Applying Behavioral-Ecological Theory to Plant Defense: Light-Dependent Movement in Mimosa pudica Suggests a Trade-Off between Predation Risk and Energetic Reward

Abstract

Many animal species tolerate different amounts of predation risk based on environmental conditions and the individual's own condition, often accepting greater risk when energetically stressed. We studied the sensitive plant Mimosa pudica to see whether it too accepts greater risk of predation when less light energy is available. This plant displays a defensive behavior of rapidly folding its leaves when stimulated by touch, thereby decreasing visibility to herbivores. Averting herbivory involves a trade-off because leaf closure results in a reduction in light foraging. We manipulated the light environment of individual M. pudica plants and recorded the time it took a plant to reopen its leaves following stimulation as a measure of tolerance of predation risk. As predicted by theory, avoidance behavior was sustained longer under high light conditions than under more light-limited conditions. These findings suggest this species balances the risk and reward of antiherbivore behavior in relation to current environmental conditions and that behavioral-ecological theory is a useful framework for understanding plant responses to predators.

An improved protocol for in vitro propagation of the medicinal plant Mimosa pudica L.

“…The growth is annual and, despite presenting erect stem when young, they become creeper plants at the adult phase. The leaf sensitiveness to mechanical, electrical or thermal stimuli is a feature of this species, evidenced by the fast closure of leaflets when disturbed (Jensen et al, 2011). M. pudica is used in folk medicine, mainly in Asian countries, whereas its extracts are attributed diuretic, astringent and antispasmodic activities.…”

“…On the other hand, M. pudica is described as a highly invasive pantropical weed, having a negative impact on natural and agricultural ecological systems (Klonowska et al, 2017). Although presenting fast and easy propagation in nature, the seeds of M. pudica are subject to biotic and abiotic agents, which affect the germination success (Jensen et al, 2011).…”

A comparison of plants and animals in their responses to risk of consumption

“…Foraging decisions by plants follow predictions of state-dependent models developed for animals [34]. For example, shaded plants allocate resources preferentially towards growth and away from defense [39,40] and light-starved plants are willing to tolerate greater risk of herbivore attack [41].…”

“…The repertoire of plant perception and response to risk has similarly been limited by evolutionary variation, although several key 'animal-associated' traits have also appeared in the plant lineage. For example, while plants do not generally move to escape herbivores, more limited leaf movements or fluttering may provide defense against herbivores [41,60,61].…”

Boolean function applied to Mimosa pudica movements

“…The greatest peculiarity of this plant, also called a woody herb, is the rapid movement of leaflets, and some authors suggest that this species balances the risk and reward of antiherbivore behavior in relation to current environmental conditions. 2 When touched, the leaves close up and reopen after a few minutes (Seismonastic or thigmonastic movements). These types of movements (also observed in Venus fly trap plant) are mostly because of the fast loss of water from swollen motor cells, resulting in temporary collapse of cells and quick curvature in the parts where these cells are located.…”