Detection of maize bushy stunt phytoplasma in leafhoppers collected in native corn crops grown at high elevations in southeast Mexico

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Abstract

Phytoplasmas are wall-less bacteria, unculturable in vitro, and transmitted primarily by leafhoppers (Cicadellidae). Maize bushy stunt disease has been linked to phytoplasmas belonging to the16SrI-B subgroup and vectored by leafhoppers in the genus Dalbulus spp. (Hemiptera: Cicadellidae). The recent detection of maize bushy stunt affecting native corn, maize, in the southeast highlands of Mexico motivated the survey to determine which leafhoppers were associated with this crop during the 2013-2014 growing season. We detected 7 leafhopper genera in native corn cultivated 2,400 meters above sea level (masl), with 4 of these genera reported for the first time in corn. Based on external morphology and male genitalia, we identified Idiodonus wickhami(Ball) (Hemiptera: Cicadellidae), Amblysellus grex(Oman) (Hemiptera: Cicadellidae), Empoasca fabae (Harris) (Hemiptera: Cicadellidae), Macrosteles quadrilineatus (Forbes) (Hemiptera: Cicadellidae), and Dalbulus elimatus (Ball) (Hemiptera: Cicadellidae). We were not able to identify the leafhopper genera Graphocephala (Hemiptera: Cicadellidae) and Erythridula (Hemiptera: Cicadellidae) to species because of a lack of male leafhoppers. Nymphal stages of I. wickhami also were identified using taxonomic and molecular tools. The presence of adults and nymphs of I. wickhami in the crop suggest that native corn grown in the southeast highlands of Mexico is a feeding and reproductive host for I. wickhami. Moreover, I. wickhami was found infected with 16SrI-B strain maize bushy stunt-Ver while D. elimatus, a well-known maize bushy stunt phytoplasma vector, was found infected with the 16SrI-B strain maize bushy stunt-Pueb.

Key Words: Maize, phytoplasma, MBS, Idiodonus spp., Dalbulus spp.

Resumen

Los fitoplasmas son bacterias sin pared celular, no cultivables in vitro, y transmitidos principalmente por saltahojas (Cicadellidae). La enfermedad del enanismo arbustivo de maiz (enanismo arbustivo del maíz, por sus siglas en inglés) se ha relacionado con fitoplasmas pertenecientes al subgrupo 16SrI-B y transmitidas por saltahojas dentr del género Dalbulus spp. (Hemiptera: Cicadellidae). La detección reciente de maize bushy stunt que afecta el maíz nativo en el altiplano sureste de México, motivó el sondeo para determinar cuales saltahojas estan asociadas con este cultivo durante la temporada de crecimiento del 2013-2014. Detectamos 7e géneros de saltahojas en el maíz nativo cultivado a 2,400 msnm, con 4 de estos géneros reportados por primera vez en maíz. En base a la morfología externa y los genitales masculinos identificamos a Idiodonus wickhami (Bola) (Hemiptera:...