Hemiptera plant. Phloem sap, which has a higher concentration of sugars and nitrogen, is under positive pressure unlike the more dilute xylem sap. Most of the Sternorrhyncha and a number of Auchenorrhynchan groups feed on phloem. Phloem feeding is common in the Fulgoromorpha, most Cicadellidae and in the Heteroptera. The Typhlocybine Cicadellids specialize in feeding on non-vascular mesophyll tissue of leaves, which is more nutritious than the leaf epidermis. Most Heteroptera also feed on mesophyll tissue where they are more likely to encounter defensive secondary plant metabolites which often leads to the evolution of host specificity. Obligate xylem feeding is a
Sugary drink tax were estimated to be $147 billion a year in 2009. In the same year, the American Heart Association reported that the soft drinks and sugar sweetened beverages are the largest contributors of added sugars in Americans' diets. Added sugars are sugars and syrups added to foods during processing or preparation and sugars and syrups added after preparation. Excessive intake of added sugars, as opposed to naturally occurring sugars, is implicated in the rise in obesity. Philadelphia and Berkeley are the first two cities to pass a tax on sugary drinks in the U.S. Berkeley's tax of 1 cent/oz of sugary