Dennis D. Calvin

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Eleven spectral vegetation indices that emphasize foliar plant pigments were calculated using airborne hyperspectral imagery and evaluated in 2004 and 2005 for their ability to detect experimental plots of corn manually inoculated with Ostrinia nubilalis (Hübner) neonate larvae. Manual inoculations were timed to simulate infestation of corn, Zea mays L., by(More)
Insect phenology models are widely used for decision support in pest management and more recently in phytosanitary risk assessments. The development of generic and flexible modeling tools means that phenology models can be quickly created using an insect’s developmental threshold temperatures and degree-day requirements. To assist scientists and field(More)
A 3-yr, multi-state survey of farmers who had planted transgenic Bacillus thuringiensis (Bt) corn was conducted to evaluate perceptions of Bt corn performance and its utility as a management option for European corn borer, Ostrinia nubilalis (Hübner). A questionnaire was sent to farmers in Illinois, Iowa, Kansas, Minnesota, Nebraska, and Pennsylvania who(More)
Field studies in Pennsylvania and Maryland were conducted during 2000, 2001, and 2002 to test the applicability of published yield loss relationships developed in central Pennsylvania for European corn borer, Ostrinia nubilalis (Hübner), management in warmer, longer season corn, Zea mays L., grain production regions of the northeastern United States. Both(More)
Effects on monarch butterfly, Danaus plexippus L., after continuous exposure of larvae to natural deposits of Bacillus thuringiensis (Bt) and non-Bt pollen on milkweed, were measured in five studies. First instars were exposed at 3–4 and 6–7 d after initial anthesis, either directly on milkweed plants in commercial cornfields or in the laboratory on leaves(More)
Reproductive development of female European corn borer, Ostrinia nubilalis (Hübner), was investigated and a classification system proposed. Females collected in a blacklight trap during 1982 and 1983 were dissected and their reproductive system examined. Female reproductive systems were divided into six stages based on ovum development within the ovarioles,(More)
Genetically engineered corn hybrids that contain a cry gene from the bacterium Bacillus thuringiensis Berliner (Bt) are gaining popularity for controlling the corn pest Ostrinia nubilalis (Hübner). Continuous use of Bt corn, however, could select for O. nubilalis that are resistant to this corn. Monitoring for insect resistance is important, because it(More)
Synchronization between a parasitoid and its preferred host is an essential strategy for successful biological control. Two ecotypes of Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) in North America are distinguished by their voltinism. In this study, the differential impact of a specialist parasitoid, Macrocentrus cingulum Brischke (Hymenoptera:(More)
Bt maize has become increasingly popular with United States (U.S.) growers since it was commercially available in 1996. Yield protection, reduced need for insecticides, improved grain quality, and ease of use are benefits that motivated growers to plant 32 percent of total acres to Bt maize in 2004. Rapid adoption of a technology raises many questions(More)
Oviposition by European corn borer, Ostrinia nubilalis Hübn, was examined in relation to sweet corn development from 1994 to 1996, and related to harvest infestation levels. Stepwise multiple regression and linear regression showed that 79-87% of the variability of larvae per ear or proportion of ears infested at harvest was explained by the number of egg(More)