Unusual presence of Ornidia robusta (Diptera: Syrphidae) causing pig myiasis in Argentina

Occurrence and anatomical distribution of myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in swine

Cochliomyia hominivorax (Diptera: Calliphoridae) has been considered the most important cause of myiasis in animals in the South America with most cases being recorded in cattle. In Brazil, the risk of myiasis in swine population is underestimated, leading to difficulties in the implementation of preventive measures. The aim of this study was to report the occurrence of myiasis infesting a swine population over a one-year period and to evaluate the anatomical distribution of these larvae on the animal's body. From May 2019 to April 2020, a total of 2038 inspections were carried out on pigs reared in two farms located in the state of Pernambuco, Northeastern Brazil. Fly larvae retrieved were morphologically identified and the anatomical distribution of myiasis was graphically represented by a heat map indicating its frequency in swine based on the interpolation of data. Cochliomyia hominivorax larvae (n = 78) of second (n = 29) and third (n = 49) developmental stages were recovered in 13 animals (0.64%) out of 2038 inspections performed. The occurrence of myiasis was detected in eight anatomical sites, with higher concentration on the forehead region and on ears. Data herein obtained provide valuable information on the epidemiology and biological aspects of C. hominivorax affecting pigs. In addition, it indicates that the forehead and ears are important sites of parasitism most likely due the high frequency of skin lesions in these areas.

A world review of reported myiases caused by flower flies (Diptera: Syrphidae), including the first case of human myiasis from Palpada scutellaris (Fabricius, 1805)

Rat-tailed larvae of the syrphid species Palpada scutellaris (Fabricius, 1805) are documented causing an enteric human myiasis in Costa Rica. This is the first time that the genus Palpada is recorded as a human myiasis agent. We report a 68-year-old woman with intestinal pain and bloody diarrhea with several live Palpada larvae present in the stool. Using molecular techniques (DNA barcodes) and both electronic and optical microscopy to study the external morphology, the preimaginal stages of the fly were unambiguously identified. An identification key to all syrphid genera actually known as agents of human and animal myiases is provided for larvae, puparia, and adults. Moreover, a critical world review of more than 100 references of Syrphidae as myiasis agents is also given, with emphasis on the species with rat-tailed larvae.

Artemisia spp. essential oils against the disease-carrying blowfly Calliphora vomitoria

BACKGROUND

Synanthropic flies play a considerable role in the transmission of pathogenic and non-pathogenic microorganisms. In this work, the essential oil (EO) of two aromatic plants, Artemisia annua and Artemisia dracunculus, were evaluated for their abilities to control the blowfly Calliphora vomitoria. Artemisia annua and A. dracunculus EOs were extracted, analysed and tested in laboratory bioassays. Besides, the physiology of EOs toxicity and the EOs antibacterial and antifungal properties were evaluated.

RESULTS

Both Artemisia EOs deterred C. vomitoria oviposition on fresh beef meat. At 0.05 μl cm-2 A. dracunculus EO completely inhibited C. vomitoria oviposition. Toxicity tests, by contact, showed LD50 of 0.49 and 0.79 μl EO per fly for A. dracunculus and A. annua, respectively. By fumigation, LC50 values were 49.55 and 88.09 μl l-1 air for A. dracunculus and A. annua, respectively. EOs AChE inhibition in C. vomitoria (IC50 = 202.6 and 472.4 mg l-1, respectively, for A. dracunculus and A. annua) indicated that insect neural sites are targeted by the EOs toxicity. Finally, the antibacterial and antifungal activities of the two Artemisia EOs may assist in the reduction of transmission of microbial infections/contaminations.

CONCLUSIONS

Results suggest that Artemisia EOs could be of use in the control of C. vomitoria, a common vector of pathogenic microorganisms and agent of human and animal cutaneous myiasis. The prevention of pathogenic and parasitic infections is a priority for human and animal health. The Artemisia EOs could represent an eco-friendly, low-cost alternative to synthetic repellents and insecticides to fight synanthropic disease-carrying blowflies.