You are here

Understanding phoretic biota of the mountain pine beetle in northern Colorado

Date: August 19, 2015


Background

(Left) Tarsonemus ips transports fungal spores tinted blue. (Right) The mite (Trichouropoda hirsuta), a new record from northern Colorado mountain pine beetles during recent beetle epidemic. Photos by Javier E. Mercado.
(Left) Tarsonemus ips transports fungal spores tinted blue. (Right) The mite (Trichouropoda hirsuta), a new record from northern Colorado mountain pine beetles during recent beetle epidemic. Photos by Javier E. Mercado.
There is minimal knowledge of phoretic processes (where one species transports another) of mountain pine beetle in Colorado. Mountain pine beetles kill trees with the aid of blue-stain fungi. It is important to understand which blue-stain fungi has been vectored by mountain pine beetle during recent epidemics. This is important so we can later compare it to endemic populations, which might help us understand potential causes of fluctuations in the beetle populations. Is also important to understand if blue-stain fungi is dispersed by other organisms associated with the beetle such as phoretic mites. Mites can introduce fungi that helps to kill the tree or that helps or affects the beetle negatively.

Approach 

Mountain pine beetles attacking three host pines in northern Colorado were collected summers of 2011-2013, and mites and blue-stain fungi carried by mites and beetles were sampled and compared.

Figure 3. Leptographium longiclavatum newly recorded blue-stain fungus vectored by mountain pine beetles and mites in northern Colorado. Photo by Javier E. Mercado.
Figure 3. Leptographium longiclavatum newly recorded blue-stain fungus vectored by mountain pine beetles and mites in northern Colorado. Photo by Javier E. Mercado.

Key Findings

We found that like the beetles, phoretic mites are important vectors of pathogenic blue-stain fungi in northern Colorado (Fig.1), and they carry three blue-stain fungi. Before this research the mountain pine beetle was the only known vector of blue-stain fungi to trees in northern Colorado.

A new mite was identified from northern Colorado (Fig 2.), this mite increased during the three year sampling, which coincided with a mountain pine beetle population decline, further research is needed to understand how the mite affects the beetle or blue-stain fungi.

A third blue-stain fungi (Leptographium longiclavatum, Fig 3.), was also recorded for the first time in northern Colorado.

Our findings set a base line of information of the blue-stain fungi and its carriers present during a mountain pine beetle epidemic. Contrasting our findings to those present during non-epidemic populations in the future will shed new information on why epidemics happen. Our findings also shows that the potential impacts of mites on bark beetle population decline is something worth investigating in the hopes of finding new ways to control beetle epidemics.

Featured Publications

Mercado, Javier E. ; Hofstetter, Richard W. ; Reboletti, Danielle M. ; Negron, Jose , 2014


Principal Investigators: 
Forest Service Partners: 
Danielle Reboletti, Forest Health Protection
External Partners: 
Dr. Richard Hofstetter, Northern Arizona University
Colorado State University
Research Location: 
Roosevelt National Forest, Larimer County, Colorado