Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2008
Publication Date: 3/2/2009
Citation: Lewis, L.C., Bruck, D.J., Prasifka, J.R., Raun, E.S. 2009. Nosema pyrausta: Its Biology, History, and Potential Role in a Landscape of Transgenic Insecticidal Crops. Biological Control. 48(3):223-231. Interpretive Summary: Several insect pests of major crops are infected with microorganisms that help reduce damage caused by these insects. The European corn borer (ECB) is infected with such an organism, Nosema pyrausta, which reduces the number of corn borer eggs laid, the number of eggs that hatch, and the number of insects that survive. Nosema pyrausta most likely arrived in the United States (U.S.) from Europe with the ECB in the early 1900s. This manuscript reviews the research conducted on the association of N. pyrausta with the European corn borer in the U.S. over the past 60 years. Nosema pyrausta has persisted in ECB populations throughout the U.S. It has a history of increasing and decreasing in cycles, similar to the cycles shown for ECB but delayed one or two years. Temperature extremes, plant resistance, and toxicants worsen the negative effect of N. pyrausta on European corn borers. Agronomic practices have changed greatly over recent decades, including the production of genetically-modified corn resistant to ECB; however, N. pyrausta remains in the ECB populations, and recent surveys suggest the cycles of N. pyrausta and ECB today are similar to those reported decades earlier. This report is of use to those conducting research in pest management and to corn growers.
Technical Abstract: Nosema pyrausta, a microsporidium, is an important population regulator of the European corn borer, Ostrinia nubilalis. Nosema pyrausta was described from O. nubilalis in Europe in 1928. Ostensibly it was introduced to the United States (U.S.) with O. nubilalis in 1917-1918; however, it was not reported from O. nubilalis in the U.S. until 1950. This manuscript is a review of the research on the relationships between N. pyrausta and O. nubilalis. Additional data are presented on the incidence of N. pyrausta in O. nubilalis populations from many parts of the U.S. These data demonstrate that N. pyrausta continues to be present and fluctuates in populations of O. nubilalis as it has since its discovery in the U.S. some 60 years earlier. Also, the patterns of its presence remain similar through changes in corn production, including crop rotations, reduced tillage, and (most significantly) widespread planting of Bacillus thuringiensis (Bt) transgenic corn.