Morphology and identification of first instars of the European and Mediterranean blowflies of forensic importance. Part I: Chrysomyinae.

Light microscopy photographs, line illustrations and scanning electron micrographs are provided for first instars of Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius) and Protophormia terraenovae (Robineau-Desvoidy) (all: Diptera: Calliphoridae). The following morphological structures are documented: pseudocephalon; antennal complex; maxillary palpus; facial mask; thoracic and abdominal spinulation; spiracular field; posterior spiracles, and cephaloskeleton. New diagnostic features of the cephaloskeleton and the spinulation of abdominal segments are described. Verification of earlier descriptions revealed major discrepancies among published data. The present results allow for the clarification, correction and, especially, complementation of existing information provided by numerous authors. Finally, an identification key for first-instar larvae of European and Mediterranean Chrysomyinae of forensic importance is presented.

Clinical and microbiological efficacy of MDT in the treatment of diabetic foot ulcers.

OBJECTIVE: To assess the clinical and microbiological efficacy of maggot debridement therapy (MDT) in the management of diabetic foot ulcers unresponsive to conventional treatment and surgical intervention. METHOD: Consecutive diabetic patients with foot wounds presenting at the vascular surgery unit and the diabetic foot unit of Alexandria Main University Hospital were selected for MDT. Lucilia sericata medicinal maggots were applied to the ulcers for three days per week. Changes in the percentage of necrotic tissue and ulcer surface area were recorded each week over the 12-week follow-up period. Semiquantitative swab technique was used to determine the bacterial load before and after MDT. RESULTS: The sample comprised 10 patients with 13 diabetic foot ulcers. The mean baseline ulcer surface area was 23.5cm2 (range 1.3-63.1), and the mean percentage of necrotic tissue was 74.9% (range 29.9-100). Complete debridement was achieved in all ulcers in a mean of 1.9 weeks (range 1-4). Five ulcers (38.5%) were completely debrided with one three-day MDT cycle. The mean reduction in ulcer size was significant at 90.2%, and this occurred in a mean of 8.1 weeks (range 2-12). The mean weekly reduction in ulcer size was 16.1% (range 8.3-50). Full wound healing occurred in 11 ulcers (84.6%) within a mean of 7.3 weeks (range 2-10). The bacterial load of all ulcers reduced sharply after the first MDT cycle to below the 10(5) threshold, which facilitates healing. CONCLUSION: The results highlight the potential benefits of MDT in diabetic wound care in developing countries. MDT was proved to be a rapid, simple and efficient method of treating these ulcers.

Competitive interaction between larvae of Lucilia sericata (Meigen) and Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae).

Rearing of L. sericata and C. albiceps in pure cultures of a variety of densities, at four constant temperature regimes, demonstrated an inverse relationship between egg density and the total development (F(2,6) = 264.35 and F(2,6) = 71.87 For L. sericata and C. albiceps, respectively p < 0.05), survivorship (F(2,9) = 68.41; p < 0.001 forL. sericata and F(2,9) = 12.35; p < 0.05 for C. albiceps) and adult size (For L. sericata: males F(2,9) = 58.94 and females F(2,9) = 140.09. For C. albiceps: males F(2,9) = 43.62 and females F(2,9) = 167.99. In all cases p < 0.001) of both species. Addition of C. albiceps reduced the development time and survivorship of L. sericata at a variety of densities and proportions at 17 and 23 degrees C. While at 29 and 35 degrees C, a complete elimination of L. sericata was recorded. Neither egg density nor temperature has a significant effect on the sex ratio of the resulting adults. It seems that the interaction between these species is a highly asymmetric case of competition.

Key to third-instar chrysomyinae (Diptera: Calliphoridae) from carrion in the continental United States.

The introduction of 4 Chrysomya Robineau-Desvoidy spp. to the Americas has made obsolete previously published keys to Nearctic calliphorid larvae, particularly those covering the subfamily Chrysomyinae. To assist forensic entomologists, ecologists, and public health workers, we provide a key to 3rd instars of 8 chrysomyine species reported from or likely to occur in carrion within the continental United States. The rare (in the United States) species Cochliomyia aldrichi Del Ponte, C. minima Shannon, and Chloroprocta idioidea (Robineau-Desvoidy) are not included because specimens and suitable descriptions were unavailable.

Arthropod succession on exposed rabbit carrion in Alexandria, Egypt.

In 1988 and 1989, seasonal field studies on exposed rabbit carcasses were conducted in Alexandria, Egypt, to describe the decomposition process and arthropod succession patterns. Four decomposition stages were recognized: fresh, bloated, decay, and dry. Carcasses in summer and spring decayed at a much faster rate than those in fall and winter. The bloated stage in summer lasted longer than in spring because of the difference in breeding biology of the primary flies infesting carcasses in these seasons. Dipterous larvae of the family Calliphoridae, and to a lesser extent of the families Sarcophagidae and Muscidae, were responsible for the process of carrion degradation. Carrion-arthropod communities in cooler seasons were distinguished from those in warmer seasons by the presence of certain dipterous (muscids and fanniids) and coleopterous larvae, and by adults of small flies such as sphaerocerids and scatopsids. The presence of adult psychodids, sciarids, and phorids was unique to the winter carrion-arthropod community. Eleven species of carrion-breeding Diptera were found to coexist in the study site. The coexistence of the 2 calliphorids Chrysomya albiceps (Wiedemann) and Lucilia sericata (Meigen) in carrion in fall and spring is a new record for the Palaearctic Region. In spring, 3rd instars of C. albiceps were observed preying on the pupae of their own species. Although the carcasses were of equal size and simultaneously exposed, there was considerable variation in the rate of decay among fall carcasses only, which was attributed to unknown reasons at the beginning of the experiment and to heavy rains later on. This affected oviposition and the feeding period of maggots. Approximately 100 arthropod species were recovered on carcasses throughout the study. Diptera was the predominant group, whereas Coleoptera ranked 2nd. Carcasses in cooler seasons were richer in species than in warmer seasons.

The effect of killing and preservative solutions on estimates of maggot age in forensic cases.

Length of the oldest maggots recovered from a body often provide an accurate estimate of the time since death. The length of maggots of Protophormia terraenovae (Robineau-Desvoidy) of known age, at peak of feeding, was measured after 5 days immersion in one of 15 killing and preservative solutions, some of which are routinely used at autopsy and in forensic entomology; controls were killed in boiling water. There was shrinkage in all 15 solutions which translated into an underage error of 9.7 h in 70% ethanol, 11 h in San Veino and 16.8 h in formalin. Larvae of Calliphora vicina (Robineau-Desvoidy) underwent even greater shrinkage, which resulted in an underage error of 19.2 h in 70% ethanol, 26.4 h in formalin and 28.8 h in San Veino. Young third instar larvae underwent more shrinkage than older ones, with underage errors (in hours) as follows: P. terraenovae-70% ethanol 24 and San Veino, 24; C. vicina-70% ethanol, 7.2 and San Veino, 14.4. Maggots killed in boiling water and then placed in preservative solutions did not shrink. Length of the crop, which may be useful in age estimates of postfeeding larvae, was not altered significantly for forensic purposes in these solutions. The highly significant alterations in maggot length underscore a need for standardization in the treatment of maggots collected at the crime scene and at autopsy if their length is to be interpreted in a valid and consistent way. Recommendations are made for treatment of maggots wherever they are collected.

Chrysomya albiceps and C. rufifacies (Diptera: Calliphoridae): contribution to an ongoing taxonomic problem.

Until recently, the two biologically equivalent blow flies Chrysomya albiceps (Wiedemann) and Chrysomya rufifacies (Macquart) had disjunct distributions outside the Americas; the former was Palaearctic, the latter Australasian and Oriental. The two species are now spreading throughout the Americas and coexist in Argentina. The predatory "hairy" larvae of both species are difficult to separate, which could result in taxonomic errors. New diagnostic characters are presented to differentiate the third instars of the two species. The usefulness of the prostigmatic bristle as a diagnostic taxonomic character in distinguishing adults of these species is questioned.

Different developmental strategies in two boreal blow flies (Diptera: Calliphoridae).

The minimum developmental rates of Protophormia terraenovae (Robineau-Desvoidy) and Calliphora vomitoria (L.) were measured at four temperatures: 12.5, 23, 29, and 35 degrees C. Although both species are Holarctic in distribution and hemisynanthropic, there are important differences in the response of their developmental stages to various temperature regimes. The eggs and feeding larvae of P. terraenovae responded linearly to temperatures from 23 to 35 degrees C, but development was retarded at 12.5 degrees C. The feeding larvae took about 11 times longer to develop at 12.5 than at 23 degrees C, indicating poor cold adaptation. The converse is true of C. vomitoria, which took only 2 times as long at 12.5 than at 23 degrees C but failed to complete development at 29 and 35 degrees C. Our laboratory data and field studies of others suggest that, in nature, P. terraenovae and C. vomitoria prefer breeding in larger carcasses as a survival tactic and means of extending their distribution into colder regions.