Geographical variation in egg diapause in Sympetrum frequens

The effects of photoperiod and temperature on the termination of egg diapause were examined in Sympetrum frequens. Eggs were obtained from adult females collected from three locations in Japan and incubated under short- or long-day photoperiods at a constant temperature of 25, 20, or 15°C. Egg diapause was eventually terminated in all treatments. Because differences…

Oviposition behaviour of Sympetrum frequens (Selys) (Odonata: Libellulidae)

Oviposition behaviour by Sympetrum frequens, a species endemic to Japan, has been observed throughout its entire breeding season, which extended for about one month after the harvest of rice. Approximately 50% of oviposition events occurred during the first week of the reproduction period. Sunny oviposition sites were preferentially selected by ovipositing pairs. The starting time…

Seasonality of prey size selection in adult Sympetrum vicinum (Odonata: Libellulidae)

Sympetrum vicinum is a sit and wait predator, which takes off and pursues small flying insects during its long flying season (July to November). We investigated whether foraging individuals become less discriminating regarding prey size selection during the fall season because the changeable fall weather has an impact on the prey population. To investigate the…

Genetic identity of Japanese Sympetrum frequens and Korean S. depressiusculum inferred from mitochondrial 16S rRNA sequences (Odonata: Libellulidae)

The Japanese endemic Sympetrum frequens is considered as the insular vicariant of S. depressiusculum, widely distributed in the Eurasian Continent. In Korea, morphologically intermediate specimens have been collected, mixed with typical S. depressiusculum. The taxonomical status of these two species is thus questionable. To clarify their status, sequencing of mitochondrial 16S ribosomal RNA (rRNA) was…

Additions to the knowledge of Sympetrum sinaiticum, Dumont (Odonata: Libellulidae)

New information shows that S. sinaiticum, is not divided into subspecies, as hitherto supposed. The subspecific name tarraconense, Jödicke, 1994 must be regarded as a junior synonym of sinaiticum., In contrast, the name arenicolor, Jödicke, 1994 denotes a taxon at full species rank, characterized by its larval and ligula morphology. This species is taxonomically identical…

Body temperature regulation in a late-season dragonfly, Sympetrum vicinum (Odonata: Libellulidae)

Body temperature regulation and behavioral responses to temperature variation in the field were investigated in Sympetrum vicinum, a common North American libellulid that is most abundant as a mature adult in autumn. Because of its late flight season, this species is faced regularly with cooler environmental temperatures than most dragonflies investigated heretofore. By virtue of…

Lifetime egg production of captive libellulids (Odonata)

The estimation of lifetime egg production (LEP) is a central question in ecology, since the number of eggs produced determines the potential size of the following generation. In this study, I tried to obtain a rough estimation of the LEPs in libellulids in outdoor cages. The main questions were: (1) does hand feeding influence females’…