A Pharm-Ecological Perspective of Terrestrial and Aquatic Plant-Herbivore Interactions

Abstract

-We describe some recent themes in the nutritional and chemical ecology of herbivores and the importance of a broad pharmacological view of plant nutrients and chemical defenses that we integrate as "Pharm-ecology". The central role that dose, concentration, and response to plant components (nutrients and secondary metabolites) play in herbivore foraging behavior argues for broader application of approaches derived from pharmacology to both terrestrial and aquatic plant-herbivore systems. We describe how concepts of pharmacokinetics and pharmacodynamics are used to better understand the foraging phenotype of herbivores relative to nutrient and secondary metabolites in food. Implementing these concepts into the field remains a challenge but new modeling approaches that emphasize tradeoffs and the properties of individual animals show promise. Throughout we highlight similarities and differences between the historic and future applications of pharm-ecological concepts in understanding the ecology and evolution of terrestrial and aquatic interactions between herbivores and plants. We offer several pharm-ecology related questions and hypotheses that could strengthen our understanding of the nutritional and chemical factors that modulate foraging behavior of herbivores across terrestrial and aquatic systems.

Seed fate and decision‐making processes in scatter‐hoarding rodents

“…The reasons for these variable results are complex. Numerous environmental and physiological constraints may produce behaviours in field studies that differ from expectations based on nutrient content alone (Forbey et al, 2013). Proteins, lipids, and carbohydrates are absorbed with different efficiencies, have different energetic content, and require different amounts of energy to metabolize (Robbins, 1993).…”

“…Instead, they would be best addressed through controlled laboratory experiments that link seed choice, digestive and metabolic physiology, and animal condition (e.g. Smith & Follmer, 1972;Raubenheimer & Simpson, 1997;Forbey et al, 2013).…”

Explaining Human Recreational Use of ‘pesticides’: The Neurotoxin Regulation Model of Substance Use vs. the Hijack Model and Implications for Age and Sex Differences in Drug Consumption

“…Plant choice in non-human animals is heavily influenced by toxin concentration, which appears to be assessed by chemosensors in, e.g., the mouth and gut, followed by conditioned learning and social learning (e.g., observing mother’s plant choices) (73, 74). Complete avoidance of plant toxins is not an option, however.…”

“…At the same time, because plant toxins can provide fitness benefits, regulatory mechanisms should not, and could not, completely eliminate exposure to plant toxins but instead balance dose-dependent costs vs. benefits, and adjust intake accordingly [Ref. (74, 77, 78), and references therein].…”

Declines in plant palatability from polar to tropical latitudes depend on herbivore and plant identity

“…As an example, tissue palatability, a quantifiable trait that integrates nutritional content, morphological and chemical defenses, and consumer feeding behavior (Forbey et al. ), is generally lower in the tropics than at higher latitudes for most vascular plants (e.g., Basset , Pennings et al. , Morrison and Hay , Anstett et al.…”