Evaluation of Trichogramma nubilalis and Bacillus thuringiensis in management of Ostrinia nubilalis (Lepidoptera: Pyralidae) in sweet corn
1995
A biological control program for European corn borer, Ostrinia nubilalis (Hubner), using Trichogramma nubilalis Ertle & Davis and Bacillus thuringiensis var. kurstaki was tested in plots of sweet corn 1990 and 1991. Trichogramma were released during the egg mass recruitment period of O. nubilalis to bracket the peak egg mass deposition period. One or two B. thuringiensis applications were targeted against host larvae that escaped T. nubilale parasitism in the egg stage. The European corn borer phenology model adequately predicted the timing and shape of the adult flight and egg recruitment periods in 1990 and 1991. The released Trichogramma parasitized 70 and 56% of the European corn borer eggs in 1990 and 1991, respectively. In both years, < 20% of the host eggs hatched in the Trichogramma release plots, compared with 38-56% in the control plots. Total mortality of European corn borer from egg deposition to sweet corn harvest was 94 and 92% in 1990 and 1991, respectively. The stage structure of the European corn borer population at sweet corn harvest in 1991 did not differ between the Trichogramma release and no release plots. The proportion of sweet corn ears free of European corn borer larvae varied with position of the plots relative to nearby sundangrass, and ranged between 0.7 and 0.9 in the release plots, compared with 0.6-0.65 in control plots in 1990 and 1991. respectively.
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