Ecological and evolutionary impacts of an invasive supergeneralist pollinator on an ancient coevolutionary plant-insect interaction

Popular Abstract

Moth Wars: The Honeybee Strikes Back

In an ecosystem far, far away, there is a plant, a moth and a bee. Deep in the mountains of Sierra Nevada, the plant and the moth are living happily together. But then, an invading foe arrives, the invasive honeybee, that with the help of dark, mystic powers (humans) conquers all land they touch. Our little duo of plant and moth would not be the first to perish under the honeybee’s invasion. Will they follow the same path as countless others? Or will they persist? Let's find out!

Once upon a time, everyone was where they were supposed to be. Then, explorers and adventurers travelled far and wide, exchanging ideas and cultures. That is all fair and square, until stowaways emerged from the dark bottoms of ships and the deepest pockets of saddles. And left alone in a new environment the stowaways became kings and queens, ruling with true tyranny.

Sounds like a horrible nightmare, right? I truly wish I could tell you that this is all made up, but that is simply not the case. And the stowaways aren´t impoverished children or neglected princesses, they are rats, snails and pigeons. I am talking about invasive species that are spread by humans. These are species that have spread outside of their native environment and established in a new ecosystem. They are literally invading new territory, and wreaking havoc. Many invasive species flourishes because their natural predators are not around or there simply isn't any competition. That doesn't sound too good, does it? Especially not for the native species that are rare and specialized.

One such example is the plant called the Woodland star (Lithophragma bolanderi) and its specialized moth-pollinator Greya pollitela (that is so rare that it doesn't even have a proper, non-latin name). This specific pair, the moth and the Woodland star, lives together in the Sierra Nevada Mountains of California and they have been hanging out so much for so long that they are taking after each other. They have co-evolved, as the mossy academics says. The moth has taken it so far so that it cannot survive without the plant, but the plant isn't really as dedicated. In some areas, the plant seems to be doing just fine with very little of the moth around, instead being pollinated by other pollinators (that also visits other plants).

However, an extremely invasive species has landed in the Sierra Nevadas. It is no one less than the honeybee (Apis mellifera) that comes from Europe/Africa and is now used in the US to pollinate crops. But isn't the honeybee good? Is it even a threat? That is what I have been investigating! To do so, I measured how good of a pollinator the honeybee is for the Woodland star. This (sounds like it) is easily done: I took a honeybee, let it visit flower after flower of the Woodland star and then counted how many seeds that came from this. Then, to see if the honeybee already had changed the Woodland star, I also measured the nectar of the Woodland star. Nectar is a sweet liquid in the bottom of flowers that the plants use as a reward for pollinators that visit them. The Greya moth only lives on nectar when it is an adult. In other areas where the honeybees are invasive the native flowers have stopped producing nectar. Because why should they? They will get pollinated anyhow, as there is such an extreme number of available pollinators (hive after hive with honeybees).

My investigation shows that the honeybee has not affected the amount of nectar that these flowers produce. Instead, the nectar amount has evolved whether there is more or less of the moth. That makes sense, as the moth - the specialized pollinator - has been around the plant longer. When it comes to the seeds my study paints the picture in darker colours. The honeybee can pollinate the plant, which was kind of obvious (it is a pollinator, after all). In areas with more moths, the moths are better at pollinating the plant than the honeybee. Makes sense that the specialized pollinator is better than the newcomer, right? But in areas where there are less of the moth, my study indicates that the moth and the honeybee are equally good of a pollinator for a plant. Maybe this doesn't seem that bad, but let me rephrase it: The specialized pollinator that has evolved with the plant for 65 million years is as good of a pollinator as the invasive pollinator in some areas. And the honeybee is a competitive enemy. It has help (by us), after all. So how will the moth survive in these places?

Is it all over then? Time to hold a funeral and wave goodbye?
Absolutely not! We still have time. We always have; until the very last moth there is always hope. We still must investigate if the plant has evolved in relation to any of its other traits to the taste of the honeybee, so future studies are needed. And it doesn't seem like the honeybee has changed the amount of nectar of the plants, so it could have been worse. With the right conservational methods, like not having millions of invasive honeybees invading nature reserves, and further studies of the system we can save our moth and our plant. It's just to start, and we know where and when to start: right here, right now.





Master Degree project in Biology 60 credits 2024
Department of Biology, Lund University

Advisor: Magne Friberg, Pamela C. Santana & Lina Herbertsson
Department of Biology, Lund University

• author: Lundgren, Anna
• supervisor: Magne Friberg; Pamela Santana; Lina Herbertsson
• organization: Degree Projects in Biology
• course: BION03 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Biology and Life Sciences
• language: English
• id: 9185118
• date added to LUP: 2025-02-13 09:33:40
• date last changed: 2025-02-13 09:33:40