Evaluation of natural plant chemical defenses in comparison to Bacillus thuringiensis on the survival and feeding preferences of Ostrinia nubilalis

Abstract

The European corn borer (ECB), Ostrinia nubialis (Hübner), is an herbivorous pest of over 200 documented hosts, especially corn (Zea mays L.), in the United States and Canada, and had been labeled a “generalist herbivore.” The feeding behavior of insects, including ECB, depends on perception of multiple physical and chemical features presented by the plant and the insect’s response to these cues. Recently, in the United States there has been little evidence of ECB presence outside of cornfields. Generalist insect species have the ability to evolve over time into specialists when the focal plant is common, predictable and abundant. All of these criteria are met by corn in the United States. This study investigated the growth and survivorship of ECB on a range of hosts that vary in defensive chemistries and their preferences among these hosts (sweet corn, Cry1F Bt corn (maize), non-Bt near isoline maize, cucumber, squash, tomato, and green bean). Experiments were conducted in the growth chamber, greenhouse, and field to determine survival under different conditions. Survival was significantly higher on non-Bt corn hosts than any other host provided. Choice feeding assays were conducted to determine preference based on biomass consumption. Results generally supported the expected outcome with greater consumption of non-Bt corn hosts. From the results on survival and preference, it can be concluded that non-Bt corn is the most suitable host plant for ECB, thus strongly supporting ECB corn specialization.