Mechanisms of soybean host plant resistance against Megacopta cribraria (F.) (Hemiptera: Plataspidae)

Authors: LAHIRI, S - North Carolina State University; REISIG, D - North Carolina State University; Dean, Lisa; REAY-JONES, F - Clemson University; GREENE, J - Clemson University; Carter Jr, Thomas; Mian, Rouf; FALLEN, B - Clemson University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2020
Publication Date: 7/5/2020
Citation: Lahiri, S., Reisig, D.D., Dean, L.L., Reay-Jones, F.P., Greene, J.K., Carter Jr, T.E., Mian, R.M., Fallen, B.D. 2020. Mechanisms of soybean host plant resistance against Megacopta cribraria (F.) (Hemiptera: Plataspidae). Environmental Entomology. https://doi.org/10.1093/ee/nvaa075.
DOI: https://doi.org/10.1093/ee/nvaa075

Interpretive Summary: The valuable soybean crop is subject to damage by a number of insect pest including a type of nymph known as Megacopta cribraria. In order to reduce the need for chemical pesticide applications, resistance of the soybean plant itself to insect attack has been the source of successful plant breeding programs. This work studied the mechanism of this resistance in order to better understand how the plant is able to produce certain chemicals that repel the insect pests. Using physical barriers or "cages" to expose the growing plants of 16 different soybean varieties to the insects, the experiments were performed. After exposure or protection from the insects, the leaves of the plants were collected and analyzed for free amino acids and small volatile chemicals produced. The data analysis identified several varieties with natural resistance to the insect attack and found that certain free amino acids are related to the resistance. Also, some of the volatile chemicals were found to be natural insect repellents.

Technical Abstract: A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as NO2-7002 and PI567352B. There was a positive correlation of nymph development with twelve essential FAAs in plant tissue. Five plant volatiles (hexanal, 2-pentylfuran, beta-cyclocitral, cis-9-hexadecenal, n-hexadecenoic Acid) were correlated with subsequent nymph development in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides direction for developing soybean varieties for M. cribraria management.