Effect of the Presence of Live or Dead Insects on Subsequent Captures of Six Stored-Product Beetle Species: The Relative Species Matters.

In trapping programs prior capture of individuals of the same or different species may influence subsequent attractiveness of the trap. To evaluate this process with stored-product insects, the effect of the presence of dead or alive adults in traps on the behavioral responses of six stored-product insect species, Tribolium confusum Jacquelin du Val, T. castaneum (Herbst) (Coleoptera: Tenebrionidae), Sitophilus oryzae (L.), S. granarius (L.) (Coleoptera: Curculionidae), Oryzaephilus surinamensis (L.) and O. mercator (Fauvel) (Coleoptera: Silvanidae), was studied in choice tests under laboratory conditions. Two series of tests were carried out. In the first series, the choice was between either alive or dead adults of same species and blank (no adults). Overall, dead adults had the strongest influence, increasing the response of S. oryzae, S. granarius, O. surinamensis, and O. mercator and decreasing the response of the two Tribolium species. Presence of alive adults generally did not result in a response different from blank, except for T. castaneum and O. surinamensis that had a reduced response. In the second series of tests, the choice was between alive or dead individuals of the species vs. alive or dead individuals of its relative cogeneric species. For choices between alive individuals, S. oryzae, S. granarius, and O. surinamensis showed a preference for alive individuals of the same species vs. the cogeneric species, and for all the other species there was no preference. For choices between dead individuals, T. castaneum exhibited a preference for individuals of the same species, while S. oryzae, S. granarius, and O. mercator showed a preference for individuals of the cogeneric species, and all other combinations did exhibit a preference. Our results suggest that traps containing alive and dead individuals of the same and other species can seriously affect the response and capture of additional insects.