Japan experienced dengue outbreaks vectored by Aedes albopictus during the Second World War. The probable vector density that caused the largest dengue outbreak in Nagasaki in 1942 was estimated using a mathematical simulation model. The estimated vector density was 15·0–558·0 per person when various assumptions of uncertain parameters were applied, such as proportion of symptomatic cases, vector mortality, and human biting rate of A. albopictus. When the most favourable disease spread conditions, such as a combination of the exclusive human biting rate and the longest vector survival were assumed, the vector density was 15–25 mosquitoes per person. Unusually high vector density due to wartime practices, and the traditional Japanese lifestyle were presumably responsible for the earlier dengue outbreak. If an outbreak occurs in present-day Japan, it is unlikely to spread as much as the previous one, as environmental conditions and human behaviour have changed in a protective manner.

The rates of water loss and humidity preference of carabids from dry tropical habitats have been studied and compared with corresponding data from temperate carabids and tropical tenebrionids. Within each group of beetles the rate of relative water loss decreases with increasing body size. Carabids from dry tropical areas have rates of water loss which are lower than those of temperate species, but considerably higher than the values for tenebrionids from dry tropical habitats. Small temperate carabids can stay in dry air for only a few hours, whereas large tropical tenebrionids may survive for weeks without becoming critically dehydrated. Given the choice between a dry and a humid atmosphere, well hydrated beetles of all groups will initially choose the dry atmosphere. Most temperate carabids will switch to humid atmosphere after a few hours and tropical carabids after 1–3 days, whereas tropical tenebrionids may remain in dry air for almost 3 weeks. The temperate carabids are very sensitive to dehydration and will shift to a humid atmosphere when dehydrated by only 2–5%. Tropical carabids and tenebrionids will shift first when they are dehydrated by 7–20% of their body weight in a hydrated state, implying that these beetles are considerably less sensitive to water loss than temperate carabids.