Toxic Honey From Native Plant Causes Illness

Coriaria-arborea-small.jpgDate: March 24 2008

At least nine people have now become severely ill from eating honey from the Coromandel that appears to have been contaminated with tutin and Hyenanchin - a hydroxytutin derived from tutin.

The toxic honey appears to have been contaminated as a result of bees visiting tutu (Coriaria arborea). The process involves honey dew being excreted onto the leaves of tutu by the tiny sap sucking passion vine hopper (Scolypopa australis) and then bees gathering the honeydew.

Tutin, and its derivative, hyenanchin are extremely toxic to humans, but only a few areas in NZ regularly produce toxic honey. These include the Coromandel Peninsula and Eastern Bay of Plenty and the Marlborough Sounds. To produce toxic honey, all of the following conditions are required.

* High concentrations of tutu bushes

* High numbers of vine hoppers

* Hot dry weather to allow the honeydew to build up on the tutu (rain can wash it off)

* An absence of more attractive food sources for bees, usually caused by drought

* Presence of honey bees (Apis mellifera) being managed for honey production.

Tutu is the classic poisonous plant of NZ. It is a widely distributed native species found throughout New Zealand, particularly along stream banks and in regenerating native bush. Some of the first animals introduced to NZ by Captain Cook in the 18th Century were poisoned by it. The plant caused losses in cattle and sheep. All parts of the plant are poisonous except the succulent black, soft petals surrounding the seeds.

Tutin acts on the central nervous system leading to excitement, convulsions, exhaustion and can lead to a comatose state. Breathing is usually affected, so too is memory.

A number of people have been killed, incapacitated and hospitalised over the years from eating toxic honey. The last recorded case from commercial honey was in 1974 involving 13 patients. There have been 9 cases since 1974 with the last known poisoning occurring in 1991 in the Eastern Bay of Plenty area.