ARS | Publication request: BIO-BASED SUGARBEET ROOT MAGGOT (DIPTERA: OTITIDAE) MANAGEMENT BY INTEGRATING CEREAL COVER CROPS AND THE FUNGAL ENTOMOPATHOGEN METARHIZIUM ANISOPLIAE

Submitted to: Entomological Society of America Regional Meetings
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 2003
Publication Date: March 4, 2003
Citation: MAJUMDAR, A., BOETEL, M.A., JARONSKI, S., DREGSETH, R.J., SCHRODER, A.J. BIO-BASED SUGARBEET ROOT MAGGOT (DIPTERA: OTITIDAE) MANAGEMENT BY INTEGRATING CEREAL COVER CROPS AND THE FUNGAL ENTOMOPATHOGEN METARHIZIUM ANISOPLIAE. NCB-ESA North Central Branch Entomological Society of America. 2003. POSTER ABSTRACT.

Technical Abstract: A field trial was conducted in 2002 in a commercial sugarbeet, Beta vulgaris L., field near St. Thomas (Pembina Co., North Dakota) to evaluate an integrated approach using oat, Avena sativaL., and rye, Secale cerealeL., cover crops in combination with a virulent strain (MA-1200) of Metarhizium anisopliae (Metschnikoff) Sorkin, for management of the sugarbeet root maggot Tetanops myopaeformis (Röder). A split-split-plot field design was used with oat and rye cover crops as main treatments, seeding rates (0, 1.5, and 3.0 oat bushel equivalents [OBE] per ac) as sub-level treatments, and MA-1200 formulations (granular at plant and foliar postemergence) compared with terbufos 15G and an untreated control as sub-sub-level treatments. Relative levels of control were evaluated on a 0 to 9 damage rating (DR) scale (0 = no visible feeding injury, 9 = 75% of root surface scarred), and contrasts were used to compare treatment means. Under the moderate T. myopaeformis feeding pressure that developed in the plots (mean DR of 6.08 in untreated controls), MA-1200 formulations provided significantly better root protection when combined with cover crops than treatments with no cover. In general, granular MA-1200 performed significantly better when combined with rye than with oat (mean DR 4.67 and 5.72, respectively). Granular MA-1200 in the presence of oat at 3.0 OBE/ac had significantly lower root injury (mean DR=5.45) than in the absence of a cover crop (mean DR= 6.70). Also, sugarbeet plots receiving postemergence foliar MA-1200 had significantly less root feeding injury when combined with the rye cover at 3.0 OBE/ac (mean DR= 4.5) than their non-cover counterparts (mean DR=6.22). Findings from our first test of this novel integrated strategy indicate a positive interaction between M. anisopliae and oat and rye cover crops for management of T. myopaeformis. Results also suggest that complex tritrophic interactions can occur between the entomopathogen, the cover crop, and the target insect. The field experiment will be repeated in 2003.