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

Abstract

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. © 2012 Wiley Periodicals, Inc.

Cuticular hydrocarbons as a tool for the identification of insect species: Puparial cases from Sarcophagidae

“…Mendonça et al (2010, 2012a,b) used scanning electron microscopy for the description of morphological features present in the immature stages of Calliphoridae ( Chrysomya albiceps (Wiedemann, 1819), C. megacephala and C. putoria ) that cannot be observed clearly with the aid of light microscopy. These features in addition to classical taxonomy and the HC profiles are tools that may help clarify identification problems of cryptic insect species.…”

Fluorescence Imaging of Posterior Spiracles from Second and Third Instars of Forensically Important Chrysomya rufifacies (Diptera: Calliphoridae),

“…C. Intensity surface plots of differential fluorescence intensity and spatial distribution throughout posterior spiracle z series and between fluorescence channels. Z disks of the step indicated at left of a 53 image z series were analyzed for the spatial distribution of fluorescence intensity (intensity surface plot, ISP ) and visualized in three fluorescence channels using matched y ‐axis scaling. Merged images of the relevant Z disk are shown at left for reference.…”

“…Throughout these imaging experiments, we noted specific structural features including the ecdysial scar, rima, peritreme area, spiracular hairs, and intraspiracular processes that were differentially apparent between fluorescence channels, suggesting that imaging protocols can be targeted to highlight desired structural features in a straightforward manner. The level of resolution and detail in the resulting images supports the premise that confocal imaging could be used to discern larval developmental stage at a fine level of resolution.…”

“…Current methods to distinguish between larval stages are viewing the spiracles under low‐resolution light microscopy . Viewing the larvae using SEM provides far greater resolution but is technically challenging and resource intensive .…”

“…In this study, we postulated that confocal or fluorescence microscopic analyses of blowfly larvae could improve estimates of TOC through: providing new parameters for distinction of larval stage, such as the intensity and distribution of autofluorescent proteins or secondary metabolites, and increasing spatial resolution of morphological features. We conducted a pilot study using epifluorescence and confocal analysis of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) larvae, which frequently are encountered on human remains in select regions of the world reared under laboratory conditions.…”