Mode of Action of Novel Pyrazoloquinazoline on Diamondback Moth ( Plutella xylostella ) Ligand-Gated Chloride Channels.

In our previous study, a series of novel pyrazoloquinazolines were synthesized. Pyrazoloquinazoline 5a showed high insecticidal activity against the diamondback moth ( Plutella xylostella ) and no cross-resistance to fipronil. Patch clamp electrophysiology performed on P. xylostella pupae brains and two-electrode voltage clamp electrophysiology performed on Xenopus Laevis oocytes indicated that 5a might act on the ionotropic γ-aminobutyric acid (GABA) receptor (GABAR) and glutamate-gated chloride channel (GluCl). Moreover, 5a 's potency on Px GluCl was about 15-fold higher than on fipronil, which may explain why there was no cross-resistance between 5a and fipronil. Downregulation of the PxGluCl transcription level significantly enhanced the insecticidal activity of 5a on P. xylostella . These findings shed light on the mode of action of 5a and provide important insights into the development of new insecticides for agricultural applications.