Water mites (Acari: Hydrachnidiae) parasitic on aquatic hemipterans in Japan, with reference to host preferences and selection sites

Abstract

Water mites are known to temporarily live on the surface of aquatic insects in their life cycle. Investigations of the host-parasite relationship between water mites and aquatic insects are quite limited in Japan. Therefore, we examined several aquatic hemipterans to clarify the parasitic nature of water mites on aquatic insects. During the survey, the following seven hemipteran species were collected from farm ponds and rice fields in Kanagawa, Yamanashi, and Hyogo prefectures in 2011 and 2012: Appasus japonicus, Appasus major, Laccotrephes japonensis, Aquarius paludum, Ranatra chinensis, Kirkaldyia deyrolli, and Notonecta triguttata. Among these species, water mites were found only on Ap. japonicus and R. chinensis. The water mites were all in a post-larval resting stage and identified as Hydrachna spp. The mites attached to R. chinensis were clearly larger than those on Ap. japonicus. Although mites do not select by host sex and their abundance was not affected by the host body size, their abundance per female host was greater than per male host. Further, the mite parasitism on nymphs was greater than that on adults in Ap. japonicus. Concerning site selection on a host body of R. chinensis for attachment, mites significantly prefer the leg and meso-and metathoraxes to the abdomen, respiratory siphon, and head of a host insect. The results mentioned above accorded well with several studies in Europe.

Parasitism of water mites (Acari: Hydrachnidiae) on <i>Appasus japonicus </i>in a paddy field in Sagamihara City, Kanagawa Prefecture, Japan

“…Aquatic heteropterans were collected by hand with a scoop net like that used in Abé et al (2015). For each heteropteran insect collected at the study area, the specific name, developmental stage, sex, body size, and presence or absence of water mites were recorded.…”

“…The number of mites observed on a certain host individual was given as "intensity" and indicated as a range in some cases. The number of mites estimated per host individual (or certain body part) was expressed as "average intensity" (Abé et al, 2015). The prevalence and intensity of mites were examined for the juvenile and adult hosts or the female and male hosts.…”

“…Most of the studies on the host-parasite relationship between water mites and host insects have been executed mainly in Europe (Abé et al, 2015). The correspondence of the water mites to host insect taxa was especially well investigated.…”

“…According to their report, most of the studies on water mite parasitism in Japan treat dipteran hosts (Yamada, 1918;Miyazaki, 1933Miyazaki, , 1935Miyazaki, , 1936Miyazaki, , 1945Miyazaki, , 1947Uchida and Miyazaki, 1935;Imamura, 1950aImamura, , 1951aImamura, , 1951bImamura, , 1952aHirabayashi and Fukunaga, 2007). On the other hand, studies on mite parasitism on other insect taxa, such as heteropterans (Masuda, 1934(Masuda, , 1942Imamura, 1952b;Nagasawa et al, 2008;Morimoto, 2012;Abé et al, 2015), coleopterans (Masuda, 1934(Masuda, , 1935a(Masuda, , 1935b(Masuda, , 1942, odonates (Miyazaki, 1936;Imamura, 1950bImamura, , 1951cImamura, , 1951dImamura and Mitchell, 1967;Kobayashi and Toda, 2005), and plecopterans (Imamura, 1950c), are rather limited. In addition, most of the studies mentioned above are descriptive works on host-parasite correspondence between mite and host taxa.…”

“…In addition, most of the studies mentioned above are descriptive works on host-parasite correspondence between mite and host taxa. Detailed studies on the host-parasite relationship are scarce (Abé et al, 2015). Accordingly, this paper aims to obtain knowledge concerning the preference of water mites for species, developmental stages, sexes, body sizes, and body sites of heteropteran hosts collected in a paddy field in Sagamihara City in Japan.…”