Oviposition preference of Plutella xylostella in response to simulated herbivory on Brassica oleracea

Jasmonic acid (JA) is an organic compound commonly released by plants as a regulatory response to abiotic and biotic stresses such as herbivory. Due to this response, JA is being considered to play an important role in the future of agricultural pest control and a great amount of research is required to fully understand the mechanisms across different plant species.

In laboratory experiments, herbivory was simulated by mechanically damaging samples of Brassica Oleracea (Common cabbage) to induce this anti-herbivory response. The response was tested using the oviposition preference of Plutella xylostella (Diamondback moth).

Previous studies have shown that JA-treatment on Common cabbage made them more attractive for oviposition by the Diamondback moth. This preference was assumed to be due to the plants’ constitutive use of JA so we expected to see oviposition preference toward the mechanically damaged samples.

Contrary to our hypothesis, the mean number of eggs laid on both control and treatment plants were very similar suggesting no significant oviposition preference of the moth.

This result suggests that the anti-herbivory response was not triggered by our method of mechanical damage and may be much more complex. It is possible the anti-herbivory response may be species (herbivore) specific ie. detection of saliva or simply that the level of damage needs to be examined further.

Keywords: Plutella xylostella, Brassica oleracea, Jasmonate, choice test, plant defence, pest control.