Population Dynamics of Whiteflies and Associated Viruses in South America: Research Progress and Perspectives.

By having an extensive territory and suitable climate conditions, South America is one of the most important agricultural regions in the world, providing different kinds of vegetable products to different regions of the world. However, such favorable conditions for plant production also allow the development of several pests, increasing production costs. Among them, whiteflies (Hemiptera: Aleyrodidae) stand out for their potential for infesting several crops and for being resistant to insecticides, having high rates of reproduction and dispersal, besides their efficient activity as virus vectors. Currently, the most important species occurring in South America are Bemisia afer, Trialeurodes vaporariorum, and the cryptic species Middle East-Asia Minor 1, Mediterranean, and New World, from Bemisia tabaci complex. In this review, a series of studies performed in South America were compiled in an attempt to unify the advances that have been developed in whitefly management in this continent. At first, a background of the current whitefly distribution in South American countries as well as factors affecting them are shown, followed by a background of the whitefly transmitted viruses in South America, addressing their location and association with whiteflies in each country. Afterwards, a series of management strategies are proposed to be implemented in South American fields, including cultural practices and biological and chemical control, finalizing with a section containing future perspectives and directions for further research.

Outbreaks of Bemisia tabaci Mediterranean species in vegetable crops in São Paulo and Paraná States, Brazil.

The whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is one of the most important agricultural pests and virus vectors worldwide. Bemisia tabaci is considered a complex of cryptic species with at least 44 species. Among them, the species Middle East-Asia Minor 1 (MEAM1, formerly B biotype) and Mediterranean (MED, formerly Q biotype) are the most important, and they have attained global status. In Brazil, MEAM1 was first reported in the 1990s and is currently the predominant species in the country, meanwhile, MED was recently reported in the South and Southeast regions and was found to be mainly associated with ornamental plants. Currently, an increasing problem in the management of whitefly infestations in greenhouses associated with bell pepper was observed in São Paulo State, Brazil. The whiteflies were collected and identified based on a microsatellite locus (primer pair BEM23F and BEM23R) and the mitochondrial cytochrome oxidase I gene followed by restriction fragment length polymorphism analysis and sequencing. We observed that MED was the predominant species collected on bell pepper, but it was also found on tomato, cucumber, eggplant, and weeds grown in greenhouses. In open field, we found MED on tomatoes, bell peppers, and eggplants. In addition, MED was identified in Goiás State in association with ornamental plants. The begomovirus Tomato severe rugose virus and the crinivirus Tomato chlorosis virus was detected on bell pepper and tomato, respectively. Only MED specimens were found associated with the virus-infected plants. Moreover, we also investigated the endosymbionts present in the MED whiteflies. The collected populations of B. tabaci MED harbored a diversity of secondary endosymbionts, with Hamiltonella (H) found predominantly in 89 specimens of the 129 tested. These results represent a new concern for Brazilian agriculture, especially for the management of the newly introduced whitefly MED species, which must be implemented to limit the spreading and establishment of this pest in different crops in this country.

Distribution and phylogenetics of whiteflies and their endosymbiont relationships after the Mediterranean species invasion in Brazil.

The Bemisia tabaci is a polyphagous insect and a successful vector of plant viruses. B. tabaci is a species complex and in Brazil native species from the New World (NW) group, as well as the invasive species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) were reported. For better understanding the distribution of the different species four years after the Mediterranean species invasion in Brazil, whiteflies were collected from 237 locations throughout the country between the years of 2013 and 2017, species were identified and the facultative endosymbionts detected. The survey revealed that MEAM1 was the prevalent species found on major crops across Brazil. It is the only species present in North, Northwestern and Central Brazil and was associated with virus-infected plants. MED was found in five States from Southeast to South regions, infesting mainly ornamental plants and was not associated with virus-infected plants. The prevalent endosymbionts identified in MEAM1 were Hamiltonella and Rickettsia; and the mtCOI analysis revealed low genetic diversity for MEAM1. In contrast, several different endosymbionts were identified in MED including Hamiltonella, Rickettsia, Wolbachia and Arsenophonus; and two distinct genetic groups were found based on the mtCOI analysis. Monitoring the distribution of the whiteflies species in Brazil is essential for proper management of this pest.

First report of Bemisia tabaci Mediterranean (Q biotype) species in Brazil.

BACKGROUND: The whitefly Bemisia tabaci is a major cosmopolitan pest and comprises a complex of more than 36 cryptic species that cause serious damage to agricultural crops worldwide. In this study, the Mediterranean species of B. tabaci, formerly known as Q biotype, was identified for the first time in Brazil. RESULTS: Adult B. tabaci were collected from different localities and hosts from Rio Grande do Sul, the southernmost state of the country that borders Uruguay and Argentina. Partial sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene indicated that B. tabaci MED species appears to be restricted to the province of Barra do Quaraí, infesting Capsicum annuum cultivated in greenhouses and Ipomoea batatas in open fields. The partial mtCOI sequences obtained shared 100% nucleotide identity with reference sequences for the Q biotype reported from Uruguay. The secondary endosymbionts Hamiltonella and Cardinium were detected by PCR in the new identified MED species from Brazil, similarly to the Q biotype from Uruguay. CONCLUSION: Our results indicate the presence of the MED species in Brazil. The close monitoring of this new identified species in the southern region of Brazil is essential to avoid its geographical expansion to more important agricultural areas in the country.