Survival Rates for Two Dung Beetle Species, Onthophagus lenzii HAROLD and Liatongus phanaeoides WESTWOOD(Coleoptera:Scarabaeidae), in the Field

Survival rates from egg to adult, including the survival rates during winter, were studied in the field for two dung beetle species, Onthophagus lenzii and Liatongus phanaeoides, from 1984 to 1987. To examine the effect of insects coming into dung pats on the survival rates of the two species, the survival rates were assessed under two sets of rearing conditions, one with a dung pat and the other without a dung pat on the soil surface. The survival rates from egg to adult before overwintering were 50.0% (without dung) in 1985, 52.4% (without dung), 55.0% (with dung) in 1986 for O. lenzii. For L. phanaeoides the survival rates, including the overwintering larval survival rates, were 32.0% (without dung), 33.6% (with dung) in 1985, 50.0% (without dung) in 1986. For both species the survival rates from egg to adult in the plot with dung were not lower than those without dung. This suggested that the effect of the insects coming into dung pats on the survival rates was negligible. Onthophagus lenzii overwinters as an adult, and the overwintering survival rates were 68.0% in 1984/85, 25.0% in 1985/86, and 51.0% in 1986/87 for five pairs, and 63.8% in 1984/85, 12.0% in 1985/86, and 47.0% in 1986/87 for ten pairs. Liatongus phanaeoides overwinters as a larva. The survival rates were 52.9% in 1985/86 and 83.3% in 1986/87. The overwintering survival rates for both species were lower in 1985/86 when winter temperature was low. The survival rates from egg to pre-reproductive adult, including the survival rates during winter, were 9.0% in 1985 and 26.0% in 1986 for O. lenzii; 33.0% in 1985 and 50.0% in 1986 for L.