Traps and Product Samples as Indicators of Stored-Product Insects in Flour Mills

1. Traps and Product Samples as Indicators of Stored-Product Insects in Flour Mills Andy R. Allen and Bhadriraju Subramanyam Department of Grain Science and Industry Kansas State University Manhattan, KS 66506

2. Objectives • To determine the types and numbers of insect species associated with four commercial flour mills in Kansas and Nebraska, based on insects captured in traps and those found in product residues • To use traps and product samples to monitor stored-product insects in the Kansas State University (KSU) pilot flour mill • Suggest sampling and pest management recommendations based on our findings

3. Mill Locations Four commercial flour mills (1-4), and the KSU flour mill (M) NE 3 4 M KS 1 2

4. Mill Information 1Mill 4 has one wheat flour mill and one corn mill (354 MT/day) 2All mills follow a regular sanitation schedule

5. Materials and Methods Commercial mill trapping • Pitfall and aerial sticky traps: grid fashion • CFB/RFB aggregation pheromone and IMM sex pheromone lures from Trécé (Adair, OK) • A single pitfall or sticky trap per 20-23 m2 • Total no. traps in mills 1, 2, 3, and 4 were 182, 150, 108, and 176, respectively • 10 pitfall and 10 aerial sticky traps were placed around the outside perimeter of each mill • Trapping duration: 14-16 d (7 Jul to 31 Jul 2003)

6. Materials and Methods KSU Pilot mill trapping • Traps, lures, and arrangement were similar to that used in the four commercial mills • Flour mill and cleaning house contained 45 and 40 pitfall and aerial sticky trap pairs, respectively (5-10 pairs per floor) • One pitfall or aerial trap per 11 m2 • Sampled weekly for 29 weeks, from 8 Jun to 2 Jan 2002 • Trap catch expressed as mean no. insects per trap • Total no. samples: 2,520

7. Materials and Methods Product sampling • (1) Dirty incoming wheat, (2) moving mill stock, (3) processing equipment, (4) rebolt sifter scalps, and (5) spilled stock found on floors and other structural surfaces • Sieved for live adult insects • Incubated for 46 days and re-sieved for live adults • Pilot mill: weekly for 29 weeks • Commercial mills: before and after the 14-16 d trapping period • Insects expressed as mean no. per gram of product

8. Materials and Methods

9. Relative Abundance of Insects in Four Commercial Flour Mills • 42 insect species from 5 orders and 24 families were collected in trap and product samples from all four mills (8,426 total insects, insideandoutside samples)

10. Flour Mill 1: Inside Mill RFB=T. castaneum, HFB=T. stercorea, CRP=Cryptolestes spp., IMM=P. interpunctella, FGB=A. advena, CAD=T. mauritanicus, TRG=Trogoderma spp., CFB=T. confusum, LGB=R. dominica, STGB=O. surinamensis

11. Flour Mill 2: Inside Mill

12. Flour Mill 3: Inside Mill

13. Flour Mill 4: Inside Mill

14. Relative Abundance of Stored-Product Insects in the KSU Pilot Mill RFB=T. castaneum, IMM=P. interpunctella, STGB=O. surinamensis, RGB=C. ferrugineus, LGB=R. dominica, andMW=S. zeamais

15. KSU Mill: Cleaning House Product Samples

16. KSU Mill: Flour Mill Product Samples

17. Infestation in Product Categories Mean no. adult insects in five product categories Sample size range: dirty wheat (2-4), moving stock (68-113), processing equipment (34-589), rebolt scalps (2-8), and floor residues (8-237)

18. Simpson’s Index of Diversity Simpson’s index ranges from 0 to 1 (1 indicates high diversity and 0 indicates low diversity)

19. Commercial Mills: Morisita’s Index Similarity of Species Composition Based on Trap Captures Within Mills Morisita’s index ranges from 0 to 1 (1 indicates complete similarity and 0 indicates no similarity)

20. Commercial Mills: Morisita’s Index Similarity of Species Composition Based on Insects in Products Within Mills

21. Summary of Commercial Mill Sampling • P. interpunctella were found in all four mills, primarily outdoors and it was the most abundant of all species • Few P. interpunctella were found in products except in mill 4 • The most abundant beetle pests in the commercial mill environments were: T. castaneum (1 and 2), T. confusum (3), and T. stercorea • Similarity of species composition was greatest between mills 1 and 2 based on trap captures and between mills 1 and 4 based on product samples

22. Summary of KSU Pilot Mill Sampling • T. castaneum (RFB) was the most abundant insect species in trap and product samples • RFB were more common in the break rolls and low grade stocks in the flour mill, and the cooling tower and the bucket elevator in the cleaning house • Diversity of insect species was greater for traps than for product samples • Diversity of insect species was greater for the commercial mills than the KSU pilot flour mill

23. Sampling and Pest Management Recommendations • Trap captures did not truly represent resident insect populations • Both techniques should be used to gauge IPM intervention • It is important to close doors and windows to prevent entry of P. interpunctella present outdoors. • Regular cleanout of mills will reduce food sources on which the insects can colonize • Need to understand utilization by insects of patchy food resources in mills • Need to understand movement of insect species between indoor and outdoor habits and within the mill

24. Acknowledgments • USDA/MAFMA • USDA/CREES (RAMP) • Participating Milling Companies • Pictures courtesy USDA Grain Marketing and Production Research Center