Progress 09/15/03 to 09/14/07
Outputs
OUTPUTS: Alternate methods to control aphids in grain crops are required to replace broad-spectrum organophosphates and carbamates. Research in the field and laboratory examined interactions of non-chemical control strategies, plant resistance and biological control, utilizing modifications to a practical system of wheat (Triticum aestivum), sorghum (Sorghum bicolor), greenbugs (Schizaphis graminum), and predaceous lady beetle (Hippodamia convergens). Effects of convergent lady beetle on wheat and sorghum genotypes that differed in resistance to greenbug biotypes E and I were studied in split plots at three sites in Kansas and Texas. The state of Texas and most of Kansas experienced severe drought during most of this study. Also encountered were wheat rust and hail. Biotype I greenbugs to be used to infest plants in the field were counted and placed on plants in a greenhouse. The plants infested with greenbugs were spread over rows of plants in plots of wheat or sorghum in the field.
The infested plants in the field were caged. Plants in two infested cages were used as checks, and lady beetle larvae were put into the remaining cages of plants infested with greenbugs. Plants in six other plots were used as noncaged checks to assess natural infestation. At biweekly intervals, plants were examined for greenbugs, and numbers of greenbugs per plant and dead plants were recorded in each subplot. Duplicate field plots were sprayed with chlorpyrifos for comparison. Plants were harvested by subplot, and grain samples were evaluated for yield, volume weight, and kernel weight. Most greenbugs were found on susceptible plants in the field plots. Susceptible wheat at San Marcos yielded 10% less than resistant wheat whether or not the wheat was protected by being inside a cage. Resistant sorghum at San Marcos outyielded susceptible sorghum by 11% outside the cages. In Sherman County, Texas, the greenbug-susceptible wheat yielded 22% less overall inside cages and 14% less
overall outside cages than did greenbug-resistant wheat. Approximately a 26% yield advantage was obtained from planting greenbug-resistant sorghum and a 27% yield advantage was obtained by keeping greenbugs from feeding on the sorghum. Combining biological and chemical controls in the research plots added a 16% yield advantage. The effect of five wheat genotypes on three biotypes of greenbug (C, E, and I), Rhopalosiphum padi aphid, and lady beetle larvae also was studied in a greenhouse. Lady beetle larvae suppressed the greenbugs on four wheat lines but did not reduce the number of biotype C or E greenbugs on TXGBE273 wheat. A brochure was developed to describe the research and alternate methods for managing greenbugs in sorghum and wheat. The brochure was distributed to farmers and crop consultants at meetings in Kansas, Texas, and Oklahoma, including field days at the research sites. Two students who participated in the research graduated with Master of Science degrees.
PARTICIPANTS: Dr. Bonnie B. Pendleton - Principal Investigator - oversaw the research and reporting involved with the project, supervised the research and academic programs of two M.S. student, and helped supervise research by the staff involved with the project. Dr. Roxanne A. Shufran Bowling - Principal Investigator - directed the field research involved with the project and helped supervise the research by staff involved with the project. Dr. Gerald J. Michels, Jr. - Principal Investigator - assisted with supervising the research of two M.S. students and staff involved with the project. Two part-time research technicians/associates maintained plants and aphid and lady beetle colonies in the greenhouse. Three technicians prepared and maintained and collected data in the field plots at the three sites during the summers. Two M.S. students researched aphids and lady beetles in the laboratory and greenhouse. These graduate students received their Master of Science degrees.
TARGET AUDIENCES: Farmers and crop consultants in Kansas, Oklahoma, and Texas were educated at meetings each year, including demonstration field days held at the research sites. Each also received a copy of the brochure developed from the research to manage aphids in sorghum and wheat. Results of the research also were presented at state extension, regional and national entomology, national sorghum, and other professional meetings each year. Two minority graduate students who participated in the project graduated with Master of Science degrees.
Impacts
As water becomes scarcer in the Great Plains region of the United States, farmers are changing to more water-use efficient crops such as sorghum and wheat. The major insect pest of both crops is greenbug. The only foliar insecticides available for use against aphids in wheat and sorghum are broad-spectrum organophosphates and carbamates. Research in the field and laboratory examined interactions of non-chemical control strategies, plant resistance and biological control, utilizing modifications to a system based on wheat, sorghum, greenbugs, and predaceous lady beetle. Effects of convergent lady beetle on survival and yield of greenbug-infested wheat and sorghum genotypes differing in resistance to greenbug biotype were determined for Kansas and Texas. Most greenbugs were found on susceptible plants in field plots. Susceptible wheat at San Marcos in central Texas yielded 10% less than resistant wheat whether or not the wheat was protected inside a cage. Resistant
sorghum at San Marcos outyielded susceptible sorghum by 11% outside the cages. In Sherman County, Texas, greenbug-susceptible wheat yielded 22% less overall inside cages and 14% less overall outside cages than did resistant wheat. Approximately a 26% yield advantage was obtained from planting greenbug-resistant sorghum, and a 27% yield advantage was obtained by keeping greenbugs from feeding on the sorghum. Combining biological and chemical controls in field plots added 16% yield advantage. In a greenhouse study, lady beetle larvae suppressed greenbugs on four wheat lines but did not reduce the number of biotype C or E greenbugs on TXGBE273 wheat. In a laboratory study, lady beetles ate an equal number of greenbugs from resistant or susceptible sorghum plants. Two Master's students graduated who participated in the research. An Extension brochure was developed, and applied on-farm demonstrations were used to transfer technology to farmers and crop consultants. The research results are
being implemented by farmers in Kansas, Oklahoma, and Texas to manage aphids in sorghum and wheat without the use of broad-spectrum organophosphates and carbamates.
Publications
- Pendleton, B., R. Shufran, R. Bowling, J. Michels, J. P. Michaud, P. Sloderbeck. 2003. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum. Texas Cooperative Extension publication.
- Bowling, Roxanne, Robert Bowling, Bonnie Pendleton, and G. J. Michels, Jr. 2004. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum, pp. 81-83. In Proceedings of the 2004 Bushland AG Day Summer Crops Field Day, 31 August 2004, Bushland, Texas.
- Bowling, Roxanne, Bonnie Pendleton, Robert Bowling, and G. Michels. 2005. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum, pp. 40-41. In Proceedings of the Fifty-third Annual Meeting of the Southwestern Branch of the Entomological Society of America and the Annual Meeting of the Society of Southwestern Entomologists, 28 February-3 March 2005, Albuquerque, New Mexico.
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Progress 10/01/05 to 09/30/06
Outputs
The entire state of Texas and most of Kansas experienced severe drought conditions starting in late 2005 and continuing through 2006. Cages were erected on 4 January 2006 in an experimental wheat plot in San Marcos, TX. Wheat grew slowly because of lack of moisture. Wheat at San Marcos was treated on 8 February 2006 with fungicide to control rust. The wheat was hand-infested with greenbugs and ladybugs on 4 April 2006, using a technique developed while infesting sorghum during the first year of the study. Greenbugs were counted and placed on wheat plants in a greenhouse. The entire plant infested with greenbugs in the greenhouse was removed from the plastic pot and spread over rows of plants to be infested in plots of wheat in the field. The first count on 11 April 2006 in wheat at San Marcos revealed no greenbugs and no lady beetle larvae or adults. The wheat plants deteriorated because of drought and heat. No lady beetles were counted on wheat during the duration of
the study. Greenbugs did not successfully colonize the wheat plants. Wheat in the plot at San Marcos received a major hail event at harvest but the susceptible wheat consistently yielded 10% less than the resistant wheat whether or not the wheat was protected by being inside a cage. In the plot in Sherman County, TX, the greenbug-susceptible wheat yielded 22% less overall inside the cages and 14% less overall outside the cages than did the greenbug-resistant wheat. When sorghum seed was originally planted at the San Marcos, TX, site, cotton seed from the adjacent plot was mistakenly planted over the plot. The landowner applied a broadleaf herbicide to eliminate the cotton plants from the plot. Cages were erected after the plots were treated with herbicide. Drought conditions continued, but one rainfall event helped the sorghum grow. Sorghum in cages was infested with greenbugs on 23 May 2006. The first count on 31 May 2006 revealed limited infestation, with most greenbugs counted on
susceptible plants; however, one cage had greenbugs only on resistant plants. Overall damage by greenbugs on plants was minimal to none, with little apparent damage. Lady beetles were introduced into the cages on 15 June 2006, but were absent at the next count on 22 June. Overall abundance of greenbugs remained very low, with little damage to the plants; however, native aphids were abundant in some cages and caused some damage to plants. Sorghum was harvested on 30 July 2006. Drought at San Marcos confounded the results. The resistant sorghum yielded 15% less than the susceptible sorghum inside the cages but outyielded the susceptible sorghum by 11% outside the cages. We were trying to harvest something even if the plots were in very poor condition. The Texas Panhandle site in Sherman County was planted with sorghum on 5 June 2006, but germination was sparse because of extreme drought. Sorghum in the plot was abandoned and not harvested because of poor conditions. We could not even
put up eight cages because the stand was so uneven due to lack of moisture. The sorghum plot at Hays, KS, was planted on 21 June 2006. Germination was sparse and the plot was abandoned because of extreme drought.
Impacts
In the US, most wheat and sorghum grain is produced in Kansas and most seed sorghum is produced in Texas. As water becomes scarce, farmers will change to more water-use efficient crops such as sorghum and wheat. The major insect pest of both crops is greenbug. The only foliar insecticides available for use against aphids in wheat and sorghum are broad-spectrum organophosphates and carbamates. Implementation of the 1996 Food Quality Protection Act resulted in need for alternate controls for greenbug. Research in the field and laboratory examined interactions of non-chemical control strategies, plant resistance and biological control, utilizing modifications to a practical, well-developed system based on wheat, sorghum, greenbugs, and predaceous lady beetle. Effects of convergent lady beetle on survival and yield of greenbug-infested wheat and sorghum genotypes differing by resistance to greenbug biotype will be determined for Kansas and Texas. The combined effect of
predation and host resistance on minimizing the economic impact of greenbugs will be known. The effect genetic differences in host plants have on greenbugs and on predaceous coccinellids will be determined. Observed differences in aphid response will be determined in relation to specific resistance genes in genetically different wheat and sorghum lines. An Extension brochure was developed and applied on-farm demonstrations were used to transfer technology to farmers and consultants. The research will provide alternatives to use of broad-spectrum organophosphates and carbamates to control aphids.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
Effects of the beneficial lady beetle, Hippodamia convergens, on the survival and yield of infested wheat, Triticum aestivum, and sorghum, Sorghum bicolor, genotypes differing by their resistance to biotypes of greenbug, Schizaphis graminum, are being studied at three sites in Kansas and Texas. Because Kansas ranks first in wheat and sorghum production and Texas ranks first in sorghum seed production and second in overall sorghum production, performing the research in these two states was most appropriate. Of primary interest is the combined effect of predation and host resistance on minimizing the economic impact of greenbugs. Also of interest is the effect genetic differences in host plants have on greenbugs and on predaceous lady beetles, the hypothesis being that beneficial lady beetles would be significantly impacted from feeding on greenbugs from resistant wheat and sorghum genotypes. A large study in a greenhouse was completed on the effect of five wheat
genotypes on three biotypes of greenbug (C, E, and I); one additional aphid species, Rhopalosiphum padi, commonly found on wheat; and lady beetle larvae. A few of the significant preliminary results showed that lady beetle larvae on wheat line TXGBE273 were unable to reduce the number of greenbug biotype C or E after 14 days. The research suggested that use of this wheat line should be minimal for future wheat advancements because of the unfavorable effect on the primary biological control agent in the Texas High Plains. Lady beetle larvae suppressed all three greenbug biotypes fairly well on the four other wheat lines studied. With assistance from an Extension Communications Specialist, a brochure was developed to describe the project to end-users. The brochure was distributed at meetings, including a field day at one of the research sites. A significant outcome of the field research has been the education of end-users -- wheat and sorghum producers and crop consultants. The producer
from the northern Texas research site spoke out during the field day at his farm and described the benefits he saw in the research plot. It is important that the producer realizes an advantage to a new management tactic. Thus far, approximately a 26% yield advantage has been obtained from planting greenbug-resistant sorghum and a 27% yield advantage was obtained by keeping greenbugs from feeding on the sorghum. Combining biological and chemical controls in the research plots added a 16% yield advantage.
Impacts
In the US, most wheat and sorghum grain is produced in Kansas and most seed sorghum is produced in Texas. As water becomes scarce, farmers will change to more water-use efficient crops such as sorghum and wheat. The major insect pest of both crops is greenbug. The only foliar insecticides available for use against aphids in wheat and sorghum are broad-spectrum organophosphates and carbamates. Implementation of the 1996 Food Quality Protection Act resulted in need for alternate controls for greenbug. Research in the field and laboratory examined interactions of non-chemical control strategies, plant resistance and biological control, utilizing modifications to a practical, well-developed system based on wheat, sorghum, greenbugs, and predaceous lady beetle. Effects of convergent lady beetle on survival and yield of greenbug-infested wheat and sorghum genotypes differing by resistance to greenbug biotype will be determined for Kansas and Texas. The combined effect of
predation and host resistance on minimizing the economic impact of greenbugs will be known. The effect genetic differences in host plants have on greenbugs and on predaceous coccinellids will be determined. Observed differences in aphid response will be determined in relation to specific resistance genes in genetically different wheat and sorghum lines. An Extension brochure was developed and applied on-farm demonstrations were used to transfer technology to farmers and consultants. The research will provide alternatives to use of broad-spectrum organophosphates and carbamates to control aphids.
Publications
- Pendleton, B., R. Shufran, R. Bowling, J. Michels, J. P. Michaud, P. Sloderbeck. 2003. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum. Texas Cooperative Extension publication.
- Bowling, Roxanne, Robert Bowling, Bonnie Pendleton, and G. J. Michels, Jr. 2004. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum, pp. 81-83. In Proceedings of the 2004 Bushland AG Day Summer Crops Field Day, 31 August 2004, Bushland, Texas.
- Bowling, Roxanne, Bonnie Pendleton, Robert Bowling, and G. Michels. 2005. Alternatives to organophosphates and carbamates for managing aphids in wheat and sorghum, pp. 40-41. In Proceedings of the Fifty-third Annual Meeting of the Southwestern Branch of the Entomological Society of America and the Annual Meeting of the Society of Southwestern Entomologists, 28 February-3 March 2005, Albuquerque, New Mexico.
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