A target-specific feeding toxicity of ß1 integrin dsRNA against diamondback moth, Plutella xylostella

Integrin is a cell-surface protein consisting of a and beta heterodimers. A predicted amino acid sequence of an integrin subunit of the diamondback moth, Plutella xylostella, was highly homologous to other lepidopteran beta 1 subunits and possessed essential functional domains. The beta 1 integrin of P. xylostella (beta Px1) was expressed in all developmental stages of P. xylostella. It was also expressed in all tested tissues including hemocyte, fat body, gut, and epidermis of last instar. When beta Px1 expression was suppressed by injection of dsRNA specific to beta Px1 (dsRNA beta Px1), the treated larvae exhibited significant suppression in immune response and also suffered significant larval mortality. When dsRNA beta Px1 was orally fed to young larvae, it suppressed the expression of aPx1 and resulted in a significant mortality. By contrast, a dsRNA specific to beta 1 subunit of Spodoptera exigua gave little adverse effects on beta Px1 expression and larval development when it was treated by injection or oral administration, though these two genes showed 71 parts per thousand sequence homology. These results suggest a target-specific RNA interference of dsRNA beta Px1, which causes significant mortality to P. xylostella by feeding treatment. (c) 2011 Wiley Periodicals, Inc.