CONTENTS
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. |
