Host Association of Spodoptera frugiperda (Lepidoptera: Noctuidae)

JUAREZ, M.L.; MURÚA, MG; GARCIA, M.G.; ONTIVERO, M. I.; VERA, M.T.; VILARDI, J.C.; GROOT, A.T.; CASTAGNARO, A.P.; GASTAMIZA, G.; WILLINK, E.

JOURNAL OF ECONOMIC ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2012 vol. 105 p. 573 - 582

0022-0493

Spodoptera frugiperda (J.E. Smith) is composed of two genetically distinct strains,the so-called corn strain and the rice strain. Whether the two strains differ in their host use isunclear, because laboratory experiments have not been able to show consistent host performanceor preference differences between them, and Þeld studies showed high rates of hybridization, aswell as some degree asymmetric host use. To determine the distribution of the two strains andtheir association with host plants, we collected fall armyworm larvae from different crops (corn,rice, alfalfa, and sorghum) and grasses in 15 different localities over 4 yr in Argentina, Brazil, andParaguay. The strain identity was analyzed using two polymorphisms in the mitochondrialcytochrome oxidase subunit I gene. We identiÞed the corn and rice haplotypes and three typesof populations were characterized based on the frequencies of the individuals that belonged toany of these haplotypes: in 44% of populations the corn haplotype predominated, in 44% ofpopulations the rice haplotype was the most frequent, and 11% of populations showed bothhaplotypes at similar proportions. In total, eight populations (47%) showed the expected pattern,two populations (12%) were polymorphic within the same Þeld, and seven populations (41%)showed the inverse pattern. Taken together, there was no consistent pattern of host associationbetween the two sympatric genotypes and their respective host plants. This investigation supportsthe need for additional studies to determine which other forces keep the genotypes separate, andwhat is the degree of genetic differentiation between these populations.