Evaluation of South American Rice Varieties for Resistance to Rice Delphacid: Potential Sources for Breeding Programs

© 2020 Southwestern Entomologist. All rights reserved. The rice delphacid, Tagosodes orizicolus (Muir), is a major insect pest of rice (Oryza sativa L.) in Latin America. When abundant, the insect causes hopperburn and loss of yield potential as well as being a vector of rice hoja blanca virus. The insect pest was discovered in rice in the southern U.S. on multiple occasions, most recently in 2015 and 2018. To promote development of a sustainable management program, eight Nicaraguan rice varieties were evaluated in greenhouse and field experiments for resistance to the pest. Insect densities in the field were measured using a battery-powered vacuum sampler during as many as five sample dates before and after flooding. Two field experiments with separate planting dates and locations allowed detection of resistance when insects were naturally few and when abundant. Densities were 40-46 and 31-47% lower on Fedearroz 2000, Linea 34, and Altamira 1N varieties than on the most susceptible variety, INTA Dorada, in the first and second field experiments, respectively. An experiment in a greenhouse confirmed that insect densities were lowest on Fedearroz 2000, Linea 34, and Altamira1N. Densities on these varieties were 55-73% lower than on susceptible standard Bluebonnet 50. Overall, Fedearroz 2000, Linea 34, and Altamira 1N were more resistant than was the susceptible standard Bluebonnet 50. The varieties might be useful in management programs against the delphacid in Central America and serve as potential sources of resistance for incorporation into breeding programs in the U.S