Wheat antixenosis, antibiosis and tolerance to infestation by Delphacodes kuscheli (Hemiptera: Delphacidae), a vector of “Mal de Río Cuarto” in Argentina.

BRENTASSI, M. E, CASTRO A.M*, CORRALES C., SNAPE J. W. AND DIXON AFG. EN REVISIÓN

JOURNAL OF ECONOMIC ENTOMOLOGY

Entomological Society of America, Maryland, USA

Lugar: Maryland, USA; Año: 2009 vol. 102 p. 1801 - 1807

0022-0493

Abstract   “Mal de Río Cuarto”, is the most important virus disease of corn, Zea mays L., in Argentina. It is caused by the Mal de Río Cuarto virus (MRCV), which is a persistant virus transmitted by Delphacodes kuscheli. Since corn is not a natural host of D. kuscheli,  it has little protection from this pest  In contrast, wheat is one of the main hosts of this vector and a reservoir of MRCV. The aim of this work was to identify genes involved in antixenosis, antibiosis and tolerance of infestation by D.kuscheil in wheat, which might be used to reduce the population level of this vector on corn. A set of recombinant dihaploid (RDH) lines for chromosome 6A derived from the F1 cross between “Chinese Spring” (CS) x “Chinese Spring (Synthetic 6A)” (S6A) substitution line, were used for mapping. The S6A parental line is resistant to the MRCV vector. Antixenosis, antibiosis and tolerance were evaluated using conventional tests in controlled environmental conditions. Most of the RDH and S6A showed higher levels of antixenosis against D. kuscheli than the parental lines. The RDH lines showed highly significant antibiosis in terms of the duration of 1st, 3rd and 5th nymphal instars, develpmental time (d), survival and fecundity. On S6A the developmental time was significantly longer and adult stage shorter, consequently planthopper longevity and fecundity were reduced compared to those reared on CS. There were highly significant differences in the tolerance to D. kuscheli based on the chlorophyll content of the 1st and 2nd leaves, foliar area and above ground fresh and dry weights. The duration of the fifth nymphal instar and the developmental period were significantly associated with Xgwm1017 marker loci, located at 48 cM on 6AL. Another QTL accounting for the variation in chlorophyll content of the first leaf was associated with the interval between loci Xgwm459 and Xgwm334a, located in the telomeric region of the 6AS chromosome arm.  The alleles with positive effects came from S6A. Antibiotic resistance of RDH could be useful for controlling the population increase of the MRCV vector on wheat, since prolonging d increases the period between two subsequent generations, so reducing the abundance of infective populations colonizing corn.