Competition between the bush fly and a dung beetle in dung of differing characteristics

Abstract

A range of densities of bush fly (Musca vetustissima) eggs and dung beetle (Onthophagus binodis) adults were placed on either nutritious spring or poor summer dung in the laboratory at 25 ~ Intra-and interspecific competition were greater for flies in summer dung than in spring dung, and intra-and interspecific competition were greater for dung beetles in spring dung than in summer dung. In summer dung fly size and survival were influenced by both beetle and fly densities. Flies in summer dung were smaller, and below a headwidth of about 2.0 mm there was a correlation between size and survival. Mortality was probably due largely to death of larvae. Also beetles produced very few brood balls, and shredded this dung, particularly at high densities. In spring dung, beetle brood ball production which was greater was reduced by both beetle and fly densities, and beetles left the pads earlier at high fly densities. Fly survival was influenced by beetle density, but less than in summer dung, and not by fly density. Mortality was probably caused by death of eggs. These data support field observations that dung beetles cause higher fly mortality in summer dung than spring dung. Entomol. exp. appl. 41:83 90, 1986 9 Dr W. Junk Publishers, Dordrecht -Printed m the Netherlands

The roles of beetles and flies in yak dung removal in an alpine meadow of eastern Qinghai-Tibetan Plateau

“…A potential mechanism could be asymmetrical competition between the 2 species groups, as suggested by the many previous studies that have demonstrated a negative relationship between beetles and flies when they coexist in the same pat (Bornemissza, 1970;Hughes & Tyndale-Biscoe, 1978;Ridsdill-Smith, Hayles & Palmer, 1986). Under natural conditions, the maggot survival rate ranges from 0.3 to 12.5% (Tyndale-Biscoe & Vogt, 1991), and it is even smaller if the maggots coexist with beetles in the same dung (Ridsdill-Smith, Hayles & Palmer, 1986). The asymmetrical competition for dung resources could be caused by mechanical damage to the eggs by beetles (Ridsdill-Smith, Hayles & Palmer, 1986).…”

“…Therefore, there should be a niche separation and a possible complementarity between the 2 species groups. However, both laboratory and field experiments (Bornemissza, 1970;Hughes & Tyndale-Biscoe, 1978;Moon, Loomis & Anderson, 1980;Feehan et al, 1985;Ridsdill-Smith, Hayles & Palmer, 1986;Mariátegui, 2000;Bishop et al, 2005) show that there is a negative relationship between dung coprophagous beetles and flies. For example, the mortality rate of fly maggots is evidently elevated by mechanical damage by beetles (Mariátegui, 2000;Bishop et al, 2005).…”

A brown-world cascade in the dung decomposer food web of an alpine meadow: effects of predator interactions and warming

“…Although both flies and coprophagous beetles are usually two major species contributing to dung decomposition in the study site, the role of flies is modest when the coprophagous beetles are included, because flies often spend a shorter time within dung pats than do beetles (Mohr 1943) and are often outcompeted by beetles (Ridsdill-Smith et al 1986, Wu andSun 2010). This has been widely suggested by a strong negative relationship between the two groups in both laboratory and field experiments (Bornemissza 1970, Feehan et al 1985, Ridsdill-Smith et al 1986, Bishop et al 2005. In a previous independent study, we also showed that coprophagous beetles could remove dung as quickly as both beetles and flies did together (Wu and Sun 2010).…”

The brown-world role of insectivores: Frogs reduce plant growth by suppressing detritivores in an alpine meadow

“…For example, the number of dung beetles on day 6 was significantly lower in the dung + frog treatment than the dung-only treatment, whereas it was higher on the other sampling days. This inconsistency is possibly due to the frogs that mediated the competition between flies (maggots) and dung beetles, as revealed in both laboratory and field experiments (Ridsdill-Smith, Hayles, & Palmer, 1986;Bishop, Mckenzie, Spohr, & Barchia, 2005). Dung beetles are often competitively superior to flies (Ridsdill-Smith et al 1986), but the frogs might exert a strong top-down control on beetle abundance, which would benefit the maggots.…”

“…This inconsistency is possibly due to the frogs that mediated the competition between flies (maggots) and dung beetles, as revealed in both laboratory and field experiments (Ridsdill-Smith, Hayles, & Palmer, 1986;Bishop, Mckenzie, Spohr, & Barchia, 2005). Dung beetles are often competitively superior to flies (Ridsdill-Smith et al 1986), but the frogs might exert a strong top-down control on beetle abundance, which would benefit the maggots. Maggots could remain within dung pats for about ten days until pupation (Wu & Sun, 2010) without being attacked by the frogs, and moreover large quantities of maggots assembled in the central part of dung pats could limit the activities of dung beetles (Halffter & Edmonds, 1982).…”