ARS | Publication request: Increased Expression of a cGMP-Dependent Protein Kinase in Rotation-Adapted Western Corn Rootworm (Diabrotica virgifera virgifera L.)

Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 29, 2008
Publication Date: July 1, 2008
Citation: Garabagi, F., French, B.W., Schaafsma, A.W., Pauls, K.P. 2008. Increased Expression of a cGMP-Dependent Protein Kinase in Rotation-Adapted Western Corn Rootworm (Diabrotica virgifera virgifera L.). Insect Biochemistry and Molecular Biology. 38:697-704.

Interpretive Summary: A new `variant¿ behavior in Western Corn Rootworm (WCR) has resulted in egg-laying into non-cornfields, compared to `normal¿ deposition of eggs in cornfields, allowing these insects to circumvent crop rotation as a population control strategy. No morphological or genetic characteristics have been defined to differentiate between the normal and variant biotypes. Cyclic GMP dependent protein kinases (PKG) have been implicated in the regulation of behaviors in invertebrates, insects, and nematodes, including foraging behavior in fruit flies. A cDNA with homolog to the fruit fly, Drosophila melanogaster, foraging gene (called Dvfor1) was cloned from WCR. The deduced DvFOR1 protein is about 70% similar to FOR proteins in Drosophila, silkworm, and honeybees. It contains a coiled coil region, two tandem cyclic nucleotide-binding domains, a serine/threonine kinase catalytic domain, and a serine/threonine kinase catalytic domain extension, which are all characteristically found in PKG proteins. Real-time polymerase chain reaction assays of foraging transcript levels in heads of normal and rotation adapted female WCR obtained from lab-reared colonies indicated that the variants had higher levels (25%) of PKG expression than normals. The magnitude of this increase is similar to that observed in Drosophila rover phenotypes compared to sitter phenotypes. However, WCR contains at least two different foraging gene transcripts, which complicates establishing a direct link between the level of gene expression and WCR behavior.

Technical Abstract: A new `variant¿ behavior in Western Corn Rootworm (WCR) has resulted in egg-laying into non-cornfields, compared to `normal¿ deposition of eggs in cornfields, allowing these insects to circumvent crop rotation. No morphological or genetic characteristics have been defined to differentiate between the normal and variant biotypes. Cyclic GMP dependent protein kinases (PKG) have been implicated in the regulation of behaviors in invertebrates, insects, and nematodes, including foraging behavior in Drosophila. A cDNA with homolog to the Drosophila melanogaster foraging gene (called Dvfor1) was cloned from WCR. The deduced DvFOR1 protein is approximately 70% similar to FOR proteins in Drosophila, silkworm (Bombyx mori) and honeybee (Apis mellifera). It contains a coiled coil region, two tandem cyclic nucleotide-binding domains, a serine/threonine kinase catalytic domain, and a serine/threonine kinase catalytic domain extension, which are all characteristically found in PKG proteins. Real-time PCR assays of foraging transcript levels in heads of normal and rotation adapted females of WCR obtained from lab-reared insect colonies indicated that the variants had higher levels (25%) of PKG expression than normals. The magnitude of this increase is similar to that observed in Drosophila rover phenotypes compared to sitter phenotypes. However, Diabrotica contains at least two different foraging gene transcripts, which complicates establishing a direct link between the level of gene expression and insect behavior.