Invasive Species Compendium

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Abstract

Molecular characteristics of three cold resistance genes and their roles in temperature stress response in two Bemisia tabaci cryptic species.

Abstract

Bemisia tabaci (Hemiptera: Aleyrodidae) has a wide range in temperature tolerance. The large differences in geographical distributions between two of its cryptic species in China, the invasive Mediterranean cryptic species (MED) and the native AsiaII3 cryptic species, may be influenced by their molecular responses to temperature. To determine the molecular responses, we cloned the sequences of three cold resistance genes each encoding the proteins trehalase, dopa decarboxylase and trichohyalin of the two B. tabaci cryptic species. By comparing the respective amino acid sequences of the trehalase and dopa dedcarboxylase genes, we found that there were different amino residues between the two cryptic species. Subsequently, using RNAi and feeding individuals double-stranded RNA (dsRNA), we individually silenced the three genes in both cryptic species and observed the changes in whitefly adults in response to exposure to high and low temperatures. We found that the heat and cold tolerances of the two species were significantly reduced, with the exception of the lack of change observed in cold tolerance response of adults of the native species that consumed dsTreh1 (trehalase). Overall, the study demonstrated that all three genes participated in the regulatory process in response to temperature stress. Moreover, Treh1 likely plays a key role in cold tolerance for the B. tabaci invasive species, and it may be a key factor in influencing the geographical distribution and dispersal of MED populations in China.