Life-history variation in three coexisting species of carnid flies (Diptera: Carnidae), Carnus hemapterus, Hemeromyia anthracina and Hemeromyia longirostris

Abstract

Abstract. Seasonal cycles constitute a major challenge for organisms since they may influence the genetic composition of a population, the species structure of a community and the interactions between organisms. Diapause is frequently used by insects to synchronize their life cycle with seasonal changes and is regarded as a key factor in the coexistence of competing species. Here the occurrence, abundance and emergence patterns of three poorly-known species of carnid flies (Carnus hemapterus Nitzsch, 1818, Hemeromyia anthracina Collin, 1949 and Hemeromyia longirostris Carles-Tolrá, 1992), which overwintered in the nests of several bird species at two localities, are reported and evidence of possible interspecific competition sought. Larvae of all three species were found in association with carrion and detritus. Both Hemeromyia species co-occurred in around 50% of the nests and Carnus with each of the Hemeromyia species at a lower rate (30-40% of the nests). Coexistence of all three carnid species was rare. We did not find any evidence of interspecific competition in the larval stage. Coexistence did not reduce the number of flies that emerged of any of the three species and the abundance of some species was even positively related. Species-specific emergence patterns and different habitat selection criteria (Carnus hemapterus seemed to avoid nests lined with vegetable material), which diminished the overlap between species were found. Such spatial and temporal segregation could facilitate the coexistence of these closely related species, which have similar ecological requirements, and might influence the seasonal dynamics of this poorly-known assemblage of insects inhabiting the nests of birds.

Intra‐specific variability in life‐cycle synchronization of an ectoparasitic fly to its avian host

“…Sample parasite emergence was defined by three variables: the weekly percentage of emerged flies, the length of emergence period (in days), and the date when 50% of Carnus flies emerged (in Julian days). We considered the date of 50% sample emergence as a reliable estimator of seasonal emergence progress for individual nests since most flies emerge around this date (Valera et al 2006b, Calero‐Torralbo and Valera 2008).…”

“…We also determined the sample's total abundance of flies, which was equal to the number of flies emerging in the nest sample, because the number of emerged flies was not clearly related to nest material weight (Spearman rank correlations for each year: p > 0.1, see also Valera et al 2006b, Calero‐Torralbo and Valera 2008).…”

Reproductive anatomy and fecundity estimation of the haematophagous ectoparasite Carnus hemapterus

“…Since we collected gravid females, we are unable to report on egg maturation at the time of emergence (and thus on significant fitness variables like the ovigeny index and initial egg load, see Jervis and Ferns 2004). However, we did record continuous maturation of follicles and since flies of different ages were probably sampled (adult C. hemapterus emergence is continuous, Valera et al 2003Valera et al , 2006 our results suggest that carnid females are synovigenic. This is important because it implies that both the number of laid eggs at a given moment and the egg load (the number of mature eggs carried by a female at a given moment in her lifetime) represent only a fraction of the true potential fecundity.…”

“…After a diapause usually lasting several months (Guiguen et al 1983; but see Valera et al 2006), nymphs emerge the following spring at the time after nesting sites have been reoccupied by birds. Adults are initially winged and capable of flying, but they typically lose their wings once they have found a suitable host (Roulin 1998(Roulin , 1999.…”

Invasion of <i>Carnus hemapterus</i> (Diptera: Carnidae) into the human external ear canal in Yokohama City

“…In Japan, C. hemapterus was collected from the nestlings of Corvus corone in Nagano Prefecture and from the nests of Eurystomus orientalis in both Tottori and Hiroshima Prefecture and of Dendrocopos major in Hokkaido (Iwasa et al, 2008). In Europe and the United States, many hosts have been reported, including Tyto alba, Upupa epops, Falco sparverius, Sturnus vulgaris, Merops apiaster (Bequaert, 1942;Liker et al, 2001;Petrescu and Adam, 2000;Valera et al, 2006a). It is recognized that the larvae of C. hemapterus are saprophages and develop in bird nests, excrements, and dead organisms.…”