Habitat manipulation in lowland rice-coconut cropping systems of the Philippines--an effective rodent pest management strategy?

Background: Reduction of vegetation height is recommended as a management strategy for controlling rodent pests of rice in South-east Asia, but there are limited field data to assess its effectiveness. The breeding biology of the main pest species of rodent in the Philippines, Rattus tanezumi, suggests that habitat manipulation in irrigated rice-coconut cropping systems may be an effective strategy to limit the quality and availability of their nesting habitat. The authors imposed a replicated manipulation of vegetation cover in adjacent coconut groves during a single rice-cropping season, and added artificial nest sites to facilitate capture and culling of young.

Results: Three trapping sessions in four rice fields (two treatments, two controls) adjacent to coconut groves led to the capture of 176 R. tanezumi, 12 Rattus exulans and seven Chrotomys mindorensis individuals. There was no significant difference in overall abundance between crop stages or between treatments, and there was no treatment effect on damage to tillers or rice yield. Only two R. tanezumi were caught at the artificial nest sites.

Conclusion: Habitat manipulation to reduce the quality of R. tanezumi nesting habitat adjacent to rice fields is not effective as a lone rodent management tool in rice-coconut cropping systems.