Comparative observations on oviposition and development of two ixodid ticks, Ixodes persulcatus Schulze and I. nipponensis Kitaoka and Saito, under different temperatures

Abstract

The oviposition, development and survival of the two Ixodes species, I. persulcatus and I. nipponensis, were observed at 16 to 35℃ and ca. 100% RH. The preoviposition periods of I. persulcatus and I. nipponensis were prolonged with decreasing temperatures ranging from 16 to 30℃. The preoviposition period of I. persulcatus was shorter at low and middle temperatures (16 to 25℃) than that of I. nipponensis. The critical low temperature for oviposition of I. persulcatus was 2.9℃, which was lower than that (5.6℃) of I. nipponensis. The egg hatchability of I. nipponensis was high at 16 to 32℃, but that of I. persulcatus was markedly reduced at a high temperature (32℃). The incubation period of eggs of I. persulcatus was considerably shorter at a low temperature (16℃) than that of I. nipponensis. The critical low temperatures for hatching of eggs of I. persulcatus and I. nipponensis were 2.2 and 7.4℃, respectively. Engorged larvae and nymphs of I. nipponensis molted at all temperatures from 16 to 35℃, whereas those of I. persulcatus did not molt at a high temperature (35℃). The developmental periods of engorged larvae and nymphs of I. persulcatus were markedly shorter at a low (16℃), when compared with those of I. nipponensis. The critical low temperatures for molting of engorged larvae and nymphs of I. persulcatus were -2.7 and 6.0℃, respectively, while those of respective stages of I. nipponensis were 9.6 and 13.5℃. These results suggest that I. persulcatus is adapted to cooler conditions than I. nipponensis.