Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment



First Advisor

Dr. John J. Obrycki

Second Advisor

Dr. Jennifer A. White


Hippodamia convergens is a widely distributed insect predator in the United States and parts of Canada and Mexico. Several insectaries collect overwintering adults from aggregation sites in the Rocky Mountains during their winter dormancy. Collected beetles are then sold throughout the United States for augmentative biological control. This practice could have negative impacts on local populations of Hippodamia convergens in the Eastern United States. Intra-specific variation among H. convergens populations was examined for two characteristics of adults: photoperiodic induction of diapause and the presence of three known male-killing endosymbiont bacteria; Wolbachia, Spiroplasma, and Rickettsia. Four populations of H. convergens were examined; two populations were collected in Kentucky and Illinois, and two populations were purchased from biocontrol companies in Arizona and California. No differences were observed among populations in their responses to diapause inducing photoperiods. Also, no evidence was found to indicate that the three endosymbiotic bacteria exist within the four H. convergens populations. The results from these experiments indicate that there are no differences in response to diapause inducing photoperiods, meaning that it is not likely to affect timing of diapause induction. The lack of endosymbionts would indicate that there are no reproductive barriers to intra-population matings