Record Details
Studies on the flight behavior of Ips confusus (Lec.) (Coleoptera : Scolytidae) in response to attractants
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Studies on the flight behavior of Ips confusus (Lec.) (Coleoptera : Scolytidae) in response to attractants |
| Names |
Gara, R. I. (Robert Imre), 1931-
(creator) Rudinsky, Julius A. (advisor) |
| Date Issued | 1964-08-04 (iso8601) |
| Note | Graduation date: 1965 |
| Abstract | The flight behavior of Ips confusus (Lec.) was primarily studied under field conditions, but augmented with complementary laboratory studies whenever feasible. The experiments were mostly conducted in areas of endemic population levels, but also under epidemic and prairie conditions. The techniques and devices used in marking, releasing, attracting, and trapping of the test beetles in the field are described in detail. The flight behavior of Ips confusus under laboratory conditions were studied by means of flight bars, standardized flight mills, and a laboratory olfactometer that incorporated flying scolytids. Flight behavior was also observed under restricted flying conditions as found in a large flight arena and in a 27 cubic meter screened cage. By attracting Ips confusus to baited field olfactometers over short distances, it was possible to observe the entire flight from take-off to subsequent response and landing. From these studies the following conclusions can be made: Beetles take-off with the wind and respond against it. The responses to attractants occur immediately, indicating that flight exercise is not a prerequisite in the response of this species. When Ips confusus are attracted, over longer distances (i.e., 500 meters) they clearly respond against the wind. The distance over which the beetles responded directly and in appreciable proportions was between 500 and 1000 meters. The relative attractiveness of the test material depend on the intensity of attack and on the age of the material. Responding beetles aggregate in greater numbers on the strongest attractive source. Beetles released from either end of an attractant gradient respond in greater proportions to the strongest attractant, regardless of wind direction. By measuring the wind at various heights it was noted that Ips confusus response flights were densest in the regions of the least wind. When relatively high winds prevail, the flights are restricted practically to ground level. Light conditions seem to have little influence on response flights except that direct solar radiation seems to be avoided. Both released beetles and the field population exhibit diurnal response patterns that apparently are temperature dependent. The ability to respond to attractants was found to vary from beetle to beetle, with sex, within a brood, and from population to population. Beetles which had responded once (termed responding beetles) repeatedly responded better than unselected, freshly emerged beetles (termed emerging beetles). This heterogeneity in response was due to the response ability of individuals rather than to their flight capacity. Females and responding beetles are superior in response over distances greater than 25 meters, but males and emerging beetles respond in larger proportions over distances up to 25 meters. Within the rime brood, the ability to respond decreases from the first developing beetles to the later emerging individuals. There also seem to be large differences in the response ability among various populations. These findings suggest that the differences are due to physiological condition of beetles and populations rather than to inherited. abilities. Further studies are suggested on the possible influence of various host materials on beetle development The relative ability of beetles to respond to attractants can be used as a criterion of their physiological performances. |
| Genre | Thesis/Dissertation |
| Topic | Douglas fir beetle |
| Identifier | http://hdl.handle.net/1957/49047 |
