A quiet bush clad reserve in the heart of the Manawatu, a New Zealand region, seems an unlikely place to find a bronze Brazilian on parade but if you look hard enough you might just spot one.
Horizons Regional Council has just released 300 tradescantia leaf beetles into an area of the regional park, Totara Reserve, in a bid to tackle the invasive tradescantia (wandering willy).
The release is one of the first times the beetle has been used as a bio-control agent anywhere in the world, the beetle having been released in Auckland also.
“It’s fantastic to be involved in pioneering new ground in the control of tradescantia. It’s a fast growing weed that suffocates native seedlings and has proved difficult to manage,” said Neil Gallagher, Horizons’ environmental management officer.
Adult beetles chew holes around the edges of the leaves, and in some cases eat the entire leaf, leaving the weed with little hope of survival.
“It’s early days but we’re hopeful the beetle will prove effective in controlling the weed.”
At just 5 millimeters long, you’ll be hard pressed to find one of these bronze beauties, but Horizons is hopeful the public will see the long-term benefits of their presence.
“A lot of time and research has gone into these bugs and, if we can get a colony established we’re pretty confident they’ll give tradescantia a run for its money,” said Neil Gallagher, Environmental Management officer.
Mr Gallagher thinks the beetles will adapt well to their new home.
“The beetle is very host-specific so we don’t expect it to eat anything other than tradescantia. We also know there to be few insects that could attack the beetle so there’s a strong chance a colony can be established.”
A native to areas of Brazil and Argentina, the tradescantia leaf beetle was imported by Landcare Research in 2007 and has been undergoing testing prior to release.
The beetle was due for release in 2008 but the discovery of a parasite in its gut meant the release was delayed until the colony was clear.
It is not yet known how many eggs the beetle can lay but similar beetles lay between 200 and 400 over several months. The tradescantia beetle has a life span of up to five months.