Spatial and host‐plant partitioning between coexisting Bemisia tabaci cryptic species in Tunisia

Abstract

The whitefly Bemisia tabaci is a species complex including at least 24 morphologically indistinguishable species among which the Mediterranean (Med) and Middle East-Asia Minor I (MEAMI) species containing the biotypes commonly known as Q and B, respectively. These B and Q biotypes (hereafter referred to as MEAMI and Med species) are the most invasive agricultural pests of the B. tabaci complex worldwide. The spread of MEAMI and more recently of Med species into regions already invaded by other B. tabaci populations has been frequently seen to lead to their displacement by Med species. In Tunisia, in contrast to usual observations in the Mediterranean basin, Med and MEAMI species have been seen to co-occur in the main crop producing regions. Based on fine population genetics and field spatial distribution analyses, we found that the co-existence of these two interacting species was based on habitat partitioning including spatial and hostplant partitioning. Although they co-occurred at larger spatial scales, they excluded one another at sample scale. We observed neither spatial overlapping nor hybridization between MEAMI and Med B. tabaci. Vegetable crops were the main hosts for MEAMI specimens while 99.1% of the B. tabaci collected on the ornamental, Lantana camara, were Med specimens. Different patterns of genetic diversity were observed between the two species, as well as among Med specimens sampled on the ornamental versus vegetables, with the highest genetic diversity found in Med B. tabaci sampled on L. camara. These findings lead us to focus our discussion on the role played by lantana, human pressure, and competition, in the spatial and genetic patterns observed in the whitefly B. tabaci.

Apparent competition between major pests reduces pest population densities on tomato crop, but not yield loss

“…Tuta absoluta and B. tabaci are two major pests on tomato crops that are frequently co-occurring in the Mediterranean region (Desneux et al 2010(Desneux et al , 2011Parrella et al 2012;Saleh et al 2012). Therefore, it appears essential to develop pest management strategies aimed at simultaneously regulating both pest species, but also to increase our understanding of both direct and indirect interactions that are likely occurring between them.…”

“…Its recent and rapid invasion of Afro-Eurasia from South America (Desneux et al 2010(Desneux et al , 2011 has highlighted the need to search for new IPM practices, or to readjust the already-existing biological control programs (Chailleux et al 2012. This invasive alien pest frequently co-occurs in European tomato crops with another major tomato pest, the whitefly B. tabaci (Gennadius; biotype Q; Hemiptera: Aleyrodidae), which is a widespread European indigenous species (Parrella et al 2012;Saleh et al 2012). This sap-feeding insect causes direct damage and vector viruses to plants (Oliveira et al 2001;Jiao et al 2012).…”

First report of the Sub-Saharan Africa 2 species of the Bemisia tabaci complex in the Southern France

“…These 29 specimens were also characterized by a high frequency of null alleles for many loci (for example, f locusBtIs1.11 = 1, f locusBtIs1.14 = 1, f locusBtIs1.1 = 0.78, f locusBem15 = 0.60) among which for the locus BtIs1.2 diagnostic of the Med and MEAM1 species (Saleh et al 2012). For the other diagnostic locus BtIs1.9, these specimens had alleles ranging from 264 bp to 278 bp which is within the typical allelic range of the Med species.…”

“…and for some individuals, by additional previously identified loci (Gauthier et al 2008;Hadjistylli 2010;Hadjistylli et al 2014). The COI fragment gene of at least one individual per sample was sequenced, particularly in the case of specimen(s) which showed no or no typical digestion patterns with restriction enzymes, or numerous null-alleles with the microsatellite loci distributed in multiplex sets for population genetics studies (Saleh et al 2012;Gauthier et al 2014). The specimens for which DNA was sequenced were assigned to B. tabaci species according to the match between their consensus COI sequences of 676-bp and homologous COI sequences from GenBank.…”

“…Since the B. tabaci complex consists of morphocryptic species, we used diagnostic and highly discriminatory molecular markers, including variation in nuclear microsatellites and mitochondrial cytochrome oxidase I (COI) through PCR-RFLP and DNA sequencing (Saleh et al 2012;Gauthier et al 2014;Laarif et al 2015). Here, we focus on the first report of the sub-Saharan Africa 2 (SSA2) species in Southern France and the possible implications of such a result in the context of invasion of the Mediterranean area by new B. tabaci species.…”