Abstract:
The whitefly Bemisia tabaci cryptic species complex contains some important
agricultural pest and virus vectors. Members of the complex have
become serious pests in South Africa (SA) because of their feeding habit
and their ability to transmit begomovirus species. Despite their economic
importance, studies on the biology and distribution of B. tabaci in SA are
limited. To this end, a survey was made to investigate the diversity and
distribution of B. tabaci cryptic species in eight geographical locations
(provinces) in SA, between 2002 and 2009, using the mitochondrial
cytochrome oxidase I (mtCOI) sequences. Phylogenetic analysis revealed
the presence of members from two endemic sub-Saharan Africa (SSAF)
subclades coexisting with two introduced putative species. The SSAF-1
subclade includes cassava host-adapted B. tabaci populations, whereas
the whiteflies collected from cassava and non-cassava hosts formed a
distinct subclade, referred to as SSAF-5, and represent a new subclade
among previously recognized southern Africa clades. Two introduced
cryptic species, belonging to the Mediterranean and Middle East–Asia
minor 1 clades, were identified and include the B and Q types. The B
type showed the widest distribution, being present in five of the eight
provinces explored in SA, infesting several host plants and predominating
over the indigenous haplotypes. This is the first report of the occurrence
of the exotic Q type in SA alongside the more widely distributed
B type. Furthermore, mtCOI PCR-RFLP was developed for the SA context
to allow rapid discrimination between the B, Q and SSAF putative
species. The capacity to manage pests and disease effectively relies on
knowledge of the identity of the agents causing the damage. Therefore,
this study contributes to the understanding of South African B. tabaci
species diversity, information needed for the development of knowledge-
based disease management practices.
