FLIGHT INITIATION OF LESSER GRAIN BORER (COLEOPTERA, BOSTRICHIDAE) ASINFLUENCED BY TEMPERATURE, HUMIDITY, AND LIGHT

The rate that stored-product insects migrate by flight into a grain st orage facility is influenced by environmental conditions that mediate flight activity. The influence that temperature, humidity, and light i ntensity have on the initiation of flight by the lesser grain borer, R hyzopertha dominica (F.), was examined in the laboratory. Flight initi ation by male and female beetles up to 8 wk old was examined. Lower an d upper temperature thresholds for flight were calculated to be 19.9 a nd 41.6 degrees C, respectively. Humidity did not influence flight ini tiation within this temperature range. The optimal temperature resulti ng in the highest percentage of flights was 30.7 degrees C. Male and f emale R. dominica flight activity was similar. Greatest flight activit y occurred in beetles up to 1 wk old, whereas older adults exhibited l ittle flight activity. This suggests that, once R. dominica infest a b ulk of grain, they tend to stay and reproduce rather than leave. Migra tion by flight is possible during the summer when wheat is harvested a nd stored, but temperatures may limit migration in fall when corn and sorghum are harvested or wheat is aerated. Early fall aeration when te mperatures are >20 degrees C could cause R. dominica to be attracted t o volatiles emanating from the bin.