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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #197757
Title: INFLUENCE OF PLANT SEVERING ON MOVEMENT OF OSTRINIA NUBILALIS LARVAE IN ZEA MAYS HYBRID SEED PRODUCTION FIELDS

Author
item Reardon, Kate
item Hellmich Ii, Richard
item Sumerford, Douglas
item Lewis, Leslie
item REARDON, BRENDON - APHIS, NEW JERSEY
item CALVIN, DENNIS - PENNSYLVANIA STATE UNIV.

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2007
Publication Date: 8/1/2007
Citation: Reardon, K.T., Hellmich II, R.L., Sumerford, D.V., Lewis, L.C., Reardon, B.J., Calvin, D.D. 2007. Influence of Plant Severing on Movement of Ostrinia nubilalis Larvae in Zea mays Hybrid Seed Production Fields. Journal of Economic Entomology. 100(4):1129-1135.

Interpretive Summary: The use of Bacillus thuringiensis (Bt) corn, which are plants that contain an insecticide that kills European corn borer larvae, is becoming popular with growers. If growers overuse this type of corn to control European corn borer, the insects may become resistant. Monitoring for insects that are resistant is very important in order for growers to continue using this corn. A new way to locate resistant insects is being considered that involves the use of corn-drying bins that all seed corn companies use to dry seed. A possible problem with using the drying bins is that insects that are found in the drying bins could have eaten non-Bt corn most of their lives and then moved into a Bt-corn plant. The first purpose of this study was to find the best time to plant the corn, early, mid, or late in the season along with the best time to cut down the male rows to decrease the number of larvae that move from the non-Bt corn to the Bt corn. The second purpose was to figure out how far larvae move away from male corn plants once they were cut down. Tests were conducted in the summers of 2002 and 2003 imitating a hybrid-seed production field. The results suggest planting early and cutting down the male plants within two weeks after tasseling will reduce the number of larvae that move between plants. This will decrease the chance that a larva will move from a non-Bt-corn plant to a Bt-corn plant. Larvae moved into all four rows of the female corn, but they mainly moved and stayed in the row closest to the cut male plants. This information will be useful to growers and other stakeholders interested in protecting the Bt technology, which should allow growers to protect their corn for years to come.

Technical Abstract: Genetically-engineered corn hybrids that contain a cry gene from the bacterium Bacillus thuringiensis (Bt) are gaining popularity for controlling the corn pest Ostrinia nubilalis. Continuous use of Bt corn, however, could select for O. nubilalis that are resistant to this corn. Monitoring for insect resistance is important because it could help maintain the Bt technology. A possible technique is to collect larval insects in commercial drying bins following harvest from Bt-seed-production fields. A drawback to this method is that these collections may be contaminated by insects that moved as later instars from destroyed non-Bt male rows into the adjacent Bt female rows. These larvae have little to no exposure to Bt toxin resulting in possible “false positives.” The objectives of this study were to first find which combination of planting date and destroy date produces the least number of larvae that move from non-Bt male plants to Bt female plants; and then determine how far larvae move from downed male plants into Bt female plants. Field studies in 2002 and 2003 were designed to simulate a hybrid-seed production field. Results suggest that movement of O. nubilalis larvae from male corn is minimized when corn is planted early and male plants are destroyed by two weeks post-anthesis. This reduces the likelihood of false positives by reducing the number of susceptible larvae moving between Bt and non-Bt plants. Also larvae moved to all four female rows, but there were significantly more larvae found in row one than all other rows. These results could be used to develop a monitoring program to find O. nubilalis larvae with resistance to Bt corn in field populations of O. nubilalis.