Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2010
Publication Date: 2/1/2010
Citation: Tian, L., Ji, B., Liu, S., He, C., Jin, F., Gao, J., Stanley, D.W., Li, S. 2010. JH biosynthesis by reproductive tissues and corpora allata in adult longhorned beetles, Apriona germari. Archives of Insect Biochemistry and Physiology. 75(4):275-286. Interpretive Summary: Use of classical insecticides has introduced severe problems in agricultural and environmental sustainability. Two of most pressing problems are the ability of pest insects to resist classical insecticides and the negative influence of insecticides on ecosystems. One approach to reduce the environmental insecticide load is based on the concept of disrupting insect hormone systems to cripple insect development. This idea grew from discovery that chemicals that naturally occur in a few plant species block insect development. Although this modern approach to insect control is feasible, direct application is problematic. The concept of disrupting insect development is limited by lack of detailed knowledge of insect hormone systems. To help solve this problem, we are investigating the production of a specific hormone. We show that the hormone is produced via a recognized mechanism and show for the first time that the hormone is produced in specific tissues with adult insects. This new research will be directly useful to scientists who are working to improve the usefulness of disrupting insect development. The ensuing improved methods will benefit a wide range of agricultural producers, and people who rely on agricultural products, by supporting the long-term sustainability of agriculture.
Technical Abstract: We report on juvenile hormone (JH) biosynthesis from long-chain intermediates by specific reproductive system tissues and the corpora allata (CA) prepared from adult longhorned beetles, Apriona germari. Testes, male accessory glands (MAGs), ovaries and CA contain the long-chain intermediates in the JH biosynthetic pathway, farnesoic acid (FA), methyl farnesoate (MF) and JH III. Testes and ovaries, but not CA, produced radioactive JH III following addition of **3H-methionine and, separately, unlabeled methionine, to the incubation medium. We infer that endogenous FA is methylated to MF in testes and ovaries. Addition of farnesol led to increased amounts of FA in testes, MAGS, ovaries and CA, indicating oxidation of farnesol to FA. Addition of FA to incubation medium yielded increased JH III, again indicating methylation of FA to MF in testes, MAGs, ovaries, but not CA. Addition of MF to incubation medium also led to JH III, from which we infer the epoxidation of MF to JH III. JH biosynthesis from farnesol in the testes, MAGS and ovaries of A. germari proceeds via oxidation to FA, methylation to MF and epoxidation to JH III. This is a well-known pathway to JH III, described here for the first time in reproductive tissues of longhorned beetles.