Date of Award
Master of Science
Matt E. O'Neal
Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an economic pest of soybean in the North Central US. Efforts to develop aphid resistant soybeans have focused on genes referred to as Resistance to Aphis glycines or Rag-genes. These genes confer antibiosis and some antixenosis resistance without changes to the plant’s morphology. Host plant resistance can also be conferred by morphological features, such as trichomes that can negatively affect herbivores. However, little research has been conducted to determine how soybean trichome densities effect A. glycines population growth and their interactions with natural enemy predation. To determine the impact of trichomes on both A. glycines and their natural enemies, we first compared 10 soybean isolines that varied by the density of trichomes that were present in a controlled laboratory setting. In addition, we included A. glycines-susceptible and -resistant (i.e., containing Rag1 and Rag2) varieties as positive and negative controls, respectively. We then compared two soybean cultivars with extreme variation in trichome density and conducted a caged study. Two artificial infestations timings (i.e., vegetative and reproductive) of A. glycines were either exposed to or protected completely from natural enemies in a field setting. In addition, we also included A. glycines-susceptible and -resistant (i.e., containing Rag1 and Rag2) varieties as positive and negative controls, respectively. Trichomes did not impact A. glycines in a laboratory setting or A. glycines and their natural enemies during both field infestations, however, unusual results were observed during the R1 infestation due to immigrating aphids. Ultimately, trichomes should not be the used for managing A. glycines.
Shelby Rae Pritchard
Pritchard, Shelby Rae, "Impact of soybean trichomes on Aphis glycines (Hemiptera: Aphididae) and their interaction with natural enemy abundance and predation" (2017). Graduate Theses and Dissertations. 15400.