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Title: Control of larval and egg development in Aedes aegypti with Ribonucleic acid interference (RNAi) against juvenile hormone acid methyl transferase

Author
item VAN EKERT, EVELIEN - University Of Florida
item POWELL, CHARLES - University Of Florida
item Shatters, Robert - Bob
item BOROVSKY, DOV - Dov Borovsky

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2014
Publication Date: 8/9/2014
Citation: Van Ekert, E., Powell, C.A., Shatters, R.G. Jr., Borovsky, D. 2014. Control of larval and egg Development in Aedes aegypti with Ribonucleic acid interference (RNAi) against juvenile hormone acid methyl transferase. Journal of Insect Physiology. doi:10.1016/IP.2014-08001.

Interpretive Summary: A novel and insect specific method for control of the mosquito was demonstrated using a strategy called Ribonucleic acid interference (RNAi) that shuts down specific genes within the insect as a result of the insect feeding on a specific type of genetic material that matches a target gene within the mosquito. A method of delivery using engineered yeast to produce double stranded RNA, dsRNA (genetic material recognized by the mosquito cells as invading virus genetic material) was demonstrated. When this dsRNA contained a sequence matching that of a mosquito gene involved in the biosynthesis of mosquito juvenile hormone, the mosquito cells were tricked into shutting down the synthesis of this hormone resulting in inhibition of female egg development and inhibition of normal larval development. This work is presented as a strategy that could be adapted as a highly mosquito specific control strategy.

Technical Abstract: Ribonucleic acid interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including mosquitoes and many other insects. Little has been done, however, to harness this approach in order to control adult and larval mosquitoes. Juvenile hormone (JH) plays a pivotal role in the control of reproduction in adults and metamorphism in larval mosquitoes. This report describes an approach to control Aedes aegypti using RNAi against JH acid methyl transferase (AeaJHAMT), the ultimate enzyme in the biosynthetic pathway of JH III that converts JH acid III (JHA III) into JH III. In female A. aegypti that were injected or fed jmtA dsRNA targeting the AeaJHAMT gene (jmtA) transcript, egg development was inhibited in 50% of the treated females. In mosquito larvae that were fed transgenic Pichia pastoris cells expressing long hair pin (LHP) RNA, adult eclosion was delayed by 3 weeks causing high mortality. Northern blot analyses and qPCR studies show that jmtA dsRNA causes inhibition of jmtA transcript in adults and larvae, which is consistent with the observed inhibition of egg maturation and larval development. Taken together, these results suggest that jmtA LHP RNA expressed in heat inactivated genetically modified P. pastoris cells could be used to control mosquito populations in the marsh.