title: The choosing of sleeping position in the overnight aggregation by the solitary bees Amegilla florea urens in Iriomote Island of Japan.
abstract: In addition to the process of joining the sleeping aggregation, the choice of sleeping position is an important night-time behaviour of small diurnal insects because of the increased risk for predator attacks as well as bad weather. The aggregation behaviour of the solitary bee Amegilla florea urens was investigated to elucidate the choice of sleeping position on substrates. Male and female constructed single-sex aggregations on hanging leaves during May and June, respectively. Most individuals tended to form aggregations with other individuals while few individuals slept alone. During the aggregation forming, both the number of individuals that tried to join the aggregation and the completion time of aggregation increased with the number of sleeping individuals, whereas the success rate of joining was unaffected. The sleeping positions of subsequent arrivals on the substrates were higher than those of the first arrivals in female aggregations. Therefore, the first female to arrive tended to be located near the bottom of a hanging substrate. Dissecting sleeping females showed that they contained mature oocytes, indicating that sexually mature individuals formed aggregations. In male aggregations, however, we could not find a clear relationship between the position on substrates and the arrival sequence. We suggest that the purpose for sleeping in aggregations might be a dilution effect for nocturnal predation and that the females that finished both nesting and foraging quickly could choose the optimal positions in the aggregation when they arrived on the sleeping substrates.
authors.affiliation: Laboratory of Conservation Ecology, Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba city, Ibaraki, 305-8572, Japan. tomoyoko@envr.tsukuba.ac.jp.
authors.forename: Tomoyuki
authors.identifier: http://orcid.org/0000-0003-2192-2568
authors.initials: T
authors.lastname: Yokoi
authors.affiliation: Laboratory of Conservation Ecology, Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba city, Ibaraki, 305-8572, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Idogawa
authors.affiliation: Laboratory of Entomology, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara city, Nara, 631-8505, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kandori
authors.affiliation: Laboratory of Conservation Ecology, Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba city, Ibaraki, 305-8572, Japan.
authors.forename: Aoi
authors.initials: A
authors.lastname: Nikkeshi
authors.affiliation: Laboratory of Conservation Ecology, Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba city, Ibaraki, 305-8572, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D005260:Female; D062312:Islands; D007564:Japan; D008297:Male; D009425:Nesting Behavior / Q000502:physiology*; D012737:Sex Factors; D012890:Sleep; D012919:Social Behavior
keywords: Dilution effect; Oocyte development; Sequential order; Sleeping; Solitary bee