URBANA, Ill. – Although it would seem logical that large numbers of roosting birds would attract more mosquitoes that carry West Nile virus and contract the disease when bitten, recent research at the University of Illinois found the opposite to be true. That is, when large groups of birds roost together the chances that an individual bird will get bitten by mosquitoes carrying West Nile virus and subsequently contract the disease actually go down.
“Our study is the first field-based evidence to support what’s called the ‘encounter-dilution effect’ acting in a vector-borne disease system with an experiment,” said U of I researcher Bethany Krebs. “There have been other laboratory and modeling studies that suggest that mosquitoes feed less per individual in a group than they do on a solitary bird but it’s hard to get the information in natural settings.”
The experiment was conducted over a period of three years. “We trapped mosquitoes inside and outside of roosts from 2010 to 2012 to determine whether roosts attracted more mosquitoes than non-roost sites,” Krebs said. “Then we sent the mosquitoes to a lab in Texas that ran analyses on them to determine if they carried the virus. Uninfected house sparrows were used as sentinel birds to assess host risk of West Nile exposure in 2012—the timing coincided with the historical period of peak West Nile virus transmission in the Chicago study areas known to be ‘hot spots’ for the disease.”
The house sparrows were placed in flight cages—23 birds in cages near communal roosts and 25 in non-roost cages. Krebs explained that sentinel birds are used by public health departments as sort of a “canary-in-the-coal mine” early warning system to detect the presence of a vector-borne disease.
“Only three sparrows near roosts contracted West Nile virus whereas 11 birds in non-roost cages were infected,” Krebs said. “So the risk of West Nile virus exposure for those sentinel birds caged within roosts was significantly lower than for birds caged in non-roost locations.”
Jeff Brawn, U of I ecologist and department head of the Natural Resources and Environmental Sciences, described how this study sheds light on the spread of vector-borne diseases, such as West Nile virus, compared to those transmitted via direct contact. “If you’re in a group, the probability of infection goes way up with direct contact diseases such as colds and flu,” Brawn explained. “This study confirmed that the risk is spread out among the individuals in the herd; in the case of West Nile virus, which is a vector-borne disease, individual risk is minimized.”
Brawn said that they don’t understand why some birds roost and others of the same species do not. But this study shows that those who do choose to roost together benefit by the lower risk of exposure to West Nile virus infection.
The maintenance and transmission of West Nile virus goes something like this: The common mosquito Culex pipiens is the carrier (vector) of the disease. The mosquitoes bite birds, usually at night while they are roosting and infect them with the virus. Crows and jays typically die after they contract West Nile virus, but robins are called “super-amplifiers of the disease.” They are able to serve as hosts for the virus. Later, other mosquitoes bite the infected birds, get the virus, and transmit it to another host—which could be another bird or a human.
This brings to a close almost 10 years of research on West Nile virus in the Chicago area supported by funding from the National Science Foundation. “This was the last year that we were planning to do significant field work in that area of Chicago,” Krebs said.
Brawn said that a study like this that has many components also requires experts from many disciplines. “It can only happen when you have field biologists, mosquito specialists, disease experts, epidemiologists–that team of researchers that worked on this project is multi-faceted. That’s what it takes to do this kind of work. We collected blood samples from the birds and sent those to be analyzed. We sent the mosquitoes to someone else who knew how to do all of the genetic analysis. It’s a team working together.”
Brawn added that, although the study was on birds, it could provide an interesting implication with respect to human behavior and health risk. “If you are in the woods alone, you may have a greater probability of getting bitten than if you are in a large group of people,” he said.
“Host group formation decreases exposure to vector-borne disease: a field experiment in a ‘hotspot’ of West Nile virus transmission” was written by Bethany L. Krebs, Marilyn O. Ruiz, and Jeffrey D. Brawn from the University of Illinois; Tavis K. Anderson from Georgia Southern University; Tony L. Goldberg and Christina M. Newman from the University of Wisconsin; Gabriel L. Hamer from Texas A&M; Uriel D. Kitron from Emory University; and Edward D. Walker from Michigan State University. The research was published in the Proceedings of the Royal Society B: Biological Sciences and was supported by the National Science Foundation Ecology of Infectious Disease program.
EPA concludes neonicotinoid seed treatments of negligible benefit to soybean production
URBANA, Ill. - On Oct. 15, the U.S. Environmental Protection Agency issued a report on the benefits of neonicotinoid insecticidal seed treatments to soybean production in the United States. Neonicotinoid insecticidal seed treatments include imidacloprid, thiamethoxam, and clothianidin. According to University of Illinois crop sciences professor Mike Gray, the analysis concentrated only on the potential benefits of imidacloprid and thiamethoxam used as seed treatments.
“Although clothianidin is registered for use as a soybean seed treatment, the authors of the report considered its use ‘minor’ as compared with the other two neonicotinoids,” Gray said.
Gray also pointed out other key points from the report.
- “On average, from 2008-2012, neonicotinoid-treated seeds were applied on 30 percent of soybean acres (with some individual years approaching 40 percent of soybean acres).” page 3
- Within the Corn Belt (Illinois, Indiana, Iowa, Missouri, and Ohio, 2008-2012) 5,413,000 and 5,368,000 acres of soybeans were planted with imidacloprid and thiamethoxam seed treatments, respectively. This translates into 433,600 and 151,700 pounds of imidacloprid and thiamethoxam, respectively, used during those years (2008-2012). page 4
- Across the United States from 2008-2012, 1,151,000 pounds of imidacloprid and thiamethoxam were used as seed treatments on soybeans. page 4
- For this analysis, early-season insects were the primary focus and included many familiar Corn Belt pests such as soybean aphids, bean leaf beetles, cutworms, thrips, and some soil insects (for example, wireworms, seedcorn maggots). page 5
- “This analysis provides evidence that U.S. soybean growers derive limited to no benefit from neonicotinoid seed treatments in most instances. Published data indicate that most usage of neonicotinoid seed treatments does not protect soybean yield any better than doing no pest control.” page 13
- “In cases where pest pressure does necessitate some type of insect control, efficacious alternatives are available for the key foliar pests of soybeans at a comparable cost per acre.” page 13
“The authors of this EPA report acknowledge that the use of neonicotinoids within soybeans is largely prophylactic — an insurance based form of pest management,” Gray said. “In their analysis, they estimate that insecticidal seed treatments cost on average approximately $7.50 per acre. They also point out that foliar insecticides, labeled for use in soybeans, generally cost less than $7 per acre (11 insecticides identified).”
Gray added that the authors of this EPA report make the following assumptions:
- “Nearly all soybean growers are already making foliar pesticide applications of some sort and thus have access to the necessary equipment for application. In addition, growers would not have to make an additional field pass as foliar alternative insecticides that target the same pest spectrum as neonicotinoid seed treatments are applied at the same time as a number of current foliar sprays (including herbicides, fungicides, miticides, etc.) and can be tank mixed. No yield gains are expected from neonicotinoid seed treatments, which means the only potential economic impact would be the cost of an insecticide used as a foliar spray.” page 10
“Some of these assumptions can be challenged, especially on very large farms across the Corn Belt in which producers rely upon aerial applications of pesticides rather than making their own ground-based treatments,” Gray said. “Additionally, the use of fungicides, although increasingly common in recent years, is not routine within every midwestern soybean field. Therefore, application of an insecticide and fungicide tank mix should not be considered a given on most soybean fields, nor should that of a herbicide and insecticide combination. The optimum time to apply a herbicide for weed control can vary considerably from that to deter insect damage.”
Gray explained that the information in this report raises considerable doubt regarding the economic benefits of these insecticidal seed treatments to soybean producers. “The use of insecticidal seed treatments within the soybean production system clearly functions as an insurance-based form of pest management,” he said. “For large commercial farms across the Midwest landscape, many producers typically do not scout soybean fields and utilize economic thresholds to make management decisions for insect pests.”
Over the years, Gray said producers could save on insecticide costs within many midwestern soybean fields by only treating when economic levels of a given insect pest surface. Yet he added that the long-term trend regarding insect management within large-scale commercial corn and soybean production systems reveals an increasing reliance on product-based inputs (insecticidal seed treatments, Bt hybrids) versus labor and management costs (scouting and use of economic thresholds).
“It will be interesting to see if the U.S. EPA considers a similar analysis for these insecticidal seed treatments in corn production systems,” he said.
No-till agriculture may not bring hoped-for boost in global crop yields, study finds
URBANA, Ill. - No-till farming, a key conservation agriculture strategy that avoids conventional plowing and otherwise disturbing the soil, may not bring a hoped-for boost in crop yields in much of the world, according to an extensive new meta-analysis by an international team that included a University of Illinois crop sciences researcher and was led by the University of California, Davis.
As the core principle of conservation agriculture, no-till has been promoted worldwide in an effort to sustainably meet global food demand. But after examining results from 610 peer-reviewed studies, the researchers found that no-till often leads to yield declines compared to conventional tillage systems, except it still shows promise for yield gains in dryland areas.
The landmark findings from their review were published Oct. 22 in the journal Nature.
“The big challenge for agriculture is that we need to further increase yields but greatly reduce our environmental impacts,” said Cameron Pittelkow, who co-authored the study as a postdoctoral scholar at UC Davis and is now on the faculty at U of I. “The common assumption that no-till is going to play a large role in the sustainable intensification of agriculture doesn’t necessarily hold true, according to our research findings.”
Conservation agriculture is currently practiced on 125 million hectares of land globally, an area nearly as big as the total U.S. cropland. Three key principles guide the concept: minimizing soil disturbance (also called no-till farming), protecting the soil with cover crops or leftover crop residue, and rotating the crops.
The goals of conservation agriculture are to improve long-term productivity, profits, and food security, particularly under the threat of climate change. Because conservation agriculture avoids tillage, it is less time-consuming and can be more cost-effective than conventional farming methods.
In recent years, however, there has been some disagreement about the impact of no-till farming practices on yield.
“This review was a tremendous undertaking and is probably the largest meta-analysis done in agriculture,” said co-author Bruce Linquist, a Cooperative Extension specialist at UC Davis.
After assessing more than 5,000 side-by-side observations, the researchers concluded that on average no-till negatively impacts yields at the global scale, yet several opportunities exist for more closely matching or even exceeding conventional tillage yields.
For example, yield reductions were minimized when the principles of crop rotation and residue retention were also practiced, highlighting the importance of implementing all three conservation agriculture principles as part of an integrated management system rather than no-till alone.
Moreover, when adopted in dry climates in combination with the other two principles of conservation agriculture, no-till farming performed significantly better than conventional tillage, likely due to the higher retention of soil moisture.
Dryland ecosystems are home to 38 percent of the world’s population, and millions of acres of land in arid regions of sub-Saharan Africa and South Asia have been identified as suitable for sustainable intensification. Yet the authors also caution that practicing no-till in dryland areas without the implementation of the other two principles of conservation agriculture decreases yields.
In regions with moist climates and sufficient precipitation, no-till farming actually resulted in yields that were on average 6 to 9 percent lower than with conventional tillage methods.
“No one has ever stated that there would be a significant decline like this,” said Chris van Kessel, a professor of plant sciences at UC Davis and co-author of the study. “Our findings suggest that broad implementation of conservation agriculture may not be warranted in all areas, particularly where residue retention and crop rotation practices are hard to implement.”
“Productivity limits and potentials of the principles of conservation agriculture,” was recently published online in Nature, and can be accessed at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13809.html.
Co-authors are Cameron M. Pittelkow of University of Illinois, Xinqiang Liang of Zhejiang University, China; Mark E. Lundy of the UC Davis Department of Plant Sciences; Kees Jan van Groenigen and Natasja van Gestel, both of Northern Arizona University; Johan Six and Juhwan Lee, both of the Swiss Federal Institute of Technology, Switzerland; and Rodney T. Venterea of the U.S. Department of Agriculture – Agricultural Research Service.
This article was adapted from a press release from the UC Davis Department of Plant Sciences News and Media Relations office.
Attachment + parenting: Building an emotional foundation that endures
URBANA, Ill. - Child development professionals call it secure attachment—a young child’s deep sense of knowing her parents are there for her. That bond gives a secure base from which to explore the environment, protection in times of uncertainty, and a source of joy in everyday interactions, according to University of Illinois attachment experts Nancy McElwain and Kelly Bost.
As a result of that security, children come to believe that they are competent in managing challenging situations, are worthy of care and attention, and can trust others in close relationships. And that sense of well-being can endure throughout a child’s lifetime.
So how do kids develop a secure attachment? “It depends on how a parent responds when the child is distressed or upset and needs emotional support,” says Bost, professor of human development and family studies.
Parents have a key role in helping kids learn how to regulate and express their emotions. Secure attachment gives young kids an emotional foundation as they learn how to handle powerful feelings like sadness, frustration, social fearfulness, and anger, says McElwain, professor of human development and family studies.
“When parents punish their children for being sad, angry, or scared, kids learn to hide their emotions instead of showing them. These children become increasingly anxious when they experience these feelings because they know they’ll face negative consequences,” she adds.
Here are some everyday examples of how parents can replace negative responses with more effective ones when challenges arise:
Say a young child returns from a birthday party crying because her friend neglected her, choosing to play with another child instead.
- Rather than dismiss her sadness (“Just forget about it, honey. Don’t be sad”), support your child as she experiences this difficult emotion: “I’m sorry you’re upset. Let me give you a hug.”
- Instead of minimizing the emotional reaction (“Don’t be a baby. You’re making a big deal out of nothing”), help your child identify and understand her feelings: “I know that you feel sad and hurt that Betsy played with Estela more than she played with you. Tell me how you feel about that.”
- Rather than punish her (“Go to your room until you can control yourself”), help her problem-solve: “Let’s think of something you can say or do if this happens again.”
In recent research, the two experts have discovered some really good reasons for nurturing attachment in young children.
Bost has discovered that a parent’s attachment style, which is thought to stem from the mom’s or dad’s own attachment-related experiences, may influence parenting behaviors that have been implicated in childhood obesity.
In a recent study, insecure parents were significantly more likely to respond to their children’s distress by becoming distressed themselves or dismissing their child’s emotion.
A child who doesn’t learn how to properly handle sadness or frustration is more likely to engage in comfort eating, using food for self-soothing, she says.
McElwain’s research has taken her in a different direction. “Because a child’s early attachments are close and emotionally intense, those first relationships may be important in guiding the way children think about and function in other close relationships in later life,” she says.
She has learned that children who are securely attached develop stronger early friendships, “probably because they enter relationships with positive expectations. If they’ve had a secure, emotionally open parent–child relationship, they’re more responsive to their peers, and that promotes more positive interactions with friends during the early school years.”
In another benefit, McElwain says, a securely attached child who encounters a peer who doesn’t interact well can adapt to the situation and be assertive, by either making suggestions or giving directions.
McElwain’s research has shown that little boys, especially those who are prone to feeling anger, fear, or frustration intensely, may need extra support when their emotions threaten to overwhelm them.
“In our culture, boys are discouraged from expressing their emotions. If you add parental punishment to these cultural expectations, the outcome may be especially detrimental for boys who often experience negative emotions intensely,” she says.
Bost says that parents shouldn’t confuse a difficult temperament with an insecure attachment. “You may have a fussy infant, but if you respond to him sensitively and consistently, he will develop a strong bond with his parents and will likely go on to develop close relationships with others.”
Registration open for 2014 AGMasters Conference
URBANA, Ill. – Online registration is now open for the 2014 AGMasters Conference scheduled for Dec. 15 and 16 at the iHotel and Conference Center, Chamapign, Ill.
The 6th annual conference, hosted by University of Illinois Extension, will begin with a general session that features speakers covering a variety of topics including: potential water protection rules and standards, implications of the new Farm Bill, agrichemical/agribusiness/industry education initiatives, and the practical implications of evolutionary principles regarding resistance development by insects, plant pathogens, and weeds.
Following the general session, attendees can choose 8 out of 16 specialized sessions. Topics offered include:
- Cover crops
- Managing big data
- Refining herbicide application techniques
- Palmer amaranth biology/ecology
- Western corn rootworm resistance to Bt
- Understanding and managing Pythium
- Methods to reduce nitrogen and phosphorus losses
- White mold and soybean production
- Fusarium head blight of wheat
- Use of drones for aerial scouting
- Advance in corn genetics
- Management of insects in stored grain
- Soybean management with pollinator considerations
Leading the workshops will be speakers from Iowa State University, Michigan State University, Ohio State University, Purdue University, University of Guelph, University of Illinois, University of Minnesota, University of Nebraska, and the University of Wisconsin.
According to Mike Gray, a U of I professor of crop sciences, space in the breakout sessions is limited, and those with interest in this conference are strongly encouraged to register early to help ensure the availability of specialized classes of most interest.
The registration fee for this event is $250 through Dec. 5. Enrollment in the specialized sessions is on a first-come, first-served basis.
“One of the most popular features of this two-day event is the opportunity to interact with instructors from many universities in small classroom-style sessions” Gray said. “The instructors have been encouraged to solicit input and questions from the participants. So please come loaded up with questions for these researchers to address.”
Continuing education credits (CCA) are offered in the following categories: professional development (1.5), crop management (4.0), IPM (10.5), nutrient management (1.5), and soil and water management (3.5).