Date: 3/31/99

Time: 10:00

Type: Symposium

Number: 224

Sex pheromone mating disruption: A 'natural' for integrating with transgenic crops

*T. Baker, Department of Entomology, Iowa State University, Ames, IA 50011
Contact e-mail: tcbaker@iastate.edu

The female sex pheromone of the European cornborer, Ostrinia nubilalis, was released from two dispenser types and in two deployment patterns, a Shin-Etsu rope formulation spaced 2 m apart and a widely-spaced (35 m) pattern using a high-emission-rate system called the Metered Semiochemical Timed Release System (MSTRSTM). They were deployed in three different farms in the grassy aggregation sites where most cornborer mating occurs. Size of the grassy areas treated ranged from 3 to 8 acres. Over the two summer flights, disruption of trap catch exceeded 97%. Most importantly, mating by females, as assessed by spermatophore counts from ca. 2,000 freely flying females captured with sweep nets, was significantly suppressed by the disruption treatments. The mean number of matings per first generation female was 1.33 in the MSTRS plots and 1.58 in the rope plots, compared with 1.88 in the untreated check plots. During the second flight, the number of matings per female averaged 1.63 in the MSTRS plots, 1.56 in the rope plots, and 2.17 in untreated check plots. The data indicate that the disruption treatments delay the first matings by females, but do not prevent first matings entirely, and thereafter suppress the ability of females to mate a second time. Pheromone mating disruption offers a heretofore overlooked, potentially useful strategy for delaying the onset of resistance to Bt corn because its effect will be greatest in preventing the rare, resistant adults that emerge from Bt corn from finding each other, compared with a lesser effect on the more common, susceptible adults.

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