Effect of Temperature and Duration of Trapping on Four Stored Grain Insect Species

Abstract

Capturing stored grain insects with drop traps in wheat was affected by insect species, grain temperature, and trapping duration. These results were obtained using four insect species (Tribolium castaneum (Herbst), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Cryptolestes ferrugineus (Stephens), three grain temperatures (10.0, 21.1, and 32.2°C), and four trapping intervals (I, 2, 4, and 7 d). Higher grain temperatures resulted in significantly more insects trapped when all species were combined. This significance is largely due to the highly significant numbers of C. ferrugineus captured at high temperatures. The other species followed the same pattern. At each temperature, C. ferrugineus was caught in the greatest numbers and R. dominica in the least. S. oryzae and T. castaneum were captured in intermediate numbers. Across species, longer trapping durations resulted in significantly more insects being captured. Across durations, C. ferrugineus was caught the most, R. dominica the least, with the other two species intermediate. Within species, only C. ferrugineus . showed significant differences in the number trapped among the sampling periods. The trend, however, was consistent for all insect species. This study emphasizes the need to consider differences in insect species, grain temperatures, and trapping durations when drop traps are used to estimate insect abundance.