Nutrient intake in the third instar larvae of Anomala cuprea and Protaetia orientalis submarmorea (Coleoptera: Scarabaeidae) from a mixture of cow dung and wood chips: Results from stable isotope analyses of nitrogen and carbon

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The nutrient intake of the third instar larvae of Anomala cuprea (Ac) and Protaetia orientalis submarmorea (Pos) (Coleoptera: Scarabaeidae) from a mixture of cow dung and wood chips of two wood species (Cryptomeria japonica and Quercus mongolica), was assayed by the stable isotope technique. The values of δ¹⁵N and δ¹³C (deviations of ¹⁵N/¹⁴N and ¹³C/¹²C from the standard materials) were measured in the following samples: (1) the integument plus the head of the 3rd instar larvae of both species reared in 1999 autumn fed with a mixture of cow dung and wood chips or with leaf mold, (2) cow dung, (3) wood chips, and (4) leaf mold as the larval food before onset of rearing. The δ values of the bodies of larvae fed with leaf mold differed with the beetle species. The δ¹⁵N values of the larval bodies of both species fed with the mixture were close to those of cow dung, whereas the δ¹³C values were in between those of cow dung and wood chips. Therefore, both species were presumed to obtain almost all their nitrogen from cow dung, and their carbon from both cow dung and wood chips.