Degree Name
Master of Science (MS)
Semester of Degree Completion
1977
Thesis Director
Michael Goodrich
Abstract
In an attempt to better understand the host-parasite relationship of the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) and Bathyplectes curculionis (Thomson) (Hymenoptera: Ichneumonidae), all life stages of the parasite were monitored throughout the spring. Sampling was conducted on a degree day basis from early March to late May in an alfalfa field in Mason County, Illinois.
Dissections of host alfalfa weevil larvae revealed 2nd and 3rd host instars were preferred larvae for oviposition. Peak parasite densities were found to precede peak total host larval densities, but coincided with peak densities of the preferred 2nd and 3rd instars. Larger host instars were superparasitized at a higher rate than smaller instars. No correlation was found between percent parasitism and host density.
The standard procedure for determining percent parasitism of an alfalfa field by rearing large larvae was found to give an artificially high estimate, compared to dissection.
Insecticide treatments in central Illinois coincide with peak spring emergence of the parasite. A method for predicting spring emergence is suggested that may enable insecticide applications to be adjusted around the parasite population.
Recommended Citation
Barney, Robert John, "Interrelationships of Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) and Bathyplectes curculionis (Thomson) (Hymenoptera: Ichneumonidae) in Illinois with Emphasis on Host-Parasite Densities, Distribution of Parasites Within Available Hosts and Estimates of Percent Parasitism" (1977). Masters Theses. 3358.
https://thekeep.eiu.edu/theses/3358
