Rattus tanezumi and Rattus argentiventer are the major rice field rats in the Philippines. The Philippines is the number one rice exporter in the world and the annual losses from rodents range from 5-10%. This figure can increase to 30-50% during an outbreak year. In 2007 and 2010, eruptions of populations of the rice field rat were reported in the Philippines and elsewhere in Southeast Asia including Indonesia, Laos PDR, and Myanmar. The impact of rodent outbreaks on food security of small scale farmers is significant. Our knowledge, however, of the main drivers that cause rodent outbreaks in lowland rice agro-ecosystems in Southeast Asia is still at a basic level. I studied the breeding ecology of R. tanezumi and R.argentiventer in lowland rice agro-ecosystems of the Philippines as a basis to develop ecologically-based rodent management (EBRM) to assist farmers in reducing the annual losses caused by rodents. I also studied the factors that influence the development of high population growth rates of rice field rat populations in the Philippines and Myanmar to develop proactive strategies to prevent high rodent population densities.
Both R. tanezumi and R.argentiventer were opportunistic breeders, taking advantage of pulses in food availability regardless of the season. Asynchronous planting, using rice varieties with different times to maturity, the availability of abandoned agricultural land, and the availability of plenty of food post-harvest (stubble stage) were main factors driving high rodent population densities. Based on the understanding of factors influencing the breeding ecology of rice field rats in lowland irrigated rice systems in the Philippines and Myanmar, I recommend 1) community action within 2 weeks of planting, and again at the maximum tillering or early booting stages, 2) the synchronous planting of rice, 3) using rice varieties with similar maturation time, and 4) good field sanitation including the reduction of spillage of rice grain at harvest. Together, these strategies are important actions for preventing the build-up of high rodent population densities and may lead to better harvest outcomes for local farmers.
|Advisor:||Propper, Catherine R., Singleton, Grant R.|
|Commitee:||Hinds, Lyn A., Shuster, Stephen M., Theimer, Tad|
|School:||Northern Arizona University|
|School Location:||United States -- Arizona|
|Source:||DAI-B 73/09(E), Dissertation Abstracts International|
|Subjects:||Plant biology, Ecology, Asian Studies, Agriculture|
|Keywords:||Breeding ecology, Ecologically-based rodent management, Rice field rats, Rodent outbreaks, Southeast asia|
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