New ambrosia beetle marching across the US

Nursery growers have been struggling with ambrosia beetles for decades. In the southeast it is

Scopes-eye view of camphore shot borer fresh from a trap mixed in with granulate and other ambrosia beetle species. Photo: Andrew Ernst, NCSU.

Scopes-eye view of camphore shot borer fresh from a trap mixed in with granulate and other ambrosia beetle species. Photo: Andrew Ernst, NCSU.

primarily the granulate ambrosia beetle, Xylosandrus crassiusculus. In the Northeast and Midwest the predominate species is Xylosandrus germanus. These are tiny beetles that make tiny albeit lethal holes in trees. 

In the past several years a new species has been detected in several states including Florida, Tennessee, North Carolina, and just last month Virginia. This is the camphor shot borer, Cnestus (used to be Xylosandrus) mutilatus, and it is BIG. At least by ambrosia beetle standards this one makes holes as big as a pencil instead of then tiny 2mm holes made by other species. You can find out all about it in a thorough publication from University of Tennessee.  

We trap at 5 -10 nurseries every year around Johnston County, North Carolina. In 2011-2013 we captured 1 or 2 camphor shot borers each year. This year we captured about a dozen from at least 3 different nurseries. So it is here to stay and will probably become more of a problem over time. 

Camphor shot borer in a twig photographed by Matt Bertone, NCSU.

Camphor shot borer in a twig photographed by Matt Bertone, NCSU.

Thrips vs. Mites: an Epic Fight

This is a guest blog by Post-Doctoral Researcher Sarah Jandricic, who specializes in Greenhouse Entomology. You can read more about our greenhouse research program here.

The fight is about to begin! In one corner of the ring we have the number one pest of greenhouse crops in the world: the western flower thrips.

Western flower thrips and damage on petunia leaf. Photo: SD Frank

Western flower thrips and damage on petunia leaf. Photo: SD Frank

This nasty little insect might look like a lightweight, but it’s in the heavy-weight class when it comes to damage. By sucking out the contents of individual plant cells, thrips cause a scratched, or “silvered” appearance to leaves and flower petals. Adding insult to injury, thrips can also transmit lethal plant viruses like Impatiens Necrotic Spot Virus.

In the other corner, we have the fan favorite – the predatory mite! Cucumeris are notorious for killing and eating 1st instar thrips (the life stage that hatches directly out the egg), and are sold commercially for control of thrips in greenhouses. Adult mites can eat 4 to 10 of these 1st instar thrips each day. But Cucumeris has yet to face its current opponent: the older and larger 2nd instar Western flower thrips.

Ding Ding Ding! The fight has begun!

The video of our fight (Sarah Jandricic and Matt Bertone, NCSU), shows Cucumeris making repeated attacks to the flank of Western flower thrips! But what’s this? The thrips is using its abdomen to land repeated blows to the head and body of Cucumeris! Despite a valiant effort from our plucky predator, it just can’t seem to find an opening. After several rounds, it’s clear that our 2nd instar Western flower thrips has won the fight.

But hold on, folks. Breaking news is coming from the post-fight interview…

It turns out that defending itself from the mite has cost our 2nd instar thrips dearly. Thrips engaging in this sort of battle spend less time feeding, cause less damage to plants, and ultimately are less successful in completing development into adults.

So, the story is clearly not over. The Frank Lab at NCSU is currently investigating ways to capitalize on effects of mite “intimidation” on 2nd instar thrips for better control of this pest in greenhouse crops.

Stay tuned for more updates on this big battle occurring in the tiny world of insects!

 

 

Ambrosia beetles trickling out

After a cool spring I was beginning to think the ambrosia beetles would never come out. Although we have found a few early non-pest species we have not seen the main -granulate ambrosia beetle- until now.  We found a couple in traps at cooperating nurseries in Johnston Co, NC. Of course it is freezing this week which could delay them again. The same thing happened last year when we got a few at a time as the weather alternated

Frass tooth-pick from adult ambrosia beetles boring into trees. Photo: SD Frank

Frass tooth-pick from adult ambrosia beetles boring into trees. Photo: SD Frank

between warm and cold.

In experimental trees at lake wheeler and sentinel trees at nurseries we have not had any attacks but it is probably time to start management if you haven’t already.

Management of ambrosia beetle damage requires pyrethroid applications every 3 weeks to the trunks of trees. Ambrosia beetles usually attack below the first scaffold branches so you do not need to spray the canopy. Most folks apply permethrin with an airblast sprayer. We have tested a manual sprayer and fold more complete, even coverage.

You can read about it in a recent paper. The manual sprayer has two opposing nozzles to

Dual nozzle spray wand for permethrin applications. Photo: SD Frank

Dual nozzle spray wand for permethrin applications. Photo: SD Frank

quickly cover tree trunk with insecticide. It takes a little longer but uses less insecticide and reduces drift and secondary mite outbreaks. Ambrosia beetle attacks also increase when trees are overwatered so resist irrigation until it is warm and trees start leafing out. Summaries of ambrosia beetle biology and management can be found in industry articles, an open source publication in the Journal of IPM, and in a free iBook about nursery pest management

 

 

New App for Nursery and Landscape Pest Management

The Southern Nursery IPM Working Group (SNIPM), of which several faculty at NCSU are members, has just released and exciting new App available for iPhones and Android phones.  The App predicts the emergence of arthropod, disease, and weed pests based on degree day estimates, provides diagnosis help, and even pesticide recommendations.  This is a very comprehensive tool that should prove valuable to industry and extension personnel.  A complete description can be found on the website http://www.ipmproapp.com/.