Seasonal Development of Leptotrombidium pallidum (Acari: Trombiculidae) Observed by Experimental Rearing in the Natural Environment

Abstract

Engorged larvae of Leptotrombidium pallidum Nagayo, Miyagawa, Mitamura & Tamiya, the vector mite of scrub typhus in Japan, were reared by feeding them with fresh eggs of the collembolan Sinella curviseta Brook while confined in small plastic containers under natural conditions in a copse. The larvae were collected from wild rodents (Apodemus speciosus) in autumn 1985 and spring 1986. Adults were kept alive for 2 yr or longer. The larvae obtained in autumn became dormant in the cold winter season, and growth recommenced in the spring. Thus, the development of mites collected in April became synchronized with that of larvae obtained in the autumn. Most larvae developed into protonymphs in May, deutonymphs in June, tritonymphs in July, and adults in August. The females laid eggs in two consecutive summers. Some larvae collected in autumn were kept in a refrigerator until the following summer. They developed into deutonymphs, tritonymphs, or adults and then became dormant in the winter. Development restarted the next spring and all became adult by summer, when the females laid eggs. Under experimental conditions, all larvae are hatched in the autumn, unlike the natural situation in which two peaks of larval occurrence on wild rodents are observed in autumn and spring.

Meteorological factors affecting scrub typhus occurrence: a retrospective study of Yamagata Prefecture, Japan, 1984–2014

“…To elucidate the relationship between meteorological factors and scrub typhus, the ecology of trombiculid mites, which transmit the pathogen, must be understood. Fortunately, a life-cycle of L. pallidum, which is the main vector of scrub typhus in our study, has been well investigated by Takahashi et al using their semi-natural experimental rearing system [2,26]. In brief, the adult mites lay eggs in July and August.…”

The effects of mite parasitism on the reproduction and survival of the Taiwan field mice (Apodemus semotus)

“…Furthermore, we did not find sex-biased parasitism in either breeding or non-breeding season. This is one of the few empirical studies on host-parasite ecology from a relatively under-studied geographic region (Southeast Asia), where warm and wet climates year-round may allow ectoparasites with free-living stages to breed more frequently and persist at high densities (Takahashi et al 1993;Waller 1997;Shatrov and Kudryashova 2006). Sex-biased parasitism is a complex phenomenon that can be influenced by the biology of particular host and parasite species, mediated by environmental factors, and exhibited spatial and temporal variation (reviewed by Krasnov et al 2012).…”

“…Although seasonal patterns of mite development are still unclear, available reports suggest that these mites could retard their development at any stage in the cold period (e.g. temperature <10°C; Takahashi et al 1993). In the tropics, these mites may continue their development without any conspicuous diapause and have a much shortened life cycle (reviewed by Shatrov and Kudryashova 2006).…”

Trombiculid fauna and seasonal occurrence of Leptotrombidium scutellare and Leptotrombidium pallidum in endemic and non-endemic areas for tsutsugamushi disease in Oita Prefecture, Japan

“…Asanuma (1983) (Suzuki, 1973(Suzuki, , 1977; called the Direct method by Suzuki, 1980), and also from the ground surface using a black cloth (Suzuki and Tabaru, 1987; (Fig, 1) (1980). Suzuki (l978, 1980Suzuki (l978, , 1981 Takahashi et al (1993Takahashi et al ( , 1994 …”