Effects of temperature and humidity on oviposition, molting, and longevity of Dermanyssus gallinae (Acari: Dermanyssidae).

The juvenile development and survival of Dermanyssus gallinae (De Geer) kept in vitro at different temperatures and humidity were investigated to obtain biological baseline data for a Swedish population. Individual females, eggs, larvae, and protonymphs were observed with regard to egg production, duration of various stages, and longevity when kept at different temperatures and relative humidities. Female mites laid eggs at temperatures between 5 and 45 degrees C with the highest numbers laid at 20 degrees C and 70% RH, but development to larvae and protonymphs was only observed at temperatures ranging from 20 to 25 degrees C. The average duration of oviposition varied from 1.0 to 3.2 d within the temperature range 20-45 degrees C but was gradually increased to 28 d at 5 degrees C. Specimens survived for up to 9 mo without access to food when kept in the temperature range of 5-25 degrees C. Temperatures > 45 degrees C and at -20 degrees C were found to be lethal. Longevity was similar for females and protonymphs kept at 30 and 45% RH, but it was enhanced at 70 and 90% RH for protonymphs. This study showed that D. gallinae can survive for a long time without feeding if the microclimate is suitable, but it does not thrive at low relative humidities and at temperature extremes. This indicates that changing of the abiotic conditions in infested poultry houses could be a possible measure to reduce mite populations.