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

• Published in: European journal of entomology Vol. 116; no. 1; pp. 158 - 172
• Main Authors: MEZOFI, Laszlo, MARKO, Gabor, KOVACS, Peter, MARKO, Viktor
• Format: Journal Article
• Language: English
• Published: Ceske Budejovice Institute of Entomology 01.01.2019; Institute of Entomology, Biology Centre, Czech Academy of Science
• Subjects: activity profile; Animal behavior; araneae; beneficial arthropods; carrhotus xanthogramma; Circadian rhythm; Circadian rhythms; diel activity; Diurnal; Females; Hunting; Locomotor activity; Males; natural photoperiod; philodromus cespitum; Rodents; Salticidae; Schedules; Sex; Sex differences; sexual differences; Sexual dimorphism; Species; Spiders; temporal niche; ultradian rhythmicity
• DOI: 10.14411/eje.2019.017
• ISSN: 1210-5759

Circadian rhythms play an essential role in the adaptation of organisms to the environment and may show species-specifi c or sex-specifi c 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.