New biopesticide will battle bad weevils


Anyone who knows me knows how much I love bugs, and I usually don’t write about diseases. But when there’s a disease that will kill one of the big problem insects out there, that really gets my attention.

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I first heard about Metarhizium anisopliae fungus awhile ago. It’s by no means a recent discovery. This fungus was first used experimentally in 1879 to control wheat grain beetles. In recent years it has been brought back into the spotlight to help control difficult pests such as black vine weevils. M. anisopliae really caught my attention because of its ability to control black vine weevil larva in nursery settings, yet still be an environmentally sensitive product.

Denny Bruck and his research team at the USDA’s Agricultural Research Service facility in Corvallis, Ore., have been working with Metarhizium. They’ve found that this beneficial fungus likes to hang around.

They incorporated the fungus in soilless media and then monitored the results over a two-year period. They checked periodically for the fungus and its ability to control black vine weevil larva. They found that through the year the rate of infection varied. Infections declined over the growing season but then rebounded again during the fall and winter. This rebound allowed infection of new larva in the spring of year two.

This means there is potential for this fungus to control black vine weevil for two growing season in containerized plants with only one application of Metarhizium.

East Coast trials

For all of you on the East Coast, don’t feel left out. Work has also been done by Cornell Cooperative Extension. Entomologist Dan Gilrein found that Metarhizium incorporated or drenched into growing media controlled the older and larger life stages of black vine weevil larvae better then conventional insecticides.

It also caused death within five to seven days after the larvae had come in contact with the spores. Very promising.

After hearing these initial reports I was super exited to get my hands on some, but was super disappointed to find it was not commercially available at that time. Very frustrating.

Recently I was excited to learn that this helpful fungus was finally coming to the commercial market. It’s going to be sold under the brand name Met52 by Novozymes Biologicals. It will first be available in Washington and Oregon for 2008 (just a few months away) and then to the rest of the country in 2009.

On the market

Met52 will be a granular product with a four-hour restricted-entry interval (REI). Novozymes Biologicals is also going to be applying for an OMRI listing for the product. An OMRI listing means it can be used on organic crops.

Novozymes Biologicals is also working to put research behind Met52. This year the company is conducting 90 trials against 35 different insect targets.

Many of you in the South may not be concerned at all about black vine weevil. But there may be other applications of this beneficial fungus.

Some initial work has been done looking at Metarhizium for control of Diaprepes abbreviatus, another damaging root weevil. The initial work combined Metarhizium with a sub-lethal dose of imidacloprid.

This caused a synergism allowing the time of death to greatly be reduced, as well as increased mortality. More work still needs to be done with D. abbreviatus to know for sure if Metarhizium is going to be able to control this pest effectively.

Science is finding many more fungus species that are our friends in the battle against pest insects. Having Metarhizium in the arsenal against these pesky root weevils is going to give growers a great advantage while still being soft on the environment.

What is Metarhizium anisopliae?

Metarhizium anisopliae is a naturally occurring beneficial fungus found in soil. It is considered a bioinsecticide.

The fungus is applied and the spores attach to the body of the target pest. The spores then germinate, penetrating the insect’s body.

The fungus continues to grow inside and on the host, covering the insect in a coating of white fuzz, ultimately leading to its death. Other insects in the area may also become infected if they come in contact with dead infected hosts.

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For more: Denny Bruck, (541) 738-4026; Dan Gilrein, (631) 727-3595; Novozymes Biologicals, (919) 494-3209;

- Suzanne Wainwright-Evans