Ambient temperature and dietary supplementation interact to shape mosquito vector competence for malaria

Courtney C. Murdock, Simon Blanford, Shirley Luckhart, Matthew B. Thomas

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The extent to which environmental factors influence the ability of Anopheles mosquitoes to transmit malaria parasites remains poorly explored. Environmental variation, such as change in ambient temperature, will not necessarily influence the rates of host and parasite processes equivalently, potentially resulting in complex effects on infection outcomes. As proof of principle, we used Anopheles stephensi and the rodent malaria parasite, Plasmodium yoelii, to examine the effects of a range of constant temperatures on one aspect of host defense (detected as alterations in expression of nitric oxide synthase gene - NOS) to parasite infection. We experimentally boosted mosquito midgut immunity to infection through dietary supplementation with the essential amino acid l-Arginine (l-Arg), which increases midgut nitric oxide (NO) levels by infection-induced NOS catalysis in A. stephensi. At intermediate temperatures, supplementation reduced oocyst prevalence, oocyst intensity, and sporozoite prevalence suggesting that the outcome of parasite infection was potentially dependent upon the rate of NOS-mediated midgut immunity. At low and high temperature extremes, however, infection was severely constrained irrespective of supplementation. The effects of l-Arg appeared to be mediated by NO-dependent negative feedback on NOS expression, as evidenced by depressed NOS expression in l-Arg treated groups at temperatures where supplementation decreased parasite infection. These results suggest the need to consider the direct (e.g. effects of mosquito body temperature on parasite physiology) and indirect effects (e.g. mediated through changes in mosquito physiology/immunity) of environmental factors on mosquito-malaria interactions in order to understand natural variation in vector competence.

Original languageEnglish (US)
Pages (from-to)37-44
Number of pages8
JournalJournal of Insect Physiology
Volume67
DOIs
StatePublished - 2014

Keywords

  • Ambient temperature
  • Arginine
  • Immunity
  • Malaria
  • Mosquito
  • Nitric oxide

ASJC Scopus subject areas

  • Insect Science
  • Physiology
  • Medicine(all)

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