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RNAi-mediated knockdown of transformer-2 in the predatory mite Metaseiulus occidentalis via oral delivery of double-stranded RNA

Pomerantz, Aaron F., Hoy, Marjorie A.
Experimental & applied acarology 2015 v.65 no.1 pp. 17-27
Metaseiulus occidentalis, RNA interference, biological control agents, double-stranded RNA, eggs, gene expression, genes, genetic engineering, insects, pests, predatory mites, progeny, reproduction, sex determination, sex ratio, virgin females
Little is known about the process of sex determination at the molecular level in Metaseiulus occidentalis, a parahaploid species and natural enemy of phytophagous pest mites. Detailed knowledge of the sex-determination pathway could allow genetic manipulation of M. occidentalis to produce more female offspring, which could improve its effectiveness as a biological control agent. RNA interference is useful for assessing the function of putative sex-determination genes by reducing or eliminating gene expression. In many insect species the transformer-2 (tra-2) gene is an upstream regulatory element in the sex-determination cascade, and knockdown of tra-2 expression can alter the sex ratio. We assessed whether oral delivery of tra-2 double-stranded RNA to M. occidentalis virgin females would affect the sex of her progeny. Females that ingested tra-2 dsRNA produced significantly fewer eggs compared to control females suggesting that tra-2 is somehow involved in reproduction by females. However, the sex ratio of the few progeny that were laid was not altered, so it is unclear whether tra-2 is involved in sex determination. This is an initial step towards elucidating the molecular components of sex determination in M. occidentalis.