Help the Yoder Lab map and study the activity of Joshua trees’ specialized pollinators, yucca moths!

This is cross-posted from the Joshua Tree Genome Project website. Yoder Lab grad student Pryce Millikin needs your help observing Joshua trees to figure out where their specialized pollinator moths are active. Skip down to the three steps you can follow to help us, or read more background here:

Joshua trees need our help. These icons of the southwestern desert face mounting pressures from climate change, development, and wildfires. Conservation organizations and agencies are working hard to make sure the trees have a future by preserving Joshua tree woodlands and replanting damaged populations. But there are important things we still don’t know that could be important — like how Joshua trees’ specialized pollinators will fare in a climate-changed future.

Yucca moths (Tegeticula antithetica and T. synthetica), exclusively pollinate the eastern and western Joshua trees (Yucca brevifolia and Y. jaegeriana). The moths emerge when the trees are flowering to meet and mate in the flowers. Each female moth then gathers pollen in specialized mouthparts and carries it from one flower to another, where she lay eggs inside the floral pistil and pollinates the flowers by stuffing pollen into receptive tip of the pistil. As pollinated Joshua tree flowers develop into fruit, the moth eggs inside them hatch, and the moth larvae eat some of the seeds developing inside the fruit before tunneling out and burrowing into the sandy soil to form a cocoon.

Joshua trees and yucca moths cannot survive without each other, so protecting Joshua trees requires us to protect their pollinators. However, we don’t understand how the moths know when the trees are flowering. If they emerge in a year when the trees don’t flower, they have nowhere to lay their eggs — and the trees only flower about once every four years. We can identify the weather that cues the moths to emerge by tracking where they have been active in any given year, and comparing weather in times and places where the moths are active to times and places where they aren’t. Because the moths are the trees’ only pollinators, we can track their activity by tracking Joshua tree fruit.

That’s where you come in! We need more observations of Joshua trees bearing fruits and flowers to be able to figure out what is going on with these moths. We need to know where the trees are flowering and where they are making fruit — when the moths were present. Fortunately, there’s a app that will let anyone contribute their own observations of Joshua trees to help this work.

There are three main steps to pitching in on this project:

1. Download iNaturalist

The iNaturalist app is available for both iPhone and Android, and you can even share observations (with dates and location information added) directly from inaturalist.org. Go there to set up a profile and install the app.

2. Join our project

When you’re set up on iNaturalist, navigate to the project page for our study of Joshua trees and their pollinators, and click “join”. This helps us organize records for research. Joining the project will let you send us your observations directly, and give you the option to get updates about our research, and how to help improve the data we get from iNaturalist.

3. Observe some Joshua trees!

Next, go make some records of Joshua trees using the app. This might be right in your backyard or neighborhood, if you live in the Mojave Desert, or maybe on a Spring Break trip to Death Valley National Park or Las Vegas. We especially need records in the northwestern Mojave, between Lancaster and Lone Pine, California; in Nevada; and in western Arizona. If you see a Joshua tree with flowers or fruits, take a photo with a clear view of the flowers or fruit, then upload it to the app. When you do, you can use options in the app to mark that you see flowers or fruit, and to contribute it directly to our Joshua Trees and Yucca Moths project.

You can also upload photos of trees with no flowers or fruit — they are still really cool looking, and we can use that data, too!

4. (Optional) Come back later to see if those flowers turned into fruit

If you live close to the place where you make your observations, you can come back a few weeks after seeing flowers to find out whether they’ve become fruit. That means yucca moths have been at work! You can take a second round of observations, with photos of the fruit, and upload them to iNaturalist again. It’s not just allowed, but encouraged to provide multiple records in the same location, even of the same tree, to let us track the whole process of flowering and fruiting.

With all these observations, we can train machine-learning models to predict what weather and climate factors are causing the trees to flower, and what factors cue the moths to know when to emerge and find flowers. The trained models will help us understand if the trees and the moths may fall out of sync with each other as climates have changed, which could threaten the long-term stability of both these species. We have to understand what is driving the life cycles of these moths to ensure we can protect them.

The more observations we have, the better our predictions will be! Thanks in advance for your help, and we’ll hope to see you in the iNaturalist app.