Differential Ability of Necrophagous Diptera to Colonize Concealed Resources: Empirical Evidence From a Field Experiment in Brazil.

Field studies in forensic entomology seem to assume that a cadaver is a resource equally accessible to flies, irrespective of the species' size, behavior, and sensorial capacity. We aimed to challenge this assumption by experimentally manipulating baited traps in order to test whether the accessibility to decomposing baits is related to the following: (i) the diversity of necrophagous dipterans; (ii) the body size of adults; and (iii) the female sexual maturity stage. The experiment was performed in a rainforest fragment in Northeastern Brazil, in an area characterized by high levels of homicides. Traps baited with decomposing chicken liver had three levels of access: easy (six openings on the trap), intermediate (three), and difficult (one). A total of 750 adults of Calliphoridae, Fanniidae, Muscidae, Phoridae, and Sarcophagidae were collected. Of the 18 species recorded, Megaselia scalaris was the most abundant (46.8%) followed by Lucilia eximia (29.7%) and Chrysomya megacephala (9.8%). The number of species increased significantly with the accessibility level, but overall abundance did not differ, as a consequence of the numerical dominance of M. scalaris. A strong female bias (>91%) was observed in all traps. For Calliphoridae specimens, 90% of the females caught in traps under intermediate and difficult access were sexually mature. By empirically demonstrating that limitation of access and exclusion of visual stimuli do not deter several dipteran species from reaching a substrate, we expand the knowledge on the factors that can shape the colonization of concealed human cadavers, including variables such as insect size and stage of sexual maturity.

A novel use of infra-red spectroscopy (NIRS and ATR-FTIR) coupled with variable selection algorithms for the identification of insect species (Diptera: Sarcophagidae) of medico-legal relevance.

Unequivocal identification of fly specimens is an essential requirement in forensic entomology. Herein, a simple, non-destructive and rapid method based on two vibrational spectroscopy techniques [Near-Infrared Spectroscopy (NIRS) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy] coupled with variable selection techniques such as genetic algorithm-linear discriminant analysis (GA-LDA) and successive projection algorithm-linear discriminant analysis (SPA-LDA) were applied for identifying and discriminating six species of flesh flies (Diptera: Sarcophagidae) native to Neotropical regions. This novel approach is based on the unique spectral "fingerprints" of their biochemical composition. One hundred sixty (160) NIRS and FT-IR specimens (120 male, 40 female) were acquired; different pre-processing methods such as baseline correction, derivative and Savitzky-Golay smoothing were also performed. In addition, the multivariate classification accuracy results were tested based on sensitivity, specificity, positive (or precision) and negative predictive values, Youden index, positive and negative likelihood ratios. Principal components analysis (PCA) was employed for male vs. female category using NIRS, strongly showing the separation between the classes with only three principal components and 99% explained variance. Differentiation between the genera Oxysarcodexia, Peckia and Ravinia was efficiently confirmed by both techniques. In comparison with other biological methods, this approach represents an effective choice for fast and non-destructive identification in forensic entomology.

Diurnal and Nocturnal Flight Activity of Blow Flies (Diptera: Calliphoridae) in a Rainforest Fragment in Brazil: Implications for the Colonization of Homicide Victims.

Nocturnal flight of blow flies (Diptera: Calliphoridae) is a controversial issue in forensic entomology. We performed two field experiments to investigate the diurnal and nocturnal activity of six blow fly species in a rainforest fragment in Brazil. Initially, nocturnal (17:30-05:30) versus diurnal (05:30-17:30) flight activity was investigated. Only 3.9% of adults were collected at night, mostly the native species Mesembrinella bicolor, and nocturnal oviposition did not occur. In the second experiment, collection of adults took place at the following intervals: 05:30-08:30, 08:30-11:30, 11:30-14:30, and 14:30-17:30. The proportions of adults did not differ significantly among the four diurnal intervals, except for Hemilucilia segmentaria, which was captured more frequently in the early morning. Calliphoridae has predominantly diurnal behavior, not laying eggs in darkness. The association of the native species M. bicolor, Hemilucilia semidiaphana, and H. segmentaria to forested areas reinforces the forensic relevance of data on their flight pattern.

Effect of bait decomposition on the attractiveness to species of Diptera of veterinary and forensic importance in a rainforest fragment in Brazil.

Insects associated with carrion can have parasitological importance as vectors of several pathogens and causal agents of myiasis to men and to domestic and wild animals. We tested the attractiveness of animal baits (chicken liver) at different stages of decomposition to necrophagous species of Diptera (Calliphoridae, Fanniidae, Muscidae, Phoridae and Sarcophagidae) in a rainforest fragment in Brazil. Five types of bait were used: fresh and decomposed at room temperature (26 °C) for 24, 48, 72 and 96 h. A positive correlation was detected between the time of decomposition and the abundance of Calliphoridae and Muscidae, whilst the abundance of adults of Phoridae decreased with the time of decomposition. Ten species of calliphorids were registered, of which Chrysomya albiceps, Chrysomya megacephala and Chloroprocta idioidea showed a positive significant correlation between abundance and decomposition. Specimens of Sarcophagidae and Fanniidae did not discriminate between fresh and highly decomposed baits. A strong female bias was registered for all species of Calliphoridae irrespective of the type of bait. The results reinforce the feasibility of using animal tissues as attractants to a wide diversity of dipterans of medical, parasitological and forensic importance in short-term surveys, especially using baits at intermediate stages of decomposition.

Necrophagous beetles associated with carcasses in a semi-arid environment in northeastern Brazil: implications for forensic entomology.

Data on the ecology and bionomics of necrophagous beetles are scarce in tropical countries despite their relevance in forensic investigations. We performed a survey on the diversity and temporal pattern of colonization of beetles on pig carcasses in a fragment of dry forest in northeastern Brazil. We collected 1550 adults of diverse feeding habits from 12 families, of which 96% had necrophagous and/or copro-necrophagous habits and belonged to four families: Dermestidae, Scarabaeidae, Cleridae and Trogidae. Three species, Dermestes maculatus, Necrobia rufipes and Omorgus suberosus are reported for the first time with an expanded geographical distribution that includes the semi-arid region in Brazil. Adult beetles were collected as early as 24h after death. One endemic species, Deltochilum verruciferum, stood out in terms of numerical dominance and temporal occurrence during different stages of decomposition. Its intimate association with carrion emphasizes their potential role in forensic entomology in the region.

Dipterans associated with a decomposing animal carcass in a rainforest fragment in Brazil: notes on the early arrival and colonization by necrophagous species.

This study aimed to provide the first checklist of forensically-important dipteran species in a rainforest environment in Northeastern Brazil, a region exposed to high rates of homicides. Using a decomposing pig, Sus scrofa L. (Artiodactyla: Suidae), carcass as a model, adult flies were collected immediately after death and in the early stages of carcass decomposition. To confirm actual colonization of the carcass, insects that completed their larval development on the resource were also collected and reared until adult stage. A diverse assemblage of dipterans composed of at least 28 species from seven families with necrophagous habits was observed within minutes after death. Besides Calliphoridae and Sarcophagidae, species from forensically-important families such as Phoridae, Anthomyiidae, and Fanniidae were also registered. Eleven species were shown to complete their development on the carcass. The majority of individuals emerged from larvae collected at the dry stage of decomposition. Hemilucilia segmentaria Fabricius (Diptera: Calliphoridae), H. semidiaphana (Rondani), and Ophyra chalcogaster (Wiedemann) (Muscidae) were the dominant species among the colonizers, which supports their importance as forensic evidence in Brazil.

Necrophagous species of Diptera and Coleoptera in northeastern Brazil: state of the art and challenges for the Forensic Entomologist / Espécies necrófagas de Diptera e Coleoptera na Região Nordeste do Brasil: estado da arte e desafios para o Entomologista Forense

Inventories on necrophagous insects carried out in Brazil encompass mostly species from the southeastern and central-western regions of the country. This review aims to produce the first checklist of necrophagous Diptera and Coleoptera species of forensic relevance in northeastern Brazil, an area that concentrates high rates of homicides. We performed a literature survey on scientific articles, theses and dissertations regarding necrophagous insect species in the region, and contacted scientists who develop research on forensic entomology. Fifty-two species of Diptera belonging to eight families with previous record of necrophagy were reported in the region: Sarcophagidae, Calliphoridae, Muscidae, Fanniidae, Piophilidae, Phoridae, Anthomyiidae and Stratiomyidae. Coleopteran species from six families of forensic relevance were registered, although taxonomical identification remained superficial. Bait traps were the most frequent methodology used, followed by collection on animal carcasses. Seven Dipteran species from two families were registered on human cadavers. All species had been previously reported in other Brazilian states and/or other countries, although none has been effectively used in legal procedures in the region. The status of research on forensic entomology in northeastern Brazil is incipient, and the checklist produced here contributes to the knowledge on the local diversity of necrophagous insects.

Inventários de insetos necrófagos no Brasil abordam em sua maioria espécies das regiões Sudeste e Centro-Oeste do país. Esta revisão visa apresentar um checklist de espécies necrófagas de Diptera e Coleoptera de importância forense no Nordeste brasileiro, uma área que concentra elevadas taxas de homicídio. Nós conduzimos uma revisão bibliográfica consultando artigos, teses e dissertações sobre espécies necrófagas na região, e contatamos cientistas que desenvolvem pesquisa em entomologia forense. Cinquenta e duas espécies de Diptera pertencentes a oito famílias com registro prévio de necrofagia foram registrados na região: Sarcophagidae, Calliphoridae, Muscidae, Fanniidae, Piophilidae, Phoridae, Anthomyiidae e Stratiomyidae. Espécies de Coleoptera de seis famílias de importância forense foram listadas, embora a identificação taxonômica tenha sido superficial. Armadilhas contendo iscas foram o método de coleta mais frequente, seguidas de coleta sobre carcaças animais. Sete espécies de Diptera pertencentes a duas famílias foram registradas sobre cadáveres humanos. Todas as espécies haviam sido previamente registradas em outros estados brasileiros e/ou em outros países, embora nenhuma tenha sido efetivamente utilizada em procedimentos legais na região. O status da pesquisa em entomologia forense no Nordeste do Brasil é incipiente, e o checklist apresentado neste trabalho contribui para sistematizar o conhecimento sobre a diversidade local de insetos necrófagos.

Bionomics of two forensically important blowfly species Chrysomya megacephala and Chrysomya putoria (Diptera: Calliphoridae) reared on four types of diet.

The use of heterogeneous animal tissues for the rearing of necrophagous insect species can produce uneven biological data, which can compromise the determination of larval age and, consequently, estimates for post-mortem intervals. We investigated the development of two species, Chrysomya megacephala and Chrysomya putoria (Diptera: Calliphoridae), reared on four substrates: minced beef (control) and semi-synthetic diets with the addition of sardine, rumen or chicken eggs. No differences in total developmental times were detected among larvae reared on different diets. Length and width of larvae were partially affected by the type of food. Third instar larvae and pupae of both species were heavier on beef treatment when compared with other substrates. Overall mortality was lower when beef was used as food. Longevity of adults and sex ratio were not negatively affected by the use of diets. Egg-based diet was the least effective for both species. Given the fact that several bionomical parameters of larvae reared on diets were close to those obtained when minced beef was offered, and considering the putrid odour, frequency of contamination and lack of homogeneity of animal tissue, semi-synthetic diets can be used for rearing C. megacephala and C. putoria.

Parity and age composition for Anopheles darlingi root (Diptera: Culicidae) and Anopheles albitarsis Lynch-Arribálzaga (Diptera: Culicidae) of the northern Amazon Basin, Brazil.

Parity and age composition for Anopheles darlingi and Anopheles albitarsis in the northern Amazon Basin, Brazil, were investigated. Anopheline ovaries and ovarioles were examined in order to determine whether hourly and seasonal parity status for the vectors An. albitarsis and An. darlingi would vary in two different landscapes (forest and savanna/forest) where malaria is endemic in the northern Amazon Basin. A total of 1,199 anophelines (535 An. darlingi and 664 An. albitarsis) was dissected for parity status, ovariole dilatations, and follicular stages. The total number of nulliparous and parous females for both species varied by time of collection, locality, and season. During the rainy season for the first two h of collection, more nulliparous An. albitarsis and An. darlingi females were collected in the first hour (18:00-19:00), but during the second hour (19:00-20:00) more parous females of both species were captured. During the dry season in Copaíbas, more parous females of An. albitarsis were observed in the first hour while more nulliparous females were observed in the second hour. Nulliparous and parous females of both species for both hours were not significantly different at Road 19 in the dry season. This location was characterized by a forest malaria pattern of transmission with higher numbers of parous females and population stability in the dry season. In Copaíbas, the density and parity of An. darlingi increased during the rainy season, and it could be classified as an alluvial malaria pattern of transmission. For Copaíbas, control measures would be more successful if adopted at the transition from dry to rainy season. Further investigation on longitudinal spatio-temporal change in longevity and survival rates would help us to clarify differences in vector competence for An. darlingi and An. albitarsis and add to the understanding of differences regarding prevailing landscapes in malaria epidemiology in the northern Amazon Basin.

Tetrahymenidae infection in mosquito populations in a malaria-endemic region of the Amazon.

In a field survey performed in a malaria-endemic region of Northern Amazon, Brazil, we encountered ciliate protozoa of the family Tetrahymenidae infecting adults and larvae of the following mosquito species: Culex sp., Anopheles albitarsis l.s., Anopheles strodei, Anopheles mattogrossensis, Anopheles darlingi, and Anopheles oswaldoi l.s. Based on morphological features and life style, we have tentatively identified the parasite as Lambornella sp. The association appears pathogenic for the mosquito. Prevalence of infection in both larvae and adults was higher in the dry season.

Histopathology of Holochilus brasiliensis (Rodentia: Cricetidae) infected with Schistosoma mansoni (Schistosomatida: Schistosomatidae)

A prevalência da esquistossomose em áreas alagadas do Nordeste brasileiro é agravada pela presença de hospedeiros alternativos, como o roedor Holochilus brasiliensis. Entretanto, os efeitos de Schistosoma mansoni nesse hospedeiro, tanto no indivíduo como na população, são desconhecidos. Em investigação dos efeitos patológicos da invasão por S. mansoni no fígado e baço de H. brasiliensis, dez animais infectados (cinco machos e cinco fêmeas) e seis sadios (três machos e três fêmeas) tiveram seus fígados e baços extraídos 42 dias após o tratamento. Lâminas histológicas foram preparadas e examinadas sob microscópio de luz. Os fígados de machos infectados continham ovos do parasito com granulomas intensos ou moderados, enquanto as fêmeas mostraram dano tissular leve ou moderado. Os ovos do parasito também foram observados no baço de machos e fêmeas. Observou-se uma leve diferença entre machos e fêmeas quanto à resposta à invasão por S. mansoni

Differential crop damage by healthy and nucleopolyhedrovirus-infected Mamestra brassicae L. (Lepidoptera: Noctuidae) larvae: a field examination.

Baculovirus infection in Lepidoptera can alter both larval mobility and feeding rates, which can in turn affect pathogen transmission and dispersal in the field. We compared the damage to cabbage plants in the field caused by healthy and nucleopolyhedrovirus-infected Mamestra brassicae L. (Lepidoptera: Noctuidae) larvae released as second and fourth instars. There was no significant difference in plant consumption by healthy and infected larvae for the first 4 days after release. From day 5 onwards, infected larvae caused significantly less defoliation. This pattern was similar for larvae at both larval instars. Defoliation was greater for fourth instars throughout the experiment.

Does the presence of weeds affect Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) infestation on tomato plants in a semi-arid agro-ecosystem? / A presença de plantas invasoras afeta a infestação de tomateiros por Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) em um agro-ecossistema do semi-árido?

Integrated Bemisia tabaci (Gennadius) management requires quantitative knowledge on the mechanisms of persistence of pest populations in non-commercial host plants. We investigated B. tabaci oviposition preference among tomato and four weed species, and the insect population fluctuation under field conditions in the semi-arid region. At weekly intervals, we determined the level (number of eggs and nymphs per leaf) and the density of infestation (number of eggs and nymphs per leaf area) in all species. We observed an oviposition preference gradient among the species, with different degrees of attractiveness; Acanthospermum hispidum was the most infested species whereas Amaranthus deflexus was the least infested one. We also detected a significantly higher infestation on tomato when planted solely, which indicates a dilution effect on tomato infestation in the presence of weeds. Weeds can act as important reservoirs for whiteflies and/or their natural enemies or even as viral sources for cultivated plants. Their incorporation in integrated B. tabaci management programs depends on how those variables can be manoeuvred for the reduction of insect damage.

O manejo integrado de Bemisia tabaci (Gennadius) exige o conhecimento quantitativo dos mecanismos de persistência de populações em hospedeiros não comerciais. Este trabalho investigou a preferência para oviposição de B. tabaci entre tomate e quatro espécies de plantas invasoras, e a flutuação populacional do inseto em condições de campo no semi-árido nordestino. Semanalmente, foram determinados o nível (número de ovos e ninfas por folha) e a densidade de infestação (número de ovos e ninfas por área foliar) nas cinco espécies. Observamos diferentes graus de atratividade, formando um gradiente de preferência para oviposição entre as espécies, sendo Acanthospermum hispidum a espécie mais infestada e Amaranthus deflexus a menos infestada. Foi detectada ainda uma infestação significativamente mais elevada em parcelas contendo apenas tomateiros, sugerindo um efeito de diluição da infestação do tomateiro quando na presença de invasoras. Plantas invasoras podem representar importantes reservatórios para a mosca branca e/ou seus inimigos naturais, ou ainda fontes de inóculo viral para plantas cultivadas. Sua inserção em programas de manejo integrado de B. tabaci em tomateiro depende de como estes fatores podem ser manipulados para a redução dos danos causados pelo inseto.

Host Stage Structure and Baculovirus Transmission in Mamestra brassicae L. (Lepidoptera: Noctuidae) Larvae: a Laboratory Examination of Small Scale Epizootics / Estrutura Etária do Hospedeiro e Transmissão de Baculovírus em Larvas de Mamestra brassicae L. (Lepidoptera: Noctuidae): Uma Análise de Epizootias em Pequena Escala em Laboratório

Os efeitos da estrutura etária e da densidade do hospedeiro na transmissão horizontal de um baculovírus foram investigados em laboratório, utilizando-se populações de lagarta do repolho, Mamestra brassicae L. (Lepidoptera: Noctuidae). Os insetos foram mantidos a três combinações de ínstares e três densidades populacionais em recipientes fechados contendo larvas infectadas. As larvas foram observadas diariamente e o número de mortes e o tempo letal foram registrados. Os níveis de mortalidade viral foram marginalmente superiores em recipientes contendo hospedeiros sob maior densidade populacional. As larvas apresentaram um risco de infecção aparentemente maior quando combinações de instares mais avançados foram usadas. Os níveis de mortalidade de larvas mais velhas foram maiores que as de larvas mais jovens. As médias de tempo letal das populaç ões larvais foram maiores para larvas mais jovens, observando-se um declínio mais acentuado na curva de sobrevivência das larvas em estágio mais adiantado de desenvolvimento.

The effects of stage structure and host density on baculovirus horizontal transmission were examined in the laboratory using larvae of the cabbage moth, Mamestra brassicae L. (Lepidoptera: Noctuidae). Insects were reared at three instar combinations and three host densities in closed containers with infected larvae. Insects were observed daily and the number of deaths and time to death were recorded. Levels of virus mortality were marginally higher in the containers where a higher density of hosts was introduced. Larvae appeared to have a greater risk of infection when late instar combinations were used. Final levels of mortality of older larvae were significantly higher than those of younger larvae. Mean times to death of larval populations were longer for larvae at earlier instar combinations, with a faster decrease in survivorship of older larvae over time.