Paloma Martins Mendonça

Identification of fly eggs using scanning electron microscopy for forensic investigations

Forensic entomology is the science that studies the role of insects in decomposing corpses and one of the most common uses is to estimate the post-mortem interval (PMI) based on insect activity on a decomposing body. Usually, flies are the first insects to reach a carcass and are able to oviposit on carrion within a few hours after death. Scanning electron microscopy (SEM) gives detailed information about morphological characters helping to identify the immature forms of flies and consequently serves as a tool in crime scene investigations. Sometimes, only eggs and larvae are found in corpses. Some dipteral species are important because their larvae develop in organic matter. The aim of this study is to identify eggs of species of forensic importance, such as Chrysomya megacephala, Chrysomya putoria, Lucilia cuprina, Lucilia eximia and Ophyra aenescens, using scanning electron microscopy (SEM). C. megacephala had no anastomosis or holes at the top of the islands and C. putoria had few anastomoses and no holes, whereas L. eximia and O. aenescens were found to have anastomoses and holes and L. cuprina had only anastomoses. The median area was bifurcated anteriorly in C. megacephala, L. eximia and O. aenescens and rounded in C. putoria and L. cuprina. Also the sculptures observed in the chorionic cells, the length and the way that median area ends up posteriorly are characteristics of great diagnostic value to identify muscoids of forensic importance.

Ultramorphological characteristics of immature stages of Chrysomya albiceps (Wiedemann 1819) (Diptera: Calliphoridae), a fly specie of forensic importance.

Forensic entomology is an area of science that serves as a tool in crime scene investigations. Usually, flies are the first insects to reach a dead body and can oviposit just a few hours after arrival. Therefore the knowledge of immature stages is essential for correct identification of the species found on corpses. Scanning electron microscopy gives detailed information about morphological characters helping to identify the immature forms and consequently serves as a tool in crime scene investigations. C. albiceps is a very important fly for forensic entomologists because its larvae are almost always present on a dead body and it is facultative predators and therefore can alter the composition of species present at the carcass. The aim of this study is to identify eggs, larvae, and puparia of C. albiceps using SEM. Eggs were elongated with the anterior region ending in a “Y” shape and the posterior end was tapered. The micropyle was a well‐adorned orifice with some projections around it. The first instar larva was composed of 12 segments separated by spines. Only one spiracular opening could be seen at the posterior spiracle. Body tegument was smooth and tubercles were not seen. Antennae and maxillary palps were visible. Second and third larval instars were very similar to first instar, except for the presence of anterior spiracle. However, body tegument was composed of net‐like patches and tubercles were visible. Tubercles present at the third instar larvae were robust and erect. Puparia showed a retracted cephalic region and curved tubercles. Microsc. Res. Tech. 73:779–784, 2010.

Effects of latex from “Amapazeiro” Parahancornia amapa (Apocynaceae) on blowfly Chrysomya megacephala (Diptera: Calliphoridae) post-embryonic development

Nowadays, insect control is usually carried out using chemical insecticides, but insect resistance and other negative side effects have prompted the search for alternatives. Biopesticides provide a positive alternative to synthetic pesticides because they have low impact on the environmental, low toxicity to humans and low costs among other advantages. This research was carried out to evaluate the activity of Parahancornia amapa (Huber) Ducke (Apocynaceae) lyophilized latex on the post embryonic development of Chrysomya megacephala (F.) (Diptera: Calliphoridae). Larvae treated with 1.0% latex showed a shorter post embryonic development period (larval, pupal and newly hatched larvae to adult); whereas larvae treated with 3.0% latex provoked a prolongation of these periods. Viability (53%) was also very low at the newly hatched larvae to adult period for larvae treated with 3.0% latex, indicating that latex from P. amapa at high concentrations could change C. megacephala post embryonic development.

Ultrastructure of immature stages of the blowfly Chrysomya putoria (Wiedemann, 1818) (Diptera: Calliphoridae)

Forensic entomology is an area of science that serves as a tool in crime scene investigations. Usually, flies are the first insects to reach a carcass and can oviposit just a few hours after arrival. Therefore, the knowledge of immature stages is essential for correct identification of the species found on corpses. Scanning electron microscopy (SEM) gives detailed information about morphological characters helping to identify the immature forms of flies. Chrysomya putoria (Wiedemann) is a very important fly for forensic entomology, because it has high population densities and is easily found in colonizing carcasses, moreover, it is also a possible causative agent for secondary myiasis. The aim of this study is to identify larvae and puparia of C. putoria using SEM. The first instar larvae were composed of 12 smooth segments separated by spines. Antennae and maxillary palps were visible. Anterior spiracle was absent and only one spiracular opening could be seen at the posterior spiracle. Second and third larval instars were similar to first instar, except for the presence of anterior spiracle that is composed by 11–12 spiracular ramifications. At the anal segment, two spiracular openings were found in second instars and three openings in third instar larvae. Puparia showed a retracted cephalic region and none of the head structures were visible. Microsc. Res. Tech. 2011.,

Ultrastructure of larvae and puparia of the blowfly Chrysomya megacephala (Diptera: Calliphoridae)

Chrysomya megacephala is a forensic important fly, and its immature forms also cause myiasis. The adults are the first insects to reach a carcass and can oviposit just a few hours after arrival. Therefore, the knowledge of immature stages of flies is essential for correct identification of the species found on corpses. Scanning electron microscopy (SEM) gives detailed information on the morphological characters that can help identify the immature forms of flies. The aim of this study is to identify larvae and puparia of C. megacephala using SEM. The larval instar body of C. megacephala is similar at all instars. The integument is smooth with small spines located at the limit of all segments. The cephalic region has a group of robust spines with one or two tips. The puparia are very similar to third instar larvae, except for the cephalic structures that are retracted. The integument shows the wrinkles from the third instar larvae and posterior spiracle disc with three spiracular openings localized on the top of an elevation. In conclusion, SEM provides some characteristics to distinguish among Chrysomya species that could help entomologists to identify immature found on corpses. Microsc. Res. Tech. 2012.

Biological Activity of Yangambin on the Postembryonic Development of Chrysomya megacephala (Diptera: Calliphoridae)

Abstract Phytochemicals endowed with hormonal, antihormonal, or toxic activity are potential agents for insect control. Thus, we became interested in testing Brazilian plant metabolites on Chrysomya megacephala (F.) (Diptera: Calliphoridae), a public health menace that is one of the most prevalent flies in Brazilian urban areas. We tested the lignan yangambin, from the leaves of Ocotea duckei Vattimo (Lauraceae). Topical treatment of eggs and first instars with yangambin as well as feeding larvae a yangambin-treated diet resulted in inhibition of postembryonic development, morphological alteration, and oviposition reduction.

Ultrastructure of immature stages of Peckia (Euboetcheria) collusor (Diptera: Sarcophagidae)

Peckia (Euboettcheria) collusor (Diptera: Sarcophagidae) is a necrophagous insect and represents an important role in forensic entomology, as it is always collected at animal/human corpses. Immature sarcophagids are extremely similar in morphological aspects and can be found colonizing both fresh and mummified bodies. Flesh fly larvae are reported to cause accidental myiasis. In the Neotropical regions little is known about the ultrastructure of immature stages of Sarcophagidae. Scanning electron microscopy gives detailed information on the morphological characters, which can help identify the immature forms of the flies. The aim of this study is to identify larvae and puparia of P. (E.) collusor using this methodology. The integument with net-like patches and the shape and disposition of intersegmental spines of the larval instars can be used to distinguish this flesh fly larva. The number of spiracular ramifications is variable at larval instars. The puparia are very similar to third instar larvae, except for the cephalic structures that are retracted. In conclusion, scanning electron microscopy could help entomologists to identify the immature forms of P. (E.) collusor in forensic investigations and consequently serves as a tool in crime scene investigations.

Rearing Chrysomya megacephala on artificial diets composed of varying concentrations of albumin

Larvae of the blowfly Chrysomya megacephala were reared on an artificial diet composed of five different concentrations of albumin (2, 4, 6, 8 and 10%) and the control group was fed on putrid bovine meat. No larvae developed in the 2 and 10% albumin concentrations. The period from newly hatched larvae to adults reared on 4, 6 and 8% albumin was 13.1, 13.1 and 13.6 days, respectively, whereas for the control group, it was 11.2 days. Concentrations of 4, 6 and 8% albumin proved viabile for larval periods of 29.3, 44.0 and 57.3%, respectively, whereas for the control group, it was 77.3%. Pupal viability was 77.3, 36.4 and 83.7%, while for the control group, it was 84.5%; the newly hatched larvae to adult viability was 21.3, 16.0 and 48.0%, respectively, and for the control group, it was 65.3%.

Ultrastructural studies of some character of Diptera (Muscidae) of forensically importance

Insects are important in the decomposition of cadavers. In the field of forensic entomology, the taxonomic identification is essential to proceed to any procedure. The use of these insects in medico criminal investigation is the object of forensic entomological studies; the flies are generally attracted to cadavers and one of the most important contributions is to estimate the postmortem interval. The scanning electron microscopy, which allows rapid and accurate identification of character could be used to help identify different species of forensics flies, has been highlighted as it allows better visualization of the external morphology of immature and some adults. The aim of this study was to describe the katepisternals in females of Morellia humeralis and Biopyrellia bipuncta; the ommatidia of the compounds eyes of the male of B. bipuncta; the antennae of females of Ophyra aenescens and Ophyra albuquerquei and the ocellar triangle of the last two species and O. chalcogaster examined by scanning electron microscopy to help increase the anatomical database on flies for forensic importance. The katepisternals of M. humeralis and B. bipuncta were densely covered by different groups of sensilla. The surface of the ocellar region of O. aenescens was not covered by sensilla, but in O. albuquerquei and O. chalcogaster were densely covered by different types of sensilla. The coeloconic sensilla were only found in the flagellum of O. albuquerquei.

Ultrastructure of immature stages of Lucilia cuprina (Diptera: Calliphoridae) using scanning electron microscopy.

The blowfly Lucilia cuprina is distributed worldwide and is a mechanical vector of pathogens. It can cause myiasis in humans and is strongly related to forensic entomology, as it is frequently found on human and animal corpses. However, most of the L. cuprina found on corpses are the immature stages of this fly. Correct identification is very important for forensic entomology but at present only the identification keys of adult L. cuprina are available. Thus, the aim of this paper was to describe and analyze the morphological characteristics of all larval instars and the puparia of L. cuprina using scanning electron microscopy (SEM).