Large‐scale releases of Trichogramma ostriniae to suppress Ostrinia nubilalis in commercially grown processing and fresh market sweet corn

Abstract

We evaluated the egg parasitoid Trichogramma ostriniae (Pang et Chen) (Hym.: Trichogrammatidae) for control of European corn borer [Lep.:Crambidae: Ostrinia nubilalis (Hu¨bner)] in fields of commercial processing sweet corn in New York in 2002 and 2003.We made inoculative releases of 75 000 T. ostriniae/ha when corn was at midwhorl and regional O. nubilalis activity had begun. Each release field was paired with a similar non-release control. The incidence of egg mass parasitism, number of stalk tunnels, incidence of ear damage and effect on insecticide spray decisions were evaluated. Parasitism of cumulative number of O. nubilalis egg masses was 51.3 ± 7.2% and 43.5 ± 5.7% (mean ± SEM) in release fields in 2002 and 2003 respectively. The incidence of ear damage by O. nubilalis was not affected by T. ostriniae in either year of the study. There was no difference in stalk damage between release fields and control fields in either 2002 or 2003. However, individual comparisons between paired release and control fields showed reduced stalk tunnelling in 10 of 19 fields, but ear damage was reduced in only two of 19 fields. Neither the number of actual insecticide sprays nor the number of decisions to spray based on sequential sampling were affected significantly by releasing T. ostriniae. In a separate but related study, where releases were conducted in commercial fresh market sweet corn and used higher rates of release, T. ostriniae had no effect on the number of insecticidal sprays. In an additional experiment using small plots of sweet corn, ear damage was similar whether plots were treated with T. Ostriniae or with insecticide. Additional research should focus on improving the timing, frequency and rate of releases.

Egg Parasitoids in Biological Control and Integrated Pest Management

“…In most cases, however, recent trials of Trichogramma augmentation in agricultural crops, whether used inundatively (Andow et al 1995, Glenn and Hoffmann 1997, Scholz et al 1998, Mills et al 2000, Suh et al 2000a, Hommay et al 2002, Lundgren et al 2002 or as a seasonal inoculation (Wang et al 1988, Hoffmann et al 2002, Gardner et al 2007, have not provided sufficient control as a stand alone treatment. While targeting the egg stage is often an effective strategy for preventing crop damage (Hassan 1993), for some pests increased egg mortality can result in reduced larval mortality with the result that there is no reduction in crop damage (Van Hamburg and Hassell 1984).…”

Enhancing biological control of corn earworm, Helicoverpa zea and thrips through habitat management and inundative release of Trichogramma pretiosum in corn cropping systems

“…Studies have shown that the inoculative release (75,000 female wasps per hectare, at whorl stage) of Trichogramma ostriniae Pang and Chen resulted >40% parasitism per generation of O. nubilalis Pang egg masses, significantly higher than control plots in field corn and sweet corn fields (Gardner et al, 2007;Hoffman et al, 2006;Wright et al, 2001Wright et al, , 2002, and increased total generational mortality significantly . These studies suggested, although inoculative releases of T. ostriniae effectively suppress O. nubilalis infestation, refinement in timing, rate of release and frequency of release could enhance the benefits of using these parasitoids inoculatively.…”

The Present and Future Role of Insect-Resistant Genetically Modified Maize in IPM

“…(Hymenoptera. Trichogrammatidae), are used for the inundative control of O. nubilalis in Switzerland (Bigler, 1986) and Ostrinia furnacalis (Lepidoptera: Crambidae) in China (see section 5.4.3), but this strategy has not been cost-effective in the USA (Andow et al, 1995;Gardner et al, 2007). To control D. v. virgifera, entomopathogenic nematodes have been tested with mixed results (Munson and Helms, 1970;Wright et al, 1993;Ellsbury et al, 1996;Jackson, 1996).…”