Of Flies and Phenomena (Drosophila Reintroduction)

“I got your back, Sebastian. For the cause!!!”

Have you ever witnesses some sort of natural phenomenon? It doesn’t have to be super rare; it could be Manhatten-henge, it could be the Queensland Morning Glory, a solar eclipse, an aurora, it could even be a rainbow. It doesn’t matter what you experienced, what matters for this post is that these phenomena only occur under certain conditions.

One way that a decade plus of active native reforestation has changed my perspective is I see native Hawaiian forest as less a place to visit or a thing to restore but rather as a system of interdependent relationships. One doesn’t go to a specific site to see native forests or post a 10 min YouTube rebuild video with a fully intact native forest at the end. To me, if you have the ongoing relationships between the soil, between the native pollinator, between the native seed disperser, etc, and those relationships are strong; you may have a chance to see native forests develop. In some ways I see native forests currently behaving more like an ephemeral natural phenomenon. If those conditions are in place the phenomenon of native forests can happen. What better way to see this in action than being able to restore one of those relationships with the release of an endangered native fly, Drosophila hemipeza.

Native Hawaiian insect biodiversity is something that I haven’t really detailed here at Studia Mirabilium. But the whole of the native Hawaiian microfauna is just as interesting and strange as its charismatic megafauna. It wasn’t just ducks and geese evolving into weird and wonderful forms.

The native picture winged flies in the genus Drosophila and Scaptomyza are thought to be descended from perhaps 1 or 2 colonizing species. These have undergone a spectacular radiation and there are currently thought to be roughly over 400+ different native species that evolved here in Hawai’i. The native picture winged flies have evolved interesting differences in mouth parts, lekking behavior, and host plants for egg laying.

Apologies for the grainy photos, but these taken from my iPhone are of the endangered species Drosophila hemipeza. It’s hard to tell the scale for the photos but they are much larger than the common fruit flies (Drosophila melanogaster) you see in your house; D. hemipeza is just a bit smaller than a housefly. It’s from a special day for these flies when they were reintroduced to native forests. This species is a main focal point of extensive efforts by scientists to help in its conservation. They have, through research and effort, developed a way to captive rear this species to help ensure its survival. A big part of the challenge is that many of its host plants (Clermontia, Cyanea) are themselves highly endangered.

That’s where we come in. Our efforts to rehabilitate this part of native forest have really helped with the lobeliad populations, especially Clermontia kakeana. Our fairly secure native forest with its robust population of host plants makes it an appealing area for reintroduction.

The cavalry has arrived!
Drosophila hemipeza on Cyanea crispa

Here I am releasing several D. hemipeza on a possible host plant, the endangered Cyanea crispa. I would have to imagine that this relationship between fly and host plant has not been seen in a long time.

This brings me back to my earlier thoughts on rare phenomena. Is seeing an endangered native fly on its endangered native host plant something you see just once in a blue moon? Right now, given the headwinds native biota face, it really feels that way. I have mentioned before that we reforesters are basically keystone individuals; take us out of the equation and the forest can revert back to non native fairly quickly. The conditions that allowed the mirage to shimmer disappear, and it can literally fade before our own eyes. 12 years of work in the same forest and we have seen how areas ebb and flow with our activities. The conditions are not conducive yet.

But what gives me hope is while, yes we are keystone individuals, we must also remember that we are placeholders. We are doing these roles until hopefully the native species can return and continue those roles as they have done for millions of years. Whatever role these flies play helps the forest ecosystem as a whole. We will happy cede the role we play to them. The more relationships become reconnected the more the phenomena can stabilize. Wildfires started in adverse conditions are easily put out and would be just another phenomenon rarely seen. But they have positive, self reinforcing feedback loops. Once it gets going it can take a lot of effort and resources to put a raging wildfire out. Our hope is that as the forest gets healthy, as the relationship become stronger, as the conditions become more suitable, the mirage that is native Hawaiian forests today stabilizes and becomes a raging biological wildfire tomorrow that is just as difficult to extinguish.


Drosophila hemipeza 5 year Review

Recovery Outline for 12 Hawaiian Picture-Wing Flies

DLNR January 2023 Press Release

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