Objective Application of dsActin to control the proliferating, multiple-hosting, insecticide-resistant invasive western flower thrips on vegetables and ornamental crops in China was investigated.
Method Synthetic dsActin or dsGFP (as control) was introduced into the 2nd-instar nymphs of Frankliniella occidentalis (Pergande) by either membrane-feeding or microinjection. The treated thrips were collected for mRNA expression detection by RT-qPCR at 24, 48 and 72 h after the treatment. Effects of 0.5 μg·μL−1 dsRNA on the body length, wing or thorax malformation, and mortality of the insects were monitored in an individual culture experiment conducted in the laboratory.
Result The relative expression of Actin mRNA in the thrips was similar to that of control 24, 48 and 72 h after membrane-feeding. But the expressions in the injection group decreased to 68% in 24 h, 56% in 48 h, and 53% in 72 h. Significantly higher mortality rate (44%-98% in 24-120 h), shorter body length (90% of control), and higher bodily deformation rate (41%) were observed in the dsRNA-treated thrips than control.
Conclusion The Actin mRNA expression in F. occidentalis was significantly suppressed by dsActin injection at the test level to induce malformations or death in the insects. It suggested that an in vivo RNA interference method was made available for studying the gene functions and control of thrips.
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