Evidence for pre-zygotic reproductive barrier between the B and Q biotypes ofBemisia tabaci(Hemiptera: Aleyrodidae)

Abstract

The degree of reproductive isolation between the B and Q biotypes of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is currently not clear. Laboratory experiments have shown that the two biotypes are capable of producing viable F1 hybrids but that these females are sterile as their F2 generation failed to develop, indicating, most likely, a post-zygotic reproductive barrier. Here, we confirm, by molecular and ecological tools, that the B and Q biotypes of Israel are genetically isolated and provide two independent lines of evidence that support the existence of a pre-zygotic reproductive barrier between them. Firstly, monitoring of mating behaviors in homogeneous and heterogeneous couples indicated no copulation events in heterogeneous couples compared to approximately 50% in homogeneous B and Q couples. Secondly, we could not detect the presence of sperm in the spermathecae of females from heterogeneous couples, compared to 50% detection in intra-B biotype crosses and 15% detection in intra-Q biotype crosses. The existence of pre-zygotic reproductive barriers in Israeli B and Q colonies may indicate a reinforcement process in which mating discrimination is strengthened between sympatric taxa that were formerly allopatric, to avoid maladaptive hybridization. As the two biotypes continued to perform all courtship stages prior to copulation, we also conducted mixed cultures experiments in order to test the reproductive consequences of inter-biotype courtship attempts. In mixed cultures, a significant reduction in female fecundity was observed for the Q biotype but not for the B biotype, suggesting an asymmetric reproductive interference effect in favour of the B biotype. The long-term outcome of this effect is yet to be determined since additional environmental forces may reduce the probability of demographic displacement of one biotype by the other in overlapping niches.

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

“…No hybrids were detected in our study, suggesting that they are genetically isolated in the field. This is consistent with (1) F ST values for MEAMI and Med B. tabaci estimated at national and sampling scales in Tunisia (0.31 B F ST B 0.58) and with the results of previous studies (Moya et al 2001;Simón et al 2007;Dalmon et al 2008), (2) the percentage divergence between Med and MEAMI mtCOI haplotypes in the present study (4.9-5.4%) and in different parts of the world (Boykin et al 2007;Dinsdale et al 2010) which identifies them as two distinct species, and (3) the widely reported reproductive incompatibility between the two species (Elbaz et al 2010;Xu et al 2010;De Barro et al 2011;Sun et al 2011). Currently, although Med and MEAMI species are the most frequently observed species in the Mediterranean basin, they are often observed separately (Bosco et al 2006;De la Rúa et al 2006;Tahiri et al 2006;Tsagkarakou et al 2007;Dalmon et al 2008;Vassiliou et al 2008).…”

“…The whitefly B. tabaci is a complex containing at least 24 morphocryptic species (i.e., genetically distinct but morphologically indistinguishable), most of which are reproductively incompatible (Dinsdale et al 2010;Elbaz et al 2010;Xu et al 2010;Wang et al 2010;De Barro et al 2011;Sun et al 2011). Among the 24 B. tabaci putative species delineated by Dinsdale et al (2010), the Mediterranean (Med) and the Middle East-Asia Minor I (MEAMI) species, have attracted particular attention in the past 30 years.…”

Evidence for a new genetic variant in the Bemisia tabaci species complex and the prevalence of the biotype Q in southern Italy

“…These clades, defined on the basis of a [3.5% sequence divergence criterion, have been proposed to represent individual cryptic species (De Barro et al 2011). Absence of gene flow has been observed between clades at 3.5% divergence limit (Elbaz et al 2010;Xu et al 2010), further supporting the concept of B. tabaci as a complex of morphologically indistinguishable species. According to present knowledge, B and Q biotypes have been considered as two different cryptic species, named the Mediterranean species and the middle east-Asia minor 1 species respectively, within the Africa-middle east-Asia minor major genetic group (Dinsdale et al 2010).…”

“…Furthermore, biotype Q has resulted more tolerant to high temperatures (Bonato et al 2007). However, different responses to host plants (species and cultivars) have emerged between biotypes B and Q relative to life-history traits and population dynamics (Nombela et al 2001;Bonato et al 2007;Iida et al 2009), and reproductive interference has been shown to advantage biotype B colonization in the absence of chemical control (Pascual and Callejas 2004;Pascual 2006;Elbaz et al 2010). Hence, each biotype can be advantaged over the other depending on the specific environmental and agricultural context.…”

Begomoviroses no cultivo do tomateiro no brasil : variabilidade e caracterização de novas espécies virais e diversidade do vetor bemisiatabaci

“…A estrutura de espécies proposta por Dinsdale et al (2010) também é apoiada pela evidência de incompatibilidade reprodutiva entre alguns dos grupos genéticos (Xu et al, 2010) ou ainda, pela redução no desempenho biológico da progênie (De Barro & Hart, 2000;Elbaz et al 2010). Os atuais critérios de classificação, com base em marcadores moleculares, sugerem que o uso do termo biótipo, neste contexto, é errôneo e enganoso (De Barro et al, 2011;Marubayashi et al, 2013).…”