North American strains of Aedes albopictus, an Asian mosquito recently introduced into the Western Hemisphere, exhibit photoperiodic sensitivity and cold-hardiness characteristics similar to strains originating from temperate zone Asia. Trade statistics for used tire imports, the most likely mode of introduction, also indicate a north Asian origin. Aedes albopictus, an important vector of dengue and a potential vector of many other arboviral diseases, may therefore have the capability of infesting much of temperate North America.

Male accessory glands were implanted in virgin females of Aedes aegypti. When exposed to males, females copulated readily but were not inseminated; they remained sterile for life. Extract from one male could sterilize more than 64 females. The active principle may be a protein or peptide. Intraspecific transplant prevented insemination in 12 species, including Aedes, Anopheles, and Culex; interspecific transplant gave partial protection.

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Eggs of five strains of Aedes albopictus (Skuse) were obtained in both diapause and nondiapause conditions and exposed to various cold acclimation regimes in the laboratory, after which they were subjected to diverse chilling treatments. Larvae that survived chilling as eggs survived to the pupal stage. Eggs of Aedes aegypti (L.) and Aedes triseriatus (Say) were included as control species. Eggs of temperate Ae. albopictus were more cold-hardy than eggs of Ae. aegypti but less cold-hardy than the eggs of Ae. triseriatus. Cold acclimation and diapause enhanced cold hardiness of only temperate Ae. albopictus. Cold acclimation had a greater influence on cold hardiness than did diapause. Both the temperature and the duration of cold acclimation modulated cold hardiness. Cold hardiness induced in the laboratory was similar to cold hardiness induced in the field in northern Indiana. The cold hardiness of Ae. albopictus from central Florida was intermediate in comparison with temperate and tropical strains. Tropical Brazilian Ae. albopictus and tropical Asian Ae. albopictus were similar in cold hardiness.

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