Morphological, genetic and biological differences in two populations of Aleyrodes proletella from northwestern China

The cabbage whitefly Aleyrodes proletella L. (Hemiptera: Aleyrodidae) is a serious pest of vegetables and horticultural crops and invaded Xinjiang in northwestern China in 2013. In 2016, the author observed a whitefly population “Loaded” type which was different from the typical A. proletella in the morphology of eggs, nymphs, pupae and adults. This phenomenon has not been previously documented. The aim of this study is to determine whether the two types constitute separate gene pools using morphological comparisons, genome sequencing and mating experiments. We found that the mycetome color in the “Bare” type was light yellow, the length of the first abdominal setae was 15 μm and the nymphs were directly shed by the ecdyses. The back of the “Loaded” type was covered by ecdyses in an imbricate pattern with the first abdominal setae concatenate. The mycetomes were orange-red and the length of the first abdominal setae was 200 μm. Multiple sequence alignments of the mitochondrial DNA Cytochrome c oxidase subunit I (mtDNA COI) genes were 91.42% identical while the homology of the ribosomal DNA internal transcribed spacer 1 (rDNA ITS1) region was 89.64% (Gap=15.91%). Reciprocal crosses at both the individual and population levels indicated reproductive isolation between the two types since all crosses failed to produce female offspring. Although there are significant differences between these two types, considering the still rather weak evidence of specific diversity, further work is required to satisfactorily assess their taxonomic status.