We examined the relationship between spatial variation in the number of vector mosquitoes of Japanese encephalitis, Culex tiritaeniorhynchus, collected by dry ice baited traps and the patterns of land use around each trap location. By using CDC miniature light traps enhanced with 1 kg of dry ice, we collected mosquitoes at 13 trap sites inside 3 cowsheds and 10 outdoor-trap sites distributed at 6 rural villages in Toyama Prefecture, Japan. Significant differences in the number of captured mosquitoes were observed among the trap sites. Multiple regression analysis was performed to explain the observed spatial variation in mosquito numbers among the 10 outdoor-traps by choosing a set of land use components and using the distance from the cowshed as predictors. Twelve “land use components” were distinguished and the proportion of area covered with each component was calculated within a circular area around each trap location. Four different radii of the circular area were used in the regression analysis and the best model explained 66.6% of the variation when the radius was 150 m long. The rural-agricultural landscape represented by paddy fields had the largest regression coefficient suggesting a strong association with the spatial variation in the number of mosquitoes captured by dry-ice baited traps.
The banding patterns of polytene chromosomes from the larval silk glands of the black fly Simulium suzukii from Taiwan are resolved relative to other species in the Simulium tuberosum group. Simulium suzukii is chromosomally most similar to the Simulium tani complex, sharing 11 fixed inversions, relative to the standard map for the Simulium tuberosum group, but differing by three fixed inversions and by having unique sex chromosomes and autosomal polymorphisms.
We analyzed the ultrasonic calls of adult black rats, Rattus rattus, with acoustic analysis software, Adobe Audition 2.0. The rats intermittently produced 1 to 7 ultrasound waves in a series of calls. The waves showed a higher frequency and longer duration at the start of the calls than in the subsequent waves. The mean frequencies of the calls at the start, 28.9±3.0 kHz, were significantly higher than at the end, 27.5±2.3 kHz (p<0.0001). The mean frequencies in females, 28.5±1.5 kHz, were significantly higher than in males, 26.3±1.4 kHz (p<0.0001). The mean duration of the ultrasound calls in females, 920±612 ms, was longer than in males, 700±416 ms. There was a significant difference between males and females in the duration of the calls (p<0.01).