Functional, evolutionary and ecological aspects of feeding-related mouthpart specializations in parasitoid flies

Abstract

This paper considers mouthpart specializations for feeding among dipteran parasitoids, and places them in both an evolutionary and an ecological context. Parasitoid flies display specializations in relation to feeding on solidified honeydew, removing floral nectar from long, narrow, tubular corollas, and feeding on host materials. No species have as yet been identified which display particular specializations for pollen-feeding, but we consider it likely that they exist. Marked sexual dimorphism in mouthpart structure appears to occur only in the Phoridae. Mapping the occurrence of apparatus for removing floral nectar from long, narrow, tubular corollas ('concealed nectar extraction apparatus' or CNEA) onto published cladograms for Diptera shows that the evolution of such feeding apparatus has occurred many times independently. In contrast to parasitoid Hymenoptera, possession of CNFA is more often an autapomorphy for taxa above subfamily level in apparently two cases for superfamilies (Acroceroidea and Nemestrinoidea). We conclude that whereas in parasitoid wasps the pattern of occurrence of CNEA is mainly attributable to ecological expediency, in parasitoid flies phylogenetic history has also played a major role. We discuss the fitness advantages of the different feeding specializations among parasitoids generally (i.e. both Diptera and Hymenoptera) in relation to various ecophysiological factors. 0 1998 The Linnean Society of London ADDITIONAL

Surface ultrastructure of prestomal teeth of some flies in the families Calliphoridae, Muscidae and Sarcophagidae

“…In feeding habits, adult flies of the families Calliphoridae, Muscidae and Sarcophagidae shared a resemblance in proboscis structure and adult food; for example, feeding on nectar and juices exuding from ripe fruit (Gilbert and Jervis 1998;Krenn et al 2005). In view of the medical importance and geographical distribution of the flies examined in this study, C. pinguis was reported as associating with the bacteria Escherichia coli, Proteus mirabilis, Proteus rettgeri, Proteus vulgaris and Providencia spp.…”

How many species of arthropods visit flowers?

“…At least 79 of the currently recognised 159 families contain recorded flower-visitors or pollinators (Table S2), with the most important being Syrphidae, Acroceridae, Conopidae, Bombyliidae, Muscidae, Anthomyiidae, Calliphoridae, Sarcophagidae, and Tachinidae (Gilbert and Jervis 1998;Larson et al 2001). Most flies visit flowers to feed on nectar, since the mouthparts of most species are adapted to feed on fluids .…”

“…However, the pollination biology of meadow systems tends to be well studied compared to forest habitats (see Kearns 2001;and data in Fontaine et al 2009), so it is possible that pollination by flies is more prevalent than currently assumed in forests. Also in parallel with the Coleoptera is the likely high number of transitions from other feeding modes or diets to florivory (Gilbert and Jervis 1998), since most dipteran families are not exclusively or in many cases even predominantly anthophilous. Flower-visiting may therefore be a derived trait in many families rather than an inherited trait, again stressing the frequency with which a wide range of insect lineages have evolved the flowervisiting habit.…”

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

“…Although pollen feeding is widespread in Diptera, no species with mouthpart structures exclusively used for pollen feeding have been identified (Gilbert and Jervis 1998). It is interesting to note that the only adaptations to pollen feeding are the labellar food furrows described for Syrphidae (Schuhmacher and Hoffmann 1982) but a clear adaptational value of the food furrows is questionable, since they are lacking in many pollen feeders (Krenn et al 2005).…”