Semisynthesis and Pesticidal Activities of Derivatives of the Diterpenoid Andrographolide and Investigation on the Stress Response of Aphis citricola Van der Goot (Homoptera: Aphididae)

To discover natural-product-based pesticides, 7β-oxycarbonylandrographolide derivatives were stereoselectively constructed from a labdane diterpenoid andrographolide. Among them, 2′-( n )Pr-1′,3′-dioxin-7β-oxy( m -Cl)benzoylandrographolide ( IIc ), 2′-( n )Pr-1′,3′-dioxin-7β-oxyacetylandrographolide ( IIf ), 2′-( p- Me)Ph-1′,3′-dioxin-7β-oxy( o -Cl)benzoylandrographolide ( Vb ), and 2′-( p- Me)Ph-1′,3′-dioxin-7β-oxy( m -Cl)benzoylandrographolide ( Vc ) against Mythimna separata displayed the most promising growth inhibitory activity; 2′-( n )Pr-1′,3′-dioxin-7β-oxy( o -Cl)benzoylandrographolide ( IIb: LC 50 = 0.406 mg/mL) and IIc (LC 50 = 0.415 mg/mL) exhibited the most pronounced acaricidal activity (andrographolide; LC 50: 5.106 mg/mL) and good control effects against Tetranychus cinnabarinus; compounds Ic, IIe, and Va – c (LD 50 = 0.035–0.039 μg/nymph) showed potent aphicidal activity (andrographolide: LD 50 = 0.178 μg/nymph), and compounds IIe and Vb showed good control effects against Aphis citricola . Moreover, it was found that Hsp70 of A. citricola was an important gene involved in stress response to andrographolide and its derivatives.