EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 116: 158-172, 2019 | DOI: 10.14411/eje.2019.017

Circadian rhythms in the locomotor activity of the spiders Carrhotus xanthogramma (Salticidae) and Philodromus cespitum (Philodromidae): Temporal patterns and sexual differencesOriginal article

László MEZŐFI¹, Gábor MARKÓ^2,3, Péter KOVÁCS⁴, Viktor MARKÓ¹

¹ Department of Entomology, Szent István University, Ménesi út 44, Budapest 1118, Hungary; e-mails: mezofilaszlo@gmail.com, marko.viktor@kertk.szie.hu

² Department of Plant Pathology, Szent István University, Ménesi út 44, Budapest 1118, Hungary; e-mail: marko.gabor3@gmail.com

³ Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány P. sétány 1/C, Budapest 1117, Hungary

⁴ Mining and Geological Survey of Hungary, Columbus utca 17-23, Budapest 1145, Hungary; e-mail: kovacs.retep@gmail.com

Circadian rhythms play an essential role in the adaptation of organisms to the environment and may show species-specific or sex-specific differences even within a closely related taxonomic group. Although spiders (Araneae) are sexually dimorphic in several morphological and behavioural features, there are very few studies on the sex-specific differences in their biological rhythms. This study evaluated the circadian rhythm in the locomotor activity of two agrobiont hunting species of spider, Carrhotus xanthogramma (Latreille, 1819) (Salticidae) and Philodromus cespitum (Walckenaer, 1802) (Philodromidae), under natural photoperiod conditions. Particular attention was paid to possible differences between the sexes in both species. We found that C. xanthogramma is a strictly diurnal species with a mean activity peak in the morning in both sexes and the females are more active than males. The locomotor activity rhythm of males was richer in ultradian (shorter than a day but longer than an hour) components, although the relative power of these components was negligible compared to the main, 24-h period component. In accordance with these results, the diel pattern of locomotor activity of C. xanthogramma can be described by a unimodal cosine curve. In contrast to C. xanthogramma, both sexes of Ph. cespitum showed cathemeral activity (i.e., activity occur within both the light and dark portions of the daily cycle) and females and males follow quite different activity schedules: females were most active at night, shortly before nautical dawn, whereas males were most active early in the morning. Unlike C. xanthogramma, Ph. cespitum has more ultradian components, with higher relative power especially in females, where besides the 24-h circadian component there is a particularly strong 12-h ultradian period. Based on these factors, females of Ph. cespitum show a bimodal and males a unimodal pattern.

Keywords: Araneae, Carrhotus xanthogramma, Philodromus cespitum, diel activity, circadian rhythm, activity profile, ultradian rhythmicity, locomotor activity, sexual differences, natural photoperiod, temporal niche, beneficial arthropods

Received: January 31, 2019; Revised: April 23, 2019; Accepted: April 23, 2019; Published online: May 28, 2019  Show citation