Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2002
Publication Date: 3/3/2003
Citation: TOEWS, M.D., PHILLIPS, T.W., SHUMAN, D. ELECTRONIC AND MANUAL MONITORING OF CRYPTOLESTES FERRUGINEUS (COLEOPTERA: LAEMOPHLOEIDAE) IN STORED WHEAT. JOURNAL OF STORED PRODUCTS RESEARCH. 2003. v. 39. p. 541-554. Interpretive Summary: The use of passive grain probe traps to estimate insect populations in grain bins is well documented. Although these traps provided increased sensitivity in detecting adult insects and the ability to sample continuously over an extended time period, there have been several drawbacks associated with their use. One is that the passive traps' data is not available until the bins are entered and the traps' contents are examined. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL have developed a system called the Electronic Grain Probe Insect Counter (EGPIC), an electronic insect monitoring system with infrared-beam sensors that provides a remote log of time-stamped insect captures with reduced need for bin entry once a system is installed. EGPIC represents a unique research tool for the study of grain insect ecology because it provides real-time data on insect activity at known locations in a grain bin. A field study of rusty grain beetle behavior was conducted with EGPIC by scientists in the Department of Entomology and Plant Pathology, Oklahoma State University. They examined how the rates of insect capture were affected by (1) insertion of probe traps into the grain, (2) time of day, and (3) air temperature fluctuations when probes were placed near the grain surface. The knowledge gained from this study is helping scientists understand insect behavior and provide guidelines to help the stored grain industry relate trap catches to insect population densities in storage bins. The study has also demonstrated how use of an automated monitoring system can enable managers to determine when grain fumigation or other insect control measures are warranted.
Technical Abstract: Trapping studies were conducted with field populations of Cryptolestes ferrugineus in small steel bins filled with stored wheat. Traps tested in a comparison experiment included two types of commercially available probe-pitfall traps and the trapping body of the Electronic Grain Probe Insect Counter (EGPIC) system. Quantity of insects captured was compared among the three traps. Insect captures in PC pitfall traps, whether at the grain surface or 17 cm below the surface, exceeded those found in WB II probe and EGPIC probe bodies. Number of C. ferrugineus captures was similar between the EGPIC probe bodies and WB II probe traps. With probes positioned near the grain surface, insect counts generated by the EGPIC system were analyzed for changes in rate of capture after inserting the probe, changes within a single 24 h period, and variation with temperature. EGPIC counts varied from 0.5 counts per hour to 5.9 counts per hour throughout the study. C. ferrugineus counts increased with increasing daily mean air temperature and decreased when air temperature decreased. There was a consistent increase in rate of counts during the early evening hours. Increased activity of C. ferrugineus in the early evening hours may have been due to insect response to higher air temperatures near the grain surface late in the day, although grain temperature near the trap varied little throughout the day. Alternatively, diel periodicity in C. ferrugineus may be due to an independent circadian rhythm as evidenced in other grain insects. Rate of counts did not vary consistently with days after the probe was inserted into the grain.