The re-introduction and initial re-establishment of Lydella stabulans grisescens R.-D., a parasite of the European corn borer (Pyrausta nubulalis (Hbn.)), in Delaware
| Author(s) | Van Denburgh, Robert S. | |
| Date Accessioned | 2025-11-25T13:36:15Z | |
| Date Available | 2025-11-25T13:36:15Z | |
| Publication Date | 1961 | |
| Abstract | Between 1947 and 1951 the tachinid fly Lydella stabulans grisescens R.-D., which was released in Delaware between 1941 and 1946, averaged 21.4 percent annual parasitism of the European corn borer, Pyrausta nubilalis (Hbn.). Subsequent to 1951 the parasite appeared to decline in abundance. ☐ The purpose of this work was to instigate a program of biological control against the European corn borer in Delaware in order to reduce its abundance. In the Fall of 1958 and Ppring of 1959, overwintering borers were collected to ascertain the status of l. stabulans grisescens. Results indicated the fly to be no longer present in the state. ☐ In the spring of 1959, a biological control program against the corn borer was undertaken by the University of Delaware, assisted by the United States Department of Agriculture's European Corn Borer Research Laboratory in Ankeny, Iowa. Adult L. stabulans grisescens were sent from Iowa and released in June, 1959. Six release sites were selected throughout the State and a total of 2,933 flies were released. ☐ In the fall of 1959 and winter of 1960 corn borer larvae were collected and sent to the Iowa laboratory in order to determine establishment and dissemination of L. stabulans grisescens. For each release area, whenever possible, 16 fields were sampled in addition to the release field. Starting from the release site samples were taken at intervals of one-half, one, two, and four miles in four directions; North, South, East, and West. In most cases each sample consisted of 50 borers. In all, a total of 88 fields were sampled and 4,239 corn borer larvae were collected and observed for parasitism. ☐ For all fields sampled, parasitism by L. stabulans grisescens averaged 0.6 percent and it was recovered from 18.2 percent of these fields. The range of parasitism was from 2.1 to 7.7 percent. Parasite recoveries were made from at least one field in each release area except one, for a total of 16 positive fields. Average parasitism for these 16 fields was 3.45 percent. Maximum dispersal was at least two miles. ☐ The average percentage parasitism (3.45%) in fields where the fly was recovered compares favorably with the percentage parasitism by L. stabulans grisescens in release areas of the State in the 1940’s at intervals of from one to two years after release. Since L. stabulans grisescens had completed two generations in Delaware by the time parasitism data was determined in the Spring of 1960, it is highly probable that this fly is re-established in Delaware. | |
| Advisor | Bray, Dale F. | |
| Degree | M.S. | |
| Department | University of Delaware, Department of Entomology and Applied Ecology | |
| Unique Identifier | 1553739964 | |
| URL | https://udspace.udel.edu/handle/19716/36766 | |
| Language | en | |
| Publisher | University of Delaware | |
| dc.subject.lcsh | European corn borer | |
| dc.subject.lcsh | Parasitic insects | |
| Title | The re-introduction and initial re-establishment of Lydella stabulans grisescens R.-D., a parasite of the European corn borer (Pyrausta nubulalis (Hbn.)), in Delaware | |
| Title | Reintroduction and initial reestablishment of Lydella stabulans grisescens R.-D., a parasite of the European corn borer (Pyrausta nubulalis (Hbn.)), in Delaware | |
| Type | Thesis |