Here is a Strange . . .   

We started trapping moths of the Western bean cutworm at the SE Farm near Beresford in '02.
The peak moth flight in that area had always been during the third or fourth week of July.  And
there was only one peak per growing season.

This 2006 season, however, a second moth flight occurred starting on the third week of August.

What I am still puzzling over is:  Where did these moths come from?  What is the meaning of all
of these in the grand scheme of things?  Will it happen again next season?

Another extremely interesting observation is the absence of a discernible second peak in the
2006 European corn borer moth flight.
                                                                      

Is this species replacement happening right before our very eyes?  Maybe it was just the heat,
or the sticky humidity.  Right, Buford?  (Updated:  10-19-06)
 

Who Are These Guys?     
                                             

I had no idea that the northern corn rootworm adult can gouge the kernels of corn (Bt-plus corn
in this case).  Just the northern though; I have not seen the western adults feed on the kernels
yet.  I suppose, this kind of injury may not be too important at the moment but we'll sure keep an
eye on the NCR from now on.  They are not just silk feeders anymore.  Photos above.  What did
their larvae do again?

Another insect that could become important is the sap beetle.  Larvae and adults can both be
found in the ears.  And they make the corn ears quite messy with molds.  Incidentally, some
growers call sap beetles as "beer beetles."  I thought they were just "picnic beetles."

These insects used to be last.  Are they now first?  Buford has a less divine explanation:
"Obviously, we unwittingly expanded the niche hypervolume of certain ecologically disadvantaged
bugs."  "Cousin Johnny also mentioned something about an island biogeography thing wherein
them corn species will be in a state of flux for some time, enough to keep them grad students busy
for years." "No man is an island but them Bt-corn fields could be, if you think about it."

There goes Buford again with his fancy hypervolume, flux, and island stuff; whatever those mean . . .
(Updated: 12-1-06)

In the meantime, kindly take a look at this recent publication by some unknown scientists:

                Catangui, M. A., and R. K. Berg.  2006.  Western bean cutworm, Striacosta albicosta (Smith)
                                (Lepidoptera: Noctuidae), as a potential pest of transgenic Cry 1Ab Bacillus thuringiensis
                                corn hybrids in South Dakota.  Environmental Entomology 35: 1439-1452.  Free PDF.
 

Pardon Me, Is That Aspergillus flavus in Your Ears?

                                                                     

It was a dry and hot season.  I was in our corn plots at the SE Farm last week and saw some triple
stacked (Bt-corn borer + Bt-rootworm + glyphosate resistance genes) corn with fine looking molds
in the ears.  The ears were injured by western bean cutworms in early August (see above photo).

Even Hercules has the ear as Achilles' Heel because no Bt-corn is effective against sap beetles
and corn rootworm adults.  Achillex EAR^© quadruple stacked corn hybrid anyone? (Updated: 9-19-06)
                                                     
Old stuff from previous years:

                                       Ear is the Achilles' Heel

                                       Cry 1 Ab Crying Over Western Bean?
                                       
                                       Richia Was Here

                                       FDA Fumonisin Guidance

                                       FDA Aflatoxin Guidance
 

Can You Say Papaipema? 
 
The common stalk borer Papaipema nebris is not susceptible to any of our Bt-corn
hybrids currently deployed on the field.  Do not be surprised if some "worm" damaged
your "protected" Bt-corn.  A seed company honcho asked me why in the world was his
corn infested with some borer about a month ago.  Well, it was La Papaipema indeed.

Other insects that also can feast on any kind of Bt-corn are sap beetles, corn leaf aphids,
and corn rootworm adults.  Western bean cutworms can feed on Cry 1Ab Bt-corn but
not on the Cry 1F Bt-corn.

You do know which one is which, right, Buford?  Click here for a review.

Incidentally, Buford tells me that the WBC reached Indiana this season. Entomologists
from that "major" university out there should be able to handle them WBC.

Whether an insect larva is susceptible or not to a Bt-corn depends on a matching receptor
of the activated protoxin in the midgut of the insect.  No receptor, no die.

                                                                             

In case you have forgotten how the Bt insecticidal crystal protein (ICP) works, here is an
excellent publication from the American Academy of Microbiology entitled "100 Years
of Bacillus thuringiensis:  A Critical Scientific Assessment."  Page 6 has an illustration
on how the Bt ICP is activated then creates holes in the gut of the poor caterpillar.
 

Univoltine Corn Borer Moth Flight High  (7-24-06) 
 
Light traps in SD areas where the univoltine European corn borer moth is known
to occur are showing high numbers of moths.  Conventional corn or Bt-corn without
the YieldGard Corn Borer or Herculex I genes must be scouted as soon as possible.

It is very hard for me to break another bad news to growers already saddled with
the drought.  This message is only for those who still have a good corn crop.

                                                                             

© Copyright 2009 by South Dakota State University.  All Rights Reserved.
 

 Web Posted on Wednesday, August 23, 2006 by Mike Catangui. Last Updated on Thursday, October 19, 2006.