SOE 306 Herbivory Defense 1 Herbivory 2 Escape in space and time 3 Resistance 4 Chemical Defenses 5 Defense in Action 6 Allocation to Defense 7 Defense against Pathogens Herbivory Herbivory The effect of herbivory depends on what is eaten Girdling Effects of herbivory Effects can depend on plant size Herbivory Herbivory reduced growth and reproduction in 82 studies What limits herbivores Herbivore populations limited by plant availability bottom up control Herbivore populations limited by abiotic factors Top down control predators limit herbivory Herbivory Herbivory from bark beetles x Limited by host availability and climate Huang et al 2020 New Phytologist Wolf Creek Pass CO Chronic Herbivory x Hazardia squarrosa Herbivory for Biological Control Cactoblastis cactorum Herbivory for Biological Control Carduus nutans Empidonax traillii extimus Diorhabda carinulata Rhinocyllus conicus Tamarix ramossima Community effects Generalist species may promote diversity and species richness Introduced herbivores can have big impacts Dr Amy Trowbridge Assistant Professor of Forest Entomology University of Wisconsin Madison amy trowbridge https amymtrowbridge wixsite com website Herbivory Defense 1 Herbivory 2 Escape in space and time 3 Resistance 4 Chemical Defenses 5 Defense in Action 6 Allocation to Defense 7 Defense against Pathogens Plant Defense Escape in Space and Time Dr Amy Trowbridge Assistant Professor of Forest Entomology University of Wisconsin Madison amy trowbridge https amymtrowbridge wixsite com website How does insect feeding impact plants UMN Extension Adaptations of plants against herbivore attack Plant Defense Escape Resistance Tolerance In space In time Indirect vs Direct Chemical vs Physical Escape in space Apparently so Apparency likelihood of a plant being found by herbivores Feeny 1970 Greater host dilution and lower tree apparency contribute to associational resistance in young trees Castagneyrol et al 2013 Journal of Ecology Escape in space Crypsis Mimosa pudica Lithos spp Monotropsis odorata Adaptations of plants against herbivore attack Plant Defense Escape Resistance Tolerance In space In time Indirect vs Direct Chemical vs Physical Escape in time Masting Benefits of masting 1 Increased pollination efficiency through synchronized flowering 2 increased seed dispersal 3 reduced seed consumption through predator satiation Escape in time Phenological mismatch Asynchrony led to reduced female pupal weight slower rate of larval development increased susceptibility to nucleopolyhedrovirus Martymyanov 2015 PLoSONE Herbivory Defense 1 Herbivory 2 Escape in space and time 3 Resistance 4 Chemical Defenses 5 Defense in Action 6 Allocation to Defense 7 Defense against Pathogens Plant Defense Resistance Adaptations of plants against herbivore attack Plant Defense Escape Resistance Tolerance In space In time Indirect vs Direct Chemical vs Physical Resistance The consequence of heritable plant qualities that result in a plant being relatively less damaged than a plant without the qualities Physical Leaf toughness Trichomes Direct Chemical Toxins Digestibility reducers Latex resin Indirect Predator food shelter Predator parasitoid attractants Structural Defenses Structural Defenses trichomes Resistance The consequence of heritable plant qualities that result in a plant being relatively less damaged than a plant without the qualities Physical Leaf toughness Trichomes Direct Chemical Toxins Digestibility reducers Latex resin Indirect Predator food shelter Predator parasitoid attractants Ant bodyguards in acacia Gijsman et al 2021 a Domatia to house ants b c Extrafloral nectaries Beltian bodies Resistance The consequence of heritable plant qualities that result in a plant being relatively less damaged than a plant without the qualities Physical Leaf toughness Trichomes Direct Chemical Toxins Digestibility reducers Latex resin Indirect Predator food shelter Predator parasitoid attractants Plant resistance direct and indirect Direct examples Toxins Digestibility reducers Herbivore Diagram courtesy of Meredith Schuman How do PSMs affect insects Disrupt membrane function nutrient and ion transport Deter signal transduction metabolism hormone controlled processes Interfere with neuroreceptors Toxicity dosage dependent compartments to minimize autotoxicity Plant resistance direct and indirect Direct examples Toxins Digestibility reducers Indirect Rewards Information Herbivore Diagram courtesy of Meredith Schuman Predators Parasitoids Indirect Defense Bodyguards Plants attract predators to consume their herbivores Mutualism between plants and predators Pearse et al 2020 Resistance defense Plant secondary metabolites PSMs compounds not directly involved in growth development or reproduction BUT required for survival and use building blocks and enzymes derived from primary metabolism compounds not directly involved in growth development or reproduction BUT required for survival and use building blocks What are some examples of secondary metabolites rimary metabolism Herbivory Defense 1 Herbivory 2 Escape in space and time 3 Resistance 4 Chemical Defenses 5 Defense in Action 6 Allocation to Defense 7 Defense against Pathogens Plant Defense Phytochemistry 3 Major classes of PSMs Changes in primary metabolism can have cascading effects N containing secondary compounds Encountered less commonly in plants than phenolics and terpenoids Synthesized from aliphatic and aromatic amino acids Aliphatics via TCA cycle Aromatics via shikimic acid pathway tryptophan tyrosin phenylalanine Classes of N containing 2o compounds 1 Alkaloids 2 Cyanogenic glycosides 3 Glucosinolates 4 Non protein amino acids Alkaloids Solanaceae Papaveraceae Ranunculaceae Apocynaceae Multiple functions Affect enzymes Inhibit DNA synthesis and repair Affect nervous system Paralysis and toxic effects postsynaptic receptors nicotine and conline coniceine Cyanogenic Glycosides Cyanogenic glycosides stable compounds in the vacuole Glucosinolates mustard oils Brassicaceae Hydrolysis products react spontaneously with compounds containing unshared pairs of electrons proteins amino acids Extreme variation in composition and concentration complicates defense role Capparidaceae Tropaeolaceae Non protein amino acids Poaceae Fabaceae Anti metabolites by providing non functional proteins Interfere with essential enzymes L DOPA hardening of cuticle Neurotransmitter mimics dopamine norepinephrine Usable forms of nitrogen Terpenes and
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