Diego J. Inclán

Signal through the noise? Phylogeny of the Tachinidae (Diptera) as inferred from morphological evidence

The oestroid family Tachinidae represents one of the most diverse lineages of insect parasitoids. Despite their broad distribution, diversity and important role as biological control agents, the phylogeny of this family remains poorly known. Here, we review the history of tachinid systematics and present the first quantitative phylogenetic analysis of the family based on morphological data. Cladistic analyses were conducted using 135 morphological characters from 492 species belonging to 180 tachinid genera, including the four currently recognized subfamilies (Dexiinae, Exoristinae, Phasiinae, Tachininae) and all major tribes. We used characters of eggs, first‐instar larvae and adults of both sexes. We examined the effects of implied weighting by reanalysing the data with varying concavity factors. Our analysis generally supports the subfamily groupings Dexiinae + Phasiinae and Tachininae + Exoristinae, with only the Exoristinae and the Phasiinae reconstructed as monophyletic assemblages under a wide range of weighting schemes. Under these conditions, the Dexiinae, which were previously considered a well‐established monophyletic assemblage, are reconstructed as being paraphyletic with respect to the Phasiinae. The Tachininae are reconstructed as a paraphyletic grade from which the monophyletic Exoristinae arose. The Exoristinae are reconstructed as a monophyletic lineage, but phylogenetic relationships within the subfamily are largely unresolved. We further explored the evolution of oviposition strategy and found that the oviparous groups are nested within ovolarviparous assemblages, suggesting that ovipary may have evolved several times independently from ovolarviparous ancestors. This counterintuitive pattern is a novel hypothesis suggested by the results of this analysis. Finally, two major patterns emerge when considering host associations across our phylogeny under equal weights: (i) although more than 60% of tachinids are parasitoids of Lepidoptera larvae, none of the basal clades is unambiguously associated with Lepidoptera as a primitive condition, suggesting that tachinids were slow to colonize these hosts, but then radiated extensively on them; and (ii) there is general agreement between host use and monophyly of the major lineages.

Interactive effects of area and connectivity on the diversity of tachinid parasitoids in highly fragmented landscapes

Although many empirical and theoretical studies have elucidated the effects of habitat fragmentation on the third trophic level, little attention has been paid to the impacts of this driver on more generalist groups of non-hymenopteran parasitoids. Here, we used the highly-diverse group of tachinid flies as an alternative model to test the effects of landscape fragmentation on insect parasitoids. Our aims were: (i) to evaluate the relative importance of habitat area and connectivity losses and their potential interaction on tachinid diversity, (ii) to test whether the effects of habitat fragmentation changes seasonally, and (iii) to further assess the effect of habitat diversity on tachinid diversity and whether different parasitoid-host associations modify the species richness response to fragmentation. In 2012 a pan-trap sampling was conducted in 18 semi-natural grasslands embedded in intensive agricultural landscapes along statistically orthogonal gradients of habitat area, connectivity and habitat diversity. We found an interaction between habitat area and connectivity indicating that tachinid abundance and species richness were more negatively affected by habitat loss in landscapes with low rather than with relatively large habitat connectivity. Although tachinid communities exhibited large within-year species turnover, we found that the effects of landscape fragmentation did not change seasonally. We found that habitat diversity and host association did not affect tachinid species diversity. Our results have important implications for biodiversity conservation as any attempts to mitigate the negative effects of habitat loss need to take the general level of habitat connectivity in the landscape into account.

Organic farming enhances parasitoid diversity at the local and landscape scales

Summary 1. The magnitude of the benefits derived from organic farming within contrasting managed landscapes remains unclear and, in particular, the potential scale-dependent response of insect parasitoids is relatively unexplored. Identifying the scale at which parasitoids are affected by organic farming will be an important step to enhance their conservation. 2. We sampled tachinid parasitoids at the centre and margin of arable and grassland fields on paired organic and conventional farms located in landscapes with different proportions of organic land. A total of 192 fields were sampled in two biogeographical regions of the UK. 3. We found that the positive effect of organic farming on tachinid parasitoid diversity can be observed at multiple spatial scales. At the local scale, we found higher abundance and species richness of tachinid parasitoids on organic than on conventional farms and on field margins than on field centres. At the landscape scale, the diversity of tachinids was higher in landscapes with higher proportions of organic land. At both scales, the positive effect of organic farming was clear for arable fields, while it was almost neutral for grasslands. 4. Synthesis and applications. Any attempt to enhance parasitoid diversity in agricultural landscapes needs to consider the local management in relation to the habitat type, location within the field and agricultural management in the surrounding landscape. To restore parasitoid diversity, the promotion of organic agriculture should aim to increase both the total extent of organic farming and the connectivity of individual farms. As the benefits of organic farming to biodiversity clearly spread beyond individual farm boundaries, any assessment of organic farming should consider these positive externalities.

Environmental heterogeneity effects on predator and parasitoid insects vary across spatial scales and seasons: a multi-taxon approach

As predator and parasitoid insects depend on multiple resources for adult feeding and reproduction, environmental heterogeneity (EH) is expected to be a key driver of their species diversity. In temperate regions, the benefits of EH are expected to vary across spatial scales and seasons, depending on species life‐history traits and temporal fluctuations in resources. We tested the importance of EH at multiple spatial scales on diversity and abundance of predator and parasitoid insects, and whether its effects changed across seasons. Insect sampling was carried out in highly fragmented landscapes in a Mediterranean region (Tuscany, Central Italy). We selected 18 semi‐natural patches, embedded in an intensive agricultural matrix. For each patch, EH was measured at three spatial scales (micro, patch, and landscape). Five groups of predator and parasitoid insects were sampled 16 times with pan traps between March and November, 2012. EH at the landscape scale positively influenced the diversity of predator and parasitoid insects, while the effects at smaller spatial scales were less evident. The strength and the direction of EH˗diversity relationship changed between groups and across seasons, indicating that the mechanisms by which EH affects predators and parasitoids are various and complex. Conservation strategies aimed at maximising the diversity of predators and parasitoids should focus more on increasing EH at the landscape scale than at the local scale.

A New Species and Synonymy of The Neotropical Eucelatoria Townsend and Redescription of Myiodoriops Townsend

The New World tropics represents the most diverse region for tachinid parasitoids (Diptera: Tachinidae), but it also contains the most narrowly defined, and possibly the most confusing, tachinid genera of any biogeographic region. This over-splitting of genera and taxonomic confusion has limited progress toward our understanding the family in this region and much work is needed to revise, redefine, and make sense of the profusion of finely split taxa. In a recent analysis of the Neotropical genus Erythromelana Townsend, two species previously assigned to this genus, Euptilodegeeria obumbrata (Wulp) and Myiodoriops marginalis Townsend were reinstated as monotypic genera. In the present study, we demonstrate that Euptilodegeeria obumbrata (Wulp), previously assigned to three different genera, represents in fact a species of the large New World genus Eucelatoria Townsend, in which females possess a sharp piercer for oviposition. We also show that the species Eucelatoria carinata (Townsend) belongs to the same species group as Eucelatoria obumbrata, which we here define and characterize as the Eucelatoria obumbrata species group. Additionally, we describe Eucelatoria flava sp. n. as a new species within the Eucelatoria obumbrata species group. Finally, we redescribe the genus Myiodoriops Townsend and the single species Myiodoriops marginalis Townsend.