John Stireman
Wright State University, Biological Sciences, Faculty Member
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Background/Question/Methods To examine the role of native perennial vegetation in agricultural landscapes in providing critical habitat for supporting ecosystem services and sustainable agriculture, we sampled mobile arthropods in... more
Background/Question/Methods To examine the role of native perennial vegetation in agricultural landscapes in providing critical habitat for supporting ecosystem services and sustainable agriculture, we sampled mobile arthropods in short-cycle, organically-managed crops in California. These agroecosystems are notoriously challenging for achieving conservation biological control because frequent disturbance precludes the establishment of resident communities of natural enemies of pests. Tachinidae, a diverse and ubiquitous family of parasitoid flies, were sampled for three seasons in 35 organic farm fields situated within a mosaic of agricultural and preserved lands in coastal California. Using a GIS, we characterized land-use and vegetative cover within 500m and 1500m, including grasslands, chaparral, oak woodlands, and coniferous forests. Results/Conclusions The abundance and species richness of tachinid flies captured in field crops in spring and summer were positively associated with the cover of semi-wild perennial vegetation, and the species richness of parasitoids emerging from sentinel lepidopteran pests exposed on potted plants in these organic vegetable fields was negatively associated with annual cropland cover. We discuss the importance of maintaining semi-wild, perennial habitat fragments as refugia to support parasitoids that provide ecosystem services in annual and short-cycle crop fields, and distinctions between fragments dominated by native versus introduced plants
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Much of the great Neotropical species richness of the parasitoid fly family Tachinidae (Diptera) is found within the exoristine tribe Blondeliini. This species diversity is particularly concentrated within a number of genera, including... more
Much of the great Neotropical species richness of the parasitoid fly family Tachinidae (Diptera) is found within the exoristine tribe Blondeliini. This species diversity is particularly concentrated within a number of genera, including the piercer-possessing genera of the “Blondelia genus group”. Unfortunately, the blondeliines are plagued with a history of taxonomic inflation, poor descriptions, and confusing morphology, thus making it unclear whether these intriguing oviposition structures are homologous or convergent. We therefore present a molecular phylogeny for the Blondeliini using three informative nuclear genes, which resolves the relationships between the key centers of diversity in the tribe and the monophyly of the Blondelia group. This framework will serve as a baseline for future taxonomic work within the tribe
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Research Interests: Geography and Tachinidae
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The Tachinidae are cosmopolitan in distribution and one of the largest families of Diptera, with approximately 1500 genera and 8500 species. All species are parasitoids of other arthropods, mostly insects, and play an important ecological... more
The Tachinidae are cosmopolitan in distribution and one of the largest families of Diptera, with approximately 1500 genera and 8500 species. All species are parasitoids of other arthropods, mostly insects, and play an important ecological role in the dynamics of host populations. The Tachinidae of the Afrotropical Region were last enumerated in a catalogue by Crosskey (1980). That work recorded 208 genera and 974 species. Our study of the Afrotropical tachinid fauna, based on literature and examination of collections, documents a named fauna of 237 genera and 1126 species. The true diversity is estimated to be significantly higher but the region may well be among the least speciose of the world’s 6 biogeographic regions. In terms of endemicity, 43% of the genera (101) are recorded only from the Afrotropical Region. The percentage is higher at the species level with 93% of the species (1043) recorded as endemic. No Gondwanan elements have been recognized among Afrotropical tachinids and the fauna shares a much greater number of genera and species with the Palaearctic and Oriental regions than with other regions. This biogeographic pattern is congruent with recent studies that suggest the diversification of the Tachinidae was a relatively recent and explosive event, perhaps beginning in the mid-Tertiary. Afrotropical host records are known for fewer than half of the tachinid genera. No notable host shifts are known from the region with the exception of Rondaniooestrus apivorus Villeneuve, the only tachinid with a bee host (Apoidea; Apis mellifera L.)
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Flies of the Tachinidae family (Diptera) are ecologically important due to their parasitism of other insects and their use in biological control. There is a general lack of knowledge about the habits and lifestyles of this very large... more
Flies of the Tachinidae family (Diptera) are ecologically important due to their parasitism of other insects and their use in biological control. There is a general lack of knowledge about the habits and lifestyles of this very large (10,000+ species) family. Since phylogenetic knowledge can aid in inferring lifestyle habits, a robust phylogeny is needed to make better decisions in the use of tachinids in biological control programs. These decisions will reduce unintended consequences of using tachinids as a biological control agent (such as the loss of native moths) and increase the likelihood of a successful control program. The phylogenetic work that has been done on Tachinidae has only focused on a single subfamily (Stireman, 2002; Tachi and Shima, 2009) or on higher level relationships (Kutty et.al., 2010). Using 6 nuclear and mitochondrial genes from 25 tribes, I created a phylogenetic framework of Tachinidae which focused on superfamily and subfamily structure. I was able to recover Tachinidae as monophyletic as well as well as the subfamilies phassiinae and exoristinae. The other subfamilies (dexiinae and tachininae) were found to be paraphyletic. The Rhinophoridae were recovered as their closest sister group and the Calliphoridae subfamily polleniinae was also closely related to Tachinidae. Further research including more species and more genes is needed in order to accurately infer the relationships among the 10,000 species in the Tachinidae family
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Abstract Pelamera atra (Rondani, 1861) is an enigmatic species of bristle fly that has been challenging dipterologists with regard to its taxonomic position within the family Tachinidae since it was first described. The species is rarely... more
Abstract Pelamera atra (Rondani, 1861) is an enigmatic species of bristle fly that has been challenging dipterologists with regard to its taxonomic position within the family Tachinidae since it was first described. The species is rarely collected and is only known from a handful of female specimens. The first ever male specimen of Pelamera atra was collected in southern Italy in 2017, revealing its possession of unique terminalia. The present paper provides the first description of a male of Pelamera atra and presents new insights about its phylogenetic position within the family based on molecular data. A maximum likelihood analysis was conducted on a selection of tachinid taxa using sequences of two nuclear protein-coding genes (CAD and MCS) to formulate the first hypothesis concerning the phylogenetic placement of Pelamera atra. Phylogenetic analyses reconstructed Pelamera atra as a member of the Tachininae sister to the (Loewiini + (Polideini + Ernestiini)) clade. This reconstruction challenges previous attempts at classifying Pelamera based on female external morphology, which instead suggested a close affinity to the tribes Brachymerini or Minthoini. Due to the morphological distinctiveness of this taxon, we here propose the placement of Pelamera atra in the monotypic tribe Pelamerini stat. rev.
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Population divergence can occur due to mechanisms associated with geographic isolation and/or due to selection associated with different ecological niches. Much of the evidence for selection‐driven speciation has come from studies of... more
Population divergence can occur due to mechanisms associated with geographic isolation and/or due to selection associated with different ecological niches. Much of the evidence for selection‐driven speciation has come from studies of specialist insect herbivores that use different host plant species; however, the influence of host plant use on population divergence of generalist herbivores remains poorly understood. We tested how diet breadth, host plant species and geographic distance influence population divergence of the fall webworm (Hyphantria cunea; FW). FW is a broadly distributed, extreme generalist herbivore consisting of two morphotypes that have been argued to represent two different species: black‐headed and red‐headed. We characterized the differentiation of FW populations at two geographic scales. We first analysed the influence of host plant and geographic distance on genetic divergence across a broad continental scale for both colour types. We further analysed the in...
Research Interests: Medical Sciences, Landscape genetics, Systems Biology, Biology, Life Sciences, and 13 moreEcology, Medicine, Molecular Ecology, Biological Sciences, Population, Insects, Species interactions, Geographical Distance, Genetic Divergence, Landscape Genetics, Medicine and Health Sciences, Isolation by distance, and Herbivore
Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of research on this issue have led to the accumulation of hundreds of data sets comparing species assemblages in larger, intact, habitats to smaller,... more
Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of research on this issue have led to the accumulation of hundreds of data sets comparing species assemblages in larger, intact, habitats to smaller, more fragmented, habitats. Despite this, little synthesis or consensus has been achieved, primarily because of non‐standardized sampling methodology and analyses of notoriously scale‐dependent response variables (i.e., species richness). To be able to compare and contrast the results of habitat fragmentation on species’ assemblages, it is necessary to have the underlying data on species abundances and sampling intensity, so that standardization can be achieved. To accomplish this, we systematically searched the literature for studies where abundances of species in assemblages (of any taxa) were sampled from many habitat patches that varied in size. From these, we extracted data from several studies, and contacted authors of studies where appropriat...
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Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory... more
Estimations of tropical insect diversity generally suffer from lack of known groups or faunas against which extrapolations can be made, and have seriously underestimated the diversity of some taxa. Here we report the intensive inventory of a four-hectare tropical cloud forest in Costa Rica for one year, which yielded 4332 species of Diptera, providing the first verifiable basis for diversity of a major group of insects at a single site in the tropics. In total 73 families were present, all of which were studied to the species level, providing potentially complete coverage of all families of the order likely to be present at the site. Even so, extrapolations based on our data indicate that with further sampling, the actual total for the site could be closer to 8000 species. Efforts to completely sample a site, although resource-intensive and time-consuming, are needed to better ground estimations of world biodiversity based on limited sampling.
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ntroduction: Tachinidae is a diverse and important group of dipteran parasitoids. The very recent and rapid radiation of the family has posed problems for taxonomic classification and for understanding evolutionary relationships among... more
ntroduction: Tachinidae is a diverse and important group of dipteran parasitoids. The very recent and rapid radiation of the family has posed problems for taxonomic classification and for understanding evolutionary relationships among taxa and patterns of host use. Methods: Here we present a molecular phylogenetic analysis of the family employing more than 350 exemplar taxa and 4 nuclear genes (ca. 6 Kb). Results/Conclusion: Maximum Likelihood and Bayesian analyses largely support modern classification schemes based on morphology and recent phylogenetic analyses, with some important exceptions. In particular, the subfamily Tachininae is both poly- and paraphyletic with one smaller lineage reconstructed as sister to all remaining tachinids, and the other main lineage also containing the subfamily Exoristinae. In general, relationships among taxa are well resolved, however, a number of relationships within the Dexiinae and between the Dexiinae and Phasiinae remain contentious. Evolutionary reconstruction of host associations indicates that, although some large clades exhibit host conservatism (e.g. Phasiinae), transitions among host orders are relatively frequent. Basal lineages tend to be associated with hemimetabolous or adult holometabolous host taxa and transitions to larval Holometabola, particularly within Lepidoptera, are associated with elevated rates of diversification
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Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in... more
Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genusPiperon insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecificPiperdiversity had measurable and site specific effects on herbivory, herbivorous insect richness, and plant mortality. The responses of these ecosystem-relevant processes to reduced intraspecificPiperrichness were often similar in magnitude to the effects of reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability were altered by both intra and interspecific richness in a site dependent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function and the importance of community and location specific contingencies in controlling function in complex tropical systems.
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Insect herbivory can vary from an inconsequential biotic interaction to a factor that contributes substantially to the diversity of plants and animals and overall interaction diversity. As herbivory is the result of numerous ecological... more
Insect herbivory can vary from an inconsequential biotic interaction to a factor that contributes substantially to the diversity of plants and animals and overall interaction diversity. As herbivory is the result of numerous ecological and evolutionary processes, including complex population dynamics and the evolution of plant defense, it has been difficult to predict variation in herbivory across meaningful spatial scales. In the present work, we characterize patterns of herbivory on plants in a species rich and abundant tropical understory genus (Piper) across forests spanning 44° of latitude in the Neotropics. We modeled the effects of geography, climate, resource availability, and Piper species richness on the median, dispersion, and skew of generalist and specialist herbivory. By examining these multiple components of the distribution of herbivory, we were able to determine factors that increase biologically meaningful herbivory at the upper ends of the distribution. Site level...
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Most insect species remain unknown and for most described species, we know nothing about their ecology and interactions. Understanding the structure of species interaction webs can provide insight into geographic patterns and ecological... more
Most insect species remain unknown and for most described species, we know nothing about their ecology and interactions. Understanding the structure of species interaction webs can provide insight into geographic patterns and ecological drivers of diversity, the stability of communities, and energy flow through ecological systems. We analysed a tachinid parasitoid‐caterpillar food web from the Ecuadorian Andes based on >70 000 caterpillar collections. Our goals were to assess how host taxon and feeding niche affects parasitism by flies and wasps, evaluate perceptions of broad diet breadth in tachinids, characterise the structure of the food web, and assess how sample size affects inferences about community structure. We found high levels of parasitism (>28%) by tachinid and wasp parasitoids and a rich tachinid community (279 spp.). Concealed caterpillars experienced low parasitism by tachinids and were more likely to be attacked by species with indirect oviposition. Indirect o...
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During a biodiversity survey in the forest of central Guyana, an adult male of the damselfly Hetaerina caja dominula Hagen in Selys was found parasitized by a tachinid larva. This constitutes the first record of a parasitoid on an adult... more
During a biodiversity survey in the forest of central Guyana, an adult male of the damselfly Hetaerina caja dominula Hagen in Selys was found parasitized by a tachinid larva. This constitutes the first record of a parasitoid on an adult odonate, and of an odonate as host of a tachinid larva. CO1 DNA sequencing of the larva placed it closest to the tachinid genera Actinodoria Townsend, Euhalidaya Walton, and Cryptomeigenia Brauer & Bergenstamm in the tribe Blondeliini (subfamily Exoristinae). Pictures are provided of the third instar fly larva protruding from the host, of its posterior spiracles, and of the first and second instar cephaloskeletons
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In a survey on hemp grown in western Kentucky we found an average of 27.8 CEW larvae per plant. We recorded 45% parasitism of CEW in these fields by two species of tachinid flies, Winthemia rufopicta and Lespesia aletiae. Most parasitized... more
In a survey on hemp grown in western Kentucky we found an average of 27.8 CEW larvae per plant. We recorded 45% parasitism of CEW in these fields by two species of tachinid flies, Winthemia rufopicta and Lespesia aletiae. Most parasitized larvae were third to sixth instars at the time of collection. We found up to 22 tachinid eggs per host larva, 89% of which typically bore between 1 and 5 eggs on the thorax. 45.9% of CEW bearing eggs died. The number of tachinid eggs per host was unrelated to host body mass, but both the number of tachinid eggs and caterpillar body mass influenced CEW survival. Larger CEW often survived parasitism and the number of fly eggs was negatively related to survival rate. The emergence of adult flies was positively correlated with the number of eggs, but no influence of the host size was found. High mortality of CEW larvae and the parasitoids developing within them in this system suggests that secondary chemicals (or poor nutrition) of the hemp diet may be...
Research Interests: Biology, Parasitism, Insects, Parasitoid, Noctuidae, and 3 moreTachinidae, Larva, and HELICOVERPA-ZEA
Calyptrate flies include about 22,000 extant species currently classified into Hippoboscoidea (tsetse, louse, and bat flies), the muscoid grade (house flies and relatives) and the Oestroidea (blow flies, bot flies, flesh flies, and... more
Calyptrate flies include about 22,000 extant species currently classified into Hippoboscoidea (tsetse, louse, and bat flies), the muscoid grade (house flies and relatives) and the Oestroidea (blow flies, bot flies, flesh flies, and relatives). Calyptrates are abundant in nearly all terrestrial ecosystems, often playing key roles as decomposers, parasites, parasitoids, vectors of pathogens, and pollinators. For oestroids, the most diverse group within calyptrates, definitive fossils have been lacking. The first unambiguous fossil of Oestroidea is described based on a specimen discovered in amber from the Dominican Republic. The specimen was identified through digital dissection by CT scans, which provided morphological data for a cladistic analysis of its phylogenetic position among extant oestroids. The few known calyptrate fossils were used as calibration points for a molecular phylogeny (16S, 28S, CAD) to estimate the timing of major diversification events among the Oestroidea. Re...
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The “Phylogeny of World Tachinidae” project kicked off with an operational meeting in June 2012 at the Canadian National Collection of Insects (CNC) in Ottawa. Goals were discussed, work plans prepared, and of course the destinations and... more
The “Phylogeny of World Tachinidae” project kicked off with an operational meeting in June 2012 at the Canadian National Collection of Insects (CNC) in Ottawa. Goals were discussed, work plans prepared, and of course the destinations and timing of major field expeditions were debated. During our three years of National Science Foundation funding we hope to gather fresh material for molecular analysis from all biogeographic regions of the world
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Diet breadth data: each row indicates the number of herbivores ("Count") with a given diet breadth at a given site. Further details (such as species or family-level diet breadth) under the "Data" column
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California’s central coast differs from many agricultural areas in the U.S., which feature large tracts of monoculture production fields and relatively simple landscapes. Known as the nations salad bowl, and producing up to 90% of U.S.... more
California’s central coast differs from many agricultural areas in the U.S., which feature large tracts of monoculture production fields and relatively simple landscapes. Known as the nations salad bowl, and producing up to 90% of U.S. production of lettuces, broccoli and Brussels sprouts, this region is a mosaic of fresh vegetable fields, coastal meadow, chaparral shrubs, riparian and woodland habitat. We tested for relationships between the percent cover of crops, riparian and other natural landscape vegetation and the species richness of parasitic wasps and flies foraging in crops, such as broccoli, kale and cauliflower, and interpreted our results with respect to the decrease in natural habitat and increase in cropland cover prompted by a local microbial contamination event in 2006. Our key results are that: (1) as cropland cover in the landscape increased, fewer species of parasitoids were captured in the crop field, (2) parasitoid richness overall was positively associated wit...
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Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful... more
Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful models for studying resource specialization, and the interaction between plants and herbivorous insects is one of the most common and consequential ecological associations on the planet. However, uncertainty persists regarding fundamental features of herbivore diet breadth, including its relationship to latitude and plant species richness. Here, we use a global dataset to investigate host range for over 7,500 insect herbivore species covering a wide taxonomic breadth and interacting with more than 2,000 species of plants in 165 families. We ask whether relatively specialized and generalized herbivores represent a dichotomy rather than a continuum from few to many host families and species attacked and whether diet breadth changes with increasing plant ...
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The family Tachinidae (“bristle flies”) is the most diverse and ecologically important group of insect parasitoids outside the parasitic wasps. It is among the most species rich families of flies (Diptera) and has experienced a recent... more
The family Tachinidae (“bristle flies”) is the most diverse and ecologically important group of insect parasitoids outside the parasitic wasps. It is among the most species rich families of flies (Diptera) and has experienced a recent adaptive radiation across the globe. We make use of a molecular phylogeny of the family to examine its rapid radiation and explore the traits of tachinid lineages that may have contributed to variation in their diversification. We apply a range of diversification analyses to assess the consistency and robustness of effects. We find that the Tachinidae are among the most rapidly diversifying families of animals. Six to eight clades of bristle flies, distributed across the phylogeny, exhibit strong evidence of accelerated diversification. Our results suggest that the use of holometabolous insect larvae, and specifically caterpillars (Lepidoptera), as hosts, is associated with increased diversification rates. However, these effects were inconsistent acros...
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It is well known that Tachinidae possess an extraordinary diversity not just in number of species, but also in terms of forms and life-history strategies. The family is notoriously difficult taxonomically for several reasons, some... more
It is well known that Tachinidae possess an extraordinary diversity not just in number of species, but also in terms of forms and life-history strategies. The family is notoriously difficult taxonomically for several reasons, some intrinsic and some due to the workers approach to them (O’Hara 2013). With over 1477 genera and 8592 species (O’Hara & Henderson 2020), it is difficult to gain a comprehensive knowledge of the family. The Tachinidae are characterized by recurrent rampant morphological homoplasies. This, along with the reliance of authors on a limited set of mainly chaetotaxic characters has led to historical taxonomic instability. Furthermore, there has been relatively little attention paid to immature stages and life histories in most taxonomic works. Despite the significant progress towards a classification that reflects the natural groupings within the family, there are still many limitations in the comprehension of the true relationships and diversity of tachinid taxa ...
Last year we documented in the pages of this newsletter an expedition to the Western Cape of South Africa in search of tachinids for the “Phylogeny of World Tachinidae” project (Cerretti et al. 2013). The project itself was discussed in a... more
Last year we documented in the pages of this newsletter an expedition to the Western Cape of South Africa in search of tachinids for the “Phylogeny of World Tachinidae” project (Cerretti et al. 2013). The project itself was discussed in a separate article (Stireman et al. 2013). In this issue of The Tachinid Times we discuss our expedition to eastern Australia in late 2013. This trip took place so recently that we have yet to fully identify our material and as a result cannot record here all of the taxa we collected. Instead, we will add the taxa to a webpage we have created about this expedition. The webpage is up and running and currently provides specific information about each collecting locality and includes images of most of the places. The webpage is located here:
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Many species of Tachinidae are important parasitoids of herbivorous insects in natural and managed systems; yet, little is known about tachinid diversity and how this diversity is distributed across space and time. Here, pan trap sampling... more
Many species of Tachinidae are important parasitoids of herbivorous insects in natural and managed systems; yet, little is known about tachinid diversity and how this diversity is distributed across space and time. Here, pan trap sampling was used to analyze the richness, microhabitat speciÞcity, and seasonal diversity of a tachinid parasitoid community in an oakÐ mesquite savanna of Southeastern Arizona. Twenty-four traps were set out monthly during the growing season in three different microhabitats (open grassland, woodland understory, and woodland canopy). In total, 79 tachinid species were sampled with an estimated total diversity of 122 species. Most individual traps sampled few species; yet, variation in species composition ( diversity) among sampling dates and microhabitats was high, accounting for 40Ð70% of the total diversity. SigniÞcant intraspeciÞc aggregation was not observed across traps or microhabitats, but it was observed across dates, suggesting that the activity o...
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world Tachinidae (see articles in The Tachinid Times 26 and 27). This collaborative project, involving myself, Jim O’Hara, Kevin Moulton, Pierfilippo Cerretti, Isaac Winkler and a long list of collaborating tachinidophiles was initiated... more
world Tachinidae (see articles in The Tachinid Times 26 and 27). This collaborative project, involving myself, Jim O’Hara, Kevin Moulton, Pierfilippo Cerretti, Isaac Winkler and a long list of collaborating tachinidophiles was initiated in 2012 with funding from the U.S. National Science Foundation. Our goal is to produce a robust phylogenetic framework of Tachinidae that can be used to inform tachinid taxonomy, systematics research, and the patterns of tachinid evolution. In previous issues of The Tachinid Times we summarized our progress to date in terms of obtaining taxa (e.g., Cerretti et al. 2013, O’Hara et al. 2014) and some of our preliminary phylogenetic findings (Stireman et al. 2013, Winkler et al. 2014). Here, we provide a brief update on some of our recent progress and associated products.