The First Release!
Today we had our first release of Galerucella beetles. They had begun to emerge from pupae in several cages, and quite a few of those cages had very little foliage left from the active larvae. A field release was in order, and our chosen location was Elkins Iron and Metal, a metal recycling yard.
It is adjacent to a large wetland that has a fair-sized infestation of purple loosestrife. It has been treated several years in a row by a contractor (Appalachian Invasive Management), with good results every year. However, the hazards of the area (large amounts of metal in precarious piles surrounding loosestrife) have made biocontrol an appealing option to replace spraying as the control method for purple loosestrife.
You can see the damage done by the reared beetles (bottom) versus the healthy purple loosestrife in the field (top)
Despite the annual treatment this location has received, the seed bed of purple loosestrife is pervasive (for at least seven years), meaning that each annual treatment creates an open canopy for more sunlight to get to the seed bed, resulting in germination. The loosestrife infestation is not wall-to-wall like the Triangle Wetland was in 2001, but it is substantial enough that it could support a beetle population. We released 9 cages of beetles at two different ends of the wetland; approximating at least 100 beetles per cage (once they all emerge from pupation), that is a pretty substantial release!
We took the sleeve cages off of each pot and gently brushed the beetles on the cages onto adjacent healthy plants. We also broke stems from the healthy plants to touch the plants in pots we put out, to create a bridge for the beetles to journey upon to find their new homes.
A Galerucella beetle on its new home.
We will leave the pots in the field until late August, then likely collect them in order to prevent litter and to re-use them for next year. The beetles can take as little as 3 years to start thoroughly controlling the loosestrife, but may take up to 10 years depending on infestation size, weather, beetle life-cycle logistics, etc. We will not be spraying the property where the beetles are released, in the hopes that the loosestrife will have a hardy enough population to allow the beetles to establish.