To promote and identify research collaboration going on at The Crosby Arboretum, I will be posting who we are working with and provide information on their projects. I hope that everyone will find the research posts interesting. I have added a blog category “Crosby Arboretum Research” to our menu.
Cnestus mutilatus. Image courtesy of C. Werle, USDA ARS Poplarville
A couple of months ago Mr. Chris Werle, Biological Science Technician at the USDA ARS Thad Cochran Southern Horticultural Research Laboratory in Poplarville, Mississippi, put out an ambrosia beetle trap here at The Crosby Arboretum. I asked Chris to tell me a little about the beetle and the trap.
chris-werle
“Exotic Asian ambrosia beetles have become important pests at tree nurseries throughout the United States. Adult female beetles can detect plant volatiles given off by stressed or injured trees, and choose these weakened trees for their new home. After tunneling under the bark, she chews up the wood and pushes it out behind her, constructing a larval gallery inside the tree with a “toothpick” of sawdust sticking out of the hole. Often this “toothpick” is the only sign of attack we see, if we aren’t paying close enough attention to our tree crop or otherwise monitoring for beetle populations.
After constructing the larval gallery, eggs are laid and the cycle begins anew. An interesting fact about ambrosia beetles is that they aren’t actually eating the trees; as the mother is building her larval gallery, she introduces a fungus to the tree. All ambrosia beetles have a special structure called mycangia which contain spores of the particular species of fungus upon which the new larvae feed. This fungus is what gives them their name, ambrosia beetle, and while the symbiotic fungus may not kill the tree host outright, it is then susceptible to other more-deadly diseases. Also, the ambrosia fungus will stain the wood, making it unusable for lumber.
Another interesting fact about ambrosia beetles; the mother beetles work to protect the colony, tending the fungal garden and cleaning the galleries of frass. This level of care leads us to classify ambrosia beetles as social insects! Other social insects like the Hymenoptera (bees, ants, wasps) typically exhibit sociality with adults caring for larvae. But the ambrosia beetles also put their larvae to work, enlarging galleries and helping with brood care and hygiene, which is unique amongst the holometabolous insects.
Xylosandrus compactus. Image courtesy of C. Werle, USDA ARS Poplarville.
In addition to tree nurseries, ambrosia beetles are also becoming cause for concern in our Southern forests. One species in particular, the redbay ambrosia beetle (Xyleborus glabratus), is responsible for large-scale mortality of two important native forest trees in Georgia, South Carolina and Florida, the redbay (Persea borbonia) and sassafrass (Sassafrass albidum). This beetle has also been found to attack avocados, an economically important agricultural crop in Florida, and was recently found to be the cause of death of hundreds of redbay trees in Jackson County, MS.
Xylosandrus crassiusculus. Image courtesy of C. Werle, USDA ARS Poplarville.
USDA researchers at the Thad Cochran Southern Horticultural Lab in Poplarville are looking for new ways to detect emerging ambrosia beetle populations, and effectively combat the infestations once they are detected. We have a trap installed at the Crosby Arboretum, and check it regularly for presence of this destructive ambrosia beetle. We have not found any redbay ambrosia beetles at Crosby to date, but as with many other exotic-invasive organisms introduced through global commerce, it is only a matter of time.“
I would like to thank Chris Werle for his wonderful write-up about the research on ambrosia beetle and our collaboration with him and the USDA-ARS in Poplarville.
While at the Arboretum, if you find any traps, please do not touch or disturb them. If you find one on the ground or one that appears damaged, please report it to Arboretum staff as soon as possible.
If you find learning about or observing insects fascinating, please be sure to come out to The Crosby Arboretum Bugfest on Friday and Saturday September 21 and 22, 2012. Chris Werle will be volunteering at Bugfest on Friday day so come out and say hello. Interesting in volunteering for Bugfest? Call me at 601-799-2311 ext 101.
Gettin’ buggy with it!
Sr Curator R. Stafne
All images and text copyright Mississippi State University, 2012.
