Date of Award
Doctor of Philosophy
E. R. Hart
The mimosa webworm (MWW), Homadaula anisocentra Meyrick, (Lepidoptera: Plutellidae), can be a serious pest of ornamental honeylocust in urbanized areas. In an effort to develop an integrated pest management program for the MWW, several studies were implemented that addressed the effects of different environmental parameters on MWW biology;In the laboratory, development time, head capsule diameter, pupal weight, mortality, and adult fecundity were measured under five constant temperature regimes. The data were subjected to traditional linear regression techniques as well as modern, computer assisted modeling procedures. Minimum developmental thresholds for the immature life stages were observed to fall within a range of 8.5-13.0°C. Maximum developmental thresholds ranged from 31.1-33.3°C. Approximately 70, 280, and 135 degree-days above a 12.3°C threshold were required to complete egg, larval, and pupal development, respectively;In the laboratory, MWW larvae were reared on the foliage of five different honeylocust clones commonly found in the nursery industry. Statistically significant antibiotic effects from feeding on 'Moraine' foliage were observed, but the differences were small and may not be "biologically significant." The observed field resistance of the cultivar 'Moraine' and the susceptibility of the cultivar 'Sunburst' may be because of ovipositional preference selection by gravid females as has been suggested by other workers;MWW mortality caused by the parasitoid Elasmus albizziae Burks (Hymenoptera: Eulophidae) during 1985, 1986, and 1987 was determined from samples of honeylocust foliage that contained first generation MWW cocoons. Conservative estimates of first generation parasitism of MWW prepupae by E. albizziae were 44, 39, and 47% for the years 1985, 1986, and 1987, respectively. The precise effect of this parasitism on MWW populations has not been determined at this time. The moderate mortality rates imposed by E. albizziae should, however, be taken into account when management practices are considered. When treatment is warranted for MWW management, it is recommended that Bacillus thuringiensis insecticides be adopted as the treatment of choice over broad-spectrum insecticides to avoid harming the parasites present.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Rex Alan Bastian
Bastian, Rex Alan, "Influence of temperature, host cultivar, and parasitism on mimosa webworm biology " (1988). Retrospective Theses and Dissertations. 8824.