Pollenia rudis y otros califóridos (Diptera: Calliphoridae) capturados en el oriente del municipio de Torreón, Coahuila, México

El objetivo del presente trabajo fue estudiar la dipterofauna asociada a las palmas W. robusta y ampliar el conocimiento sobre la taxonomía, hábitos y distribución de moscas de la familia Calliphoridae. Durante la primavera de 2018, se llevaron a cabo muestreos en palmas sanas, enfermas y muertas en la parte oriente de la ciudad de Torreón, Coahuila. El monitoreo se realizó mediante la colocación de 15 trampas con etanol al 70%. Se colectaron en total 51 individuos; de los cuales, el 65% pertenecieron a la familia Calliphoridae (33 especímenes), 25% a la familia Sarcophagidae (13 especímenes), el 4% a la familia Anthomyiidae y 6% no fueron identificadas. Se documentó por primera vez en el municipio de Torreón la presencia de Pollenia rudis Fabricius y Phormia regina Meigen, ambas especies pertenecientes a la familia Calliphoridae.

Flies Do Not Jump to Conclusions: Estimation of the Minimum Post-Mortem Interval for a Partly Skeletonized Body Based on Larvae of Phormia regina (Diptera: Calliphoridae)

Skeletonization is often perceived as an indicator of long post-mortem intervals. The finding of feeding larvae of first colonizers, on the other hand, indicates days. We present a case in which both findings were present. Larvae of Phormia regina, aged 9 days, and skeletonization of the head and part of the thorax were both found on an unidentified female body. Identification of dentures eventually led to resolution of the case and a confession, which settled the seeming contradiction in favor of forensic entomology.

Impact of Comingled Heterospecific Assemblages on Developmentally Based Estimates of the Post-Mortem Interval—A Study with Lucilia sericata (Meigen), Phormia regina (Meigen) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae)

Estimates of the minimum post-mortem interval (mPMI) using the development rate of blow flies (Diptera: Calliphoridae) are common in modern forensic entomology casework. These estimates are based on single species developing in the absence of heterospecific interactions. Yet, in real-world situations, it is not uncommon to have 2 or more blow fly species developing on a body. Species interactions have the potential to change the acceptance of resources as suitable for oviposition, the timing of oviposition, growth rate, size and development time of immature stages, as well as impacting the survival of immature stages to reach adult. This study measured larval development and growth rate of the blow flies Lucilia sericata (Meigen, 1826), Phormia regina (Meigen, 1826) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) over five constant temperatures (15, 20, 25, 30, 35 °C), in the presence of conspecifics or two-species heterospecific assemblages. Temperature and species treatment interacted such that L. sericata larvae gained mass more rapidly when in the presence of P. regina at 20 and 30 °C, however only developed faster at first instar. At later stages, the presence of P. regina slowed development of L. sericata immatures. Development time of C. vicina immatures was not affected by the presence of P. regina, however larvae gained mass more slowly. Development time of P. regina immatures was faster in the presence of either L. sericata or C. vicina until third instar, at which point, the presence of L. sericata was neutral whereas C. vicina negatively impacted development time. Phormia regina larvae gained mass more rapidly in the presence of L. sericata at 20 °C but were negatively impacted at 25 °C by the presence of either L. sericata or C. vicina. The results of this study indicate that metrics such as development time or larval mass used for estimating mPMI with blow flies are impacted by the presence of comingled heterospecific blow fly assemblages. As the effects of heterospecific assemblages are not uniformly positive or negative between stages, temperatures or species combinations, more research into these effects is vital. Until then, caution should be used when estimating mPMI in cases with multiple blow fly species interacting on a body.

Visualization of antennal lobe glomeruli activated by nonappetitive D-limonene and appetitive 1-octen-3-ol odors via two types of olfactory organs in the blowfly Phormia regina

Appetite or feeding motivation relies significantly on food odors. In the blowfly Phormia regina, feeding motivation for sucrose is decreased by the odor of d-limonene but increased by the odor of 1-octen-3-ol odor. These flies have antennal lobes (ALs) consisting of several tens of glomerular pairs as a primary olfactory center in the brain. Odor information from different olfactory organs—specifically, the antennae and maxillary palps—goes to the corresponding glomeruli. To investigate how odors differently affect feeding motivation, we identified the olfactory organs and glomeruli that are activated by nonappetitive and appetitive odors. We first constructed a glomerular map of the antennal lobe in P. regina. Anterograde fluorescence labeling of antennal and maxillary afferent nerves, both of which project into the contralateral and ipsilateral ALs, revealed differential staining in glomerular regions. Some of the axonal fiber bundles from the antennae and maxillary palps projected to the subesophageal ganglion (SOG). We visualized the activation of the glomeruli in response to odor stimuli by immunostaining phosphorylated extracellular signal-regulated kinase (pERK). We observed different glomerulus activation under different odor stimulations. Referring to our glomerular map, we determined that antennal exposure to d-limonene odor activated the DA13 glomeruli, while exposure of the maxillary palps to 1-octen-3-ol activated the MxB1 glomeruli. Our results indicated that a nonappetitive odor input from the antennae and an appetitive odor input from the maxillary palps activate different glomeruli in the different regions of ALs in the blowfly P. regina. Collectively, our findings suggest that compartmentalization of glomeruli in AL is essential for proper transmission of odor information.

Competition Among Three Forensically Important Blow Fly Species (Diptera: Calliphoridae): Phormia regina, Lucilia sericata, and Chrysomya rufifacies

Avoiding competition is thought to explain insect successional patterns on carrion, but few studies have looked at competition directly. We use replacement series experiments with three species of blow flies: Phormia regina (Meigen) (Diptera: Calliphoridae), Lucilia sericata (Meigen) (Diptera:Calliphoridae), and Chrysomya rufifacies (Macquart) (Diptera:Calliphoridae) to characterize competitive relationships. From experimental results, P. regina showed a significant competitive advantage over L. sericata. Infestation of carrion differs between L. sericata and P. regina; specifically, L. sericata oviposits on carrion without any delay, while P. regina typically delays oviposition. Our findings are consistent with the notion that differences in oviposition times represent a mechanism for L. sericata to avoid potential competition. Competition by C. rufifacies differs since C. rufifacies, in the event of a limited food supply, will prey on other maggot species. In replacement series experiments, C. rufifacies killed all P. regina in mixed treatments, representing an ultimate competitive advantage. In the United States, these two species do not often overlap because of differences in seasonal distribution. However, with climate change, phenological separation may grow less distinct. Surprisingly, in replacement series experiments with C. rufifacies and L. sericata, no competitive interactions were observed. In other studies, L. sericata has been shown to form clusters away from predaceous maggots, allowing improved survival, which may account for the absence of predation by C. rufifacies. Finally, this study shows that replacement series models are useful in measuring competition, supporting the notion that interspecific competition between necrophagous insect species may have driven life history traits of those species.

The oncometabolite L-2-hydroxyglutarate is a common product of Dipteran larval development

ABSTRACTThe oncometabolite L-2-hydroxyglutarate (L-2HG) is considered an abnormal product of central carbon metabolism that is capable of disrupting chromatin architecture, mitochondrial metabolism, and cellular differentiation. Under most circumstances, mammalian tissues readily dispose of this compound, as aberrant L-2HG accumulation induces neurometabolic disorders and promotes renal cell carcinomas. Intriguingly, Drosophila melanogaster larvae were recently found to accumulate high L-2HG levels under normal growth conditions, raising the possibility that L-2HG plays a unique role in insect metabolism. Here we explore this hypothesis by analyzing L-2HG levels in 18 insect species. While L-2HG was present at low-to-moderate levels in most of these species (<100 pmol/mg; comparable to mouse liver), Dipteran larvae exhibited a tendency to accumulate high L-2HG concentrations (>100 pmol/mg), with the mosquito Aedes aegypti, the blow fly Phormia regina, and three representative Drosophila species harboring concentrations that exceed 1 nmol/mg – levels comparable to those measured in mutant mice that are unable to degrade L-2HG. Overall, our findings suggest that one of the largest groups of animals on earth commonly generate high concentrations of an oncometabolite during juvenile growth, hint at a role for L-2HG in the evolution of Dipteran development, and raise the possibility that L-2HG metabolism could be targeted to restrict the growth of key disease vectors and agricultural pests.

Analysis of Alternative Food Sources for Rearing Entomological Evidence

Forensic entomology is a well-established tool for evaluating the death, or abuse, of a person. Insect evidence provides valuable information as related to time of colonization and movement of remains from one location to another. Blow flies (Diptera: Calliphoridae) are commonly found on human remains throughout most stages of decomposition, and when entomological evidence is collected these taxa tend to be the most numerous. However, very few crime laboratories across the country have collection and rearing protocols for these forensically important insects. A lack of knowledge in collection techniques and limited access to an appropriate food source are the main reasons for absence in adequate collection and rearing protocols. Thus, when crime scene investigators or pathologists collect insects, they are often mishandled (e.g., placed into containers with no air holes, no food, or a food source that is not sustainable for their development). To address this issue, we analyzed easily accessible and cost-efficient alternative food sources for blow flies; specifically, tuna and wet cat food compared to beef liver (control). Survivorship and development were examined for each food source using the blow flies Phormia regina (Meigen) (Diptera: Calliphoridae) and Cochliomyia macellaria (Fabricus) (Diptera: Calliphoridae). These findings provide an overview of possible alternatives that could be used as a sustainable food source in crime laboratories when immediate action from a forensic entomologist cannot be obtained.

Characterization of the Volatiles’ Profiles of the Eggs of Forensically Relevant Lucilia sericata and Phormia regina (Diptera: Calliphoridae) Blow Flies by SPME-Facilitated GC-MS

The attraction of necrophagous insects, particularly blow flies, to corpses and carrion is of ecological, economic, and agricultural importance, although the mechanisms by which it occurs are not well understood. Much of the published research on blow fly attractants has focused on volatiles emitted from carrion surrogates, but little attention has been given to the possibility that blow fly eggs themselves may emit chemical cues that are responsible for conspecific and heterospecific insect attraction. In this study, the headspace volatiles emitted from eggs representing two aggregated oviposition events that were collected 1 mo apart from two species of the Calliphoridae family (Order: Diptera), Lucilia sericata (Meigen), and Phormia regina (Meigen) were analyzed via solid-phase microextraction-facilitated GC-MS. The volatiles’ profiles were found to be consistent between samples representing the same species, but unique between the two species. Over 100 molecules covering a wide range of compound classes that included alcohols, aldehydes, esters, amines, ketones, and organosulfur compounds were identified. The profile of volatiles emitted from the L. sericata eggs contained several alkanes and aldehydes, whereas salient features of the P. regina headspace included numerous esters and ketones. Between the two species, 42 compounds were shared, several of which were carboxylic acids. Little overlap between the range of compounds detected and those reported to be emitted from decomposing remains was observed.