Body size-dependent effects on the distribution patterns of phoretic
mites of the multi-symbiont Rhynchophorus ferrugineus (Olivier, 1790)
Phoretic mites have been found attached to different body parts of red
palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), to
disperse. However, the question of how the patterns of attachment sites
are formed remains intriguing. Here, we conducted the first study of
RPW-associated phoretic mites in Portugal, particularly in the districts
of Viana do Castelo, Braga, Porto and Aveiro in Northern Portugal
(macrohabitat), and investigated the patterns of mite distribution on
six body parts of RPW (microhabitat). At the macrohabitat level, we
detected seven phoretic mite taxa actively using RPW host in each of the
four studied districts, all documented for the first time in association
with this invasive exotic species in Portugal. However, their relative
abundance (species evenness) varied between districts, as did species
diversity. All examined weevils carried mites, and the prevalence of the
different taxa did not differ between districts or sex of weevils.
Measured by mean abundance and degree of aggregation, Centrouropoda sp.
proved to be the common dominant taxon, while Acarus sp. and C.
rhynchoporus were considered common subordinate taxa and Uroovobella
sp., Mesostigmata, N. extremica and Dendrolaelaps sp. sparse taxa. At
the microhabitat level, all taxa were present in all body parts of the
RPW; the highest abundance was in a region encompassing the inner
surface of the elytra and the membranous hind wings (subelytral space).
Analysis of niche overlap revealed that the distribution patterns of
phoretic mite taxa on the RPW were not randomly structured. In the
subelytral space, interspecific coexistence of mites increased as a
function of body size difference with the dominant Centrouropoda sp. We
conclude that the distribution patterns of RPW-associated phoretic mites
show body size-dependent effects that resulted in the dominant taxon
displacing similar size taxa and accepting taxa with which it has the
greatest size difference as co-habitants.