Hormonal regulation of reproduction in bed bug, Cimex lectularius

Bed bug, Cimex lectularius is an obligatory hematophagous parasite. There is a recent resurgence in populations of this insect. To discover new target sites for development of insecticides for controlling this insect, we decided to analyze transcriptome and study the reproduction especially vitellogenesis and oogenesis in this insect. Variation in the mRNA levels of vg as well as transcription factors such as HR3 (hormone receptor 3) and kr-h1 (Krüppel homolog 1) involved in ecdysone and JH action respectively were monitored to study the effect of mating and feeding. Both feeding and mating are essential to induce vitellogenin (vg) gene expression. HR3 and Kr-h1 expression increases soon after feeding and/or mating and reach the maximum levels by three days after initiation of feeding and/or mating. RNAi-aided knockdown in the expression of genes coding for JH receptor Met (methoprene tolerant protein), its co-activator SRC (steroid receptor co-activator), GATA transcription factor or 20E (20- Hydroxyecdysone) resulted in a decrease in the number of progeny produced by female bed bugs. Further studies showed that JH and nutrition regulate vg synthesis while 20E and nutrition regulate oocyte development. Kr-h1 knockdown did not reduce vg transcripts but the embryonic development was affected, showing that Kr-h1 may be regulating embryonic development and Met might function through other downstream genes. These initial studies showed the involvement of nutrition, JH and 20E in regulation of bed bug reproduction and lay a solid foundation for future studies on molecular analysis of reproduction in this insect.