A target-specific feeding toxicity of β(1) integrin dsRNA against diamondback moth, Plutella xylostella.

Integrin is a cell-surface protein consisting of α and β heterodimers. A predicted amino acid sequence of an integrin subunit of the diamondback moth, Plutella xylostella, was highly homologous to other lepidopteran β1 subunits and possessed essential functional domains. The β1 integrin of P. xylostella (βPx1) 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 βPx1 expression was suppressed by injection of dsRNA specific to βPx1 (dsRNA(βPx1)), the treated larvae exhibited significant suppression in immune response and also suffered significant larval mortality. When dsRNA(βPx1) was orally fed to young larvae, it suppressed the expression of âPx1 and resulted in a significant mortality. By contrast, a dsRNA specific to β1 subunit of Spodoptera exigua gave little adverse effects on βPx1 expression and larval development when it was treated by injection or oral administration, though these two genes showed 71% sequence homology. These results suggest a target-specific RNA interference of dsRNA(βPx1), which causes significant mortality to P. xylostella by feeding treatment.