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Bt-Corn Beaten By Western Bean Cutworm
         

                                                                          (Click to enlarge)

Corn growers along South Dakota Highways 44 and 46 who planted Bt-corn hybrids may
be noticing injuries on the corn ears due to feeding by western bean cutworm larvae.

The pictures above were taken from a Bt-corn field in Clay County on August 19, 2002.
Most of the larvae have already dropped to the ground (to overwinter) as of last Tuesday
(September 3) when I again inspected the same cornfields.

What?  How can these obscure insects beat the mighty Bt-corn?  I thought Bt-corn
provides season-long "insect" control?

Believe it or not, I am of the opinion that none of the currently available Bt genes that are
in our Bt-corn hybrids have been able to control western bean cutworm larvae.  They have
been excellent against European corn borer larvae but totally ineffective against western
bean cutworm larvae.

Are we selecting for western bean cutworms by effectively eliminating European corn
borer larvae? 

Did we unwittingly elevate the pest status of western bean cutworm in South Dakota by
widespread use of Bt-corn hybrids?

Whereas Bt-corn resistant European corn borers have not been found in nature we
have found western bean cutworm damaged Bt-corn since 2000.

By being overly concerned with resistance management of European corn borer
(to delay the development of European corn borer resistance to Bt-corn), have we
been barking at the wrong tree?

It seems that we all forgot about the lesser known corn insects that could assume
dominant roles once the European corn borers were effectively controlled with Bt-corn.

Below are articles that I released earlier:

    7-31-01:  "Inspect Corn for Western Bean Cutworms ASAP"

    7-18-02:  "Western Bean Cutworm Will Infest Both Bt and Conventional Corn Hybrids"


  Have a safe and bountiful harvest.

 Last Updated on Tuesday, November 12, 2002 by Mike Catangui.