- Plant compounds studied for food safety chores
- Scientists pitch in to help keep salad mixes safe to eat
- Botulism assay quickly detects potent foodborne toxin
By Marcia Wood
February 7, 2014
Botulism, the sometimes deadly illness commonly associated with botched home-canning or other stored-food mishaps, has a new face. According to U.S. Department of Agriculture (USDA) molecular biologist Robert M. Hnasko, botulism today is both a food safety and a homeland security concern because bioterrorists could—using the natural toxins that cause botulism—make everyday foods and beverages deadly. The nerve-damaging toxins, called neurotoxins, are produced by a common soil-dwelling bacterium, Clostridium botulinum, and several of its close relatives.
Hnasko works for the Agricultural Research Service (ARS), USDA's chief intramural scientific research agency.
Now, a handy test strip that Hnasko and his colleagues have developed may give homeland security and food safety officials a powerful tool to use against the toxins. When put to work as the basis of a field-ready test kit, the strip can provide results in less than 20 minutes. That makes it well suited for rapid, preliminary screening in the event of a bioterrorist threat, an outbreak of foodborne botulism in which the culprit food has not yet been pinpointed, or during other emergencies.
The strip fits snugly into a holder (technically a "lateral flow device") like those in pregnancy test kits for at-home use. Only a small amount of prepared sample is needed, and the results, shown on a color display, are easy to see and understand.
The strip is equipped with laboratory-built proteins, known as monoclonal antibodies, which bind exclusively to A- or B-type (serotype) botulinum toxins. Together, these types are responsible for more than 80 percent of all cases of foodborne botulism in the United States. ARS biologist Larry Stanker led the experiments that yielded the antibodies.
Using monoclonal antibodies in a lateral-flow device to detect botulinum toxins isn't new. However, the test that Hnasko and co-researchers developed, described in detail in a 2012 article in the Journal of Immunological Methods, is likely the first of its kind that can concurrently detect and differentiate the A and B serotypes.
Hnasko and Stanker collaborated in the experiments with microbiologist Jeffery A. McGarvey and technician Alice V. Lin, all with ARS in Albany, Calif., and with former Albany research associate Kathryn H. Ching.
The botulinum investigations, highlighted in the February 2014 issue of Agricultural Research magazine, support the USDA priority of improving food safety.
The scientists are continuing to seek collaborations with test-kit developers and manufacturers to expand the test strip's food safety, medical, and homeland security applications.
Reduced myelin may contribute to poor survival of low-birth-weight piglets, and improved myelination may help the piglets survive, according to new ARS research. Click the image for more information about it.
- New system gives insight to animals' feeding habits
- Pig stress syndrome linked to gene defect
- Scientists use new method to help reduce piglet mortality
By Sandra Avant
February 6, 2014
About 10 to 20 percent of piglets do not survive to weaning, and 5 to 10 percent are stillborn. Unlocking the effects of myelin production, an important aspect of brain development, in piglets may be one of the keys to their survival.
U.S. Department of Agriculture (USDA) scientists are investigating myelin production, called "myelination," which is essential for proper functioning of the nervous system and affects coordination and reflex speed. A team led by Jeffrey Vallet, a physiologist and research leader of the Reproduction Research Unit at the Agricultural Research Service (ARS) Roman L. Hruska U.S. Meat Animal Research Center in Clay Center, Neb., is examining myelination's role in helping newborn piglets move quickly and easily to avoid being accidentally crushed by their mother, a primary cause of piglet preweaning mortality.
Scientists compared myelin content from the cerebellum, brain stem and spinal cord, which are involved in coordination and reflexes, between the largest and smallest pig fetuses during a sow's late pregnancy. They found no differences in spinal cord myelination, which develops first, between the two groups. However, significantly less myelin was found in the brain stem and cerebellum of smaller pig fetuses.
In another study, Vallet and his colleagues investigated the effects of the dietary supplement creatine, which plays a role in energy metabolism. They looked at energy metabolism and myelination in piglets. Feeding creatine to pregnant sows did not affect the birth process—the amount of time between piglets' births, number of stillbirths and preweaning mortality. However, the number of low-birth-weight piglets crushed by their mothers that received creatine was reduced.
Overall, these studies suggest that reduced myelin may contribute to poor survival of low-birth-weight piglets, and that improved myelination may help the piglet's ability to avoid the sow when necessary, according to Vallet.
ARS is USDA's principal intramural scientific research agency, and the research supports the USDA priority of promoting international food security.
Read more about this research in the February 2014 issue of Agricultural Research magazine.
Potatoes produced more tubers when exposed to higher carbon dioxide levels and erratic drought conditions in recent ARS growth chamber studies that replicated potential changes in climate. Click the image for more information about it.
- No-till could help maintain crop yields despite climate change
- USDA irrigation research: Good to the last drop
- Using less water to grow more potatoes
By Ann Perry
February 3, 2014
Research at the U.S. Department of Agriculture (USDA) suggests that potatoes are still the go-to tuber when times get tough.
Agricultural Research Service (ARS) agricultural engineer David Fleisher and his colleagues conducted studies to measure how potato plants would respond to elevated atmospheric carbon dioxide levels and the increasingly erratic rainfall patterns expected to result from global climate change. ARS is USDA's chief intramural scientific research agency, and this work supports the USDA priority of responding to global climate change.
The team conducted two outdoor chamber studies to evaluate effects of short-term drought cycles at current and elevated carbon dioxide levels. The studies were conducted using soil-plant-atmosphere research chambers that provided precise control over carbon dioxide levels, air temperature, irrigation and humidity. The chambers contained sensors that monitored air, soil, and canopy temperatures, relative humidity, and solar radiation above and below the canopy.
The quantity of solar radiation in the first study was about twice as much as in the second. Having two different study periods allowed the scientists to evaluate how variations in solar radiation during the drought periods affected plant response. In both studies, 11-day drought cycles were applied before tuber formation began and around 10 days after tuber formation began.
The researchers observed significant differences in plant response that they attributed to the variation in solar radiation, which in turn affected plant water-use efficiency and dry matter production. With all other growth factors being equal, the plants in the first study had a 30 percent to 200 percent increase in total dry matter production, depending on carbon dioxide levels and water availability.
The team also noted that the cyclic droughts resulted in lower levels of dry matter and leaf area production. They concluded that drought stress before tuber formation probably enhanced the future delivery of carbon, water and plant nutrients to tubers instead of to stems or leaves—and that this response increased under elevated carbon dioxide levels. Averaged across all drought treatments, tuber yield from plants growing under elevated carbon dioxide levels was as much as 60 percent greater than tuber yield from plants growing under current carbon dioxide levels.
By Kim Kaplan
January 31, 2014
Eating breakfast—or skipping it—may significantly influence a child's ability to solve math problems, according to a study funded by the Agricultural Research Service (ARS). This is among the new nutrition and health findings noted in the most recent issue of the ARS Food and Nutrition Research Briefs and its Spanish-language edition (Informe de investigaciones de alimentos y nutrición).
View the English edition at www.ars.usda.gov/is/np/fnrb/fnrb0114.htm.
The popular online newsletter reports discoveries from researchers at ARS laboratories nationwide.
Among other findings, the current issue reports:
• The Structural Database of Allergenic Proteins database can be used to predict if people allergic to one type of nut may also be allergic to another type of nut.
• ARS scientists are looking at olive powder and other plant compounds as a way of controlling foodborne pathogens such as Escherichia coli O157:H7.
• Prepping raw french fries for three minutes with infrared heat may lower the food's oil uptake by about one-third.
ARS Food and Nutrition Research Briefs is offered with color photos and illustrations on the Web. And by clicking the "subscribe" link on the newsletter's home page, readers can sign up for two e-mail options: They can receive the full text of the newsletter by e-mail, or simply an advisory that a new issue has been posted to the Web.
ARS is the U.S. Department of Agriculture's chief intramural scientific research agency.
A technology for detecting problems in stored apples turns out not to work well as an early warning system for Anjou pears kept in very-low-oxygen storage, ARS research shows. Click the image for more information about it.
By Marcia Wood
January 30, 2014
Fresh Anjou pears, harvested in late summer from orchards in Oregon and Washington, will usually be available in supermarket produce departments through early spring of the following year. That's thanks to, in part, science-based, long-term-storage technologies that help postpone ripening.
In ongoing studies, U.S. Department of Agriculture (USDA) researcher James P. Mattheis and his colleagues are tackling some of the problems that may affect this popular pear while or after it has been kept in refrigerated, low-oxygen storage, also referred to as controlled-atmosphere storage.
Some of this research suggests that tactics that work well for keeping fresh apples free of plant diseases or other disorders while in controlled-atmosphere storage may not necessarily be quickly or easily applied to meet Anjou pears' storage needs.
In one early study, Mattheis and coinvestigator David R. Rudell, Jr., both with the USDA Agricultural Research Service (ARS) Tree Fruit Research Laboratory at Wenatchee, Wash., and former postdoctoral research associate David Felicetti, tested chlorophyll fluorescence monitoring as a candidate "early warning system" for keeping an eye on the quality of stored pears.
According to Mattheis, the technology is used successfully to detect problems in stored apples. That's because an increase in the fluorescence levels in the chlorophyll in a stored apple's peel apparently correlates well with an increase in problems linked to low oxygen levels.
When apple chlorophyll levels go up during storage, storehouse managers know to raise the oxygen level slightly to prevent damage to the fruit.
But the Anjou research, documented in scientific articles in Postharvest Biology and Technology in 2011 and 2013, showed that the monitoring system didn't work well in detecting either black speck or pithy brown core in Anjou pears that were stored, experimentally, in extremely low oxygen conditions.
The scientists found that black speck and pithy brown core occurred despite the fact that there were no detectable changes in the affected pears' chlorophyll fluorescence levels. For that reason, Mattheis is—for now—advising packers to use caution before relying on chlorophyll fluorescence for monitoring stored Anjou pears in very low oxygen conditions.
Black speck is an unwanted speckling of the pear's skin; pithy brown core, as its name implies, discolors the pear near its core and changes the pear's texture from delectable to unpleasantly fibrous.
This and related ARS-led Anjou pear research at Wenatchee is described in the January 2014 issue of Agricultural Research magazine. ARS is the USDA's chief intramural scientific research agency.
ARS scientists and their colleagues have developed a new chick vaccination system that puts vaccines inside gelatin beads, which are fed to birds, protecting them against intestinal diseases like coccidiosis. Click the image for more information about it.
- Treating poultry diseases without antibiotics
- Egg yolk loaded with antibodies boost poultry immunity
By Sandra Avant
January 28, 2014
An alternate vaccine delivery system for newborn chicks has been developed by U.S. Department of Agriculture (USDA) scientists to improve vaccination against intestinal diseases like coccidiosis.
A common and costly poultry disease, coccidiosis is caused by tiny, single-celled parasites that belong to the genus Eimeria. Infected birds spread disease by shedding oocysts, the egglike stage of the parasite. The infected birds are slower to gain weight and grow, and sometimes die.Traditional poultry vaccine methods involve vaccinating chicks in trays on a conveyor with an electronic sprayer. However, some chicks may be missed by these methods and consequently have little defense against diseases.
The alternate system, developed by scientists at the Agricultural Research Service (ARS) Henry A. Wallace Beltsville Agricultural Research Center (BARC) in Beltsville, Md., and Southwest Research Institute (SwRI) in San Antonio, Texas, involves putting low doses of live Eimeria oocysts inside gelatin beads, which are fed to birds.
Microbiologist Mark Jenkins and zoologist Ray Fetterer, in BARC's Animal Parasitic Diseases Laboratory, examined the gelatin bead vaccine effectiveness in chicks of layer hens and broilers. One-day-old chicks were immunized by ingesting gelatin beads or with a hand-held sprayer. The group that swallowed the gelatin beads had a greater vaccine uptake than the group that received the vaccine in spray form, and was better protected against coccidiosis.
In another experiment, chicks were reared similarly to birds in a poultry house, vaccinated with the gelatin beads and later given a dose of Eimeria oocysts. The vaccine-bead-fed chicks had greater weight gains than an unvaccinated group and were more capable of converting feed into body mass.
ARS and SwRI scientists have filed a patent application for this research and are working on a gelatin bead vaccine delivery device for commercial poultry houses.
ARS is USDA's principal intramural scientific research agency.
Read more about this research in the January 2014 issue of Agricultural Research magazine.
ARS researchers and their collaborators have finished a first-of-its-kind inventory of wild relatives of important crops indigenous to the United States, such as sunflowers, or that have become naturalized to aid in the conservation of their genetic diversity. Click the image for more information about it.
- USDA and Russian scientists develop high-tech crop map
- World's blueberries protected in unique, living collection
- ARS sends third seed shipment to Norway seed vault
By Jan Suszkiw
January 27, 2014
A first-of-its-kind inventory for wild and weedy relatives of important crops has been developed by U.S. Department of Agriculture (USDA) scientists and their collaborators.
According to Stephanie Greene, a plant geneticist with USDA's Agricultural Research Service (ARS), the inventory was created to aid the conservation of these so-called "crop wild relatives" (CWRs) and ensure their availability as prized sources of genetic diversity for an array of economically important traits, including improved drought tolerance and resistance to pests and diseases.
Greene and her colleagues prioritized the U.S. national inventory based on factors such as how closely related the wild species are to crops, especially those grown for food; their availability in gene banks or protected habitat areas, and the ease or difficulty of transferring desirable traits from the wild species to their cultivated "cousins."
All told, the inventory covers 4,596 taxa from 985 genera and 194 plant families that are either indigenous to the United States or have become naturalized—established of their own accord following human introduction. Among CWR of major crops, the genus Helianthus (sunflower) is the most abundant, numbering 73 total taxa, including H. annuus (domesticated as the sunflower). Other important CWRs include species closely related to strawberries, blackberries, raspberries, blueberries, grapes, and stone fruits such as cherries and plums.
There are many examples of native wild U.S. species that have played key roles in ensuring the continued health and productivity of crops grown worldwide, according to Greene, who works at the ARS Plant Germplasm Introduction and Testing Research Unit worksite in Prosser, Wash. The inventory itself lists 17 major crops that have benefitted from traits associated with 55 native CWR.
A recent example is cultivated sunflowers worldwide, which have benefitted from wild North American relatives in the form of resistance to rust, sclerotinia, downy mildew and other diseases and pests.
Read more about this research in the January 2014 issue of Agricultural Research magazine. ARS is USDA's principal intramural scientific research agency, and this work supports the USDA priority of promoting international food security.
ARS scientists have calculated the dissolved oxygen level that catfish need for growth, giving producers an objective management measure rather than having to rely on when the fish are observed at the surface in distress. Click the image for more information about it.
- Lending a hand in hybrid catfish production
- USDA researchers seek new ways to boost catfish production
- Helping fish get rid of "itch"
By Sandra Avant
January 24, 2014
The aquaculture industry is taking notice of U.S. Department of Agriculture (USDA) research that gives the precise levels of dissolved oxygen needed to keep pond-raised catfish alive and growing.
Traditionally, fish farmers relied on daily observations to determine if fish were getting enough oxygen. If farmers saw fish sucking air at the water surface, they turned on aeration equipment. If no fish were seen, it was assumed that enough oxygen was being provided.
Les Torrans, a fish biologist in the Agricultural Research Service (ARS) Warmwater Aquaculture Research Unit in Stoneville, Miss., pinpointed the dissolved oxygen concentrations needed to keep fish alive and growing. ARS is USDA's principal intramural scientific research agency.
Dissolved oxygen is the most critical water quality factor in aquaculture. If oxygen gets too low, fish can die or become partially asphyxiated. Lack of air causes fish to lose their appetite. When they eat less, they do not grow as quickly. As a result, instead of fish reaching market size in two years, it may take four to five years.
Torrans, together with his ARS and Mississippi State University colleagues at the Thad Cochran National Warmwater Aquaculture Center in Stoneville, studied the effects of dissolved oxygen concentration on catfish growth, yield, food consumption and feed conversion.
An oxygen monitoring system was used to maintain precise minimum dissolved oxygen setpoints—3.0, 2.0 and 1.5 parts per million (ppm). Results showed that the minimum dissolved oxygen concentration for optimum production is 2.5 to 3.0 ppm. At this level, catfish growth significantly improved, fewer fish died, feed conversion improved and the production cycle was shorter.
Farmers who use good oxygen management practices can double the growth rate of fish, according to Torrans. The exact amount of aeration needed to maximize fish food intake, growth and production is now available.
Read more about this research in the November/December 2013 issue of Agricultural Research magazine.
ARS researchers and their colleagues recently tested 25 varieties of microgreens for their nutrient levels and found on average they had about five times greater levels of vitamins than their mature counterparts. Click the image for more information about it.
- Market lighting affects nutrients
- Nutrient retention of safer salads explored
Specialty Greens Pack a Nutritional Punch
By Rosalie Marion Bliss
January 23, 2014
"Microgreens" is a marketing term used to describe edible greens which germinate from the seeds of vegetables and herbs and are harvested without roots at the seedling stage. The plants at the seedling stage have two fully expanded cotyledons, or seed leaves. They are considered a specialty genre of colorful greens that are good for garnishing salads, soups, plates and sandwiches.
A U.S. Department of Agriculture (USDA) researcher has led a team of scientists who analyzed the key nutrients in 25 different varieties of vegetable microgreens. The study results could be used to estimate levels of vitamins and nutrients in microgreens, according to the scientists.
The team determined the concentration of essential vitamins and carotenoids in the microgreens. Key nutrients measured were ascorbic acid (vitamin C), tocopherols (vitamin E), phylloquinone (vitamin K), and beta-carotene (a vitamin A precursor), plus other related carotenoids in the cotyledons that are critical for human health and function.
The team showed that different microgreens contained widely differing amounts of vitamins and carotenoids. Total vitamin C content ranged from 20 to 147 milligrams (mg) per 100 grams of cotyledon fresh weight, depending on which plant species was being tested. The amounts of the carotenoids beta-carotene, lutein/zeaxanthin, and violaxanthin ranged from about 0.6 mg to 12.1 mg per 100 grams of fresh weight. For comparison, an average apple weighs 100-150 grams. In general, microgreens contained considerably higher levels of vitamins and carotenoids—about five times greater—than their mature plant counterparts.
Among the 25 microgreens tested, red cabbage, cilantro, garnet amaranth, and green daikon radish had the highest concentrations of vitamin C, carotenoids, vitamin K and vitamin E, respectively. Growing, harvesting, and handling conditions may have a considerable effect on nutrient content. Additional studies are being conducted to evaluate the effect of agricultural practices on nutrient retention.
Read more about this research in the January 2014 issue of Agricultural Research magazine.
ARS researchers and their industry colleagues tested 10 plant-derived compounds as alternative binders to guar gum in hydraulically applied mulch—hydromulch—like the one being sprayed here. Click the image for more information about it.
- Kitty litter: Potential new use for spent corn grains
- USDA scientists use commercial enzyme to improve grain ethanol production
- Researchers study benefits of barley as a biofuel crop
By Marcia Wood
January 21, 2014
Highway crews busily spraying a green coating on newly graded slopes may be working with a hydraulically applied mulch, or hydromulch. This temporary, porous layer can help protect newly sown seeds.
According to U. S. Department of Agriculture (USDA) plant physiologist Steven F. Vaughn, hydromulches typically contain water; a dye, so that crews can easily see where they've been; a mulch, such as wood fibers; and a binder, which is a compound that helps keep the mulch intact. In a series of laboratory tests, Vaughn and his colleagues have shown that half a dozen plant-derived compounds outperformed guar gum, a commonly used binder made by grinding beans of the guar plant into a powder. When water is added, the powder forms a viscous gum.
Importantly, the alternative binders may prove to be less expensive than guar gum, Vaughn notes.
Vaughn works at the National Center for Agricultural Utilization Research operated in Peoria, Ill., by USDA's Agricultural Research Service (ARS). ARS is the chief intramural scientific research agency of USDA.
The list of top-performing binders, documented in a 2013 scientific article in Industrial Crops and Products, includes xanthan gum, made by the bacterium Xanthomonas campestris, and gums extracted from seeds of two members of the mustard family, camelina and lesquerella.
Also making the list: a starch-based material, known as a high-amylose starch-lipid complex, that's made of cornstarch loosely bound to sodium palmitate, a fatty acid found in many everyday vegetable oils.
The panel of 10 compounds selected for the lab tests appears to be unique. And, although starch has been used commercially as a hydromulch binder, the high-amylose starch-lipid complexes, made with an eco-friendly method developed by Vaughn's ARS colleagues, apparently had not been previously lab-tested for this potential use.
Vaughn is now coordinating a series of outdoor tests as a follow-up to the indoor experiments. He collaborated in the research with ARS scientists Robert W. Behle, Mark A. Berhow, Steven C. Cermak, Roque L. Evangelista, George F. Fanta, Frederick C. Felker, and James A. Kenar, and with Edward Lee of HydroStraw, LLC.
Read more about this research in the January 2014 issue of Agricultural Research magazine.
ARS horticulturist Eric Brennan has found that randomly interspersing alyssum plants throughout rows of organic lettuce helps maximize visits by hoverflies that prey on lettuce pests. Click the image for more information about it.
- USDA scientists say mix-and-match cover cropping can optimize organic production
- Researchers use oxygenated phosphine fumigation to control insect pests
- Using ground covers in organic production
By Ann Perry
January 16, 2014
Studies conducted in an organic lettuce field managed by the U.S. Department of Agriculture (USDA) indicate that there's more to sweet alyssum than just good looks. Agricultural Research Service (ARS) horticulturist Eric Brennan has identified ways to improve how the pretty white flowers control aphid pests that prey on lettuce leaves. ARS is USDA's chief intramural scientific research agency.
Lettuce growers in California's central coast plant alyssum to attract adult hoverflies that feed on the flower's pollen and nectar. After eggs laid by the well-fed females hatch, the voracious larvae prey on currant lettuce aphids—an important primary insect pest of lettuce in the region. The aphids are particularly difficult to control because they colonize the interior leaves of the lettuce plant.
Brennan, who works at the ARS U.S. Agricultural Research Station in Salinas, Calif., wanted to figure out the most cost-effective alyssum planting patterns in lettuce fields to help organic producers maximize their profits. At a working research farm in Salinas that is certified for commercial organic production, he established experimental beds with eight different planting combinations of alyssum and romaine lettuce.
For two growing seasons, Brennan evaluated how alyssum biomass and flower production varied with alyssum planting density and how competition between lettuce and alyssum affected the biomass of both plants. In beds where alyssum had been planted in addition to a full complement of lettuce, the alyssum produced more blossoms per gram of alyssum dry matter.
This response indicated that the alyssum and lettuce planted in this pattern may have been in stronger competition for nutrients needed to support biomass production. But the resulting boost in blossoms increased alyssum's value as an insectary plant, which is a flowering plant cultivated in crop fields because it attracts insect predators to feed on pests.
Brennan has also concluded that randomly interspersing alyssum plants throughout all the lettuce rows could minimize competition between lettuce and alyssum and encourage adult hoverflies to forage for pollen and nectar more evenly throughout the field.
Results from this study were published in Biological Control in 2013.
Read more about this work in the January 2014 issue of Agricultural Research magazine.
ARS researchers are refining the way cotton farmers spray pesticides to control the western tarnished plant bug (Lygus Hesperus). Photo courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.
- A greener way to raise cotton and combat nematodes
- Plant hormone increases cotton yields in drought conditions
- ARS survey helps growers track two key cotton pests
By Dennis O'Brien
January 13, 2014
Research by U.S. Department of Agriculture (USDA) scientists focused on a major threat to cotton in the Southwestern United States could soon help growers cut back on insecticide use.
Growers in the Southwest often spray insecticides to control western tarnished plant bugs (Lygus hesperus). But before they do, they will walk through their fields waving hand-held nets and count the number of L. hesperus they capture. They decide to spray based on capture thresholds that vary from one region to the next.
Studies by USDA Agricultural Research Service (ARS) scientists Dale Spurgeon and W. Rodney Cooper show that these "sweepnet" survey results can be misinterpreted, and that important factors in determining when to spray-such as the age of the insects and the growth stage of the cotton-are often overlooked.
Spurgeon is based at the U.S. Arid-Land Agricultural Research Center in Maricopa, Ariz. and Cooper is with the Yakima Agricultural Research Laboratory in Wapato, Wash. They conducted the research at a former ARS research site in Shafter, Calif. ARS is USDA's principal intramural scientific research agency.
In one study, the researchers videotaped L. hesperus feeding on cotton in a laboratory and released others to feed on cotton plants in a greenhouse to assess the feeding habits and damage levels caused by two types of nymphs (3rd and 5th instars) and pre-reproductive adults. Results, published in Environmental Entomology (October 2013), showed that the older 5th instar nymphs caused significantly more damage than the younger nymphs and older adults. The results show the importance of determining the life stages of the lygus infesting the cotton, not just the total numbers.
In another study, they marked adult L. hesperus and periodically released them into rows of upland and pima cotton over two growing seasons. They collected as many of the marked insects as possible the day after each release, along with any wild L. hesperus attracted to the cotton. Releasing and re-collecting marked insects allowed them to check on the effectiveness of the collection efforts, which followed standard sweepnet protocols. Insects caught in the nets were dissected to determine their ages.
Results, published in the Journal of Entomological Science (July 2013), showed that in both species of cotton, captured populations were dominated by mature adults that cause less damage. As cotton plants grew, collection efforts also became less efficient because larger and leafier plants offered the insects more foliage for "hiding out."
The research also showed that in pima cotton, the more damage-inducing younger adults preferred to feed on the ends of the plant branches, which are substantially shielded by foliage. That makes them harder to capture and more likely to be undercounted than older adults. This wasn't an issue in upland cotton because it has a more open architecture.
Taken together, the results suggest that L. hesperus sampling methods should be re-evaluated and that growers may need to adopt different methods for different types of cotton.
Read more about the research in the January 2014 issue of Agricultural Research magazine.
- Project aims to biofortify rice for improved nutritional value
- USDA links gene flow between weedy and domesticated rice to rising carbon dioxide levels
- New rice varieties offer benefits to growers
By Jan Suszkiw
January 9, 2014
Using conventional breeding methods, U.S. Department of Agriculture (USDA) scientists have developed a new rice cultivar that can hold its own against barnyardgrass and other costly weeds, opening the door to reduced herbicide use.
David Gealy and colleagues with USDA's Agricultural Research Service (ARS) and the University of Arkansas Division of Agriculture (UADA) at Stuttgart developed the new rice, STG06L-35-061, by crossing standard U.S. long-grain varieties with indica types from Asia. Indica rices are known for their ability to outcompete many weeds using allelochemical root secretions and other defenses. But these rice types haven't caught on in the United States in large part because of their poor grain quality, notes Gealy, with the ARS Dale Bumpers National Rice Research Center in Stuttgart.
Gealy, together with UADA rice breeder Karen Moldenhauer and ARS molecular geneticist Melissa Jia, tackled the problem by crossing two commercial tropical japonica rices, 'Katy' and 'Drew,' with PI312777, an indica germplasm line. They evaluated the offspring plants as part of multi-year trials that included comparisons to other rice crosses and chose STG06L-35-061 as the top pick for high grain yield and quality, early maturity, stem strength, pest and disease resistance, allelopathy to weeds, and other desirable traits.
The team's trials included evaluations of the new cultivar in both weed-free and weed-infested plots, with barnyard grass as the dominant weed species. Several commercial cultivars, including 'Lemont,' along with indica lines, were also tested.
During the trials, conducted in 2008 and 2009, weed-suppression ratings for the new cultivar were 41 percent higher than 'Katy,' 68 percent higher than 'Lemont,' and about equal to PI 312777. In weed-free plots, the new rice averaged about 5,000 pounds of grain per acre versus 5,400 for 'Drew;' 4,000 for 'Katy;' and 4,300 for 'Lemont.'
According to Gealy, the new rice's combination of traits will make it especially suited to organic and low-input production systems.
Read more about the rice in the January 2014 issue of Agricultural Research.
ARS is USDA's principal intramural scientific research agency.