Population dynamics between the mermithid Strelkovimermis spiculatus (Nematoda: Mermithidae) and the floodwater mosquito Ochlerotatus albifasciatus (Diptera: Culicidae) over time

MICIELI, M. V.; RISSO, P.; ACHINELLY, M. F; VILLAR, M. DE LOS M.; MUTTIS, E.

BIOLOGICAL CONTROL

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2012 vol. 61 p. 55 - 63

1049-9644

We investigated the population dynamics of Strelkovimermis spiculatus in Ochlerotatus albifasciatus to determine the abiotic and biotic parameters involved in both populations of this host-parasite system. Weekly samplings performed from May 2007 through May 2010 in three ponds located in open areas of La Plata, Argentina revealed that parasitism by S. spiculatus in Oc. albifasciatus occurred throughout all seasons with differences among breedings. The highest mosquito-larva reduction was observed in a habitat where 100% of the populations were infected by nematodes that had reached the fourth-instar stage; an intermediate situation involved a lower percentage of high parasitism although nematode infection was likewise registered in 92.9% of the populations. The lowest mosquito larva reduction was recorded where only 46.0% of the populations were parasitized by low levels of nematodes. We analyzed the effects of abiotic and biotic parameters on S. spiculatus infections. The flood-surface area was the only variable significantly associated with the infection percentages. The prevalence of infection was positively correlated with the mean number of emerged nematodes per larva and with the ratio of S. spiculatus males females in each parasitized-mosquito population. We conclude that the frequency of infections over time and the levels of infection play a key role in the regulation of mosquito populations by this parasite.