Regional co-occurrence between distinct Bemisia tabaci species in Tunisia with new insights into the role of host plants

摘要

Among the Bemisia tabaci (Hemiptera: Aleyrodidae) species complex, the Middle East-Asia Minor I (MEAMI) and the Mediterranean (Med) species are the most invasive and widespread agricultural pests worldwide. Currently, only Tunisia and a few other countries are reported to still "host" these two competing species. The objective was thus to improve our knowledge on the factors, particularly the host plant, which contribute to this unusual situation. To that end, we analyzed 47 samples collected from protected and outdoor plants (ten vegetables and ornamentals) in the two main crop-producing regions of Tunisia to (i) better document the co-occurrence of several B. tabaci species and populations, and (ii) confirm the role of the host plant in the distribution pattern of each species. B. tabaci specimens were identified using at least two molecular diagnostic tests. Taken together, the tests confirmed the equivalent prevalence of Med and MEAMI species and, for the first time, the presence of some Sub-Saharan Africa 2 B. tabaci, in Tunisia. The regional co-occurrence between Med and MEAM1 was based on spatial and host-plant partitioning. Our results indicate that Med species are closely associated with ornamentals and MEAM1 with vegetables. Med displayed a higher level of genetic diversity than MEAM1, and another Med specimen characterized by a mtCOI haplotype which perfectly matched the ancestral Gennadius specimen was discovered. The role of host plant type and possible associated factors in the distribution patterns of MEAM1 and Med is discussed in the context of the co-occurrence of cryptic species.