Performance of Spodoptera frugiperda (Smith) resistant strain developing in different commercial maize hybrids in Argentina.

FATORETTO J.; VERA A.; MICHEL, ANDREW; M. GABRIELA MURÚA; A. CASMUZ

Congreso; XXVII Congreso Brasilero y X Congreso Latino-Americano de Entomología; 2018

Spodoptera frugiperda is the major pest of Bt maize in the Western Hemisphere. Recently, Cry1F field-evolved resistance of this species was confirmed in Argentina. The resistance evolution in an insect population to a Bt crop depends on a number of factors such as performance between susceptible and resistant insects. The objective of this study was to compare the performance of resistant S. frugiperda strain (rr) to Cry1F to susceptible strains (SS) when reared on different commercial maize hybrids. Strains were collected in different commercial maize hybrids: Non-Bt maize (T1), Agrisure TDMax® (T2), Agrisure Viptera® (T3), Agrisure Viptera® 3110 (T4), Genuity VT Triple Pro® (T5), and Power Core® (T6), in Tucumán province, Argentina. Three experiments were performed: 1) Collected larvae were fed on fresh leaf tissue of its respective hybrids from where they were collected until pupation. Percentages of larval survivorship, as well as the fitness of pupae and adults were estimated. With the adults obtained from each hybrid, couples from the same treatment were mated to determine longevity and reproductive parameters; 2) collected larvae (F1) were exposed to a fresh leaf of Herculex? maize to confirm if the larvae collected are resistant to Cry1F, 3) performance of rr strains was estimated and compared against SS strain. All data were analyzed statistically by Anova or Kruskal-Wallis. The percentage of survivorship from larva to adult ranged from 0 to 63%. We obtained adults from only the T1, T2, T5 and T6 strains and reproductive parameters were not significant among these strains. All larvae of T1, T2, and T6 were resistant to Cry1F. The most impacted parameter observed was larval duration, which was significantly shorter in SS strain than rr strain. Such differences might negatively influence adults? synchronism between SS and rr colonies and reduce refuge effectiveness to delay resistance. Results of this study have important implications to resistance management.