Researchers at the National Centre for Biological Sciences, Bangalore, have identified that plant defence chemicals can help build immunity of the attacking insect herbivore. These results have been published in the Journal of Chemical Ecology on the 06th of August 2019, with their story grabbing the Journal’s cover page.
Upon herbivory, plants release a specific blend of volatile chemicals that attract natural enemies of the herbivores such as parasitoids wasps. The wasps parasitise the insect larvae and thus, the volatile chemicals function as an indirect defence strategy of plants. But do these plant volatiles trigger any response in the herbivore itself? This unexplored aspect of the tritrophic interaction between the plants, herbivores and their natural enemies has been unravelled in this study.
The Bangalore based researchers analyzed the response of common cutworm (Spodoptera litura) to various herbivore-induced plant volatiles. This insect is known to infest at least 120 plant species and is a major pest in agriculture. Interestingly, upon exposure to specific plant volatiles, the cutworm larva showed a heightened immune response and volatile exposed larvae survived better against bacterial infection and parasitization than those without any prior volatile exposure. These results, for the first time, demonstrate that herbivorous insects can upregulate their immunity by sensing the volatile chemicals released by plants. These findings bring to light a novel ecological adaptation, which could now prompt agriculturists to rethink pest management strategies.
This study was supported by the Department of Science and Technology (DST, Early career award, Ramanujan Fellowship), Department of Biotechnology (DBT) and Max-Planck Society (DST- Max-Planck partner group program).
The Journal of Chemical Ecology paper can be accessed here: https://link.springer.com/article/10.1007/s10886-019-01091-3
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