Dissemination barriers to Ross River virus in Aedes vigilax and the effects of larval nutrition on their expression

Abstract

Effects of larval nutrition on vector competence of the mosquito Aedes vigilax (Skuse) (Diptera: Culicidae) from Townsville, north Queensland, for Ross River virus (RR) were examined. Larvae were reared on three different diets to create three significantly different size classes of adult mosquito. These were fed on serial dilutions of RR and then sampled on alternate days so the progression of the virus through the mosquito could be examined. No differences of vector competence could be attributed to larval nutrition. Barriers to infection and the correlation between infection rate, viral titre and transmission of RR by Ae. vigilax were also examined. The mesenteronal barrier was the only infection barrier expressed. No correlation between viral titre and transmission was detected, but a strong correlation was found between salivary gland infection and transmission rate. From this it was possible to estimate that 98.7+/-1.3% of Ae. vigilax with infected salivary glands transmit RR.

Invasive mosquitoes, larval competition, and indirect effects on the vector competence of native mosquito species (Diptera: Culicidae)

“…While several studies have examined how larval nutritional deprivation increases the ability of an adult mosquito to transmit a pathogen once infected (Alto et al 2005;Baqar et al 1980;Grimstad and Haramis 1984;Grimstad and Walker 1991;Jennings and Kay 1999;Kay et al 1989;Paulson and Hawley 1991;Takahashi 1976), few of these studies have taken into account how nutritional deprivation impacts the ability of the mosquito to become infected in the first place. In a nutshell, smaller female mosquitoes are less likely to host-feed (Klowden 1995;Sumanochitrapon et al 1998).…”

“…In contrast, findings reported here found a positive relationship between mosquito size and infection rates. Questions remain on why these two studies found opposing patterns, and why there is little consensus on the relationship between vector size and pathogen transmission overall (Anderson et al 2005;Baqar 1980;Grimstad and Haramis 1984;Jennings and Kay 1999;Kay and Jennings 2002;Nasci and Mitchell 1994;Takahashi 1976). Such inconsistencies may be the result of system and species-specific differences and may derive from how little we know about many vector-pathogen systems.…”

Larval Environmental Temperature and the Susceptibility ofAedes albopictusSkuse (Diptera: Culicidae) to Chikungunya Virus

“…However, nutritional deprivation that led to small mosquitoes had no effect on vector competence in Culex annulirostris for Murray Valley encephalitis virus (Kay et al 1989c) and Ae. vigilax for Ross River virus ( Jennings and Kay 1999). These contradictions in the effect of size on vector competence could be based on the intrinsic differences between vector-viral systems; however, it is also possible that larval conditions, such as high temperature and low nutrients or competition, produce small mosquitoes by different mechanisms that differently affect their competence as vectors.…”

Larval Temperature–Food Effects on Adult Mosquito Infection and Vertical Transmission of Dengue-1 Virus

“…albopictus adult mosquitoes that develop in areas of the world with cooler ambient temperatures (e.g., <25 C) and nutrient-poor conditions as larvae may be more likely infected with DENV compared with those exposed to nutrient-rich conditions as larvae. By contrast, other investigations have found little evidence relating larval nutrition to measurements of vector competence (e.g., Culex annulirostris Skuse and Murray Valley encephalitis virus, Kay et al 1989; Aedes vigilax Skuse and Ross River virus, Jennings and Kay 1999; Culex tarsalis Coquillett and West Nile virus, Dodson et al 2011). However, these studies used a single-temperature experimental design (range, 27-28 C), limiting the ability to identify possible nutrient-mediated changes in adult competence for arboviruses that may vary across a temperature gradient.…”