We’ve dung it again! Our exotic solution to the dung problem in Australia continues
The new species - Onthophagus vacca
- Onthophagus vacca is mostly attracted to fresh cattle and sheep dung in open pasture.
- It is active during spring and early summer and has a very strong preference for open, non-shaded sites.
- Adults emerge in early spring and feed voraciously for several weeks until they are ready to reproduce
- Adults fly only during the middle of the day when the temperature exceeds 10°C.
- The male assists the female with the construction of the nest; females tend to construct the tunnels and males to move dung from the pad to the tunnel entrance.
- The nest structure of Onthophagus vacca is rather simple with a main vertical tunnel off which secondary tunnels lead to brood chambers. Each is provisioned with a dung-mass of about 8g (0.9g dry weight) into which one egg is laid.
- Presence of a co-operating male increases the average number of brood chambers produced by a breeding female from 4 to 5 per nest.
- Brood chambers are more clustered and deeper in dry soil compared to moister soils.
- Breeding females stay an average of 115 hours at a pad, with few staying longer than 144 hours. Co-operative males tend to leave the pad somewhat earlier, the average stay being 87 hours.
- Oviposition continues for 3-4 months. The larvae develop on the dung within the brood chambers and metamorphose into adults which enter an obligatory state of arrested development until the following spring (J. Serin pers. comm.).
- Onthophagus vacca is found over an area extending from western Europe to the Caucasus region and Iran (Fig. 1).
- In southern Germany (Wassmer 1994), the species has two peaks of abundance, one in the spring and a second smaller peak in the autumn.
Previous time in Australia
Three releases of Onthophagus vacca were made in the ACT in September-October 1980. Onthophagus vacca was also released near Toodyay in WA in October 1983.
Release numbers at both sites were small and the species failed to establish.
Onthophagus is a large genus of scarabaeine beetles that occurs in Europe, Asia and Africa and Australia.
In Australia, there are well over 200 described species, which Matthews (1974) divided into eleven distribution patterns.
Generally speaking, there are fewer species as one moves south in Australia.
The so-called ‘inland eastern pattern” fits most closely with the intended target region of SE Australia and contains about 10 species of Onthophagus.
These may utilise cattle dung, but are not dependent upon it, having evolved to utilise marsupial dung.