Effects of maize grain epicuticle on grain-insect-fungus interaction

USSEGLIO VL; DAMBOLENA J S; ZUNINO, MARÍA PAULA

Congreso; VI Congress of the Latin American Association of Chemical Ecology; 2021

In general, the study of the interaction of the maize grain with its main pests, Sitophilus. zeamais and Fusarium verticillioides, is carried out independently, focused on the study of the binary grain-insect or grain-fungus interactions, without considering the dynamics joint of the three organisms. However, the results of biological interactions are only fully understood when considered in the multitrophic environment in which these species develop. The present work aimed to determine, in a silo tritrophic experimental model, using two-way olfactometers, the participation of the epicuticle of maize grains in the contamination of healthy grains, from the migration of S. zeamais and F verticillioides. For this, 4 treatments were proposed: Bitrophic G-I (maize grains + S. zeamais), Bitrophic G-H (maize grains + F. verticillioides), Tritrophic (maize grains + S. zeamais + F. verticillioides) and double control (only maize grains). After 32 days of experimentation, it was observed that both the double control, the Bitrophic GI and the Bitrophic G-H did not present fungal mycelium development, while in the Tritrophic treatment the development of mycelium and percentage of mycotoxins was higher at the end of the olfactometer where the grains conserved their epicuticle. This result is in agreement with the preference of S. zeamais for maize kernels with epicuticle, indicating that the insect would act as a vector of the fungal mycelium and promote its development. The results obtained in this work allow us to conclude that the chemicalsignaling exerted by the epicuticle of the maize grain in the interaction with S. zeamais presents apredominance in the Tritrophic grain-insect-fungus interaction, being, in this experimental system, above to the physical protection that the grain pericarp can provide.