DNA barcodes affirm that 16 species of apparently generalist tropical parasitoid flies (Diptera, Tachinidae) are not all generalists

Abstract

Many species of tachinid flies are viewed as generalist parasitoids because what is apparently a single species of fly has been reared from many species of caterpillars. However, an ongoing inventory of the tachinid flies parasitizing thousands of species of caterpillars in Area de Conservació n Guanacaste, northwestern Costa Rica, has encountered >400 species of specialist tachinids with only a few generalists. We DNA-barcoded 2,134 flies belonging to what appeared to be the 16 most generalist of the reared tachinid morphospecies and encountered 73 mitochondrial lineages separated by an average of 4% sequence divergence. These lineages are supported by collateral ecological information and, where tested, by independent nuclear markers (28S and ITS1), and we therefore view these lineages as provisional species. Each of the 16 apparently generalist species dissolved into one of four patterns: (i) a single generalist species, (ii) a pair of morphologically cryptic generalist species, (iii) a complex of specialist species plus a generalist, or (iv) a complex of specialists with no remaining generalist. In sum, there remained 9 generalist species among the 73 mitochondrial lineages we analyzed, demonstrating that a generalist lifestyle is possible for a tropical caterpillar parasitoid fly. These results reinforce the emerging suspicion that estimates of global species richness are likely underestimates for parasitoids (which may constitute as much as 20% of all animal life) and that the strategy of being a tropical generalist parasitic fly may be yet more unusual than has been envisioned for tachinids.

Phylogeny and DNA barcoding of inquiline oak gallwasps (Hymenoptera: Cynipidae) of the Western Palaearctic

“…While such cryptic lineages have been observed in other arthropod groups (e.g. Smith et al, 2006Smith et al, , 2007Starrett & Hedin, 2007), the Synergus complex is unusual in that its member species have a long history of taxonomic 580 and ecological study (Ross, 1951;Eady, 1952;Wiebes-Rijks, 1979;Nieves-Aldrey & PujadeVillar, 1985, 1986Pujade-Villar & Nieves-Aldrey 1990;Pujade-Villar 1992;Ronquist 1994;Schönrogge et al, 1995Schönrogge et al, , 1996aSchönrogge et al, , 1996bLiljeblad & Ronquist, 1998;Schönrogge & Crawley 2000;Pujade-Villar et al, 2003). -Villar, 1985;Pujade-Villar, 1992).…”

“…While approximately 1.5 million, predominantly insect, species have been described to date (de Meeus & Renaud, 2002), these represent only a small 90 proportion of estimated global diversity and molecular studies continue to reveal cryptic taxa inseparable on the basis of morphological taxonomy (e.g. Papakostas et al, 2005;Smith et al, 2006;Bergmann & Russell, 2007;Smith et al, 2007;Starrett & Hedin, 2007), increasing the magnitude of the challenge.…”

“…Heteroplasmy, introgression (with or without selective sweeps imposed by Wolbachia and other symbionts), potential selection on nucleotides, and the existence of nuclear pseudogenes can all lead to conflicts between 140 species membership and grouping by DNA barcode Hurst & Jiggins, 2005). DNA barcoding is thus best used where (i) the presence of a barcoding gap for the barcoding locus can be demonstrated empirically, and (ii) concordance in gene tree topology can be demonstrated between the barcoding locus and at least one nuclear locus (Blaxter, 2004;Ahrens et al 2007;Smith et al, 2007;Cardoso et al 2009). More broadly, the utility of 145 DNA barcoding is arguably greatest where existing morphological taxonomic expertise allows molecular and morphological approaches to be compared, revealing the shortfalls of traditional approaches but providing biological context to sequence-based taxa (e.g.…”

Vertical canopy gradient shaping the stratification of leaf‐chewer–parasitoid interactions in a temperate forest

“…Parasitoids operate at high trophic level; moreover, they are often remarkably specialized, but their autecology is poorly understood. Therefore, parasitoids are a highly threatened group that is extremely vulnerable to extinction (Shaw & Hochberg, 2001; Smith, Wood, Janzen, Hallwachs, & Hebert, 2007). In temperate and tropical forests, the major source of insect diversity is the forest canopy (Novotny & Basset, 2005; Stork, 1988).…”

Partitioning of herbivore hosts across time and food plants promotes diversification in the Megastigmus dorsalis oak gall parasitoid complex

“…High herbivore host diversity and shared generalist natural enemies can be reconciled if apparent generalist enemies in fact comprise genetically divergent cryptic lineages that each attack only a subset of the species’ recorded host range. Such structuring has been revealed in a range of systems (Forbes, Powell, Stelinski, Smith, & Feder, 2009; Hood et al., 2015; Smith, Wood, Janzen, Hallwachs, & Hebert, 2007; Smith et al., 2008; Stireman et al., 2006). More broadly, understanding how insect herbivores and parasitoid communities are structured has implications for many aspects of ecosystem management, including biological control of herbivorous pests (Carvalheiro, Buckley, Ventim, Fowler, & Memmott, 2008; Henneman & Memmott, 2001), and predicting the impacts of range expansions associated with anthropogenic introductions and climate change (Nicholls, Fuentes‐Utrilla, et al., 2010; Sax et al., 2007).…”