Analysis of the biological control of Mythimna separata (Lepidoptera: Noctuidae) by Apanteles ruficrus (Braconidae: Hymenoptera) in New Zealand.

Published online
08 Jun 1988
Content type
Journal article
Journal title
Journal of Applied Ecology

Hill, M. G.

Publication language
New Zealand


Estimated levels of larval parasitism of Mythimna separata, a pest of pasture and cereal crops in New Zealand, before and after the introduction of the parasitoid Apanteles ruficrus from Pakistan suggest that there has been an increase in average parasitism from approximately 50-55% to about 80%. Larval parasitism was found not to be density-dependent while pupal parasitism was. Parasitism is known to reduce food consumption by larvae of the host. The increased parasitism following the introduction of A. ruficrus was judged to have raised the M. separata population damage threshold in maize from approximately 240-360 larvae/m2 to 400-530 larva/m2. The success of A. ruficrus in drastically reducing the incidence of M. separata is discussed in relation to its role in reducing food consumption as opposed to its lowering the average population levels of M. separata. It is concluded that the ability of A. ruficrus to reduce the feeding potential of M. separata populations is probably the most important factor in its success as a biological control agent in New Zealand.

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