S1029: Improved Methods to Combat Mosquitoes and Crop Pests in Rice Fields
Statement of Issues and JustificationA. The need for this project as identified by stakeholders. Invasive and endemic arthropod pests make it essential to develop integrated pest management (IPM) tactics for rice-growing states. Such tactics must meet both crop production requirements and the need to reduce the populations of mosquitoes that breed in rice fields. The rice crop is of great economic importance in many U.S. regions, especially the southern states and California. 3.3 million acres of rice were planted in the U.S. in 2005. Rice is staple crop for half of the world's people, and 40% of the U.S. rice crop is exported. The U.S. was projected to be the third largest rice exporter in the world for 2005. Ensuring good rice harvests therefore promotes economic stability and food security at home and abroad. Rice has vast economic value in excess of the crop price ($1.64 billion for milled rice in 2004, U.S. Census Bureau), because this commodity supports numerous industries (e.g. human and animal food manufacturers and retailers). Rice fields provide essential habitat for wildlife, especially migratory waterfowl. However, ricelands also pose the greatest challenge for mosquito control districts in many rural areas. Riceland mosquitoes can transmit a variety of endemic and potentially invasive diseases that threaten the health of humans, livestock, and wildlife in rural areas.
The rice crop is under continual threat from resident and invasive arthropod pests. Crop losses due to arthropod pests can range up to 30%. Without scientific research on how to control these pests, growers could be faced with serious economic losses. In addition to pests that cause crop damage, there are serious issues with disease-bearing insects emanating from rice fields. Species of mosquitoes found in rice fields are some of the most efficient vectors of West Nile Virus, St. Louis Encephalitis virus, Venezuelan Equine Encephalitis virus, anaplasmosis (in cattle) and other pathogens, including the causative agents of invasive diseases (e.g. malaria, dengue fever, Japanese Encephalitis). Thus, it is imperative to perform research that identifies effective, safe, and economical IPM programs for crop pests and mosquitoes in rice fields. Control methods used by rice growers and mosquito control personnel must be coordinated, because of the ongoing threats of insecticide resistance in pests and of biological control disruption. New pest control methods are continually being developed (by our group and others). Growers and public health agencies need to know whether these products are safe and effective, and whether they affect mosquito populations either positively or negatively. Agricultural pesticides, herbicides, and production practices have the potential to either reduce mosquito populations or cause dangerous outbreaks, depending on how these techniques affect beneficial predators and resources for mosquitoes. Research is also needed to understand the biology, ecology and disease-vectoring capacity of the mosquitoes that breed in rice and associated wetlands, and to develop and test new methods of mosquito control.
Much of our work is driven by stakeholders. Our members frequently receive research requests from growers, the crop protection industry, vector abatement personnel, other public health agencies and wetland managers. Members of our group are in close collaboration, and in many cases act as liaisons between the resource managers (rice and wetlands) and the protection industries (agrichemical and vector abatement).
National and regional priorities addressed in this project include enhancing IPM in an important crop (SAAESD Programmatic Goals 4D, 4F), and reducing human and livestock health concerns (through mosquito management) (SAAESD Goals 1 I and 5 C, F). Rice fields are intrinsically multiple-use areas (SAAESD Goal 4 B,C) because rice fields function as seasonal wetlands that support numerous aquatic animals and birds (review: Lawler 2001). Much of this project is targeted toward helping growers identify which pest control practices are effective, yet safe for the biota. A CRIS search on combinations of the keywords rice, pest, arthropod, insect and mosquito showed that this is the only current or pending project addressing management of arthropod pests of rice, mosquito management in rice, or integrating strategies for managing multiple arthropod pests.
B. Importance and extent of the problem. Arthropod pests of rice can cause yield losses of up to 30% or more. Each year, mosquito-borne disease kills or disables hundreds of people in the US. There were 2949 cases of West Nile Fever in the USA in 2005 (116 deaths). Outbreaks of other viruses also occur (e.g. an average of 128 cases of St. Louis Encephalitis per year). New invasive crop pests and vector-borne diseases continually threaten our borders. Vector-borne diseases also threaten livestock. Uncontrolled mosquitoes can reduce property values, cause labor problems, and have negative effects on the tourist industry.
If this project were not done, fewer integrated pest management methods would be developed and tested in the field, and rice pest management would not be integrated with mosquito management. Growers and mosquito abatement personnel would not know which methods are most effective against pests, and which are safest for the environment, including beneficial predators that feed on rice pests and mosquitoes. This could lead to lower rice yields, greater costs of production, and environmental damage. Rice fields and associated wetlands could become a danger to public health if new production techniques were applied in ignorance of their side-effects on mosquito populations.
C. Technical feasibility. Both the plans outlined below and our track records show that this project is technically feasible. Our members have published extensively in the areas to be addressed by this project; please see 'Related, Current and Previous Research'. We will seek out a biostatistician to join our group to facilitate meta-analysis of data.
D. Advantages to performing this research as a multi-state project. Our project requires coordination of experimental designs across states, so that statistical analysis and examination of geographical block effects can meet both the goals of scientific rigor and understanding local variation. One challenge our AES scientists face is that any individual experiment station is limited in the number of experimental fields and techniques, yet several new insecticide formulations, crop varieties, and pests demand testing each year. Most investigators perform large-scale, but low replication studies so that they can show stakeholders outcomes for each new method, under local conditions and at realistic scales. While stakeholders typically find results convincing, it is difficult to make statistical inferences from these limited replication efforts. We anticipate publication of more team-authored papers in the primary literature as a result of this collaboration. Our group has a track record of joint publications (e.g. Dennett et al. 2000, 2003, Stout et al. 2002a, Lawler et al. 2003). In addition, the multi-state format allows us to develop 'rapid response' collaborative research projects that will help minimize damage as new insect pests or vector-borne diseases emerge in any of the rice-growing areas. For example, project scientists were at the forefront of efforts to understand and control Mexican rice stem borer on rice and sugar cane, as it expanded its range in the Southern region during the S-300 project period. This valuable collaborative effort will continue during this new project.
E. Benefits of this research include development of new pest control methods, and testing new insecticide formulations, crop varieties and production techniques. We will discover which methods can provide cost-effective pest control while protecting non-target species and human health. We will add to basic knowledge about crop pest and mosquito biology and ecology. This project will set an example for large-scale, geographically coordinated scientific research. For further benefits, please see 'VI B. Outcomes and Projected Impacts', below.
F. Stakeholders include: Rice growers, rural communities, mosquito and vector control districts, related public health agencies, industries that rely on rice, and pest control industries.
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