The titers of free and total carnitine were determined in selected developmental stages of mites (Tetranychus pacificus) and several insects. In general, insects contained more total carnitine than mites, and mite eggs less than other mite stages. In contrast to mammals, these arthropods contain little free carnitine, with most carnitine present as the acetate ester. Comparing metabolism of cycloprate (hexadecyl cyclopropanecarboxylate) in different developmental stages of mites indicates that selective ovicidal toxicity may result from the production of cyclopropanecarboxylic acid and its subsequent conjugation with carnitine. Thus, O-(cyclopropylcarbonyl)carnitine is a significant metabolite in mite eggs, but not in other stages. We believe that the selective ovicidal activity of cycloprate in mites may result from sequestration of carnitine as this metabolite leading to an inability to transport long-chain fatty acids into the mitochondria causing a lethal disruption of lipid utilization.
ASJC Scopus subject areas
- Agronomy and Crop Science