Generalist herbivore

An illuminating example of a community consequence of plant defensive metabolites, and of a grazer s adaptation to exploit its host plant, is the ability of some herbivores to sequester plant-derived secondary metabolites for their own defenses (e.g., Avila 1995 Marin and Ros 2004). In terrestrial systems, several specialist insects can sequester defensive chemicals from their host plants (e.g., Nishida 2002), but in aquatic plant-herbivore systems with a prevalence of generalist herbivores this is less common. However, sea hares (Anaspidea) and some other herbivorous opisthobranch molluscs are known to be able to sequester defenses from their algal foods (Avila 1995 Marin and Ros 2004). For the opisthobranch species that are known to obtain metabolites from their food, algae were the... 

Bemays EA, Minkenberg OPJM (1997) Insect herbivores different reasons for being a generalist. Ecology 78 1157-1169... 

Large, generalist marine grazers such as fishes and urchins attempt to choose foods that maximize nutritional input (e.g., protein, lipids, and carbohydrate) (Mattson 1980 Choat and Clements 1998) and minimize intake of secondary metabolites (Hay 1991). The untested assumption underlying these optimal foraging decisions is that detoxification and excretion rates are a constraint on toxin intake and thus drive feeding choice (Freeland and Janzen 1974). However, we have virtually no information on such constraints in marine herbivores, because it requires an understanding of the metabolic fate of secondary metabolites. 

Herbivores and their food plants live in a delicate balance. We distinguish generalist herbivores from specialists. It is thought that generalism... 

Free-living primates respond to plant chemistry black-and-white colobus monkeys, Colobus polykomos, avoid plant leaves with alkaloids, biflavonoids, and milky latex and prefer to eat leaves with a better ratio of nutrients to digestion inhibitors (McKey et al, 1981). The howler monkey, Alouatta palUata, a generalist herbivore, depends on more than one factor in its choice... 

To summarize, specific toxins are effective deterrents to generalist herbivores, but polyphenols produced In relatively large quantities are the only effective deterrent to specialists. Since leaf toughness and lower nitrogen content also deter many herbivores, deciduous forest trees are especially vulnerable to attack during the period of canopy development, which occurs yearly at a predictable time. Gsnopy development Is heavily dependent on available reserves of carbohydrate and nitrogen, and the production of quantitative... 

Venzon, M., Janssen, A. and Sabelis, M. W. (1999). Attraction of a generalist predator towards herbivore-infested plants. Entomologia Experimentalis etApplicata 93 305-314. 

Hagele, B. F. and Rowell-Rahier, M. (2000). Choice, performance, and heritability of performance of specialist and generalist insect herbivores towards cacalol and seneciphylline, two allelochemics of Adenostyles alpina (Asteraceae). Journal of Evolutionary Biology 13 131-142. 

Nomura M, Itioka T. 2002. Effects of synthesized tannin on the growth and survival of a generalist herbivorous insect, the common cutworm, Spodoptera litura Fabricius (Lepidoptera Noctuidae). Appl Entomol Zool 37 285-289. 

It is believed that the presence of secondary metabolites impacts on the survivorship of a cyanobacterial strain in reef habitats that are subject to intense herbivory. Under suitable environmental conditions, cyanobacteria undergo rapid increases in population size, generating large cyanobacterial mats which are not calcified or of tough texture and which therefore present a potential source of food for herbivorous fish and other generalist predators. By restricting predation, potent cyanobacterial toxins facilitate the formation of cyanobacterial blooms.48... 

Pennings, S. C., Masatomo, T. M., and Paul V. J., Selectivity and growth of the generalist herbivore Dolabella auricularia feeding upon complimentary resources, Ecology, 74, 879, 1993. 

GLUCOSINOLATE HYDROLYSIS AND ITS IMPACT ON GENERALIST AND SPECIALIST INSECT HERBIVORES... 

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