2013 Volume 18 Issue 1 Pages 45-54
We performed a bait trap survey in a Japanese cedar plantation to determine the environmental factors affecting the spatial distribution and activity of terrestrial firefly larvae. First, using cumulative numbers of captured larvae, the spatial distribution pattern was estimated at three different scales. The most important environmental factors (soil temperature, soil moisture, undergrowth coverage, and solar insolation) were then determined using statistical model selection. Larval spatial distribution was aggregated at the 5 m scale and was positively affected by soil temperature and undergrowth coverage. Distribution was random at the 1 m scale and was negatively correlated to solar insolation. At the 50 cm scale, larval distribution was aggregated but not significantly correlated to any environmental factor. Second, activity was analyzed by selecting models incorporating the daily sum of captured larvae as the response variable and environmental conditions (soil temperature, soil moisture, and occurrence of rainfall on the previous night) as the explanatory variables. Soil moisture positively influenced the daily sum of captured larvae, and the random effect involved tended to increase from July (just after the ovipositional season) to May (season prior to pupation). According to the mosaic distribution of favorable habitat at the 5 m scale, even minor distruction of habitat can be threatening. We suggest that the efficiency of future larval spatial distribution surveys will be enhanced by lightly moistening the habitat.
