Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Matthew E. O'Neal


Soybean aphid, Aphis glycines, and soybean cyst nematode (SCN), Heterodera glycines, can interact through the soybean plant resulting in increased SCN reproduction on both SCN-resistant and SCN-susceptible varieties. The management of SCN is heavily reliant on the planting of PI 88788-derived SCN-resistant varieties to limit yield loss to SCN in the current year and future years. Virulence to PI 88788 is increasing in SCN field populations due to its extensive use. Therefore, it is increasingly important to manage any factor that increases SCN reproduction on SCN-resistant varieties. Here I examined management tactics including host-plant resistance and insecticidal seed treatments to limit soybean aphid populations and disrupt the interaction between soybean aphids and SCN. Neither host-plant resistance incorporating a single resistance gene nor insecticidal seed treatments were able to prevent yield loss from soybean aphids. Furthermore, host-plant resistance incorporating a single resistance gene also failed to disrupt soybean aphid-SCN interactions. Host-plant resistance incorporating a pyramid of two resistance genes was, however capable of limiting yield loss to soybean aphids. The pyramid line also limited aphid population densities to below levels where we would expect to observe soybean aphid-SCN interactions. Future research will need to investigate the ability of a pyramid line to disrupt soybean aphid-SCN interactions in the field and the potential consequences for yield and long-term sustainable SCN population management.


Copyright Owner

Michael Thomas McCarville



File Format


File Size

197 pages