Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC(50) for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC(50) for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

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Conservation strategies for whole communities at the landscape scale have rarely been able to take into account genetic diversity because of the number of species involved. However, if species can be grouped together by geographic distribution of genetic diversity and patterns of relatedness, then landscape and genetic conservation might be more effectively combined to cope with problems of fragmentation. We report on a study that measures how genetic diversity is distributed at national and regional scales in four unrelated species of calcareous grassland insects. Samples were obtained from sites within six UK calcareous grassland regions. Genetic diversity was measured using mtDNA sequencing (four species) and allozyme analysis (two of the four species). A striking difference in mtDNA diversity was found between the chrysomelid beetle Aphthona herbigrada (23 haplotypes; mean per region 5.5) and the cicadellid bug Batracomorphus irroratus (27 haplotypes; mean per region 6.2), with high haplotype richness, and the brown argus butterfly Aricia agestis (4 haplotypes; mean per region 1.7) and the cistus forester moth Adscita geryon (5 haplotypes; mean per region 2.4) with low. At the UK scale, patterns of diversity were species specific with no general conservation strategy emerging for the community. However, there was little differentiation among regions and any splitting into more than one management unit was not clearly justified, questioning whether distribution of genetic diversity should be a concern at this spatial scale.