Global Climate Change and the Effect it has on Plant-Insect Relations

Hi everyone!

A report, written by Peter Wilf and Conrad C. Labandeira, looks at "global warming" and its effects on plant-insect relationships. Combined, insects and terrestrial plants make up the majority of Earth's current biodiversity, and taking into account that around half of the total discovered species of insects today are herbivorous, this is definitely what caught my eye. Currently, we're going through some abrupt climate change due to excess amounts of greenhouse gasses (Carbon Dioxide, Methane, etc.) that are being released into the atmosphere on a day to day basis. While the whole world is worrying over how to slow or even stop the process, this isn't the first time Earth has gone through a change in temperature. In the past, periods of warming (what we know as "global warming") and cooling (also known as an"ice age") happened well before Homo sapiens walked the land.

While it's true that the changing temperatures are cyclic, to observe what has happened in past periods of time will give scientists a gage as to what will happen in the future. The report focuses on insect and plant relations. For this report, Wolf and Labandeira observed how the climatic differences affected species diversity among plants and insects during the late Paleocene to the early Eocene. During this time, global warming was occuring; an increase of average temperature was gaged at 6°C from the Paleocene to the Eocene (14.4° to 21.3°, respectively). Looking at fossil evidence from Wyoming, USA, scientists were able to figure out the results.

After identifying 41 different types of insect damage on 39 Paleocene and 49 Eocene species of flowering plants, the evidence showed that the damage was more significant in the Eocene than in the Paleocene. This means that an increase in herbivory (eating vegetation) happened when there were warmer temperatures. In addition, insects ate more of a variety of plants in the Eocene than in the Paleocene.

One thing that was really interesting about this was the observation of certain tree species. Trees in the Betulaceae family (which includes common day Birches) were fairly common during both the Paleocene and the Eocene time periods. Two specific species of Betulaceae, Alnus spp. (Eocene) and Corylites spp. (Paleocene) were extremely common throughout both landscapes. Since Betulaceae plants are the favorite food of many insects, the two species were looked at during these two times to also compare rates of damage from insects. Scientists found that the Betulaceae species found in the Eocene period were attacked more than during the Paleocene.

So, what can we expect from this? Will bug herbivory increase and cause more destruction in our future as our current world becomes warmer and warmer? Most likely. It would be interesting to observe plant/insect relationships from the past 50 years and compare them to today. In addition, I'm curious about Betulaceae and how they are being affected with the recent global warming trends; are they also being attacked more due to increases in global temperature? It would be interesting to look more into this!

~Mel

Study ca be found at: http://www.sciencemag.org/content/284/5423/2153.full.pdf?sid=8193f9ef-e38a-4b19-aea3-7646237feb4a