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Variegated Cutworm



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[Variegated Cutworm]

[Insect Management]


Reduction in Variegated Cutworm (Lepidoptera: Noctuidae)
Injury to Peppermint by Larval Parasitoids

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

© 1986 Entomological Society of America
J. Econ. Entomol. 79: 1244-1248 (1986)


Variegated cutworm (VC), Peridroma saucia (Hübner), parasitism rates in western Oregon and peppermint leaf consumption rates of parasitized and unparasitized larvae were measured for use in a VC economic threshold model. Instars 46 consumed an average of 184 cm2, equivalent to 888 mg (dry weight) of peppermint foliage. Total consumption by larvae parasitized by Meteorus communis (Cresson) was reduced by 93%. Total parasitism rates averaged 35.1% for instars 24 and 5.4% for instar 5. Parasitism rates were related to time of season and inversely related to the log of larval instar 24 host density. M. communis contributed 11% to total parasitism, while Meloboris sp. and Campoletis sp. composed 84% of larval parasitoids reared from fieldcollected larvae. Based on final VC head capsule measurements, only 2% of all larval parasitoids reared allowed hosts to reach a size sufflcient to cause significant damage that occurs during the final two instars. Accounting for natural biological control by these early instar larval parasitoids will permit a 34% increase in economic thresholds for VC in peppermint.