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Nicotiana attenuata

Nicotiana attenuata
Nicotiana attenuata
Nicotiana attenuata

Bryant is the author of today's entry.

Today's images of Nicotiana attenuata (commonly known as coyote tobacco) were generously contributed by Danny Kessler, who researches this incredible species. Nicotiana attenuata may not appear extraordinary at first glance, but this species exhibits a number of remarkable responses to predation. Hawk moths (Manduca spp.) are both friends and foes to coyote tobacco. The adult moths are common nocturnal pollinators for this species, but the larvae (aka tobacco hornworm) are one of this plant's main predators. When a plant of coyote tobacco is subjected to the oral secretions produced by feeding hawk moth larvae, a chemical signal (jasmonic acid) is released into the air. This signal is picked up by the same individual and triggers a dramatic change in the individual's phenology. It does so rather dramatically, by switching from producing flowers that open at night (and hence attracting the hawk moth) to producing flowers that open during the day (which instead attract hummingbirds).

The figure above shows a timescale of morning opening flowers (MoF) and night opening flowers (NoF) with the black blocks representing darkness. The top photograph above shows the NoF on the left and the MoF on the right, taken at 8:00 a.m. when the NoF is still open but about to close, and the MoF is still closed but about to open. The third image shows the same pair of flowers from a top view (NoF on the right this time and MoF on the left).

In addition to changing the flower opening time, the plant will also alter the floral scents it emits, the nectar produced and the morphology of the flower! Once this switch has occurred in the plant, the number of hawk moth visitors significantly declines while the number of hummingbird visitors increases. This decline in hawk moth visitors results in a reduction in eggs that are deposited by hawk moths, thereby reducing future predation by hawk moth larvae. Pollination continues to successfully occur via hummingbirds.

This particular response is only elicited when a caterpillar of Manducca spp. begins to feed on the leaves of Nicotiana attenuata, however there are many other herbivorous predators that feed on this species. Switching pollinators is just one of many defenses in this species' arsenal. In fact, Nicotiana attenuata is somewhat of a master of chemical warfare. Its trichomes imbue feasting insects with a chemical scent that attracts insectivorous predators to come have a feast of their own. Also, as you may have guessed, this plant contains the toxin nicotine, which is harmful to virtually all other herbaceous predators (besides the hornworm) with muscle tissues, insects and smokers alike.

The keen observations made by researchers Dr. Ian Baldwin, Danny Kessler and Celia Diezel have elucidated the complex chemical and physical responses that occur when Nicotiana attenuata is predated by hawk moth larvae. But the question remains, why doesn't this species always produce morning opening flowers, and forego its interaction with the hawk moth altogether? There are a number of speculative hypotheses regarding this question but none have been proven.

For a detailed account of the research and findings conducted by Dr. Ian Baldwin and his colleagues see their paper: Baldwin, I.T. et al. 2010. Changing pollinators by Means of Escaping Herbivores. Current Biology. 20(3):237-242.

Professor Ian Baldwin and his colleagues are also featured in a recent documentary, Smarty Plants: Uncovering the Secret World of Plant Behaviour (an episode of The Nature of Things). The section on Nicotiana attenuata is around the 14 minute mark.

9 Comments

susan commented:

This plant grows in Moses Coulee, in Central Washington state. Fourteen of the fifteen species of bats found in Washington are found in Moses Coulee, one of which is the spotted bat (Euderma maculatum). The spotted bat is the only one with an echolocation call that is audible without aids to many people (mostly of the younger sort!). That is one reason The Nature Conservancy conducts a spotted bat survey in the upper Coulee every summer, using many volunteers to note and document the number of calls. It's a bat people can hear.

One summer a few years ago, one of the small teams in place near the Coulee wall, noted spotted bat calls swooping down into the nearby incised stream bed. This was questioned by some of the knowledgeable bat folks at the debriefing later that night, as the bats generally fly up high overhead. These bats were below ground level.

Turns out, upon examination in the light of day, coyote tobacco (Nicotiana attenuata) was growing in and around that stream channel. One of the main, if not THE main, foods of the spotted bat are moths.

Wendy Cutler commented:

Awesome start to the new year! Thanks, Daniel, and Danny and fellow researchers, and to Susan as well for the remarkable comment.

Bryant DeRoy commented:

Very interesting Susan! thank you for sharing

Karthik commented:

Once it switches to hummingbirds, does the plant ever switch back to the hawk moths? If so, what triggers that?

Jessica commented:

Wow, that's fascinating!

What a great start to the New Year.

Thanks for such in-depth info about how this remarkable plant responds to its friends and foes. What an amazing dance!

And Thanks, Susan, for that great follow-up.

I love this site.

Happy New Year, everyone!

Jess

michael commented:

Awesome... and thought provoking. What strategies do I (and other humans) employ to attract those I want to attract and repel those I want to repel without even being aware that I am doing it?

elizabeth a airhart commented:

i agee what a great way to start off the new year
and so many interesting comments

every woman in the world knows how this works

Janea Little commented:

Fabulous information! Thank you for sharing this complex behavior!

Dr R K S Rathore commented:

It is a great story of defence mechanisms used by Nicotiana attenuata plants against moth larvae. We often say that plants do not have nervous system for feelings but the above investigation by Prof. Baldwin and his team clearly shows that plants have been using nanotechnology for sending and receiving signals through various chemicals.

Comments are closed.

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