A heavy legacy: offspring of malaria-infected mosquitoes show reduced disease resistance.

ABSTRACT

BACKGROUND: Trans-generational effects of immune stimulation may have either adaptive (trans-generational immune priming) or non-adaptive (fitness costs) effects on offspring ability to fight pathogens. METHODS: Anopheles coluzzii and its natural malaria parasite Plasmodium falciparum were used to test how maternal parasite infection affected offspring resistance to the same parasite species. RESULTS: Daughters of exposed mothers had similar qualitative resistance, as measured by their ability to prevent infection, relative to those of control mothers. However, maternal disease exposure altered offspring quantitative resistance, measured as the ability to limit parasite development, with mosquitoes of infected mothers suffering slightly increased parasite intensity compared to controls. In addition, quantitative resistance was minimal in offspring of highly infected mothers, and in offspring issued from eggs produced during the early infection phase. CONCLUSIONS: Plasmodium falciparum infection in An. coluzzii can have trans-generational costs, lowering quantitative resistance in offspring of infected mothers. Malaria-exposed mosquitoes might heavily invest in immune defences and thereby produce lower quality offspring that are poorly resistant.