Seasonal changes in oviposition activity, hatching and embryonation rates of eggs of Aedes albopictus (Diptera: Culicidae) on three islands of the Ryukyu Archipelago, Japan

Abstract

An ovi-trap collection was made weekly both indoors and outdoors on three islands of the Ryukyu Archipelago, Japan, from May 2002 to May 2003. The total number of mosquito eggs collected from each of the islands was 17,757 in Okinawa, 11,190 in Ishigaki and 28, 375 in Yonaguni. More than 99% of the pupae and adults emerging from the eggs were Aedes albopictus, while the rest were Ochlerotatus togoi. There were no Ae. aegypti eggs confirmed. Oviposition of Ae. albopictus was interrupted by heavy rains and typhoons but continued soon after weather recovery. No eggs were collected in January in Okinawa Is., but eggs were found even in winter in Ishigaki Is. and Yonaguni Is., although the number of eggs was small. Aedes albopictus oviposited more eggs in ovi-traps outdoors than indoors. The low hatching rates of Ae. albopictus eggs during winter in Okinawa Is. in spite of high embryonation rates suggest light dormant eggs. The egg biology of Ae. albopictus in the subtropical region is discussed.