Biology and conservation of Circellium bacchus Fabricius (Coleoptera: Scarabaeidae)

Abstract

Activity of the large, flightless, telecoprid dung scarab, Circe/lium bacchus, is governed by precipitation and temperature. Mild to warm temperatures (l 8-26°C) following rain, or high relative humidity can cause a hundredfold increase in their visible numbers. Seasonal peaks therefore coincide with the warm and wet months of the year. In the Addo Elephant National Park and surrounding areas the rainfall, although distributed throughout the year, is characteristically trimodal with peaks in autumn, spring and early summer. Although once widespread this monospecific genus is now restricted to a few small populations in the southern and eastern Cape Province with the largest population enjoying the suitable habitat and protection afforded by the Park. The females of C. bacchus are responsible for rolling and burying the brood ball. The male sometimes joins the female in the final stages ofbrood ball construction. Elephant dung is preferred for feeding while the more pliable buffalo dung is mainly used for breeding. The large brood balls (43-63 mm diameter) are rolled between l O and 80 m before being buried in a brood chamber at an average depth of approximately 250 mm. Mating takes place underground one to four days after burial. The ball is reshaped into a brood pear and a solitary egg is laid in the apex. Three larval instars and the pupal stage follow, lasting approximately 4 - 4.5 months under favourable conditions. The female stays with the brood ball for the duration of the immature stages and thus only produces one or two generations per year. The males leave the brood ball five to seven days after the ball is buried. The high unnatural mortality of the beetles, caused by cars, in the Park can largely be attributed to the design of the tourist roads and public ignorance. Solutions to these problems include altering the design of the roads, and a public awareness campaign involving pamphlets and the media, highlighting the plight of the beetle.