Daniel Martín-Vega

The distribution of adult blow-flies (Diptera: Calliphoridae) along an altitudinal gradient in Central Spain

Abstract The distribution of Calliphoridae along an altitudinal gradient was investigated in Central Spain using carrion-baited traps. Significant differences were found between elevation and mean abundances of almost all species of blow-flies. Several species of flies could be grouped according to their altitudinal preferences so that samples at high elevations are defined by Calliphora vomitoria and Calliphora vicina while samples at low elevations are defined by two thermophilous species: Lucilia sericata and Chrysomya albiceps. The remaining species show preferences for mid-elevations where wooded areas are more characteristic along the altitudinal gradient. Calliphora vomitoria and Chrysomya albiceps are the most abundant species representing the 87.74 % of all captures. Both species are spatially segregated along the altitudinal gradient. The changing patterns of abundance are discussed in relation to differences in climate conditions along the altitudinal gradient concluding that the environmental variables that influence the seasonality of many species also play an important role to explain the spatial distribution.

Sarcosaprophagous Diptera assemblages in natural habitats in central Spain: spatial and seasonal changes in composition.

The composition and spatial distribution of sarcosaprophagous Diptera assemblages were studied using carrion‐baited traps along a bioclimatic gradient of natural habitats in central Spain throughout the different seasons during 1 year. Calliphoridae and Muscidae were the most abundant families, accounting for, respectively, 41.9% and 35.1% of all Diptera specimens collected. Other abundant families were Heleomyzidae (8.4%), Sarcophagidae (6.9%) and Piophilidae (5.1%). Fly assemblage compositions differed among bioclimatic levels, with Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) being the dominant species in mesomediterranean habitats, Muscina levida (Harris) (Diptera: Muscidae) the dominant species in supramediterranean habitats, and Prochyliza nigrimana (Meigen) (Diptera: Piophilidae) the dominant species in oromediterranean habitats. Differences in assemblage composition were also found among seasons. Thermophobic species such as Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) and some species of Heleomyzidae were well represented during autumn, winter and spring in the three bioclimatic levels sampled. By contrast, thermophilic species such as Ch. albiceps and Lucilia sericata (Meigen) (Diptera: Calliphoridae) and most Muscidae and Sarcophagidae species were more abundant during summer and in mesomediterranean habitats located at lower elevations. Knowledge of the preferences of some species for certain habitats may be of ecological and forensic value and may establish a starting point for further research.

New piophilid in town: the first Palaearctic record of Piophila megastigmata and its coexistence with Piophila casei in central Spain

The genus Piophila Fallén (Diptera: Piophilidae) is known from only two species: Piophila casei (L.) is a major pest, a cosmopolitan species and is commonly used as a forensic indicator, whereas Piophila megastigmata McAlpine has until now only been recorded in a natural environment in South Africa. The present work reports the first occurrence of P. megastigmata in the Palaearctic region from specimens collected by carrion‐baited traps throughout different natural habitats of central Spain. Furthermore, the species was also collected with P. casei on corpses of domestic pigs used in a carrion succession study in a periurban habitat in central Spain. Both species occurred on carrion in different seasons, but P. megastigmata was more abundant than P. casei in autumn, arriving earlier at the carcasses and persisting for a longer period. The contrary pattern was observed in spring. The presence of P. megastigmata in different localities in central Spain and its coexistence with P. casei in a periurban habitat make it a potentially useful new tool for legal medicine in Europe; thus this species must be considered in forensic entomology studies.

The “Coffin Fly”Conicera tibialis (Diptera: Phoridae) Breeding on Buried Human Remains After a Postmortem Interval of 18 Years*

Abstract:  The “coffin fly,”Conicera tibialis Schmitz (Order: Diptera, Family: Phoridae), is well known for its frequent occurrence on buried corpses, in some cases after postmortem intervals of even 3–5 years. The present report describes the presence of a large amount of individuals of C. tibialis inside the coffin of a buried human corpse exhumed 18 years after death in central Spain. Adults, some of them newly emerged, and empty puparia were found in connection with the remains. Such postmortem interval is significantly longer than previously known for this species and raises the question on the current state of knowledge about the use of insects for estimating the postmortem interval in old, buried remains.

Spatiotemporal Distribution of Necrophagous Beetles (Coleoptera: Dermestidae, Silphidae) Assemblages in Natural Habitats of Central Spain

ABSTRACT The composition, spatial distribution, and seasonal fluctuations of necrophagous Coleoptera assemblages of families Dermestidae and Silphidae are studied along a bioclimatical level gradient of natural habitats in central Spain. Both families were collected with carrion-baited traps throughout a year. The main part of the individuals occurred in spring and summer, but silphids showed different seasonal patterns depending on the bioclimatical level. The assemblage composition also differs depending on the bioclimatical level with two distinguishable groups: one corresponding to mesomediterranean habitats and the other to supramediterranean and oromediterranean habitats. The most abundant species of Dermestidae are well represented at every bioclimatical level, whereas some species of Silphidae appear to have a preference for some habitats. Such differences in spatial and temporal patterns between both families could be because of their different food and carcass size preferences.

Preliminary data on carrion insects in urban (indoor and outdoor) and periurban environments in central Spain

Although most cases involving entomological evidence occur in urban environments and under indoor conditions, there is a lack of studies determining the insect fauna of forensic importance in those environments. In the current paper we provide the first data on the composition of the forensically important insect species occurring in periurban and both indoor and outdoor urban environments in central Spain. Insects were collected fortnightly by means of carrion-baited traps, uninterruptedly during one year. Most species and individuals were collected in the periurban site, whereas the indoor urban site showed the lowest number of species and captures. Moreover, the composition of species differed among environments and seasons. A few species occurred under both indoor and outdoor conditions, including the blowfly Calliphora vicina and some Sarcophagidae species. These preliminary results suggest interesting differences in the insect composition between environments and conditions which may be of forensic importance, and represent a first step to further research into the application of insects to forensic investigations in urban environments of central Spain.

Sex-biased captures of sarcosaprophagous Diptera in carrion-baited traps

Abstract The use of carrion-baited traps is a common and widely extended practice in the study of sarcosaprophagous Diptera. However, it implies different areas of bias, one of them being the different responses of males and females to carrion bait, which results in possible biased sex ratios in the captures. In the present study, the use of carrion-baited traps revealed significant female-biased captures in the families Calliphoridae, Muscidae, and Sarcophagidae, whereas the collected species of the families Piophilidae, Heleomyzidae, and Ulidiidae showed different patterns in the observed sex ratios. Possible explanations according to existing literature and the types of mating behaviors of the different families are discussed.

Looking into the puparium: Micro-CT visualization of the internal morphological changes during metamorphosis of the blow fly, Calliphora vicina, with the first quantitative analysis of organ development in cyclorrhaphous dipterans

Metamorphosis of cyclorrhaphous flies takes place inside a barrel‐like puparium, formed by the shrinking, hardening and darkening of the third‐instar larval cuticle. The opacity of this structure hampers the visualization of the morphological changes occurring inside and therefore a full understanding of the metamorphosis process. Here, we use micro‐computed tomography (micro‐CT) to describe the internal morphological changes that occur during metamorphosis of the blow fly, Calliphora vicina Robineau‐Desvoidy 1830 (Diptera: Calliphoridae) at a greater temporal resolution than anything hitherto published. The morphological changes were documented at 10% intervals of the total intra‐puparial period, and down to 2.5% intervals during the first 20% interval, when the most dramatic morphological changes occur. Moreover, the development of an internal gas bubble, which plays an essential role during early metamorphosis, was further investigated with X‐ray images and micro‐CT virtual sections. The origin of this gas bubble has been largely unknown, but micro‐CT virtual sections show that it is connected to one of the main tracheal trunks. Micro‐CT virtual sections also provided enough resolution for determining the completion of the larval‐pupal and pupal‐adult apolyses, thus enabling an accurate timing of the different intra‐puparial life stages. The prepupal, pupal, and pharate adult stages last for 7.5%, 22.5%, and 70% of the total intra‐puparial development, respectively. Furthermore, we provide for the first time quantitative data on the development of two organ systems of the blow fly: the alimentary canal and the indirect flight muscles. There is a significant and negative correlation between the volume of the indirect flight muscles and the pre‐helicoidal region of the midgut during metamorphosis. The latter occupies a large portion of the thorax during the pupal stage but narrows progressively as the indirect flight muscles increase in volume during the development of the pharate adult.

Back from the dead: Thyreophora cynophila (Panzer, 1798) (Diptera: Piophilidae) 'globally extinct' fugitive in Spain

We report on a sensational find in central Spain of six specimens of Thyreophora cynophila ( Panzer, 1798 ), a colourful, strange‐looking piophilid fly living on carcasses of big mammals in advanced stages of decay. Published data suggest that the species is known exclusively from central western Europe (Germany, Austria and France), and was observed last near Paris, France, in the late 1840s, i.e. more than 160 years ago. Accordingly, T. cynophila was placed in 2007 as the only dipteran on a list of recent European animals considered to be globally extinct. Collection‐based data from all 16 known extant specimens found in seven European natural history museums revealed a specimen without date of T. cynophila from Algiers, Algeria. The status of the three thyreophorine piophilids known from Europe is summarized. For the smallest species we reinstate the name Centrophlebomyia anthropophaga ( Robineau‐Desvoidy, 1830 ) with Centrophlebomyia orientalis Hendel, 1907 as a subjective junior synonym (syn.n.). We speculate as to why thyreophorines, and T. cynophila in particular, have evaded detection for so long.

The immature stages of the necrophagous fly, Prochyliza nigrimana : comparison with Piophila casei and medicolegal considerations (Diptera: Piophilidae)

Flies of family Piophilidae have been recorded as major pests in the food industry, as agents of human myiasis and typically associated with carcasses in advanced stages of decay, being thus important in forensic entomology. Despite that the cosmopolitan species Piophila casei is the most cited in entomological studies, many other piophilid species develop on both carrion and animal products from the food industry. One of those species is Prochyliza nigrimana, widely distributed throughout the Holarctic and Neotropical regions. In this study, the morphological features of the immature stages of P. nigrimana are described for the first time and compared with those of P. casei. The third-instar larvae and puparium of P. nigrimana are significantly shorter than those of P. casei; the contrary pattern is observed in egg length. The number and arrangement of the lobes of anterior spiracles, which had been used as a distinctive character of P. casei in some keys, are the same in both species. Morphological features of the cephaloskeleton (such as the general shape and the distance between the tips and the base of the mouth hooks/base of the mouth hooks ratio), the arrangement of anal segment in third-instar larvae and the appearance of the ventral creeping welts in the puparium are the main characters allowing for identification of both species.