Scott-Dupree et al. 



JESO Volume 139, 2008 



Introduction 



The variegated cutworm (VCW), Peridroma saucia (Hiibner) (Lepidoptera: 

 Noctuidae) is a generalist feeder on vegetable crops, cereals, ornamentals, fruit and forage 

 crops (Rings et al. 1 976). Adults migrate into southwestern Ontario and are present throughout 

 the growing season (McClanahan and Elliot 1976). Larvae sporadically damage crops in 

 the early part of the growing season but usually are a greater problem in mid-summer, 

 especially in fields of processing tomatoes (Harris et al. 1977). While the organochlorine 

 insecticides provided effective VCW control (Harris et al. 1961), organophosphorus and 

 carbamate insecticides were less so, with effectiveness being very dependant on stage of 

 larval development and method of insecticide application (Harris and Svec 1968; Harris and 

 Kinoshita 1 977; Harris et al. 1 977). Pyrethroid insecticides provided effective VCW control 

 (Harris et al. 1977). Insecticides recommended for cutworm control in Ontario are carbaryl 

 (Sevin XLR), methomyl (Lannate LV), acephate (Orthene 75SP), permethrin (Pounce EC) 

 and lambda-cyhalothrin (Matador 120EC), with the pyrethroids being considered most 

 effective. However, recently anecdotal reports of less than adequate control have suggested 

 that VCW has developed resistance to pyrethroid insecticides. 



The objectives of this study were to: 1) monitor VCW flight in tomato fields in 

 southwestern Ontario; 2) assess the effectiveness of currently registered and reduced risk 

 insecticides on different larval instars; and, 3) determine whether VCW has developed 

 resistance to presently registered control products. 



Methods and Materials 



Flight Activity 



In Summer 2006, 6 bucket-style pheromone traps (Muti-Pher H ) (2 traps/field) baited 

 with Trece K Pherocon Cap VGC - variegated cutworm pheromone lures (Distributions 

 Solida Inc., Saint Ferreol Les Neiges, QC) were operated from late June to mid-September 

 at 3 tomato farms in Norfolk County. All traps were placed in hedgerows surrounding the 

 fields. Traps were checked weekly from 26 June to 14 September and numbers of adult 

 males captured were recorded. Pheromone lures were replaced in mid-July to maintain 

 effectiveness. A Hereon* Vaportape II (GemplerV - Div. of Lab Safety Supply Inc., 

 Madison, WI) insecticide (10% dichlorvos) strip was placed in each trap to kill adults and 

 prevent escape. 



Four pheromone traps (2 traps/field) were operated from early July to late September 

 at 2 commercial fresh-market tomato fields in Essex County. Traps were checked regularly 

 from 1 1 June to 1 9 September and numbers of adult males captured were recorded. Two 

 traps (1 at each location) did not operate correctly because of malfunctioning electrical 

 generators, therefore trap catch data were generated from only 2 traps in Essex County. 



Insecticide Effectiveness 



Insect Culture 



The laboratory colony was started in summer 2006 from late instar VCW larvae 

 collected from tomato fields in Norfolk and Essex Counties. Larvae were reared in screened 



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