Download A Field Guide to Venomous Animals and Poisonous Plants: by Roger Caras, Visit Amazon's Steven Foster Page, search PDF

By Roger Caras, Visit Amazon's Steven Foster Page, search results, Learn about Author Central, Steven Foster, , Roger Tory Peterson

This crucial consultant to defense within the box beneficial properties ninety venomous animals and greater than 250 toxic vegetation and fungi. The 340 line drawings make id quickly and easy; a hundred and sixty species also are illustrated with colour photos.

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Such differences in abundance and distribution between food sources are addressed. Gaps in availability of suitable food sources are most likely to occur in low-diversity ecosystems (including agroecosystems). These systems may show distinct peaks in food availability during flowering of the dominant plant species, or during particular sap-feeder outbreaks, but food availability is often low during the remainder of the season. Food scarcity may be aggravated when these ecosystems are dominated by nectariless plants.

Each of these steps may represent physiological hurdles that restrict the nutritional value of a food item. Suitability of plant food sources for insects Insects may be able to recognize and avoid unsuitable food sources. Positive correlations between nutritional suitability and gustatory response have been reported for several nectar-feeders (Von Frisch 1934; Wa¨ckers 2001). However, gustatory responses are not always adapted to the recognition of unsuitable food items, as illustrated by numerous reports of insect poisoning following ingestion of toxic nectar, pollen, or honeydew (Barker 1990; Detzel and Wink 1993; Adler 2001).

However, only a few studies have shown that secondary metabolites in nectar affect pollinators (Waller 1972; Carey and Wink 1994; Adler 2001). Nectar may contain (considerably) lower levels of secondary metabolites in comparison to other plant tissues (Detzel and Wink 1993). However, the picture can also be reversed. Peumans et al. (1997) showed that lectin levels in nectar from Allium porum are six times those found in foliage. Although toxic effects of nectar, or various of its components, have been well documented, it would be erroneous to conclude that floral nectar in general is an inferior food.

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