Concentrations of substituted p-benzoquinones and 1-pentadecene in the flour beetles Tribolium madens (charp.) and Tribolium brevicornis (lec.) (coleoptera, tenebrionidae)

1. 2-Methyl-1,4-benzoquinone (MBQ), 2-ethyl-1,4-benzoquinone (EBQ) and 1-pentadecene (PD) were identified in Tribolium madens and T. brevicornis by gas-liquid chromatography. 2. MBQ, EBQ and PD were extremely low in newly eclosed adults (<2.5 μg/insect). The levels of all three compounds increased with age until 30-50 days after eclosion, after which time the concentrations were maintained or increased at a lower rate. 3. Mean levels of 152-178 μg substituted p-benzoquinones and 59-63 μg PD were found in 50-75 day adult T. madens. T. brevicornis 50-75 day adults contained mean levels of 228-255 μg substituted p-benzoquinones and 105-121 μg PD. 4. The odoriferous secretion of 50-75 day adults has a p-benzoquinone composition of 32% MBQ and 68% EBQ for T. madens and 36% MBQ and 64% EBQ for T. brevicornis.