When aphids start to feed on a corn plant, the corn reacts in several ways. Within a few hours, the plant produces chemicals that strengthen the cell walls — this makes it more difficult for the aphids to pierce the cells to suck the phloem. The plant then releases volatile organic chemicals, many that are often associated with the odour of a plant. These compounds attract other insects, such as parasitic wasps that attack aphids. If the aphids continue to suck phloem from the leaves, the corn takes on another approach and releases different volatile organic chemicals in its defense against the aphids.
A recent study found that corn varieties differ in their reaction and resistance to herbivorous attacks. Most plant breeding programs are conducted in conventional farming conditions where pesticides are used. Consequently, such differences in pest resistance might not be noticed or selected for. Growing and breeding varieties with strong defence mechanisms against pests may be a way to minimize pest damage without the use of pesticides.
Sources: Dynamic Maize Responses to Aphid Feeding Are Revealed by a Time Series of Transcriptomic and Metabolomic Assays. Vered Tzin, Noe Fernandez-Pozo, Annett Richter, et al. Plant Physiology. Volume 169, Issue 3, Pages1727-43, November 2015; Characterization of biosynthetic pathways for the production of the volatile homoterpenes DMNT and TMTT in Zea mays. Annett Richter, Claudia Schaff, Zhiwu Zhang, et al. Plant Cell. Volume 28, Issue 10, Pages: 2651-2665. October 2016.
- Janet Wallace