Microsatellites reveal widespread predominance of an invasive over an indigenous Bemisia tabaci in Venezuela

Abstract

The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an important pest due to its capacity for producing strong infestations and transmitting plant viruses. The New World putative species of B. tabaci complex (NW) is the indigenous whitefly of the Americas, but only the invasive Middle East-Asia Minor 1 putative species of B. tabaci complex (MEAM1), commonly referred to as the "B biotype" was identified in a limited scope sampling in Venezuela. Similarly to MEAM1 invasions elsewhere, in this South American country there has been an increase in the geographic range and abundance of B. tabaci, and in the number of viruses that it transmits since the late 1980s. We estimated the diversity of B. tabaci to elucidate their role in the epidemiology of geminiviruses in Venezuela. Thirteen microsatellite loci were screened in samples collected from 19 localities in ten major agricultural states. A Bayesian clustering method (Structure) grouped the samples into two genetic groups. Control samples from whiteflies NW and MEAM1 and partial sequencing of the mitochondrial cytochrome oxidase I gene showed that our samples of B. tabaci populations from Venezuela fall within NW and MEAM1 groups. In this survey, MEAM1 was predominant over NW whitefly in a proportion of 35:1. No evidence was observed for gene flow between indigenous and invader whitefly. Altogether, our results stress the urgency for controlling the proliferation of the invasive whitefly.

Current status of cucurbit viruses in Venezuela and characterization of Venezuelan isolates of Zucchini yellow mosaic virus

“…Furthermore, a study of whitefly and aphid populations conducted in melon fields of Venezuela showed that whitefly populations were six‐fold greater than aphid populations in insecticide‐free conditions and up to 70‐fold under insecticide‐treated conditions (Geraud‐Pouey et al ., ). It has also been shown that the B biotype of B. tabaci is the most widespread and dominant biotype in the main agricultural regions of Venezuela (Romay et al ., ). Seventy‐eight percent of the samples positive for MeCMV were also positive for the satellite MeCMA, confirming their frequent association (Romay et al ., ).…”

Indigenous American species of the Bemisia tabaci complex are still widespread in the Americas

“…It is interesting to note that in Venezuela and Brazil (Alagoas State, northern region, and locations recorded in this study), the source tomatoes from which whiteflies were collected were managed under a regime of sustainable agriculture. In contrast, in strictly intensive and commercial tomato fields under massive use of pesticides, MEAM1 almost completely displaced the indigenous species in Brazil and Venezuela . MEAM1 populations invading Latin America appear to be more resistant to pesticides compared with indigenous whiteflies…”

“…B. tabaci individuals corresponding to NW were recently reported on tomatoes from Venezuela, 44 Brazil, Mexico and Texas, the latter representing the first report of the NW species in the United States since its rapid displacement in the late 1980s after the introduction of the MEAM1 species. 45 It is interesting to note that in Venezuela 44 and Brazil (Alagoas State, northern region, and locations recorded in this study), the source tomatoes from which whiteflies were collected were managed under a regime of sustainable agriculture.…”

Melon chlorotic mosaic virus and associated alphasatellite from Venezuela: genetic variation and sap transmission of a begomovirus–satellite complex

“…After introduction of the B biotype of B. tabaci in Latin America, local begomoviruses that were poorly transmitted by indigenous B. tabaci biotypes emerged, developing severe outbreaks due to the high transmission efficiency of the B biotype (Morales & Anderson, 2001). Thus, it can be speculated that MeCMV has also emerged from weeds as a consequence of introduction of the B biotype of B. tabaci that is now widespread in the country (Romay et al, 2011). Although MeCMV has only been found naturally infecting cucurbits, either cultivated or wild (Romay et al, 2014), surveys will be required to identify potential non-cucurbit reservoirs.…”