Tobacco (Nicotiana spp., L.) refers to a genus of broad-leafed plants of the nightshade family indigenous to North and South America, or to the dried and cured leaves of such plants. Tobacco leaves are often smoked (see tobacco smoking) in the form of a cigar or cigarette, or in a smoking pipe, or in a water pipe or a hookah. Tobacco is also chewed, "dipped" (placed between the cheek and gum), and sniffed into the nose as finely powdered snuff. The Spanish word "tabaco" is thought to have its origin in Arawakan language, particularly, in the Taino language of the Caribbean, said to refer to a roll of these leaves (according to Bartolome de Las Casas, 1552) or to the "tabago", a kind of y-shaped pipe for sniffing tobacco smoke (according to Oviedo), but Sp. tabaco (also It. tobacco) was commonly used to define medicinal herbs from 1410, originating from the Arabic "tabbaq", reportedly since the 9th century, as the name of various herbs. The word might then be European, and later applied to this plant from the Americas.

Tobacco contains the alkaloid nicotine, a powerful neurotoxin that is particularly harmful to insects. All means of consuming tobacco result in the absorption of nicotine in varying amounts into the user's bloodstream, and over time the development of tolerance and dependence. Absorption quantity, frequency and speed seem to have a direct relationship with how strong a dependence and tolerance, if any, might be created. A lethal dose of nicotine is contained in as little as one half of a cigar or three cigarettes; however, only a fraction of the nicotine contained in these products is actually released into the smoke, and most clinically significant cases of nicotine poisoning are the result of concentrated forms of the compound used as insecticides. Other active alkaloids in tobacco include harmala alkaloids.

Tobacco smoking carries significant risks including the potential to develop various cancers as well as strokes, and severe cardiovascular and respiratory diseases. ^* Significantly shorter life expectancies have been associated with tobacco smoking. ^* Many jurisdictions have enacted smoking bans in an effort to minimize possible damage to public health caused by tobacco smoking. The substantially increased risk of developing cancer as a result of tobacco usage seems to be due to the plethora of nitrosamines and other carcinogenic compounds found in tobacco and its residue as a result of anaerobic heating, either due to smoking or to flue-curing or fire-curing. The use of flue-cured or fire-cured smokeless tobacco in lieu of smoked tobacco reduces the risk of respiratory cancers but still carries significant risk of oral cancer. ^* In contrast, use of steam-cured chewing tobacco (snus), avoids the carcinogenicity by not generating nitrosamines, but the negative effects of the nicotine on the cardiovascular system and pancreas are not ameliorated. ^*

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USDA Agricultural Research Service

Fire Ant Outcompetes Other SpeciesEven in its Native Habitat
Thu, 02 Jul 2009 08:46:00 -0500
Read the magazine story to find out more. Fire ants have been found to be the most ecologically dominant species in their environment, according to a new ARS study. Photo courtesy of Pest and Diseases Image Library, Bugwood.org. Nine to 20 individual fire ant queens started U.S. fire ant population   First virus to infect red imported fire ants discovered   Red imported fire ant nemesis gains permanent foothold in Florida Fire Ant Outcompetes Other Species—Even in its Native Habitat By Alfredo Flores July 2, 2009 Even in its native Argentina, the fire ant wins in head-to-head competition with other ant species more than three-quarters of the time, according to Agricultural Research Service (ARS) scientists. ARS scientists at the South American Biological Control Laboratory (SABCL) in Hurlingham, Argentina, have been studying how different ant species fare against the fire ant as part of an effort to learn more about the behavior of this pest—an invasive species in its non-native United States. Fire ants often attack in swarms--not only causing painful stings to humans, but can even kill small animals. Little has been known, however, about the fire ant's competitive nature or how it interacts with other ants. SABCL biologist Luis Calcaterra, working closely with lab director Juan Briano, has been studying interactions between the red imported fire ant, Solenopsis invicta, and other aboveground foraging ants in two habitats in northeastern Argentina—using a combination of pitfall traps and baits to study day-to-day activity in ant communities. The pitfall trap is a 50 milliliter plastic tube buried in the ground and half-filled with soapy water. The bait is one gram of canned tuna placed on a plastic card measuring five centimeters in diameter. The trap and bait gave the scientists a way to determine ant populations at the sites, and showed the dominance of each species. Some 28 ant species coexisted with S. invicta in an open area of forest growing along a watercourse, whereas only 10 species coexisted with S. invicta in the dry forest grassland. The researchers found that the fire ants had the highest numbers in the open forest area along the watercourse. Prior to these studies, it was thought that the fire ant—now established throughout the Americas—was not dominant in its native land. But the studies showed that the fire ants were the most ecologically dominant, winning 78 percent of the interactions with other ants, mostly against its most frequent competitor, the South American big-headed ant, Pheidole obscurithorax, an ant of northern Argentina and Paraguay also introduced in the United States. And in battles with the invasive Argentine ant, Linepithema humile, the fire ants were even more dominant, winning out 80 percent of the time. This study was published in Oecologia, a journal that deals with plant and animal ecology. Read more about the research in the July 2009 issue of Agricultural Research magazine. ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture.
New Bait Lures Varroa Mite to its Doom
Wed, 01 Jul 2009 09:14:00 -0500
Read the magazine story to find out more. ARS scientists have developed a new bait that may help control varroa mites, the top pest of honey bees. Click the image for more information about it. Finding out how genes govern bees' lives   The latest buzz on Russian bees   New test on tap for detecting pesticide-resistant mites New Bait Lures Varroa Mite to its Doom By Jan Suszkiw July 1, 2009 Varroa mites could literally be walking into a trap—thanks to a new attractant developed by Agricultural Research Service (ARS) scientists in Gainesville, Fla. The 1/16-inch long parasite, Varroa destructor, is a top pest of honey bees nationwide, hindering the beneficial insects' ability to pollinate almonds, blueberries, apples, zucchini and many other flowering crops. At the ARS Chemistry Research Unit in Gainesville, research leader Peter Teal and colleagues are testing a bait-and-kill approach using sticky boards and natural chemical attractants called semiochemicals. In nature, Varroa mites rely on these semiochemicals to locate—and then feed on—the bloodlike hemolymph of both adult honey bees and their brood. Severe infestations can decimate an affected hive within several months—and rob the beekeeper of profits from honey or pollinating services. But in this case, the mites encounter a more heady bouquet of honey bee odors that lure the parasites away from their intended hosts and onto the sticky boards, where they starve. In preliminary tests, 35 to 50 percent of mites dropped off the bees when exposed to the attractants. Free-roving mites found the semiochemicals even more attractive, according to Teal. Moreover, the extra dose of semiochemicals wafting through hives didn't appear to significantly interfere with the honey bees' normal behavior or activity, added Teal who, along with postdoctoral associate Adrian Duehl and University of Florida collaborator Mark Carroll, reported the results this past January at the 2009 North American Beekeeping Conference in Reno, Nev. The team hopes ARS' patenting of the Varroa mite attractants will encourage an industrial partner to develop the technology further. Read more about the research in the July 2009 issue of Agricultural Research magazine. ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture.
Spraying Herbicide on Invasive Weeds Doesn't Always Pay
Tue, 30 Jun 2009 09:52:00 -0500
It may not always pay for ranchers to use herbicides to kill exotic invasive weeds on the range, according to a new study. Click the image for more information about it. Knowing where to look for invasive leafy spurge   Seeded pastures can sustain cattle-and native rangelands   USDA Livestock and Range Research Lab expansion unveiled Spraying Herbicide on Invasive Weeds Doesn't Always Pay, Study Shows By Don Comis June 30, 2009 It may not always pay for ranchers to use herbicides to kill exotic invasive weeds such as leafy spurge, according to a 16-year study by the Agricultural Research Service (ARS) and colleagues. Rangeland ecologist Matt Rinella at the ARS Fort Keogh Livestock and Range Research Laboratory in Miles City, MT, and colleagues conducted the study. Data they collected 16 years after a one-time aerial spraying of herbicide showed that the invasive leafy spurge (Euphorbia esula L) may have ultimately increased due to spraying. Conversely, several desirable native forbs were still suffering the effects of spraying 16 years after spraying. Although the herbicide would have dissipated within a few years, it seemed to cause a long-term plant community shift. Any increase in grass production from the herbicide spraying only lasted a year or two. The study was done on the N-Bar Ranch in Montana. Each plot was either grazed and sprayed, grazed but not sprayed, not grazed but sprayed or not grazed or sprayed. Cattle grazing helped maintain native plant numbers when herbicide was used. Cattle grazing can help native forbs thrive because cattle prefer grasses over forbs, and cattle trample soil, loosening soil for seeds that the animals inadvertently plant when seeds are caught in their hooves or fur. That said, when herbicide wasn't used, most native forbs did as well with or without cattle grazing. Herbicide caused the native plants Missouri goldenrod and yarrow to become rarer over the 16-year study period. Barring herbicides, these two species proved capable of co-existing indefinitely with the exotics. Four native perennials became rarer in sprayed plots, but only when grazing was excluded: velvety goldenrod, white prairie aster, vetch, and prairie sagewort. Herbicide spraying caused no long-term harm to four other native perennials. Rockjasmine and other plants belonging to the Androsace spp. group were not affected by the herbicide even initially. The study suggests that applying herbicides over large areas of land containing herbicide-sensitive native plants is sometimes ill-advised. The research was published in the journal Ecological Applications. ARS is the principal intramural scientific research agency in the U.S. Department of Agriculture.

USDA - Agriculture

Remarks by First Lady Michelle Obama at the U.S. Department Of Agriculture

Transcript: Secretary Tom Vilsack Hosts News Conference Call with Reporters

Johanns Signs Framework Agreement with United Nations' Food and Agriculture Organization Director General Diouf Johanns' One Year Report on Avian Influenza Actions
Agriculture Secretary Mike Johanns and Director-General Jacques Diouf of the United Nations' Food and Agriculture Organization (FAO) today signed a Framework Agreement to coordinate technical assistance between USDA and the FAO. The agreement will help to address issues important to agriculture, such as chronic hunger, plant and animal diseases including avian influenza, conservation, genetic resources and the growing demand for renewable energy resources.

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