Some Traits of the Biology and Epigean Behavior of Sisyphus schaefferi (Linnaeus) (Coleoptera: Scarabaeidae: Scarabaeinae: Sisyphini)

Abstract

A two-year field study on selected traits of the biology of the scarabaeine dung roller Sisyphus schaefferi (Linnaeus) was conducted in a natural park in the western Po Valley in northwestern Italy. Despite laboratory studies carried out over the past few decades, several aspects of the epigean behavior of the species in the wild remain uncertain. Our study revealed that 1) the species is active from early spring to late summer, with reproductive pairs being observed from mid-spring to midsummer; 2) sexual dimorphism in body weight and length is absent; 3) mating individuals are significantly heavier and longer than non-mating individuals; 4) metatibial length increases isometrically with body length and weight; 5) size and weight of the brood balls are isometric with respect to the length and weight of the male of the reproductive pair; 6) brood balls are significantly larger and heavier than food balls, and, whereas brood ball size and weight decrease as air temperature increases, food ball size and weight increase as air humidity rises, but only in non-reproductive periods; 7) pushing and pulling roles are not sex-dependent and can be reversed during the rolling process; 8) combat for balls can involve up to six individuals simultaneously.

Field Notes on the Consequences of Limb Damage and Loss in Sisyphus schaefferi (Linnaeus, 1758) (Coleoptera: Scarabaeidae: Scarabaeinae: Sisyphini)

“…Our research was conducted from 14 May 2017 to 27 August 2017 and from 4 June 2022 to 26 June 2022. Complete information about the study area and the methods applied during 2017 were reported in Rizzotto et al (2021). During 2022, the data collection was abruptly interrupted at the end of June by an extreme weather event that caused the park to close.…”

“…Each capture took place in deciduous forest litter or within a badger latrine. As in the previous work (Rizzotto et al 2021) describing the ball rolling process, we define "pulling" as the individual placed in front of the ball and moving backward, and "pushing" as the individual positioned behind the ball and moving forward.…”

“…For each captured individual, we recorded the type of damage to the antennae, elytra, wings, pro-, meso-and metathoracic legs. Body length (BL) from the pronotal anterior edge to the dorsal margin of pygidium and live weight (LW) were then measured, as extensively explained in Rizzotto et al (2021). All specimens were released immediately after measurements.…”

“…No damage or amputations have ever been observed during fights between intact individuals, even though the combats can be frequent, prolonged, and intense (see Rizzotto et al 2021).…”

“…Conversely, if the mutilated individual was pulling, its activity was hindered, especially if the damage was to a metathoracic leg; this occurred because reduced anchorage to the ground and balancing decreased the available traction power. Frequent falls during rolling prompted the partner to wait to reunite (Rizzotto et al 2021). If the absence continued, the partner could also abandon the ball.…”