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The consequences of co‐infections for parasite transmission in the mosquito A edes aegypti
Author(s) -
Duncan Alison B.,
Agnew Philip,
Noel Valérie,
Michalakis Yannis
Publication year - 2015
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1111/1365-2656.12302
Subject(s) - biology , parasite hosting , transmission (telecommunications) , host (biology) , aedes aegypti , spore , horizontal transmission , larva , obligate parasite , abiotic component , transovarial transmission , zoology , pupa , microsporidia , microbiology and biotechnology , ecology , virology , virus , world wide web , computer science , electrical engineering , engineering
Summary Co‐infections may modify parasite transmission opportunities directly as a consequence of interactions in the within‐host environment, but also indirectly through changes in host life history. Furthermore, host and parasite traits are sensitive to the abiotic environment with variable consequences for parasite transmission in co‐infections. We investigate how co‐infection of the mosquito Aedes aegypti with two microsporidian parasites ( Vavraia culicis and Edhazardia aedis ) at two levels of larval food availability affects parasite transmission directly, and indirectly through effects on host traits. In a laboratory infection experiment, we compared how co‐infection, at low and high larval food availability, affected the probability of infection, within‐host growth and the transmission potential of each parasite, compared to single infections. Horizontal transmission was deemed possible for both parasites when infected hosts died harbouring horizontally transmitting spores. Vertical transmission was judged possible for E. aedis when infected females emerged as adults. We also compared the total input number of spores used to seed infections with output number, in single and co‐infections for each parasite. The effects of co‐infection on parasite fitness were complex, especially for V. culicis . In low larval food conditions, co‐infection increased the chances of mosquitoes dying as larvae or pupae, thus increasing opportunities for V. culicis’ horizontal transmission. However, co‐infection reduced larval longevity and hence time available for V. culicis spore production. Overall, there was a negative net effect of co‐infection on V. culicis , whereby the number of spores produced was less than the number used to seed infection. Co‐infections also negatively affected horizontal transmission of the more virulent parasite, E. aedis, through reduced longevity of pre‐adult hosts. However, its potential transmission suffered less relative to V. culicis . Our results show that co‐infection can negatively affect parasite transmission opportunities, both directly as well as indirectly via effects on host life history. We also find that transmission is contingent on the combined effect of the abiotic environment.