Feeding and mating initiate juvenile hormone regulation of reproduction in bed bugs

The common bed bug, Cimex lectularius is an obligate hematophagous parasite. They cause many problems including allergic reactions or social stigma. Recent resurgence of bed bugs and difficulties in controlling them using commercially available insecticides have motivated us to study the basic biology of feeding, mating and juvenile hormone (JH) regulation of reproduction in these insects. Gene expression studies showed that feeding and mating are essential to induce vitellogenin (Vg) gene expression in the fat body, and the development of oocytes in the ovary. Topical application of JH analogue, methoprene, to virgin blood fed females induced expression of JH-response genes including Vg in the fat body and krüpple homologue-1 (Kr-h1) and forkhead box L2 (FOXL2) in the ovary. Methoprene also induced the development of oocytes in the ovary. Role of JH in reproduction was further confirmed through RNA interference-aided knockdown of its receptor Methoprene tolerant protein (Met) and steroid receptor co-activator (SRC). Knockdown of either of these genes reduced both Vg gene expression and oocyte development. Knockdown of FOXL2 reduced development of primary oocytes but did not affect Vg gene expression. Whereas, Kr-h1 knockdown had no effect on Vg gene expression or oocyte development but affected embryonic development. These data suggest that a complex cascade of gene regulation events that are initiated after feeding and mating regulate both vitellogenesis and oogenesis in these insects. Understanding the basic biology of bed bug reproduction would provide molecular targets for their control.

Keywords: vitellogenin, Cimex lectularius, juvenile hormone