Capacity of mosquitoes to transmit malaria depends on larval environment

Abstract

Background: Adult traits of holometabolous insects such as reproduction and survival can be shaped by conditions experienced during larval development. These "carry-over" effects influence not only individual life history and fitness, but can also impact interactions between insect hosts and parasites. Despite this, the implications of larval conditions for the transmission of human, wildlife and plant diseases that are vectored by insects remain poorly understood. Methods: We used Anopheles stephensi mosquitoes and the rodent malaria, Plasmodium yoelii yoelii, to investigate whether quality of larval habitat influenced vectorial capacity of adult mosquitoes. Larvae were reared under two dietary conditions; one group received a diet commonly used for colony maintenance (0.3 mg/individual/day of Tetrafin fish food) while the other group received a reduced food diet (0.1 mg/individual/day). Upon emergence, adults were provided an infectious blood feed. We assessed the effects of diet on a range of larval and adult traits including larval development times and survival, number of emerging adults, adult body size and survival, gonotrophic cycle length, and mating success. We also estimated the effects of larval diet on parasite infection rates and growth kinetics within the adult mosquitoes. Results: Larval dietary regime affected larval survival and development, as well as size, reproductive success and survival of adult mosquitoes. Larval diet also affected the intensity of initial Plasmodium infection (oocyst stage) and parasite replication, but without differences in overall infection prevalence at either the oocyst or sporozoite stage. Conclusions: Together, the combined effects led to a relative reduction in vectorial capacity (a measure of the transmission potential of a mosquito population) in the low food treatment of 70%. This study highlights the need to consider environmental variation at the larval stages to better understand transmission dynamics and control of vectorborne diseases.

Invasive species reduces parasite prevalence and neutralizes negative environmental effects on parasitism in a native mosquito

“…That the resources in the larval habitat would affect the prevalence of As . barretti infection in larvae is not surprising as studies have demonstrated that sub‐optimal conditions experienced in larval habitats carry‐over to adult mosquito phenotypes, altering immune function (Suwanchaichinda & Paskewitz, ; Telang, Qayum, Parker, Sacchetta, & Byrnes, ) and vector competence for a variety of parasite taxa including filarial worms (Breaux, Schumacher, & Juliano, ), protozoa (Moller‐Jacobs, Murdock, & Thomas, ) and viruses (Alto, Lounibos, Mores, & Reiskind, ).…”

The Stressor Effect of Ethanol and Water Extracts of the Magical Herb <i>Phytolacca dodecandra</i> (Herit) on Life History of <i>Anopheles gambiae</i> (Diptera: Culicidae) Mosquitoes

“…This is likely to alter the female mosquito fertility and fecundity (Zuharah et al, 2016), crucial vectorial traits necessary for survival. It is also likely to affect epidemiologically relevant mosquito disease transmission traits such as longevity or vector competence (Beldomenico and Begon, 2010;Muturi et al, 2011;Takken et al, 2013;Moller-Jacobs et al, 2014).…”

“…This in the end impacts fitness of adult emergence and subsequent biological life cycle (Kweka et al, 2012). On the other hand if the vector does not live long enough (vectors of diseases with intrinsic incubation period like malaria), the parasite might never be able to be transmitted, and the vector competence is therefore compromised (Garrett-Jones and Shidrawi, 1969;Muturi et al, 2011;Araujo et al, 2012;Takken et al, 2013;Lefèvre et al, 2013;Moller-Jacobs et al, 2014;Breaux et al, 2014).…”

Effect of Larval Nutritional Regimes on Morphometry and Vectorial Capacity of Aedes aegypti for Dengue Transmission

“…Many studies have highlighted that the residing environment of larval stages of mosquitoes strongly determines the adult characteristics such as individual size, teneral reserves, biting behavior, fecundity, longevity, and vector competence, which affect the overall vectorial capacity [13–16]. Any change in the environment that affects the related aspect of vector biology may result in a variation in risk of disease transmission via influencing the vectorial capacity [17]. At present, many investigations that evaluate the effect of environment on mosquito biology and aspects of Vectorial Capacity (VC) have directly focused on adult mosquitoes, with limited attention on larval stages.…”