Survival of red flour beetles on heated versus unheated concrete treated with cyfluthrin WP

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

2. Introduction • Cyfluthrin WP is a pyrethroid insecticide applied as a residual treatment on flooring surfaces • There are 2 label rates, 9.5 and 19g/1000 ft2, or 0.1 and 0.2 g/m2 • In a previous test, concrete treated with 0.2 g/m2 cyfluthrin WP was heated continually for 4-16 hours at 45 and 55° C • No difference in survival of red flour beetles (RFB) exposed on heated versus unheated concrete

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

4. Methods • Exposure arenas were constructed by pouring ready-mix concrete slurry into each of 70 Petri dishes (100 x 15 mm) • After drying, concrete disks were removed from the dishes, cyfluthrin WP applied at 20 mg/m2 on 60 arenas • Five replicates of 30 treated dishes and 5 untreated controls put in the mill and in an office at 1:30 PM 6/25 • Dishes were removed from each location 6 to 42 hours after heating commenced

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

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

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

8. Percent Survival of RFB0.5 to 120 hours post-exposure

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

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