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Abstracts - Thaís Silveira

EFFECTS OF INDUCED PLANT DEFENSES ON HERBIVORES AND PATHOGENS

Thaís Silveira1*, Guilherme P. Pinheiro1, Gustavo Q. Romero1, Mônica F. Kersch-Becker 1,2,

  1. Department of Animal Biology, State University of Campinas, Campinas-SP, Brazil.

  2. Department of Biological Sciences, University of Alabama, Tuscaloosa-AL, USA

* Correspondence: tha_silveira_@hotmail.com

Herbivory and subsequent induced plant responses have the potential to influence the composition and structure of insect communities. Herbivores can modify the morphological and chemical traits of plants, thus affecting their quality to a subsequent herbivore. However, the chemical and morphological responses of plants are specific to the type of damage. For example, plants damaged by sap-sucking herbivores or pathogens may induce responses distinct from those induced by chewing herbivores. Thus, induced resistance to pathogens and insects is viewed as a desirable and potential crop protection strategy with a relatively benign environmental impact. For this reason, the interest in developing chemicals that activate the natural defenses of plants has grown considerably. Unfortunately, our knowledge about the impact of induced plant defenses in reducing herbivory and disease incidence in the field remains limited. We investigated the impact of two chemical elicitors responsible for activating the two main defensive pathways of plants. Methyl jasmonate (MeJA) induces the jasmonic acid pathway, while the synthetic salicylate mimic benzothiadiazole-7-carbothioic acid S-methyl ester (BTH) induces the salicylic acid pathway. We exogenously applied both chemical elicitors to tomato plants (Solanum lycopersicum, var. Santa Clara) to stimulate the defensive pathways. Each plant was assigned to one of the following treatments: (i) plants sprayed with MeJA (1.0mM MeJA, 1.0 Mmol per plant), (ii) plants sprayed with BTH (1.2mM of benzo(l,2,3)thiadiazole-7-carbothioic acid(S)-methyl ester, 3.0 Mmol per plant), (iii) plants sprayed simultaneously with BTH and MeJA, and (iv) control plants. We then evaluated the responses of pathogens, herbivores and natural enemies to chemically-induced and non-induced plants in both field and laboratory experiments. We demonstrated that BTH decreased disease incidence caused by the fungi Streptopodium spp. Plants sprayed with both MeJA and BTH showed the lowest leaf damage compared to the other treatments. Chemically-induced plants affected the performance of an economic important agricultural pest, the South American tomato pinworm Tuta absoluta. This research demonstrates that chemical elicitors may offer novel solutions to pest and disease management and contributes to a broader understanding of ecological community organization.

The authors thank FAPESP (process #2015/15894-2) and CNPq (process #400892/2014-06) for funding and UNICAMP for the infrastructure offered.