How does the corn borer negatively affect corn crops?

The corn borer negatively affects corn crops primarily by extracting nutrients and moisture. This pest, specifically the European corn borer and other species, feeds on the tissues of corn plants, particularly the stems, leaves, and ears. As the corn borer larvae tunnel into the plant, they disrupt the plant's ability to transport essential nutrients and water, which can lead to reduced growth and lower yields. The damage created by their feeding can also expose the plant to secondary infections and diseases, compounding the negative impact on crop health and productivity.

In contrast, the other options address factors that are not the primary mechanisms of harm caused by the corn borer. For example, while competition for space can occur among plants, corn borers primarily damage plants through feeding rather than direct competition. Similarly, they do not prevent pollination directly; instead, their feeding can lead to poor ear formation, which might indirectly affect pollination outcomes. The issue of sunlight penetration is more related to plant density and overall health than to the specific actions of corn borers.