Ultrastructure of the Immature Stages of Musca domestica (Diptera: Muscidae: Muscinae).

Musca domestica (Linnaeus, 1758) is a muscoid species that is widespread throughout the world and acts as a mechanical vector of different enteropathogens primarily in underdeveloped countries. The adult and its immature forms are associated with decaying organic matter and can be seen visiting human corpses and animal carcass, and the larvae can also cause an infestation on human and animal wounds, feeding on the tissues. These characteristics make them have a forensic significance and, mainly, a great sanitary importance. This study aimed to analyze and describe morphological aspects of their immature stages of M. domestica, including the eggs, the first-, second-, and third-instar larvae, and the puparium using scanning electron microscopy (SEM). The eggs have standard format that all muscoid flies shared. The exochorion has some modified cells that were used for embryonic respiration. The first-instar larvae present two openings on the posterior spiracle as in the second-instar larvae, but with the last one, we can observe the anterior spiracle structure. The third-instar larvae, as in some other Muscidae species, have a posterior spiracular opening with a sinuous form that is located near the edge of the spiracular plate. The puparium morphology is equal to the third instar with a respiratory structure that helps the breathing during the metamorphosis process. This article supports the need for knowledge over the morphological characteristics of the immature forms of the muscoid Diptera (Linnaeus, 1758) at the same time helping with the correct identification of this insect phase.

Ultrastructure of immature stages of the black dump fly: Ophyra aenescens (Wiedemann, 1830) (Diptera: Muscidae: Azeliinae).

Ophyra aenescens (black dump fly) originally belonged to the New World, however, now it is spread worldwide. This fly is a mechanical vector of some pathogenic microorganisms and eggs of the human botfly (Dermatobia hominis). The adults are associated with decaying matter and the immature stages colonize animal and human corpses. It is considered an important muscid species for forensic entomology. The aim of this study was to describe the morphology of the eggs, the three larval instars and the puparia of O. aenescens using scanning electron microscopy (SEM). The spiracular opening of the first instar has an interruption in the middle of its length. Comparing to the other instar, the ventral tubercles are only developed in the first instar. The anterior spiracles have a variation in the numbers of spiracular ramification. The puparia morphology is similar to the third instar larvae, however the cephalic region is retracted and on the third thoracic segment, a respiratory structure is present. In conclusion, the SEM technique used and the results obtained are helpful to describe and differentiate the immature stages of O. aenescens and consequently support forensic and medical entomology.

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 Cochliomyia macellaria (Diptera: Calliphoridae), a fly of medical and veterinary importance.

Cochliomyia macellaria (Diptera: Calliphoridae) is known as the secondary screwworm because it causes secondary or facultative myiasis when the larvae feed on necrotic tissues. This fly has a significant medical and veterinary importance since it has been reported to transport eggs of Dermatobia hominis (human botfly), which can cause significant economic losses to livestock. Since this screwworm has been collected colonizing both pig carcasses and human cadavers, it is considered one of the most important species for forensic entomology studies. Scanning electron microscopy (SEM) gives detailed information on the morphological characteristics which can help identify the immature forms of the flies. The aim of this study was to describe and analyze the morphological characteristics of the eggs, all the larval instars, and the puparia of Cochliomyia macellaria using SEM. The egg is ellipsoid and the dorsal surface is concave. The islands inside the median area had no anastomosis, but some perforations could be observed. From the second larval instar onwards, besides the intersegmental spines, other bands of spines were observed at the abdominal segments. Two spiracular openings were visible on the first and second larval instars, which were not expected. These characteristics are specific to Cochliomyia genus. The number and the general aspect of the spine tips in the cephalic region, the intersegmental bands on the abdomen, and the number of the spiracular openings could together help identify C. macellaria.

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).

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.