, make sure that the area you live is not known for its high fire or venomous snake danger (you can inform yourself about these topics online or ask an Extension agent; e.g., Venomous Snakes of Maryland.

Fear of Insects: Understanding Our Fears to Help Conservation

October 7, 2024October 4, 2024Maryland GrowsLeave a comment

Over the years, I have been involved in several initiatives that aim to summarize and translate our knowledge of insects, biodiversity, and some of the ecological services they provide, so that it can be understood by policymakers and the general public to inform decision-making and help ourselves and the living planet. The overwhelming take-home of these works is that insects (and biodiversity in general) are declining at a very fast speed, with very negative consequences on our ability to survive in a less diverse future world. When taking on these knowledge translation activities, however, there is one topic that keeps coming back: people are scared of insects (and wildlife, generally)! Then, how to promote the protection of something we’re scared of and disgusted by? In this blog post, I decided to embark on a mission: to help us understand our fears and recognize how they may be affecting our ability to protect the natural world, and what we can do to turn the wave on this to the benefit of all. Keep reading; I promise I will not shame or judge anybody 😉.

a beautiful collection of colorful beetles on display — Insects (only beetles shown in this picture) are the most diverse and abundant group of animals and play central roles in maintaining ecosystems. Photo: “Insects Unlocked” Project, University of Texas at Austin

The biodiversity crisis – a real problem with real consequences

There is now massive evidence that biodiversity is being lost. This is true for many groups of organisms, but here I want to focus on one in particular: insects. Why? Insects are the most diverse and abundant group of animals and, as such, they are deeply embedded in the running of the natural world. This diversity and abundance turn insects into sorts of ecosystem architects and janitors. They pollinate, feed on other organisms, degrade organic material and make nutrients available for others to consume, disperse seeds, and much more! Beyond the importance of all this to all organisms, these functions, in particular, are central to allowing us to produce food, maintain soil quality and balance, sustain rich ecosystems, and naturally control pests. Promoting insect protection, however, often faces a big challenge: low traction and low engagement, given the fear of insects.

Fear of insects – an encounter between humans and our natural world

Fear and disgust of insects is a very widespread feeling, especially in developed countries and urbanized societies. Although it is understood that the presence of fear or disgust usually develops as a protection system against potential dangers (and there are a few insects that we need to be wary of!), the extent to which fear of insects is present goes beyond what would be needed to properly protect us from a potential danger… And this is starting to have an impact on our ability (and willingness) to protect this important part of biodiversity. How does this work?

People have been studying fear of insects for a while and their findings are really interesting (you can read some neat reviews on this in Current Opinion in Insect Science and Science of the Total Environment). For example, researchers think that this extreme fear of insects may have evolved as a sort of “smoke alarm” (a loud but very non-specific type of alarm). In fact, there is reason to have respect for some insects, since some of them can lead to painful and potentially fatal bites/stings or can carry diseases. The presence of fear against those insects thus makes sense, because they lead to protecting our health. However, there is a balance to be found between responding to a real danger (e.g., hitting a hornet’s nest) or to an inexistent one (e.g., encountering a moth). Because the cost of responding to an inexistent danger is not super high in this case (like for a “smoke alarm”), then an extreme response to any insect can simply appear and spread through human populations. In this case, the only way to “tune” such an extreme response is to learn how to recognize harmful from non-harmful insects, something that many programs (including this blog! 😊) try to do.

Going back to biodiversity conservation, it is illuminating and empowering to realize that the simple action of learning can lead to increased conservation actions… learning when there is reason to stay away from insects or not leads to an appreciation of their huge diversity and more engagement in their protection. Some ways to do this involve using formal learning methods like courses, books, or guides, but also some more interactive ones, such as citizen science projects like iNaturalist or group-specific projects (e.g., the fireflies atlas).

a monarch butterfly — Rearing insects at home (like this monarch butterfly) can be a fun and learning-rich experience through which our appreciation for insects can grow and our fear decrease. Photo: Tim and Selena Middleton (CC)

Another way this fear develops is through social learning. As humans, we can learn through both direct experiences and social interactions. In fact, studies have shown that a large part of this establishment of fear or disgust in humans is learned through interpersonal interactions and not innate. For example, people have discovered that before age 5, most kids are not repelled by most insects or arthropods, and that the level of fear and disgust kids show is correlated with the fear their caretakers have of them. We see this a lot in our work. The Insect Zoo of our Department at the University of Maryland (UMD) is a very popular attraction at outreach events such as UMD’s open house event, Maryland Day. When participating in this event, we see time and time again how kids are not afraid of petting insects or other arthropods, while their parents are grunting and screaming in the background at the simple sight of one. Dealing with this learned fear is a bit trickier because it requires caretakers to become more aware of how they can imprint fear in kids. However, seeking to better understand and recognize insects and their potential (or not) of harm can help break this cycle. Rearing with kids insects like butterflies can be a great positive experience for all, and can happen in pretty much any house. Engaging in learning activities with kids, such as through insect summer camps (UMD has a super-fun Bug Camp!), is another way to restrict the establishment of this type of fear.

a women holds a spider in front of a boy at the insect petting zoo — Petting zoos and other exhibits that feature insects and other arthropods can be a great way to engage kids and adults in healthy and safe interactions with organisms they may fear. Photo: UMD Department of Entomology.

Finally, there is another way this fear may appear. We said above that this sort of fear is more common in urbanized societies. It is thought that a part of the fear may come from a lack of exposure to biodiversity. Under urbanization, there is indeed a removal of contact with natural environments, with people becoming less and less exposed to wildlife. When insects are seen (often in the house), the other two types of fears may pop up and join forces to, on the one hand, trigger repulsion or fear and, on the other, increase avoidance of natural spaces that could contain “bugs.” The good news is that even in cases when there are few natural spaces available close to home, there are indeed many ways people can be exposed and establish positive experiences with insects. Visiting exhibits where insects are featured is one of these ways. You can learn about many other ways in this cool article: Teaching About Insects in a World Afraid of Bugs.

Community Partnerships for Pollinators

September 9, 2024September 9, 2024Maryland GrowsLeave a comment

When we talk about pollinators and how to help them, we have often focused on what plants can support them, who the pollinators are and some traits of their natural histories, or how to create habitat for them. However, besides individual actions that people can take to help them, other options that are very impactful also exist. In today’s post, I want to present one that involves a combination of community and institutional collaboration: the Bee City and Bee Campus USA certification.

What are Bee City and Bee Campus USA?

The certifications called Bee City and Bee Campus USA are labels that cities and campuses, respectively, can receive from the Xerces Society if they commit and act to protect pollinators and their habitats.

For those who have never heard of it, the Xerces Society is an organization interested in the conservation of invertebrates and their habitats. Over the years, it has not only become recognized as an important conservation organization but also has developed impactful and meaningful ways to support research on the topic and engage the population and institutions (and many other stakeholders!) in conservation actions that are within their reach. The Bee City and Bee Campus certification is one of those initiatives.

How does it work?

Once cities and campuses decide to receive the certification, they need to submit an application and pay an annual fee. By doing this, they commit to taking specific actions that will lead to the conservation of the thousands of species of bees and other pollinators that exist in the USA, as well as their habitats. The certification is revised every year, and if the institution or city is not performing following the set standards, the certification is not renewed. Today, many institutions and cities across the USA have joined the initiative and are actively following their commitments. If you are interested in knowing if your community is a part of the initiative, an online database exists where it is very easy to search for participating members using addresses or names.

*The Bee City and Bee Campus USA website has a neat tool to search for current members across the USA.*

The commitments that institutions and cities make when they join the initiative involve the establishment and promotion of specific actions. These actions combine institutional and community involvement, which requires the creation of an active committee that will be responsible for running programs that will help the institution reach its goals. Once this committee is created, the group is responsible for proposing and running actions within the reach of the institution. The actions need to be oriented towards promoting the protection of pollinators and their habitats through what can be generally categorized under education, direct action, community involvement, and potential revision of standard operating procedures or policies.

The Xerces Society doesn’t just provide a certification. In fact, it has over the years produced a massive number of tools that help cities or institutions understand how to run the programs. Regular webinars are organized, fact sheets distributed, general manuals and other documentation shared, and a network of participating cities established, allowing for a “hive mind” to develop.

What can some of these actions be?

Education programs involve the distribution of information among the population (for cities) or members of the campus (for campuses). This information can take many different forms but generally educates about the diversity of pollinators, the importance of promoting habitat, the key contributions of pollinators to the well-being of the community and the environment, ways to protect them through individual or joint actions, creating information guides and fact sheets, and more.

Direct actions often require involvement of the institution in establishing habitat for pollinators, distributing resources that will allow the community to protect pollinators (e.g., distributing plants, seeds, other habitat resources), actively reducing the use of pesticides, etc.

Community involvement is promoted by any program that the institution could build to allow its members to come together and engage in projects larger than any individual would be able to take on by themselves. There are many ways this can be done, but some examples are the creation of student-faculty groups that could run research projects that can then be used to inform policies and conservation actions. Others could be the establishment and promotion of institution-wide actions, such as the promotion of months with no or reduced mowing (e.g., “No-Mow Month” initiatives), the running of citizen science projects (e.g., through iNaturalist), establishing days centered around the celebration and recognition of pollinators and their services to humans and the environment (e.g., coordinating Pollinator Week activities), and others.

Finally, one of the unique reaches of this initiative is its ability to promote changes of policies and procedures regularly used by the institution/city. Under this program, the committee should propose and the city or campus implement at least some adjustments in the way the institution in question is run. For example, Integrated Pest Management (IPM) plans should be created and used if they are not already in practice, Code can be adjusted to facilitate the planting of native plants, monetary or other incentives can be offered for the creation of pollinator habitat, and more.

I would like to have my city/campus join; what do I do?

If you’re interested in having your campus or city join the initiative, first go to the Bee City/Campus website and check out the requirements and some of the how-to webinars. Along with this, for cities, you may want to get in touch with representatives and present this as a request. If you’re on a campus, get a diverse group of members together and propose this to leadership. If you still feel overwhelmed by this and feel you still have a lot of questions, reach out to Bee Cities or Bee Campuses in your area and ask them for help! They will be more than happy to explain what their path was and how they came to be, so you can also become part of the national initiative.

Heat Waves Affect Pollination Too

August 5, 2024March 7, 2025Maryland Grows2 Comments

Having grown up in the plains of Argentina, surrounded by large rivers, swamps, hot summers and humidity, I can attest that I am pretty “heat tolerant.” While others complain of the heat, I just enjoy the “embrace” that a hot day gives me. The heat in the last few weeks, however, was even too hot for me! And while I was trying to cool down, I was also worrying about what I was seeing outside: the plants, the insects, the soil… all suffering like me. And because I happen to work on some of these topics, I also knew that it wasn’t just that some plants were drying out; this heat wave (and drought) is also affecting the whole network of interactions that happen around us. So, today let me tell you a bit about how these extreme heat waves affect one of those interactions – pollination – and how what we do in our green spaces can help reduce some of those effects to the benefit of all.

Pollination is affected by heat in more ways than we usually think

Extreme heat waves and droughts such as those we have been experiencing recently affect not only us but also the ecosystems that are exposed to the heat. One of the most evident effects we may see is how much plants suffer. Just look outside and you will see hanging leaves, tiny flowers (if any), and a lot of dry material. As with all organisms, plants also have optimal temperatures at which they can survive; if the temperatures and water availability change, important body functions will not be able to be performed, and even some central parts of their bodies will fail.

In plants, one of those functions is photosynthesis, the process by which plants can make sugar using the energy of the sun, carbon dioxide (CO₂), and water. This process is the way the vast majority of plants make their food. If the process is disturbed, the plant will have less energy available to survive, grow, and reproduce. It turns out that extreme heat and water needs affect the ability of plants to photosynthesize. The consequence of this is that, suddenly, the plant has less energy available, needing to enter a sort of “survival mode.” Along with this, the heat affects several protection systems that the plant has, especially those that protect the DNA (the genetic material), as well as the functioning of the machinery that literally “builds” the different parts of the plant. This inefficient protection leads to the DNA being damaged and the plant being poorly “built”, making that part or the whole plant start malforming.

plants with browing stems due to drought — *During the heat waves, these beebalm plants had a rough time, with almost no flowers produced and a lot of the plant material simply drying out. Photo: A. Espíndola*

In relation to pollination, we know that these changes explain why, under heat and water stress, plants become smaller in size, have tiny or no flowers, lose a lot of leaves and biomass in general, and have parts that start to look “funky.” The changes in the energy availability make the composition of some secretions change as well, such as with nectar, which tends to be less rich in sugars and less abundant (especially when drought is experienced).

a plant with smaller than usual yellow flowers — *These black-eyed Susans were able to make flowers this year, but they are significantly smaller than usual! Photo: A. Espíndola*

As said before, flowers tend to be small or absent, but even when they are present, the petals and reproductive organs are often misshapen, with the plant becoming unable to produce seeds and fruits. Finally, and super importantly for pollination, a major effect of this is that heat affects pollen quality, reducing the amount that is produced and often making the pollen inviable… meaning that even if the pollen was to land on a stigma, it would likely not germinate, and fertilization would not take place. This latter point is worrisome because it means that even plants that are not animal-pollinated (e.g., plants pollinated by wind or water) will be unable to produce seeds and fruits.

Pollinators suffer the heat, and that affects their survival and pollination

Pollinating insects are also affected by the heat, and some of these effects are related to the same facts we mentioned for plants. On the one hand, like plants, pollinators also have their own DNA and “body-building” machinery that is disturbed by heat. Some of the major consequences of this are that their development can be either interrupted (the larvae or pupae die off) or interfered with. If the development is interfered with, we see malformations in different organs, such as the wings, legs and mouth parts, and particularly in males, of reproductive organs and sperm. Further, extreme heat appears to affect bee neurological abilities, with their behaviors and memory affected, as well as changes in the way they visit and manipulate flowers, which in turn makes pollination more difficult.

Along with these issues, because of the changes in nectar quality and quantity associated with plant heat stress that we mentioned earlier, the pollinators’ nutrition is also negatively impacted, which further amplifies the developmental, behavioral, and neurological problems mentioned above. Although all insects experience these types of effects when they are exposed to excessive heat, some of them are a bit better at protecting themselves from it. For example, it seems that social bees suffer less from excessive heat than solitary bees, while bees that nest in the ground or in stems tolerate it better than those that nest in cavities.

Here’s what you can do to help mitigate the effects of heat and drought

Although we can’t instantaneously reduce the heat, we can assist plants and insects to better tolerate these conditions. A very effective strategy is diversifying our green spaces, which can lead to local reductions of heat, either through the shade created by the plants and/or the reduction of the excessive presence of bare soil. In particular, this same plant diversification can also increase the amount and quality of foods available to pollinators during these heat events: more diverse plants mean more different types of possible nectar sources available to pollinators, which in turn would increase their chances of survival and boost their health.

If possible, one can also water plants in our green spaces. By doing this, the water stress will be reduced and at least part of the symptoms displayed by plants will also be mitigated. If one were to do this, it is important to water with a slow flow and for a longer period of time, so the water can properly enter the soil. Along with this, using mulch or letting the fallen leaves cover the ground will also help retain some of the soil humidity, all while also providing shelter to insects.

And besides diversifying and supporting our green spaces, it is thoroughly accepted that the current extreme heat and drought events we are seeing are a consequence of climate change. Starting to reduce our and our communities’ emissions is another way to help plants and pollinators, pollination, and at the end of the day, the production of many of the foods we depend on. You can check out this awesome website by Dr. Sara Via and learn about what we can all do, and even sign up for super informative seminars that help you become familiar with and start acting on some of these topics.

Support Our Insects at Night

June 12, 2024June 11, 2024Maryland GrowsLeave a comment

We tend to think about protecting our insects when and where we see them. This is perhaps why we may have a higher propensity to think about protecting pollinators we can see flying around rather than organisms that live in the darkness of the soil or hidden in the leaf litter. In today’s post, I would like to bring some attention to other groups of insects we may tend to forget about but which we can also help protect: insects that are active at night.

Don’t insects sleep at night?

Although many insects are generally less active at night due to the lower temperatures and their inability to move when the temperatures drop below a certain threshold, many insects are adapted to being active at night. For example, if they are pollinators of nocturnal or dusk-flowering plants such as several moth species are, they will be active when darkness falls. Other insects are active at night as predators, or at certain times of the season looking for mates and egg-laying sites. For all these insects, the absence or reduced presence of light is important for allowing them to take on what they need to do to survive and/or reproduce. For this reason, the presence of artificial night lighting in our outdoor spaces, especially in the warmer periods of the season, can interfere with these insects, leading to potentially very negative effects.

How can outdoor night lighting affect nocturnal insects?

Insects can be perturbed in different ways through outdoor night lighting. One of them is its potential interference with their temporal rhythms. In fact, like most animals, insects use light-darkness and the presence of certain night sky cues (e.g., full moon) to regulate their developmental cycles and perceive the progression of the season. The presence of supplementary lights during the night hours can lead to altered developmental cycles, making them longer or mismatching those of organisms belonging to the same species. This can lead to the insects missing their optimal mating times, losing their ability to forage on specific plants, or properly preparing for the arrival of colder nights as the season progresses.

a string of lights is hanging over a a garden firepit area at night — The use of often non-essential lighting, such as light strings and other nocturnal accent lights in our spaces, can negatively affect the development, survival, and reproduction of many nocturnal insects. Photo: P. Danilyuk (CC)

Another issue that artificial nocturnal light can produce relates to the spatial disorientation of nocturnal insects. This can occur when insects are attracted to nocturnal light sources instead of moving towards their optimal habitat. This can lead to increased predation in those areas (the insects become more exposed to being seen), as well as their spending valuable energy by spending time in an inhospitable region. Further, disorientation can happen in a more indirect way by the light’s interference with the patterns present in the canopy. In fact, many insects have been shown to use the contrast pattern of the canopy and the sky to navigate and identify optimal habitats. The presence of nocturnal artificial lights can lead to the disappearance or a stark modification of that contrasting pattern, interfering with their ability to find their way in the ecosystem and decreasing their ability to find a proper habitat for their survival.

two fireflies light up at night — Some insects like fireflies use bioluminescence for inter-species recognition and mating. Photo: T. Ota (CC)

In some cases, the presence of nocturnal artificial light can interfere with mating and intraspecific recognition behaviors. Many groups of insects, such as fireflies and glow worms, use light cues to attract and recognize each other. In regions such as ours, where fireflies represent such an important part of our ecosystem, the use of outdoor nocturnal artificial lighting can interfere with the finding of mates and can potentially lead to much reduced abilities to reproduce and sustain populations.

What can we do to reduce this type of nocturnal pollution?

The obvious answer to this question is that if we want to reduce this type of pollution, our best bet is to turn off non-essential outdoor night lights, in particular during times of the year when insects are active. Doing this may actually save us some money, but also will allow us to support a higher diversity in our area, all while potentially letting us appreciate even more the nocturnal activity that may be present in our region. For example, doing this may make it easier to support fireflies and participate in their conservation, but can also support the reproduction of plant species that depend on nocturnal pollinators.

If leaving lights on is unavoidable, one should consider the intensity that is being used. Can the light be dimmed to a lower intensity? Could it be filtered to display a color that is less disruptive to insects? The Xerces Society has put together a really neat guide on this (Firefly-Friendly Lighting Practices – PDF), and I strongly encourage you to consult it if interested.

Finally, another way we can contribute to reducing unnecessary night lighting is by engaging in our communities. Initiatives such as DarkSky can help with this, both promoting best practices at the community level and engaging in conservation through community certification programs that are conservation-effective. You can learn more about these nocturnal conservation programs here.