Baseline of Susceptibility to the CrylF Protein in Mexican Populations of Fall Armyworm

• Published in: Journal of economic entomology 2020-02, Vol.113 (1), p.390
• Main Authors: Rivero-Borja, Maribel, Rodriguez-Maciel, J. C, Gutierrez, J. A. Urzua, Silva-Aguayo, G, Chandrasena, Desmi I, Felix-Bermudez, Ninfa C, Storer, Nicholas P
• Format: Article
• Language: English
• Subjects: Biotechnology; Corn; Food; Genetically engineered foods; Genetically modified crops; Health aspects; Insecticides; Statistics
• ISSN: 0022-0493
• DOI: 10.1093/jee/toz280

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is currently the most important maize pest in Mexico. Its control is mainly based on the use of conventional insecticides. Additionally, Bt-maize expressing Cry1F protein represents an alternative to control this pest. We estimated the baseline susceptibility in Mexican populations of S. frugiperda to Cry1F protein. Twenty-eight geographical populations were field collected from Baja California Sur, Chihuahua, Coahuila, Durango, Sinaloa, Sonora, and Tamaulipas states. The [F.sub.1] neonate larvae of each population were subjected to diet-overlay bioassay. After 7 d of Cry1F exposure, the percent mortality and the percent growth inhibition with respect to the untreated control were recorded (S-LAB).The L[C.sub.50] ranged from 14.4 (6.3-24.0) (Cajeme 1, Sonora) to 161.8 ng/[cm.sup.2] (92.0-320) (Ahumada 2, Chihuahua), while the L[C.sub.95] was between 207.1 (145-363) (Obregon, Sonora) and 1,217 ng/[cm.sup.2] (510.8-7,390.0) (Rio Bravo 2, Tamaulipas). The sensitivity ratios at 50% mortality, (L[C.sub.50] field/L[C.sub.50] S-Lab) and 95% mortality were [less than or equal to]6.45 and [less than or equal to]5.05-fold, respectively. The 50% growth inhibition (G[I.sub.50]) ranged from 2.8 (0.008-9.3) (Obregon, Sonora) to 42.4 ng/[cm.sup.2] (3.6-147.0) (Cajeme 1, Sonora). The G[I.sub.95] was between 75.4 (San Luis Rio Colorado, Sonora) to 1,198 ng/[cm.sup.2] (Cajeme 1, Sonora).The relative inhibition at 50% of the growth, (R[I.sub.50] = G[I.sub.50] field /G[I.sub.50] S-LAB) was [less than or equal to]3.5 and at 95% (R[I.sub.95]) was [less than or equal to]1.91 -fold.These results indicated susceptibility to Cry1F protein in the evaluated populations of S. frugiperda. Key words: Spodoptera frugiperda, Bt protein, maize, baseline, Bt corn Spodoptera frugiperda (J. E. Smith), es la plaga de maiz mas importante en Mexico. Su control se basa en insecticidas convencionales y la proteina Cry1F del maiz Bt, es alternativa para controlar esta plaga. Se estimo la linea base de respuesta en poblaciones mexicanas de S. frugiperda a la proteina Cry1F Veintiocho poblaciones se recolectaron de Baja California Sur, Chihuahua, Coahuila, Durango, Sinaloa, Sonora y Tamaulipas. Las larvas de neonatas de F1 de cada poblacion se sometieron a bioensayo de capa. A los siete dias de exposicion, el porcentaje de mortalidad y el porcentaje de inhibicion del crecimiento se registraron. La L[C.sub.50] vario de 14