Survey of indoor cockroaches in some dwellings in Bangkok.

This study aimed to investigate the species distribution of indoor cockroaches in dwellings in Bangkok. Commercial sticky traps were used to catch cockroaches in 128 private residences (40 single houses, 49 townhouses, 39 apartments), 34 offices, and 30 small groceries. The cockroaches were identified as Periplaneta americana, Supella longipalpa, Blattella germanica, Neostylopyga rhombifolia, P. brunnea, P. australasiae, Pycnoscelus surinamensis, and B. lituricallis; two were unidentified species. The most common species were P. americana, S. longipalpa and B. germanica--most of which were nymphal stages. P. americana and S. longipalpa infested all kinds of buildings, especially private residences (50.0% and 17.2%, respectively) and offices (61.8% and 58.8%, respectively); they were also found mostly (15.1%) in mixed infestation and with no predominant species. B. germanica (26.7%) were significantly predominant in groceries. Air conditioners have no influence on cockroach distribution.

Dengue vector mosquitos at a tourist attraction, Ko Samui, in 1995.

On Ko Samui, Thailand there were two epidemics of dengue hemorrhagic fever (DHF) in 1966 and 1967, followed by endemics up to 1994. Aedes aegypti and Aedes albopictus were the vectors. From January to July 1995, 51 cases of DHF were reported, out of these were many foreigners who still suffer from dengue fever and return home with negative impression. We carried out an entomological survey around the island and collected the mosquitos to detect dengue virus by digoxigenin-cDNA probe. The data revealed that Aedes aegypti and Aedes albopictus still were abundant and some were infected with dengue virus. Visual larval survey indices (HI, CI and BI) were 90.4, 61.3 and 301.3 respectively. Biting rate (BR) of Aedes mosquitos was high, the average indoor and outdoor BR were 9.7 and 100.8 mosquitos/man-hour. From 13 pools of mosquitos, 8 strains of dengue virus were detected (61.5%). The results may encourage the local authorities to improve vector surveillance and control before the famous island becomes an unpleasant island.