Survival of red flour beetles on heated versus unheated concrete treated with cyfluthrin WP Frank H. Arthur USDA-ARS-GMPRC Manhattan KS 66502

Introduction b Cyfluthrin WP is a pyrethroid insecticide applied as a residual treatment on flooring surfaces b There are 2 label rates, 9.5 and 19g/1000 ft 2, or 0.1 and 0.2 g/m 2 b In a previous test, concrete treated with 0.2 g/m 2 cyfluthrin WP was heated continually for 4-16 hours at 45 and 55° C b No difference in survival of red flour beetles (RFB) exposed on heated versus unheated concrete

Objectives b Confirm lab results in a field trial as part of a heat treatment at the KSU flour mill b Determine survival of RFB exposed on concrete heated for different time intervals in the flour mill b Compare results with unheated concrete

Methods b Exposure arenas were constructed by pouring ready- mix concrete slurry into each of 70 Petri dishes (100 x 15 mm) b After drying, concrete disks were removed from the dishes, cyfluthrin WP applied at 20 mg/m 2 on 60 arenas b Five replicates of 30 treated dishes and 5 untreated controls put in the mill and in an office at 1:30 PM 6/25 b Dishes were removed from each location 6 to 42 hours after heating commenced

Methods cont. b On Monday 6/28, 10 adult mixed-sex flour beetles were exposed inside a plexiglass cylinder set on each dish b Percent of RFB mobile, knocked down, and dead on each disk assessed at 0.5 to 120 hours post-exposure b Mobile beetles were considered to have “survived” exposure, since they couldn’t escape the residues

Results b Survival on untreated controls at various post-exposure intervals was 98 to 100% b Time at which dishes were removed from either the mill or office was not significant with respect to survival b Data combined for time

Results cont. b Survival of RFB decreased as exposure interval increased from 0.5 to 120 hours b Survival was greater on dishes held in office versus dishes heated in the mill

Percent Survival of RFB 0.5 to 120 hours post-exposure

Conclusions b No degradation or loss of activity because of heating b Heat appeared to increase activity of cyfluthrin WP b Results with this test at 10% of maximum label rate comparable to lab tests with full rate

Feed Mill b Test will be repeated in the feed mill following the same procedures b Results compared with data from flour mill