Screening of Juvenile Hormone Receptor Complex Disruptors from Plant Essential Oil Compounds

Abstract

ABSTRACT

Insects cause extensive economic damage every year by harming important crops or transmitting diseases as vectors. Insect growth regulators (IGRs), which are compounds that disrupt the insect endocrine system, are attractive control agents due to their high target specificity, low non-target toxicity and relative safety to the environment. Using a modified yeast two-hybrid system transformed with the Aedes aegypti juvenile hormone receptor as a reporter system,juvenile hormone agonists (JHAs) and antagonists (JHANs) were identified from plant essential oil compounds. Two JHA and two JHAN candidates were selected based on their IGR activity, and their chemical structures were similar to that of juvenile hormone III. Interestingly, JHA candidates have acetate functional groups while JHAN candidates have aldehyde functional groups. All JHA and JHAN candidates displayed potent insecticidal activity against mosquito larvae, with relatively low LC50 values. In particular, JHAN candidates showed very high levels of insecticidal activity against 2nd instar larvae of Aedes albopictus mosquitoes. At sub-lethal concentrations, application of JHA candidates resulted in slower pupation of 4th instar A. albopictus larvae, while application of JHAN candidates led to faster pupation. Both JHA and JHAN candidates affected JH-induced gene expression and ovarian development. Topical application of JHA candidates on adult female mosquitoes caused an increase in hairy gene expression while application of JHAN reduced the expression of the same gene. Lastly, both JHA and JHAN candidates induced retardation of ovarian growth. Therefore, the IGR candidates identified in this study could be useful for the development of effective and environmentally safe biological control agents.

Key Words: juvenile hormone, insect growth regulator, plant essential oils, juvenile hormone agonist, juvenile hormone antagonist

Student Number: 2014-22943