Inventory of some families of Hemiptera, Coleoptera (Curculionidae) and Hymenoptera associated with horticultural production of the Alto Valle de Río Negro and Neuquén provinces (Argentina)

The knowledge of the entomological fauna in productive systems is important for the agroecological management since beneficial insects are a key resource for pest management in horticultural systems. Scientific information on the biodiversity present in a given area is essential as well as the ecological function and/or feeding habits of the insects. In Alto Valle de Río Negro and Neuquén, horticultural production systems can be described as highly dependent on chemical inputs for pest management and fertilization. The aim of this study is to carry out an inventory of the biodiversity of some families of Hemiptera, Coleoptera (Curculionidae) and Hymenoptera present in peri-urban and rural farms located in Neuquén and Río Negro, respectively. Insects were collected through pitfall and sweeping net on tomato and pepper crops and the surrounding non-cultivated areas. Idiosystatus Berg (Auchenorrhyncha) was cited for the first time from Argentina. Species cited for the first time from Neuquén: Hemiptera: Auchenorrhyncha: Acanalonia chloris (Berg), Syncharina punctatissima (Signoret), Amplicephalus dubius Linnavuori, Exitianus obscurinervis (Stål), Agalliana ensigera Oman and Bergallia signata (Stål); Hemiptera: Heteroptera: Harmostes (Harmostes) prolixus Stål and Atrachelus (Atrachelus) cinereus (Fabricius); Coleoptera: Curculionidae: Hypurus bertrandi (Perris), Naupactus leucoloma Boheman, Otiorhynchus rugosostriatus (Goeze) and Sitona discoideus Gyllenhal and Hymenoptera: Xylocopa (Neoxylocopa) augusti Lepeletier and Pseudagapostemon (Neagapostemon) singularis Jörgensen. Species cited for the first time from Río Negro: Hemiptera: Auchenorrhyncha: Amplicephalus dubius Linnavuori, Amplicephalus marginellanus Linnavuori, Circulifer tenellus (Baker) and Xerophloea viridis (Fabricius); Hemiptera: Heteroptera: Tupiocoris cucurbitaceus (Spinola), Atrachelus (Atrachelus) cinereus (Fabricius), Dichelops furcatus (Fabricius) and Harmostes (Harmostes) prolixus Stål; Coleptera: Curculionidae: Naupactus xanthographus (Germar) and Hymenoptera: Diadasia pereyrae (Holmberg) and Dialictus autranellus (Vachal)

Prediction of Early Season Beet Leafhopper Populations in Southern New Mexico

Curly top is an important widespread disease in semiarid regions that can be caused by several Curtovirus and Becurtovirus species. The strains of beet curly top virus (BCTV) have been some of the most widely reported to be associated with curly top. The viruses causing curly top are phloem limited and transmitted by the beet leafhopper (BLH), Circulifer tenellus Baker (Hemiptera: Cicadellidae). The BLH can also transmit other important pathogens such as phytoplasmas. Both the virus and insect vector have a broad host range of crops and weeds, including the winter annual weed London rocket (Sisymbrium irio L.). Prior prediction of disease would allow growers a window of opportunity to make informed management choices. A prediction model of BLH abundance was developed for southern New Mexico based on fall precipitation, which corresponds with London rocket emergence, and BLH sticky trap catch data for 2001 to 2018. Regression analyses showed positive associations between BLH numbers and October + November rainfall (P < 0.001) for two areas within southern New Mexico. A third area, where good weed management was used, had lower BLH numbers, and the relationship with precipitation was not significant (P = 0.190). Cumulative-season BLH abundance was correlated with BLH abundance in late April (r = 0.43) and late May (r = 0.56), indicating that early season knowledge of BLH abundance is useful for planning later season management. Although models based on October + November precipitation are good predictors of BLH abundance through June, they may not predict year-long BLH abundance because other environmental and biological factors contribute to subsequent BLH success and movement.

Presencia de Circulifer tenellus Baker y Beet mild curly top virus en maleza durante el invierno en el centro norte de México

Una de las enfermedades más importantes del chile para secado en el norte centro de México es la denominada amarillamientos del chile. Existe poca información acerca de la interacción entre el vector (Circulifer tenellus Baker), el Beet mild curly top virus y la maleza durante el invierno en esta región, consecuentemente el objetivo del trabajo fue identificar maleza de invierno que sirve como refugio para el vector y hospedero del virus en esta región. Entre enero y marzo de 2011 se muestrearon 26 manchones de maleza en los estados de Aguascalientes y Zacatecas. Se capturaron adultos de C. tenellus en 69.2% de los manchones de maleza muestreados; la mayoría (75.5%) de los especímenes eran hembras. El Beet mild curly top fue identificado sólo 15.4% de los sitios de muestreo infectando especies de maleza como Eruca sativa, Reseda sp., Chenopodium sp. y Solanum rostratum L.

Detection of Pathogens Associated with Psyllids and Leafhoppers in Capsicum annuum L. in the Mexican States of Durango, Zacatecas, and Michoacán

In fall 2014, 5 to 75% percent of chili and bell pepper (Capsicum annuum L.) in commercial fields located in the Mexican states of Durango, Zacatecas, and Michoacán had symptoms of deformed, small, mosaic, curled, and chlorotic leaves; shortened internodes; plant dwarfing; or phyllody and rosetting leaf tips. At the same time, leafhoppers and psyllids were observed in the fields, and more than 50 beet leafhoppers (Circulifer tenellus) and nearly 300 potato psyllids (Bactericera cockerelli) were collected from the pepper plants and adjacent weeds. Based on the insect pressure and observed symptoms, nearly 400 pepper samples were collected across this region of Mexico and tested for the presence of leafhopper- and psyllid-associated pathogens. In all, 76% of the pepper samples were found to be infected with ‘Candidatus Liberibacter solanacearum’, beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma, a strain of a curtovirus, or a combination of any two or three of these pathogens. Additionally, 77% of the collected leafhoppers and 40% of the psyllids were infected with one or more of these pathogens, in addition to Spiroplasma citri. Specifically, the leafhoppers were infected with BLTVA phytoplasma, S. citri, or a strain of curtovirus. Of particular interest, potato psyllids were not only infected with ‘Ca. L. solanacearum’ but also with phytoplasmas that belong to the groups 16SrVI subgroup A and 16SrI subgroup A. The presence of mixed infections in pepper plants and the insect vectors highlights the need for growers to effectively control both leafhoppers and potato psyllids from solanaceous crops in this region of Mexico in order to prevent the spread of these bacterial and viral pathogens.

Characterization of Beet curly top virus Strains Circulating in Beet Leafhoppers (Hemiptera: Cicadellidae) in Northeastern Oregon

The beet leafhopper, Circulifer tenellus, is an agriculturally important pest, particularly in the western United States. This insect transmits the Beet curly top virus (BCTV) to multiple crops, including bean, tomato, and pepper. In this study, we investigated the incidence of BCTV in individual leafhoppers collected at several sites in northeastern Oregon during the growing season in 2007, 2008, and 2009. Of the 800 insects tested, 151 (18.9%) were found positive for the virus. Percentage of virus incidence varied from 0% at one location in 2009 to a high of 55.6% for a location sampled in 2008. The complete virus genomes from one virus-positive insect collected in each of the 3 years were determined. BLAST analysis of the BCTV whole-genome sequences from 2007, 2008, and 2009 insects showed 98, 94, and 96% identities with the BCTV-Worland sequence (AY134867), respectively. The BCTV_2008 sequence showed the greatest identity (96%) with another BCTV genomic sequence (JN817383), and was found to be a recombinant between the BCTV-Worland type, representing the majority of the genome (approximately 2.2 kb), and the BCTV-CFH type that provided an approximately 0.8-kb fragment spanning replication-related genes C1 and C2. This area of the BCTV genome, between the C1 and C2 genes, was previously found to carry symptom determinants of the virus, and the data may suggest more severe effects of BCTV during the 2008 season. Results indicate that BCTV is common and widespread in C. tenellus in eastern Oregon and that there is substantial genetic diversity among the virus strains present in this important field and vegetable crop-growing region.