Incorporation of synthesized and dietary hydrocarbons into the cuticle and hepatopancreas of the scorpion Paruroctonus mesaensis

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Abstract
Measurable amounts of cuticular and hepatopancreas lipids were synthesized by the scorpion Paruroctonus mesaensis from [14C]‐labeled acetate, propionate, mevalonate, and leucine when animals were acclimated to 35°C and incubated for at least 72 hours. Labeled hydrocarbons comprised less than 1.5% of the activity in lipids, with most of the labeled hydrocarbons associated with the hepatopancreas. The hepatopancreas was also the site of most lipid synthesis in scorpions injected with [3H]H0. Incorporation of the latter into hydrocarbons relative to other lipid classes increased from 0.9% in 72 hours to 8.4% by day 10 in fed animals, with slightly higher values in starved scorpions. After 3 months, activity in cuticular hydrocarbons increased coincident with a decrease in hepatopancreas activity. Scorpions maintained on crickets (Acheta domesticus) which contain few n‐alkanes showed a marked decrease in cuticular n‐alkanes after 10 weeks, while scorpions maintained on grasshoppers (Trimerotropis pallidipennis) which are n‐alkane‐rich showed a corresponding increase in their cuticular n‐alkanes. Scorpions fed crickets injected with labeled n‐alkanes (C25, C27, C29) incorporated these unchanged into their cuticular hydrocarbons. These results are evidence that lipid synthesis is consistent with the low metabolic rate of the scorpion and that the synthesized hydrocarbons which slowly accumulated in the cuticle were supplemented by diet‐specific branched and n‐alkanes.