Biology subjects

Briones-May, Y.

Publications and source records attributed to Briones-May, Y..

2 recordsLinked to original sources

bioRxiv2025

From leaves to defenders: how amount and dispersion of leaf damage affect extrafloral nectar production and ant-mediated protection in wild cotton (Gossypium hirsutum)

O_LIExtrafloral nectar (EFN) drives mutualistic interactions between plants and ants. However, EFN production is costly, and its induction is predicted to vary with herbivore-related factors. We examine how the amount and within-plant damage spatial uniformity (i.e., dispersed and concentrated damage) affect EFN production and ant-mediated defence in wild cotton (Gossypium hirsutum). Previous work suggests that severe and concentrated damage is costliest to plants, leading us to hypothesise that such damage would induce greater EFN production and, consequently, stronger ant attraction and protection. C_LIO_LIWe conducted a greenhouse experiment in which plants were subjected to one of the following mechanical damage treatments: control (no damage), low damage (two damaged leaves, 30% of area removed each), high concentrated damage (two damaged leaves, 60% each), and high dispersed damage (four damaged leaves, 30% each; i.e., same total area than concentrated damage). The day after treatments, we measured EFN volume and sugar content from one nectary per plant (a per-nectary EFN response), and the number of secreting nectaries per plant (a proxy for whole-plant level EFN response). Subsequently, we performed a field experiment using the same treatments to evaluate EFN-mediated ant recruitment and ant-provided protection by placing caterpillars on plants. C_LIO_LIBoth high-damage treatments increased EFN volume per nectary, whereas low damage did not. However, against our prediction, dispersed damage was the only treatment that increased the number of secreting nectaries. Consistently, once placed in the field, plants with dispersed damage recruited more ants and caterpillars on them were more likely to be attacked by ants. C_LIO_LIContrary to expectations, plants subjected to dispersed damage exhibited a greater total investment in EFN, presumably via local induction of more nectaries per plant, and thereby enhancing ant-mediated defence. This study highlights the importance of herbivory intensity and within-plant spatial uniformity in shaping ant-plant interactions. C_LI

ecology↗

bioRxiv2025

Effects of variability in the amount and dispersion of within-plant herbivory on resistance- and tolerance-related responses in wild cotton

Herbivory triggers complex induced defensive responses in plants that may vary depending on the amount and dispersion of damage, the latter has received much less attention. We examined how wild cotton (Gossypium hirsutum) responds to different amounts of herbivory and how it is dispersed among the leaves (concentrated versus dispersed) using the specialist caterpillar Alabama argillacea. In a greenhouse experiment, plants underwent different herbivory treatments: no damage, low herbivory (two caterpillars, one on each of two leaves), high concentrated herbivory (four caterpillars, two on each of two leaves), and high dispersed herbivory (four caterpillars, each on one of four leaves). We measured extrafloral nectar (EFN), an indirect defense trait, and phenolic production, a direct chemical defense, as well as regrowth capacity (new leaf biomass two months after herbivory) as a tolerance proxy. To distinguish between local and systemic defense induction, we measured resistance-related responses on damaged and undamaged leaves. EFN was significantly and more consistently induced in damaged leaves (i.e., stronger local induction) in response to high dispersed damage. Phenolic compounds were not affected by any of the damage treatments. Additionally, wild cotton fully compensated for damage in terms of new leaf biomass under all herbivory treatments, except after high concentrated damage, suggesting higher costs incurred by this type of herbivory. These results highlight the importance of studying plant-induced defenses under varying herbivory conditions and suggest opposing effects on resistance-related (EFN, indirect) versus tolerance-related induced responses, which are known to affect tri-trophic interactions associated with wild cotton. Main ConclusionVariability in caterpillar damage to wild cotton leaves differentially shapes resistance- and tolerance-related responses; dispersed damage induces more extrafloral nectar production, and concentrated damage more strongly drives reductions in regrowth.

ecology↗