Unexpected plant-systemic insecticidal properties of alkylene-tethered bis-imidacloprid derivatives

Abstract

Alkylene-tethered bis-imidacloprid (bis-IMI) derivatives were evaluated for insecticidal activity after foliar dipping, foliar spraying and under systemic conditions. Insecticidal activity on the dipped leaves was dependent on the tether length, and heptamethylene (C7) and octamethylene (C8) derivatives, their best compounds, almost completely controlled the green peach aphid (Myzus persicae) at 10 mg l-1, while all divalent compounds were weak against the tobacco cutworm (Spodoptera litura). C6 and C7 derivatives were examined for residual and systemic activity. Complete control of the green peach aphid by both compounds was observed on evaluation 72 hr after insect release on the eleventh day after foliar treatment, and the C7 derivative showed distinguished systemic activity against the brown plant hopper (N. Lugens) and the green peach aphid. The bis-IMIs should be disqualified as insecticidal candidates on virtual screening criteria owing to its high log P value, large molecular mass and excessive numbers of hydrogen-bond acceptors and rotatable bonds. Additional criteria may be necessary to account for the plant-mobile insecticidal behavior of such novel structures as bis-IMIs. © Pesticide Science Society of Japan.