Use of ablated stalks to assess field rates of parasitism of Diatraea saccharalis (Lepidoptera: Crambidae) by Cotesia flavipes (Hymenoptera: Braconidae)

Abstract

We evaluated a technique that used ablated sections of corn stalks infested with larvae of Diatraea saccharalis F. to assess parasitism by Cotesia flavipes (Cameron) in a corn field. Stalkborer larvae were retrieved successfully from the artificially infested, ablated stalks for at least 96 h after deployment in the field. Levels of parasitism in ablated stalks attached to corn plants were comparable to levels of parasitism measured using whole plants that were artificially infested. Olfactometer comparisons showed preference by female C. flavipes for both whole plants and ablated stalks containing larval D. saccharalis, over uninfested stalks and plants. This technique provides a means to estimate parasitism of stalkborer larvae by C. flavipes without destructive sampling of agronomic plants.

Keywords:

• Stalkborer
• Diatraea saccharalis
• Cotesia flavipes
• parasitization
• Crambidae
• biological control
• olfactometer

Acknowledgments

We thank Patricia Gillogly, Pam Steele-Jones and Michael Stuchman for help with field experiments and preparing stalks in Texas. We also thank Fredy Cardona for conducting the olfactometer trials in Illinois. Parts of this study were supported Hatch project TEXO7054 from the Texas Agricultural Experiment Station and Hatch project ILLU 65-0331 from the Illinois Agricultural Experiment Station.