Variegated Cutworm

Return to:

[Variegated Cutworm]

[Insect Management]

[Home]

Toxicity of Peppermint Monoterpenes to the
Variegated Cutworm (Lepidoptera: Noctuidae)

STEVEN H. HARWOOD¹, ALISON F. MOLDENKE, AND RALPH E. BERRY

Department of Entomology, Oregon State University,
Corvallis, Oregon 97331

© Copyright 1990 Entomological Society of America

J. Econ. Entomol. 83(5): 1761 - 1767 (1990)

ABSTRACT

Toxicity of five monoterpenes to the variegated cutworm, Peridroma saucia Hübner, was evaluated. Larvae fed for 6 d from the beginning of the fifth stadium on semidefined artificial diet fortified with pulegone (0.05%, 0.1%), menthol (0.1%, 0.2%), or menthone (0.2%) weighed less than controls. Reduced growth was the result of feeding inhibition in larvae fed menthone and pulegone and to molting abnormalities in larvae receiving menthol. Menthol completely inhibited pupation at doses approximating those in peppermint (0.05 - 0.2% wet wt). Limonene (0.2%), menthone (0.1%, 0.2%), and pulegone (0.1%) also inhibited pupation. Growth, feeding, and pupation were not affected when larvae ingested limonene (0.05% or 0.1%) or alpha-pinene (0.05 - 0.2%). Growth, maximum weight, and pupal weight of neonate larvae fed artificial diet fortified with menthol, menthone (0.05%), limonene (0.05%), alpha-pinene (0.05%), or pulegone (0.025%) did not differ from those of controls. However, larval mortality was significantly higher in menthone and pulegone treatments than in the controls. The median lethal dose for pulegone applied topically to sixth instars was 1,077 ug/g; for menthone, 2,478 ug/g; and for alpha-pinene, 7,925 ug/g. Piperonyl butoxide synergized the latter two effects. Suspensions of midgut microsomes from sixth instars metabolized all five monoterpenes as indicated by disappearance of NADPH.