The wMelPop strain of Wolbachia interferes with dopamine levels in Aedes aegypti

Aedes aegypti is the main vector of dengue, one of the leading arboviral diseases of humans throughout the tropics of the world [1]. In an attempt to develop a new biocontrol approach to reduce dengue transmission, A. aegypti mosquitoes have been transinfected with the common inherited bacterial symbiont of insects, Wolbachia [2]. The wMelPop-CLA strain of Wolbachia when present in A. aegypti induces a range of effects including reductions in adult lifespan and blockage of vector competence for a range of human pathogens [2-5]. In addition some other effects have also been reported. Infected mosquitoes exhibit increases in both locomotor activity and metabolic rate [6]. As Wolbachia-infected A. aegypti females age, they obtain fewer and smaller blood meals and show increasing difficulty in completing the process of blood feeding [7,8]. Old female mosquitoes (>15 days) also display behavioral defects described as a "bendy" proboscis or jittering of the body termed "shaky", suggesting that their neuronal function is somehow impaired.The biogenic amines dopamine, serotonin and octopamine act as signaling molecules in many diverse physiological contexts, including behavior, fertility, and reproduction, and in the development of neuronal and non-neuronal tissues [9]. In insects, dopamine is involved in several other biological processes, that span from cuticle formation [10], to egg chorion hardening [11], to gonadotropic regulation [12] and to the immune response [13,14]. Dopamine is associated with locomotor defects in Drosophila [15] and mammals [16] and, in humans its deficiency is the cause of motor defects such as Parkinson disease [17].Many genes participate in the dopamine biosynthesis pathway, which is highly conserved among vertebrates and invertebrates. Initially, the enzyme tyrosine hydroxylase (TH) [or phenoloxidase - (PO)] catalyzes the conversion of tyrosine to L-DOPA [14,18], which is then decarboxylated by the enzyme dopa-decarboxylase (DDC) to dopamine