Santiago, Manuel F.
Meyer, Gail M.; Barbosa, Jose M.
University of Tennessee at Chattanooga
Place of Publication
Autumn brings ladybeetles into homes to seek shelter during the winter, which is a nuisance. Their bites may induce an allergic reaction resulting in painful rashes. Predatory ladybeetles have been used as a biological control agents. Not only do they feed on ecological pests, they also feed on the saps of ripe fruits reducing the value of the damaged crop. Two species of ladybeetles (Coleoptera: Coccinellidae) will be examined to determine the quantities of steroids and vitamins used throughout their life stages. The species examined are native, Hippodamia convergens, of North America, and an invasive, Harmonia axyridis, of Asia. The species H. axyridis was collected throughout the Chattanooga, Tennessee, and H. convergens was purchased from California. It was of interest to determine the synthesis of the biomolecules as a mean to develop agents to control their overpopulation of the invasive species and increase the population of the native beetle. Each ladybeetles gender was determined and breeding pairs were placed in their own petri dish. They were incubated (22°C) and fed fava bean aphids. Each life stage of the larvae was collected, weighed, measured, and stored (-20°C). Digestions were conducted with a methanol-hexane mixture, and filtered to remove any excess biomass. Standards of biomolecules were prepared to determine their quantities within the samples. The investigation was able to identify at micron concentrations the steroids and vitamins produced by these two species. The results showed that H. convergens had a 2-fold more estradiol than H. axyrids though they were subjected to identical breeding conditions. Between the second and third instar, there was a 6-fold increase of estradiol in H. axyridys. The beetle H. convergens had a 4-fold increase in estradiol production. Cholesterol and vitamins were also identified within the digested samples indicating that these two species produce these biomolecules for development.
B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.
Ladybugs; Hippodamia; Biological pest control agents
Hixson, Andrea, "Developmental steroids and vitamins: identified and quantified in predatory lady beetles" (2017). Honors Theses.