Blow Fly Larvae Research Articles

Tracking Movement and Temperature Selection of Larvae of Two Forensically Important Blow Fly Species Within a “Maggot Mass”

The current study responds to the lack of understanding about the temperatures experienced by individual blow fly larvae within "maggot masses." The temperature selection of both aggregating (in a mass) and nonaggregating larvae was compared and their pattern of movement assessed. Infrared imaging determined the temperatures within a mass and in the vicinity of the constituent individual larvae, whose movements were tracked by dyeing their tissues red. Individual Chrysomya rufifacies larvae selected temperatures above 27°C, significantly higher than the temperature selected by Calliphora vicina larvae (24.5°C). However, this same difference was not seen within a mass, with both species selecting temperatures around 28°C. Larval movement in a mass was nonrandom, indicating that larvae actively select their position in a mass. Furthermore, larvae have a strong tendency to select the hottest part of a mass; therefore, maximum mass temperatures might provide a reliable proxy for the actual temperatures experienced by larvae.

Coordinated Mass Movements of Blow Fly Larvae (Diptera: Calliphoridae)

I watched blow fly (Diptera: Calliphoridae) larvae in western Maine that had consumed six animal carcasses so that I could identify patterns relating to when, how, and why they left the carcasses. The blow fly larvae stayed under the carcasses on hot, dry days, and then left them on rainy nights, traveling in random directions. Following several rainless days, the larvae left the carcasses at dawn on days with heavy dew and proceeded in a single 1-2-cm-wide column directly toward the rising sun. Species composition of one larvae column was nearly all or exclusively Phormia regina.

Prevalence of Bird Blow Fly Infestation in Nests of the European Blackbird (Turdus merula)

Abstract Larvae of bird blow flies are hematophagous intermittent parasites and they infect a variety of bird host species. In this study we focused on the prevalence of infestation in nests of Turdus merula in two sites with different climate. We collected 57 nests from Bratislava (Slovakia) which has a warmer climate and 37 nests from Leipzig (Germany) where there is cooler weather during the breeding season. There is no significant difference in the prevalence of infestation and in number of puparia between these two sites. The average number of infested nests was 18.68% while the average number of blow flies per nest was 10.0 ± 7.32 with 2.54 ± 1.83 larvae per nestling.

The analysis of temporal gene expression to estimate the age of forensically important blow fly pupae: results from three blind studies

The estimation of the minimum postmortem interval can be implemented by age estimation of corpse-associated primary colonizers such as the blow flies (Diptera: Calliphoridae). In cases where pupae represent the oldest stages found on a body, their age must be added to the duration of prepupal development to estimate the minimum postmortem interval. Although methods to age blow fly larvae have been well established using morphology, length or weight and age estimation of pupae has proved challenging. In a previous work, we quantified the changes in mRNA levels of four differentially expressed genes during the metamorphosis of Calliphora vicina pupae, hence representing molecular markers for pupal age (i.e., time elapsed since pupariation). Here, we demonstrate how these data can be used to estimate pupal age with inverse prediction. We present three blind studies conducted under various conditions and show that age of C. vicina pupae can be well estimated based on gene expression data. As these data are quantitative and can be processed automatically, gene expression has the potential to outperform morphological analysis in age estimation of forensically relevant blow fly pupae.

Larval Distribution and Behavior of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) Relative to Other Species on Florida Black Bear (Carnivora: Ursidae) Decomposing Carcasses.

Larval interactions of dipteran species, blow flies in particular, were observed and documented daily over time and location on five black bear carcasses in Gainesville, FL, USA, from June 2002 - September 2004. Cochliomyia macellaria (Fabricius) or Chrysomya megacephala (Fabricius) larvae were collected first, after which Chrysomya rufifacies (Macquart) oviposited on the carcasses in multiple locations (i.e., neck, anus, and exposed flesh) not inhabited already by the other blow fly larvae. Within the first week of decomposition, C. rufifacies larvae grew to ≥12mm, filling the carcasses with thousands of larvae and replacing the other calliphorid larvae either through successful food source competition or by predation. As a result, C. macellaria and C. megacephala were not collected past their third instar feeding stage. The blow fly species, C. megacephala, C. macellaria, Lucilia caeruleiviridis (Macquart), Phormia regina (Meigen), Lucilia sericata (Meigen), and C. rufifacies, completed two developmental cycles in the 88.5-kg carcass. This phenomenon might serve to complicate or prevent the calculation of an accurate postmortem interval.

Diapause-specific gene expression in Calliphora vicina (Diptera: Calliphoridae)—a useful diagnostic tool for forensic entomology

Estimating the post mortem interval (PMImin) by age determination of blow fly larvae has been well-established for moderate temperatures. Low-temperature developmental data is only available sparsely and usually does not take overwintering strategies into account. The blow fly Calliphora vicina hibernates by diapausing in the third larval stage extending the duration of this developmental stage up to several weeks or even months. As the diagnosis of the diapause status is not possible by morphological characteristics, PMImin estimations might be biased during the cold season if only based on age determination of third instar larvae of C. vicina. Molecular markers were searched for which allows one to identify diapause in larvae. Expression analysis of 19 genes was performed in diapausing and non-diapausing larvae. Three genes encoding for heat shock proteins (hsp23, hsp24 and hsp70) were found to be up-regulated distinctly in diapausing larvae and at 1day in non-diapausing larvae. If several larvae are subjected to an analysis, a high variance in the expression level of the gene encoding for the anterior fat body protein is a further marker for diapause. The present study proves the potential use of gene expression analysis as a suitable diagnosis tool for diapause in C. vicina.

Intranasal myiasis: A rare complication of transnasal skull base surgery

A 57-year-old woman with a history of atypical intracranial meningioma had undergone multiple craniotomies and endoscopic skull base procedures over several years. She presented most recently with nasal discharge consisting of intranasal larvae. Isolated organisms from the nasal cavity and maxillary sinus were identified as blow fly larvae (Calliphoridae family). The patient was treated with transnasal debridement and antibiotic therapy. The organisms were successfully eradicated and she is free from further signs of infection. Intranasal myiasis is an unusual complication of anterior skull base surgery.

Chronic Wounds, Biofilms and Use of Medicinal Larvae

Chronic wounds are a significant health problem in the United States, with annual associated costs exceeding $20 billion annually. Traditional wound care consists of surgical debridement, manual irrigation, moisture retentive dressings, and topical and/or systemic antimicrobial therapy. However, despite progress in the science of wound healing, the prevalence and incidence of chronic wounds and their complications are escalating. The presence & complexity of bacterial biofilms in chronic wounds has recently been recognized as a key aspect of non-healing wounds. Bacterial biofilms are sessile colonies of polymicrobial organisms (bacteria, fungus, etc.) enclosed within a self-produced exopolymeric matrix that provides high levels of tolerance to host defenses, antibiotics and antiseptics. Thus, there is a need for alternative therapies to reduce biofilms in chronic wounds. In this report, we present initial findings from in vitro experiments which show that larval debridement therapy with disinfected blow fly larvae (Phaenicia sericata) reduced total CFUs (6-logs) of planktonic and mature biofilms of Pseudomonas aeruginosa or Staphylococcus aureus grown on dermal pig skin explants by 5-logs after 24 hours of exposure, and eliminated biofilms (no measurable CFUs) after 48 hours of exposure.

Effect of the canopy complexity of trees on the rate of predation of insects

AbstractThe effect of the complexity of tree canopies on the effectiveness of biological control of tree‐dwelling insect herbivores by predators has been neglected. A complex canopy provides a greater variety of resources than a simple canopy, which may result in an increase in the abundance of both herbivores and predators in complex canopies and a higher predation rate. On the other hand, it may be more difficult to locate prey in trees with a complex canopy, which may lower the predation rate. The main aim of this study is to determine the relationship between predation rate and canopy complexity. We have used a system consisting of lime trees, larvae of blowflies as prey and naturally occurring predators (mainly birds and ants). The complexity of the canopy of 12 of the lime trees was reduced by pruning, and the predation rate was determined by recording the fate of prey pinned on each of the trees for 30 min several times during the course of a year. The predation rate was negatively associated with canopy complexity. We compare these results with those reported in the literature and contrary to the widely held view conclude that a negative relationship between predation rate and canopy complexity is a common phenomenon and can be expected to be reported in studies not only on ambush but also on predators that actively search for prey.

English

The blow fly is considered to be a medically-important insect worldwide. This review is a compilation of the currently known occurrence of blow fly species in Thailand, the fly’s medical importance and its morphological identification in all stages. So far, the 93 blow fly species identified belong to 9 subfamilies, including Subfamily Ameniinae, Calliphoridae, Luciliinae, Phumosiinae, Polleniinae, Bengaliinae, Auchmeromyiinae, Chrysomyinae and Rhiniinae. There are nine species including Chrysomya megacephala, Chrysomya chani, Chrysomya pinguis, Chrysomya bezziana, Achoetandrus rufifacies, Achoetandrus villeneuvi, Ceylonomyia nigripes, Hemipyrellia ligurriens and Lucilia cuprina, which have been documented already as medically important species in Thailand. According to all cited reports, C. megacephala is the most abundant species. Documents related to morphological identification of all stages of important blow fly species and their medical importance also are summarized, based upon reports from only Thailand. KeywordsBlow fly, Distribution, Identification, Medical Importance, Thailand International Journal of Parasitology Research ISSN: 0975-3702 & E-ISSN: 0975-9182, Volume 4, Issue 1, 2012 Introduction Thailand is a country located at the centre of the Indochina peninsula in Southeast Asia. It comprises 77 provinces that cover 6 regions by location and its hot and humid climate supports a variety of tropical ecosystems. Unlike the temperate zone, tropical ecosystems provide wider niches for the survival of organisms, which are thus able to support a much larger variety of plant, animal and microbe species. Blow flies form one of many insect groups that are commonly found in the country and their families are classified as follows: Kingdom Metazoa, Phylum Arthropoda, Class Hexapoda, Order Diptera, Suborder Brachycera and Family Calliphoridae. They are characterized typically as being metallic blue, green, purple, or non metallic in color and they vary in size [1]. Blow fly larvae serve as carrion feeders that play an important role in recycling organic materials in the ecosystem. Furthermore, adults have been reported as pollinators of mango flowers in Australia [2] and Taiwan [3]. Over 1,450 blow fly species are distributed over all continents in the world, except Antarctica [1]. Based on citation in this review, the first document related blow fly was reportedly found in 1976 [4] and the first taxonomic key for blow flies (subfamily Calliphoridae) in Thailand was documented by Tumrasvin et al, [5]. The first text book relating to medically-important blow fly species of Thailand was written in the Thai language in 2010 by Associate Professor Dr. Kom Sukontason and Associate Professor Dr. Kabkaew Sukontason [6]. Over the past 36 years, there have been many scientific articles that demonstrate blow fly occurrence in several parts of Thailand as well as the fly’s biological aspects and medical importance. Although this information has increased gradually, it is still scattered. Therefore, the objectives of this review were to gather and update all information on blow flies, based upon scientific reports from only Thailand and the experience of this author. This review emphasized on mainly 3 aspects, including (i) the occurrence of blow fly species, (ii) morphological identification of all stages and (iii) their medical imCitation: Nophawan Bunchu (2012) Blow fly (Diptera: Calliphoridae) in Thailand: Distribution, Morphological Identification and Medical Importance Appraisals. International Journal of Parasitology Research, ISSN: 0975-3702 & E-ISSN: 0975-9182, Volume 4, Issue 1, pp.-57-64. Copyright: Copyright©2012 Nophawan Bunchu. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

Differential gene expression during metamorphosis: a promising approach for age estimation of forensically important Calliphora vicina pupae (Diptera: Calliphoridae)

Necrophagous blow fly larvae can provide accurate estimates of the minimum postmortem interval in death investigations. During larval development, predictable morphological changes occur and measurements of weight, length, and width are compared to species-specific growth curves for reliable age estimates. However, aging blow fly pupae is more challenging because morphological and anatomical changes are not visible with the naked eye. Thus, delicate preparation of the pupae or rearing to the adult stage seems unavoidable. Conversely, metamorphosis evokes a remodelling of the larval shape to adult structures, and gene expression analysis potentially serves as a molecular tool to mirror the ageing process of a pupa. The present study focuses on the differential expression of two newly described, arbitrarily named genes (15_2, 2014192) and two previously identified genes (actin, arylphorin receptor) during Calliphora vicina (Diptera: Calliphoridae) metamorphosis. Quantification through real-time PCR revealed significant up- and downregulation of these transcripts found to be temperature dependent and age specific, hence, a new possibility to age forensically important blow fly pupae.

The first report of pigeon maggot, Protocalliphora sp. (Diptera: Calliphoridae) from domestic pigeons in Iran

Following the report of deaths in a few flocks of domestic pigeons in the Mazandaran province, Northern Iran, we conducted an investigation on the live and dead pigeons. We found reddish larvae on the skin of the pigeons and after close analysis of the mouthparts and spiracles; they were identified as second instar larvae of Protocalliphora sp. These blow fly larvae are obligate haematophagous parasites, highly pathogenic and cause high mortality in birds. Mortality in the infected flocks was approximately 25% and mainly among nestlings and young birds. Infected birds were treated with propoxur powder which was very effective, following which no additional mortalities or larvae were found. This is the first report of this myiasis agent in Iran.

A Fly in the Ointment: Evaluation of Traditional Use of Plants to Repel and Kill Blowfly Larvae in Fermented Fish

IntroductionIn rural areas in Laos, fly larvae infestations are common in fermenting fish. Blowflies (Chrysomya megacephala, Diptera: Calliphoridae) are attracted to oviposit (and/or larviposit) onto fermenting fish which results in infestations with fly larvae. Knowledge of traditional use of plants to repel larvae during the production of fermented fish is common and widespread in Lao PDR.Research QuestionsHow effective are the most salient species in repelling, and killing fly larvae in fermenting fish?Material and MethodsThe three plant species most frequently reported to repel fly larvae during an ethnobotanical survey throughout Lao PDR were tested for repellence and larvicidal activity of fly larvae infesting fermented fish. The lethality and repellence of Tadehagi triquetrum (L.) H. Ohashi (Fabaceae), Uraria crinita (L.) Desv. ex DC. (Fabaceae) and Bambusa multiplex (Lour.) Raeusch. ex Schult. & Schult. f. (Poaceae) were tested in an experimental design using fermenting fish in Vientiane, Lao PDR.ResultsThe repellent effect of fresh material of T. triquetrum and U. crinita, and the larvicidal effect of fresh B. multiplex, is significantly more effective than that of dried material of the same species, and the total effect (repellence and larvicidal effect combined) for each of the three species was significantly more effective for fresh than for dry material. Fresh material of T. triquetrum, U. crinita, or B. multiplex added on top of the fermenting fish repelled 50%, 54%, 37%, and killed 22%, 28%, and 40% of fly larvae. The total effect was not significantly different per species at 72%, 82%, and 77%, respectively.Discussion and ConclusionsThe three most salient species are effective in repelling and killing fly larvae in the production of fermented fish, and may be essential to augment food safety during traditional fermentation in open jars.

Cuticular muscle attachment sites as a tool for species determination in blowfly larvae

First results of a new method for species determination in third instar larvae of saprophagous blowflies are introduced. Cuticular attachment sites of a limited number of transversal muscles are visualized for light microscopic analysis. After removing the muscles and staining the cuticle, the attachment sites become visible as laterally symmetrical segmental clusters of dark dots. The combined patterns of five such clusters, located in the second, third and fourth segments, show sufficient differences to allow reliable separation of externally very similar larval Lucilia sericata and Lucilia illustris as well as Calliphora vomitoria and Calliphora vicina, the most common saprophagous blowfly species in Europe. Species determination even in poorly conserved, discoloured and fragmented blowfly larvae becomes possible with this new method. The method can primarily be applied for postmortem interval (PMI) calculations in forensic entomology. Interspecific morphological similarity of the larvae and differences in growth rate make species determination an essential requisite for an exact PMI calculation.

When Entomological Evidence Crawls Away: Phormia regina en masse Larval Dispersal

In criminal and civil legal investigations the forensic entomologist usually assists in providing an estimate of the postmortem interval, which closely couples with the time or period of insect activity. A minimum period of insect activity is often interpreted and estimated by dipteran larval developmental age of the oldest specimens collected at a crime scene and/or autopsy. In entomological evidence protocols investigators are recommended to search a 2-10 m perimeter area for the oldest larvae that may have begun to disperse away from the body for burial and pupation. In this study, we described a case of a large aggregate (> 90% larvae) en masse postfeeding dispersal of blow fly larvae away from replicate swine carcasses serving as models of human decomposition. Larval dispersal was evaluated for a spring and a summer trial, with en masse characteristics only occurring during the latter. This en masse dispersal occurred in five out of six replicate carcasses and masses moved from 2 to 26 m away. These data and observations suggest the importance of performing searches > 10 m from human remains for entomological evidence at crime scenes. By missing the oldest larvae at a crime scene, interpretation of entomological evidence can be compromised and erroneous. Based on these data and observations we recommend the crime scene investigators and researchers consider increasing the search radius around crime scene remains to increase the likelihood that the oldest larvae have been collected for analysis.

EFFECTS OF THALLIUM ON THE LARVAL DEVELOPMENT OF LUCILIA SERICATA MEIGEN 1826 AND PMI ESTIMATION

Determination of larval growth rate of and forensic analysis of the age of Calliphoridae larvae on a corpse are useful evidence in legal investigations for the estimation of exact death time and time duration after death; post mortem interval. However many factors, such as temperature, tissue type and contamination of drugs and toxins, effect larval development of blow fly larvae and consequently the estimation of post mortem interval. The present study examined the larval growth rate of a forensically important blow fly species, Lucilia sericata Meigen 1826 in different concentrations (0,12; 0,25; 0,50; 1 and 2 μg/g) of toxic heavy metal Thallium under controlled laboratory conditions. Body length and weight, death ratio of larvae and pupa between experimental and control groups were compared. Results demonstrated that the development rate of larvae between uncontaminated and contaminated diets varies significantly. In short, they molted later, reached maximum length more slowly and sometimes produced significantly smaller pupae in contaminated food source. These results emphasized that the importance of determining the contamination rate of toxins in tissue for the forensic entomologist, while using development rates from standard curves based on larvae fed non-contaminated mediums.

Predatory Behaviors ofCreophilus maxillosus(L.) (Coleoptera: Staphylinidae) Towards the Invasive Blow FlyChrysomya rufifacies(Macquart) (Diptera: Calliphoridae)

Previous carrion studies have described the disruptive behaviors of the invasive hairy maggot blow fly, Chrysomya rufifacies (Macquart), towards predatory necrophilous beetles such as the hairy rove beetle, Creophilus maxillosus (L.). Such studies stated that C. rufifacies larvae repelled native blow fly larvae, predaceous beetles, and ants away from vertebrate carcasses. Our main research objective was to test the predatory behaviors and feeding patterns of C. maxillosus adults towards two blow fly species, C. rufifacies (invasive species) and the secondary screwworm, Cochliomyia macellaria (F.) (native species), in a laboratory setting. Starved C. maxillosus were placed into individual 0.47-L clear plastic cups, provided one third instar blow fly, and observed continuously for two hours. Predatory and feeding responses were recorded as: 1) alive, not eaten; 2) killed, not eaten; 3) killed, consumed partially; or 4) killed, consumed entirely. In total, 342 observations were performed, including 191 and 151 replicates of one beetle and one larva of C. rufifacies or C. macellaria, respectively. Chi-square test of independence was highly significant (P < 0.0001) for both analyses, and the likelihood of C. maxillosus ‘killing and not eating’ a fly larva versus ‘killing and eating’ the prey was highly significant per fly species (P < 0.0001). Additional observations on predatory and defensive behaviors, handling and feeding patterns, and beetle fecundity are discussed.

Detection of Gunshot Residue in Blowfly Larvae and Decomposing Porcine Tissue Using Inductively Coupled Plasma Mass Spectrometry (ICP‐MS)*

Blowfly larvae and porcine tissue contaminated with gunshot residue (GSR) were collected during summer and winter months, over a 37-day and a 60-day sampling period, respectively. Wound samples were microwave-digested and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for the detection of antimony, barium, and lead. During summer, the 37-day sampling period encompassed all stages of decomposition, except skeletonization. The three elements were detected in larvae only on days 3 and 4 after death but were detected at significant levels in tissue samples throughout the entire sampling period. In winter, no significant decomposition was observed throughout the 60-day sampling. Although temperatures were too low for blowfly activity, the three elements were detected in the tissue samples at relatively constant, significant levels. Hence, GSR determination in tissue was more dependent on decomposition stage rather than time since death.

Use of Megaselia scalaris (Diptera: Phoridae) for post-mortem interval estimation indoors

In forensic entomology, the determination of a minimum post-mortem interval often relies on the determination of the age of blow flies, since they are generally among the first colonisers of a corpse. In indoor cases, the blow flies might be delayed in arriving at the corpse. If the windows are closed, the attracting odour is confined and does not reach the flies, so that it takes longer for them to find and access the corpse. If blow flies are delayed or are unable to reach a corpse lying inside a room, much smaller flies (Phoridae) can enter and deposit their offspring. We present three indoor-case scenarios in which age determination of Megaselia scalaris gave much more accurate estimates of the minimum post-mortem interval than from larvae of Calliphoridae. In all cases, the estimated age of the blow fly larvae was between 10 and 20 days too short compared to the actual PMI. Estimation of the PMI using developmental times of Phoridae can be a good alternative to the determination of blow fly larval age, since Phoridae are found inside apparently enclosed environments (sealed plastic bags or rooms with closed doors and windows) and also at temperatures at which blow flies are inactive.

Studies on Larval Dispersal in Two Species of Blow Flies (Diptera: Calliphoridae)

The blow fly larvae leave the food source after reaching maturity, and begin to disperse in order to fi nd suitable places for pupariation, a process commonly called postfeeding larval dispersal. Some important aspects of this process were studied by allowing the postfeeding larvae of Chrysomya megacephala (Fabricius) and Chrysomya rufi facies (Macquart) to disperse from the center of a circular arena. The arena was divided into 4 circles starting from the center in order to determine the location of each pupa. The relationship between distance from the center and the weight of each pupa was evaluated statistically. It was observed that the lighter larvae tend to move longer distances. The greatest concentration of pupae was found in distances lesser than 100 cm in both the species though it was more evident in case of C. rufi facies. The study of this dispersal process can be important while estimating the minimum postmortem interval (PMI) of human cadavers during forensic investigations.