J. HYM. RES. Vol. 10(1), 2001, pp. 81-90 Effects of Parasitism by Banchus flavescens (Hymenoptera: Ichneumonidae) and Microplitis mediator (Hymenoptera: Braconidae) on the Bertha Armyworm, Mamestra confignrata (Lepidoptera: Noctuidae) 1 P. G. Mason 2 , M. A. Erlandson, and B. J. Youngs Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan S7N 0X2 Abstract. — The bertha armyworm, Mamestra configurata Walker (Lepidoptera: Noctuidae), is an important pest of canola (Brassica napus L. and B. rapa L.) and flax (Liuum usitatissirmim L.) in western Canada. It is the focus of research to develop a management program integrating micro-bial and insect parasitoid agents with cultural practices and judicious use of chemical insecticides. To develop IPM effectively it is essential to understand the impact of parasitism on feeding activity of the host. We studied the effect of parasitism by two solitary koinobiont larval endoparasitoids: Banchus flavescens Cresson (Ichneumonidae) is a native parasitoid of M. configurata; and the Eu-ropean Microplitis mediator (Haliday) (Braconidae) is a candidate for introduction to enhance the biological control effected by B. flavescens. Parasitism by B. flavescens resulted in significantly de-creased food consumption and lower biomass production but did not reduce the time that the pest would occur in the crop. Host larvae parasitized by M. mediator showed a much greater reduction in food consumed, weight gained, frass produced and the host's feeding time compared to nonparasitized larvae or those parasitized by B. flavescens. Management strategies should con-sider options that would minimize impact on parasitized larvae and introduction of M. mediator could benefit integrated management programs for M. configurata. The bertha armyworm, Mamestra confi-gurata Walker, native to North America, has been the focus of studies to determine the role of natural control agents for this pest of canola (Brassica napus L. and B. rapa L.: Bras-sicaceae) and flax (Linum usitatissitnum L.: Linaceae), the two most important oilseed crops grown in western Canada. Important natural control agents of larval stages of the bertha armyworm include viral and fungal diseases and parasitic wasps and flies (Wy-lie 1977, Wylie and Bucher 1977, Arthur and Mason 1985, Turnock 1988, Erlandson 1990). The solitary koinobiont ichneumonid Banchus flavescens Cresson is the single most 1 Saskatoon Research Centre Contribution No. 1272. -Present address, Agriculture and Agri-food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, Ontario, K1A 0C6 Canada. important larval parasitoid, occurring in more than 90% of bertha armyworm sam-pled in years when populations are declin-ing (Turnock and Bilodeau 1984, Arthur and Mason 1985) yet B. flavescens is unable to prevent outbreaks from occurring (Ma-son et al. 1998). Biologically based pest management strategies being developed for the bertha ar-myworm include microbial insecticides (nu-clear polyhedrosis virus, MacoNPV (Erland-son 1990)) and introduction of exotic para-sitoids to complement the mortality caused by native natural enemies. It is essential to understand the impact of parasitoids on the host's feeding activity so that management strategies can be developed to minimize the impact on parasitoids. The solitary koinobiont braconid parasit-oid Microplitis mediator (Haliday) has been
Effects of Parasitism by Banchus flavescens (Hymenoptera: Ichneumonidae) and Microplitis mediator (Hymenoptera: Braconidae) on the Bertha Armyworm, Mamestra configurata (Lepidoptera: Noctuidae)1
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