Progress 08/01/07 to 07/31/10
Outputs
OUTPUTS: Results of the funded research were communicated to growers using print and electronic media and verbally during grower's meetings. Cooperation with industry and state and federal regulatory agencies resulted in approval of two new insecticides for use against rice water weevils during the funding period. Adoption of these alternatives will result in reduced impact on crawfish while improving weevil management. PARTICIPANTS: Lead PI, Michael J. Stout, Departmetn of Entomology, LSU AgCenter Co-PIs: Ray MacClain, LSU AgCenter Rice Research Station, James Ottea, Department of Entomology, LSU AgCenter, and Gary Barbee, formerly LSU Department of Agronomy, now at West Texas State University. Grant funds supported a graduate student, Srinivas Lanka, who conducted the described research as part of his Ph.D. project TARGET AUDIENCES: Rice and crawfish producers in Southwest Louisiana. Rice producers in the U.S. and globally. Agriculatural scientists interested in integrated pest management. Toxicologists PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Crawfish and rice are both important commodities in Southwest Louisiana. Because the two commodities are often co-cultivated, insecticides used to manage rice water weevils in rice fields often have negative impacts on crawfish. This is particularly true of pyrethroid insecticides, which have been widely used over the past decade. Insecticidal alternatives are being considered for weevil management. Acute toxicity studies conducted in a lab demonstrated that several possible alternatives to the currently used pyrethroid insecticides - namely, chlorantroniliprole, dinotefuran, thiamethoxam, and clothianidin - are much less toxic to crawfish (approximately 500 to 10,000 times higher LC50 values) than pyrethroids. Three years of testing in simulated rice paddies using caged crawfish confirmed that very little short-term crawfish mortality results from the use of the pyrethroid alternatives in the field, while at the same time verified that these alternatives effectively control rice water weevils. Sampling of chemical levels in simulated paddies confirmed that the levels in water were below levels expected to produce high levels of crawfish mortality. Adoption of these new insecticides should reduce crawfish mortality resulting from drift or unintentional introduction of insecticide-contaminated water into crawfish ponds while at the same time more effectively controlling weevil populations. Non-insecticidal alternative for managing weevils were also considered, alone and in combination with reduced rates of insecticides. A multi-year study of the impact of planting date on rice water weevils was concluded, and showed that early planting contributes to weevil management in several ways. Use of this strategy should not impact crawfish. In addition, small-plot field studies were conducted to investigate the combined effects of reduced rates of insecticides, a cultural practice (shallow flooding), and moderately resistant rice varieties on weevil management. Results of this study showed that the different tactics had additive effects on rice water weevil densities. Early planting, shallow flooding, and plant resistance all showed promise as alternative tactics for weevil management.
Publications
- Barbee, G., W.R. McClain, S. Lanka, and M.J. Stout. 2010. Acute toxicity of chlorantraniliprole to non target crayfish (Procambarus clarkii) associated with rice crayfish cropping systems. Pest Management Science 66: 996-1001.
- Barbee, G. C. and M.J. Stout. 2009. Comparative acute toxicity of neonicotinoid and pyrethroid insecticides to nontarget procambarid crayfish associated with rice crayfish crop rotations. Pest Management Science 65: 1250-1256.
- N. Hummel and M.J. Stout. 2008. Rice water weevil control with clothianidin seed treatment, 2008. Arthropod Management Tests 34 (http://www.entsoc.org/Protected/AMT/AMT34/)
- N. Hummel and M.J. Stout. 2008. Rice water weevil control with Dermacor X-100 seed treatment, 2008. Arthropod Management Tests 34 (http://www.entsoc.org/Protected/AMT/AMT34/)
|
Progress 08/01/08 to 07/31/09
Outputs
OUTPUTS: Currently management of the rice water weevil, the major early-season insect pest of rice in Louisiana, relies heavily on post-flood applications of pyrethroid insecticides that target the adult stage of the weevil. Applications of pyrethroids are known to negatively impact crawfish production (an important aquaculture commodity) in southwest Louisiana, because pyrethroids are acutely toxic to crawfish (LC50s less than 1 ppb). A number of insecticides are being evaluated as alternatives to pyrethroids against the rice water weevil. An experiment involving simulated rice paddies was conducted to simultaneously evaluate the efficacy of several insecticides against the rice water weevil, to evaluate the impact of these insecticides on crawfish confined to the rice paddies in cages, and to evaluate the impact of the insecticides on other non-target invertebrates found in the rice paddies. Seed treatments of clothianidin, rynaxypyr, and thiamethoxam and a pre-flood foliar application of clothianidin were all as effective at controlling rice water weevils in the simulated paddies as was a foliar, post-flood application of Karate (lambda cyhalothrin, a pyrethroid). In addition, use of all of these insecticides resulted in lower numbers of non-target invertebrates in simulated rice paddies. However, all of the pyrethroid alternatives were associated with lower mortalities of caged crawfish than was use of Karate. Laboratory acute toxicity tests using rynaxyapyr (chlorantraniliprole) dissolved in water and fed to crawfish on seeds showed that rynaxypyr is several orders of magnitude less acutely toxic to crawfish than pyrethroids. A small-plot experiment was conducted in which the combined impacts of a cultural practice for weevil control (shallow flooding), use of a weevil-resistant variety, and use of a reduced rate of an insecticidal seed treatment were investigated. Data are now being analyzed. Data from several years of experiments to evaluate the efficacy of early planting as a tactic against weevils were analyzed and a manuscript is being prepared. PARTICIPANTS: Michael Stout, Project Director, Professor, Department of Entomology, LSU AgCenter Srinivas K. Lanka, Graduate Student, Department of Entomology, LSU AgCenter Ray McClain, Professor, Rice Research Station,LSU AgCenter Gary Barbee, formerly Assistant Professor, SPESS, LSU AgCenter Jim Ottea, Professor, Department of Entomology, LSU AgCenter TARGET AUDIENCES: Rice and crawfish farmers in southwest Louisiana Entomologists, toxicologists, and environmental scientists interested in the environmental and non-target effects of insecticides IPM practitioners interested in the integration of IPM tactics PROJECT MODIFICATIONS: Crawfish small-plot cage work will be modified next year, as this method often results in excessive control mortalities
Impacts
Data from the field and laboratory experiments described above strongly suggest that the new insecticides being evaluated as replacements for pyrethroids against rice water weevils (rynaxypyr, thiamethoxm, and clothianidin) will be much more compatible with crawfish production than are the pyrethroids. However, because the new insecticides do exhibit some toxicity toward crawfish, caution in their use is still warranted. The results of these experiments (efficacy data and crawfish toxicity data) were shared with farmers at several grower's meetings. In 2009. A Section 3 registration was granted by the EPA for the use of thiamethoxam seed treatment in rice. Efficacy data from our work were used to partly justify this registration. Results of the research on the use of cultural practices and on the combined use of cultural practices and other tactics (plant resistance, insecticides) were communicated to growers. Within the next year, results of studies conducted over the past 10 years on the use of cultural practices against the rice water weevil will be summarized and synthesized and this will allow revised recommendations on weevil management to be developed.
Publications
- Barbee, G. C. and M.J. Stout. 2009. Comparative acute toxicity of neonicotinoid and pyrethroid insecticides to nontarget procambarid crayfish associated with rice-crayfish crop rotations. Pest Management 65: 1250-1256.
|
Progress 08/01/07 to 07/31/08
Outputs
OUTPUTS: The results of the date of planting experiment confirm results from several prior years and will allow us to develop guidelines to help farmers predict the impact of planting date on their weevil management programs. The laboratory and field toxicity tests strongly suggest that the pyrethroid alternatives currently being tested will be more compatible with crawfish production in rice-crawfish rotational systems than are pyrethroids. The insecticide efficacy data will be used to justify further testing of insecticides and will eventually be used to justify registration of one or more of the products. PARTICIPANTS: Gary Barbee, department of Agronomy Ray McClain, Rice Research Station James Ottea, Department of Entomology Marty J. Frey, Rice Research Station John Sonnier, Rice Research Station Srinivas Lanka, Department of Entomology All of the above affiliated with LSU AgCenter except Barbee (LSU A&M). Lanka is a graduate student conducting this research as part of his dissertation project TARGET AUDIENCES: Primary clientele group is rice farmers who also cultivate crawfish. Secondariley, this work will contribute to integrated pest management literature. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Currently management of the rice water weevil the major early-season insect pest of rice in Louisiana, relies heavily on post-flood applications of pyrethroid insecticides that target the adult stage of the weevil. Applications of pyrethroids are known to negatively impact crawfish production in southwest Louisiana, because pyrethroids are acutely toxic to crawfish (LC50s less than 1 ppb). A number of insecticides are being evaluated as alternatives to pyrethroids. An experiment involving simulated rice paddies was conducted to simultaneously evaluate the efficacy of several insecticides against the rice water weevil and to evaluate the impact of these insecticides on crawfish caged in the rice paddies. A seed treatment of the insecticide Rynaxypyr (Dermacor X-100, DuPont) and a post-flood application of dinotefuran (applied three weeks after flooding) controlled rice water weevils as well as or better than a single post-flood application of lambda-cyhalothrin. However, crawfish mortalities in both Rynaxypyr and lambda-cyhalothrin plots were significantly higher than mortalities in control plots. Laboratory acute toxicity tests revealed that neonicotinoid insecticides were 300- to 13,000 times less toxic to crawfish than lambda-cyhalothrin, and that significant differences in acute toxicity existed among neonicotinoids (clothianidin was most toxic and dinotefuran least toxic). A small-plot experiment in which early planting and insecticides were jointly evaluated for their impact on rice water weevil populations showed that that populations of weevils were lower and efficacies of insecticides were greater in early-planted fields (planted in mid-March) than late-planted fields (mid-May or later).
Publications
- No publications reported this period
|
|