Plant having a chemical defense against irritating insects

Plant may repel irritating insects (Credit - Ian Grettenberger)Researchers have found plants may repel the “insect antagonists” after getting cues related to the odors of flies to attract female flies that may result in damage to the plants.

This research has been published online in the journal Proceedings of the National Academy of Sciences (PNAS).

“It’s become increasingly clear in recent years that plants are responsive to odors,” Mark Mescher, assistant professor of entomology, said in a statement. “But previous examples of this are all plant-to-plant. For example, some plants have been shown to respond to the odor of insect-damaged neighbors by priming their own defenses. What’s new about this is that it seems that plants may sometimes be able to smell the insects themselves.”

Researchers worked on tall goldenrod (Solidago altissima) plants. They exposed some of the plants to the odor of the male fly and observed the laying of eggs by female on exposed and unexposed plants by checking the characteristic scarring that happens when females pierce the stem to lay their eggs inside, said Mescher.

Researchers found that the plant started a defensive chemical response after the male emission of particular odors and females laid fewer eggs on exposed plants as they were four times more likely to lay eggs on the unexposed plants.

Researchers also found that the other herbivores such as beetles also resulted in very less damage to the tall goldenrod plants exposed to the fly odors.

“It seems that plants that are able to anticipate an attach by the fly and defend themselves against this damage will be more successful, producing higher quality seeds for the next generation,” John Tooker, assistant professor of entomology, said. “So there must be a strong advantage for plants that can perceive the fly odor.”

“I suspect that this may be happening in many plants,” Tooker added. “But we don’t yet know how widespread it is.”

Reference:

Helms, A., De Moraes, C., Tooker, J., & Mescher, M. (2012). Exposure of Solidago altissima plants to volatile emissions of an insect antagonist (Eurosta solidaginis) deters subsequent herbivory Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1218606110