Reproductive output and other adult life-history traits of black soldier flies grown on different organic waste and by-products

The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer's grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer's grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production.

Destabilization of the Bacterial Interactome Identifies Nutrient Restriction-Induced Dysbiosis in Insect Guts

Stress-associated dysbiosis of microbiome can have several configurations that, under an energy landscape conceptual framework, can change from one configuration to another due to different alternating selective forces. It has been proposed-according to the Anna Karenina Principle-that in stressed individuals the microbiome are more dispersed (i.e., with a higher within-beta diversity), evidencing the grade of dispersion as indicator of microbiome dysbiosis. We hypothesize that although dysbiosis leads to different microbial communities in terms of beta diversity, these are not necessarily differently dispersed (within-beta diversity), but they form disrupted networks that make them less resilient to stress. To test our hypothesis, we select nutrient restriction (NR) stress that impairs host fitness but does not introduce overt microbiome selectors, such as toxic compounds and pathogens. We fed the polyphagous black soldier fly, Hermetia illucens, with two NR diets and a control full-nutrient (FN) diet. NR diets were dysbiotic because they strongly affected insect growth and development, inducing significant microscale changes in physiochemical conditions of the gut compartments. NR diets established new configurations of the gut microbiome compared to FN-fed guts but with similar dispersion. However, these new configurations driven by the deterministic changes induced by NR diets were reflected in rarefied, less structured, and less connected bacterial interactomes. These results suggested that while the dispersion cannot be considered a consistent indicator of the unhealthy state of dysbiotic microbiomes, the capacity of the community members to maintain network connections and stability can be an indicator of the microbial dysbiotic conditions and their incapacity to sustain the holobiont resilience and host homeostasis. IMPORTANCE Changes in diet play a role in reshaping the gut microbiome in animals, inducing dysbiotic configurations of the associated microbiome. Although studies have reported on the effects of specific nutrient contents on the diet, studies regarding the conditions altering the microbiome configurations and networking in response to diet changes are limited. Our results showed that nutrient poor diets determine dysbiotic states of the host with reduction of insect weight and size, and increase of the times for developmental stage. Moreover, the poor nutrient diets lead to changes in the compositional diversity and network interaction properties of the gut microbial communities. Our study adds a new component to the understanding of the ecological processes associated with dysbiosis, by disentangling consequences of diets on microbiome dysbiosis that is manifested with the disruption of microbiome networking properties rather than changes in microbiome dispersion and beta diversity.

Pedrowygomyia (Diptera: Simuliidae): Discovery of a New Species After 30 yr

Pedrowygomyia is a Neotropical genus of Simuliidae composed of four species; all were described in 1989 from high-elevation (above 3,000 m) areas in the Andean region. In this article, a new species for this genus, Pedrowygomyia hanaq n. sp., is described based on all stages of development. The new species was collected in the south-central Andes of Peru at an altitude above 4,000 m, and its known distribution is currently restricted to the type-locality. Based on the pupal stage, the new species appears to be more closely related to Pedrowygomyia punapi (Wygodzinsky & Coscarón) (Diptera: Simuliidae), a species known from Argentina, Bolivia, and Chile.

Comparisons of Respiratory Pupal Gill Development in Black Flies (Diptera: Simuliidae) Shed Light on the Origin of Dipteran Prothoracic Dorsal Appendages

During the transformation of immature aquatic dipteran insects to terrestrial adults, the prothoracic pupal respiratory organ enables pupae to cope with flood-drought alternating environments. Despite its obvious importance, the biology of the organ, including its development, is poorly understood. In this study, the developing gills of several Simulium Latreille (Diptera: Simuliidae) spp. were observed using serial histological sections and compared with data on those of other dipteran families published previously. The formation of some enigmatic features that made the Simulium gill unique is detailed. Through comparisons between taxa, we describe a common developmental pattern in which the prothoracic dorsal disc cells not only morph into the protruding respiratory organ, which is partially or entirely covered with a cuticle layer of plastron, but also invaginate to form a multipart internal chamber that in part gives rise to the anterior spiracle of adult flies. The gill disc resembles wing and leg discs and undergoes cell proliferation, axial outgrowth, and cuticle sheath formation. The overall appendage-like characteristics of the dipteran pupal respiratory organ suggest an ancestral form that gave rise to its current forms, which added more dimensions to the ways that arthropods evolved through appendage adaptation. Our observations provide important background from which further studies into the evolution of the respiratory organ across Diptera can be carried out.

Biochar and gypsum amendment of agro-industrial waste for enhanced black soldier fly larval biomass and quality frass fertilizer

Black soldier fly (BSF) (Hermetia illucens L.) is one of the most efficient bio-waste recyclers. Although, waste substrate amendments with biochar or gypsum during composting process are known to enhance nutrient retention, their impact on agro-industrial waste have not been documented. Hence, this study focuses on a comparative effect of agro-industrial waste amended with biochar and gypsum on BSF larval performance, waste degradation, and nitrogen (N) and potassium retention in frass fertilizer. Brewery spent grain was amended with biochar or gypsum at 0, 5, 10, 15 and 20% to determine the most effective rates of inclusion. Amending feedstock with 20% biochar significantly increased wet (89%) and dried (86%) larval yields than the control (unamended feedstock). However, amendment with 15% gypsum caused decrease in wet (34%) and dried (30%) larval yields but conserved the highest amount of N in frass. Furthermore, the inclusion of 20% biochar recorded the highest frass fertilizer yield and gave a 21% increase in N retention in frass fertilizer, while biomass conversion rate was increased by 195% compared to the control. Feedstock amendment with 5% biochar had the highest waste degradation efficiency. Potassium content in frass fertilizer was also significantly enhanced with biochar amendment. At maturity, frass compost with more than 10% inclusion rate of biochar had the highest cabbage seed germination indices (>100%). The findings of this study revealed that initial composting of biochar amended feedstocks using BSF larvae can significantly shorten compost maturity time to 5 weeks with enhanced nutrient recycling compared to the conventional composting methods.

Revision of Simulium rufibasis (Diptera: Simuliidae) in Japan and Korea: Chromosomes, DNA, and Morphology

The widespread nominal black fly Simulium (Simulium) rufibasis Brunetti was reexamined morphologically, chromosomally, and molecularly to determine the status of populations in Japan and Korea with respect to S. rufibasis from the type locality in India and to all other known species in the S. (S.) tuberosum species-group. Morphological comparisons established that the species previously known as S. rufibasis in Japan and Korea is distinct from all other species. Consequently, it was described and illustrated as a new species, Simulium (S.) yamatoense. Simulium yokotense Shiraki, formerly a synonym of S. rufibasis, was morphologically reevaluated and considered a species unplaced to species-group in the subgenus Simulium. Chromosomal analyses of S. yamatoense sp. nov. demonstrated that it is unique among all cytologically known species of the S. tuberosum group and is the sister species of the Taiwanese species tentatively known as S. (S.) arisanum Shiraki. Populations of S. yamatoense sp. nov. included two cytoforms, based on the sex chromosomes. Cytoform A, including topotypical representatives, was found in Kyushu, Japan, whereas cytoform B was found in Korea and Honshu, Japan. Molecular analysis based on the COI mitochondrial gene generally corroborated morphological and chromosomal data that S. yamatoense sp. nov. is a distinct species and, like the chromosomal data, indicate that it is most closely related to S. arisanum, with interspecific genetic distance of 2.92-4.63%.

Modelling exposure heterogeneity and density dependence in onchocerciasis using a novel individual-based transmission model, EPIONCHO-IBM: Implications for elimination and data needs

BACKGROUND

Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin.

METHODOLOGY/PRINCIPAL FINDINGS

Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d'Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model.

CONCLUSIONS/SIGNIFICANCE

This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment.

Effect of rearing substrate on growth performance, waste reduction efficiency and chemical composition of black soldier fly (Hermetia illucens) larvae

BACKGROUND

Wastes can be used as rearing substrate by black soldier fly (BSF) larvae, the latter being exploitable as a protein source in animal feed. This research aimed to assess the influence of four rearing substrates (Trial 1 (organic wastes): a mixture of vegetable and fruit (VEGFRU) vs. a mixture of fruits only (FRU); Trial 2 (agro-industrial by-products): brewery (BRE) vs. winery (WIN) by-products) on BSF larvae development, waste reduction efficiency and nutritional composition.

RESULTS

If respectively compared to FRU and WIN, VEGFRU and BRE larvae needed less time to reach the prepupal stage (22.0, 22.2, 20.2 and 8.0 days of trial, respectively) and had higher protein content (229.7, 257.3, 312.9 and 395.7 g kg^-1 dry matter). The waste reduction index ranged from 2.4 (WIN) to 5.3 g d^-1 (BRE). BRE larvae showed the lowest saturated and the highest polyunsaturated fatty acid proportions (612.4 and 260.1 g kg^-1 total fatty acids, respectively).

CONCLUSION

Vegetable and fruit wastes and winery by-products can be used as rearing substrates for BSF larval mass production. Brewery by-products led to very promising larval performance and nutritional composition. However, given BRE limited availability, low BRE dietary inclusion levels could be used with the purpose of increasing larval performance. © 2018 Society of Chemical Industry.

Cultivation of black soldier fly larvae on almond byproducts: impacts of aeration and moisture on larvae growth and composition

BACKGROUND

The increasing production of almonds worldwide has resulted in the significant generation of byproduct streams that require end uses. One potential use for byproducts is for cultivation of additional food sources including insects. Studies were performed to determine if black soldier fly larvae (Hermetia illucens L.) could be cultivated on almond byproducts (hulls and shells) and to examine the effect of aeration and moisture on larvae growth and hull composition.

RESULTS

Increasing aeration from 0.04 to 0.36 mL min^-1 g dry weight^-1 tripled the harvest weight of larvae and increased larvae yield by a factor of five. Larvae calcium content increased by 18% with an increase in aeration from 0.04 to 0.95 mL min^-1 g dry weight^-1 . Moisture content also affected harvest dry weight and yield; increasing moisture content from 480 g kg^-1 (wet basis) to 680 g kg^-1 increased harvest weight by 56% and yield by a factor of 2. Variables did not affect larvae methionine and cysteine content. Low moisture content and aeration rate yielded an environment that supported microbial consumption of hulls over larvae consumption and growth.

CONCLUSIONS

The results demonstrate that almond hulls are a suitable feedstock for larvae production under controlled management of moisture content and aeration. © 2018 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens: Implications for mass production

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers’ yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10–42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4°C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0°C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (r_m = 0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.

Genetic variation in a colonization specialist, Simulium ruficorne (Diptera: Simuliidae), the world's most widely distributed black fly

The ability of aquatic insects to colonize Earth's most remote freshwater habitats, such as those of islands and deserts, is limited to select taxa. Among black flies, the premiere colonization specialist is Simulium ruficorne Macquart, the only species known from both the Afrotropical and Palearctic regions. We investigated the cytogenetics of S. ruficorne to gain insight into its wide geographic distribution and ability to colonize oceanic islands and deserts. On the basis of larval polytene chromosomes from 14 locations, we documented 17 novel and previously known chromosomal rearrangements and established five cytoforms (A1, A2, B, C, and D), of which probably four (A1/A2, B, C, and D) are distinct species and two (A1 and A2) represent sex-chromosome polymorphism involving a heteroband in the long arm of chromosome III. The chromosome restructuring phenomena associated with the five cytoforms are consistent with the trend in the Simuliidae that one and the same rearrangement can assume different functions in the various descendants of a common ancestor in which the rearrangement was polymorphic. The most widely distributed cytoforms are A1 and A2, which are found in North Africa, the Canary Islands, and Majorca. Simulium ruficorne, the only known black fly in the Hoggar Mountains of the central Sahara Desert, represents a cohesive population of cytoform A1 little differentiated from other North African populations of A1 and A2. Cytoform B inhabits the West African mainland, cytoform C is on Tenerife, and cytoform D is on Cape Verde. We suggest that dispersal and colonization specialists, such as S. ruficorne, are multivoltine inhabitants of temporary streams, and must relocate as their habitats deteriorate. Simulium ruficorne, therefore, should have adaptations that contribute to successful dispersal and colonization, perhaps largely physiological in nature, such as tolerance of high temperatures and droughts.

Impact of pH and feeding system on black soldier fly (Hermetia illucens, L; Diptera: Stratiomyidae) larval development

Black soldier fly (BSF) is a generalist species able to reduce large quantities of organic substrates and is thus considered as an interesting solution for waste management. Moreover, as BSF larvae accumulate high quantities of nutrients during their growth, they are valued because of their potential to produce products such as protein meal or fat for livestock feeds. Abiotic factors can influence larva growth, and a more detailed knowledge and control of these parameters can lead to the development of mass BSF breeding for the production of innovative products for animal feeds. As little information is available on the effects of the pH of substrates and feeding systems, the aim of this study was to evaluate the impact of these two factors on the activities of BSF larvae, prepupae, and adults. An experiment was performed with two fixed factors: i) pH (4.0; 6.1; 7.5; 9.5) and ii) feeding system (batch feeding system (TFS) or daily feeding system (DFS)). The pH treatments impacted larval weight on the first, third, and fifth day, but not at the end of the trial. Larval activity increased pH values from the fourth day onward, with final values of around 8.9-9.4 in all the treatments. The weight of the prepupae ranged from between 0.094 and 0.100 g. The final weight of the larvae and pupae, sex ratio, ingested food, larval mortality, percentage of emergence, and time to reach the pupa stadium were all affected by the feeding system. DFS showed the heaviest final larval weight (0.149 g), but required a longer time (11.3 d) than TFS to reach the prepupa stadium. The findings of this research could be useful for the mass production of BSF. Evaluation of an appropriate feeding system and initial pH value of the substrate are important parameters to reduce the time and to increase the weight in the production of larvae.

The influence of habitat heterogeneity and latitude on gamma diversity of the Nearctic Simuliidae, a ubiquitous group of stream-dwelling insects

Among the most prominent, large-scale patterns of species richness are the increases in richness with decreasing latitude and with increasing habitat heterogeneity. Using the stream-dwelling larval and pupal stages of North American black flies (Diptera: Simuliidae), we address 3 broad questions about species richness: (i) Does a significant latitude-richness relationship exist? (ii) How does habitat heterogeneity influence gamma diversity? (iii) What is the sign (positive or negative) of the latitude-richness and the heterogeneity-richness relationships? We found no evidence that habitat heterogeneity influences gamma diversity. The estimated peak species richness for black flies in North America was at 50-53°N, which also corresponds with peak generic richness. All plesiomorphic, extant lineages of the Simuliidae in the Western Hemisphere are found in cool mountainous environments of North America, suggesting that peak richness at 50-53°N might be a signature of this phylogenetic pattern and a reflection of underlying historical processes.

Determining the Number of Instars in Simulium quinquestriatum (Diptera: Simuliidae) Using k-Means Clustering via the Canberra Distance

Simulium quinquestriatum Shiraki (Diptera: Simuliidae), a human-biting fly that is distributed widely across Asia, is a vector for multiple pathogens. However, the larval development of this species is poorly understood. In this study, we determined the number of instars in this pest using three batches of field-collected larvae from Guiyang, Guizhou, China. The postgenal length, head capsule width, mandibular phragma length, and body length of 773 individuals were measured, and k-means clustering was used for instar grouping. Four distance measures-Manhattan, Euclidean, Chebyshev, and Canberra-were determined. The reported instar numbers, ranging from 4 to 11, were set as initial cluster centers for k-means clustering. The Canberra distance yielded reliable instar grouping, which was consistent with the first instar, as characterized by egg bursters and prepupae with dark histoblasts. Females and males of the last cluster of larvae were identified using Feulgen-stained gonads. Morphometric differences between the two sexes were not significant. Validation was performed using the Brooks-Dyar and Crosby rules, revealing that the larval stage of S. quinquestriatum is composed of eight instars.

A New Species of Simulium (Asiosimulium) (Diptera: Simuliidae) from Thailand

Simulium (Asiosimulium) saeungae sp. nov. (Diptera: Simuliidae) is described based on females, males, pupae, and mature larvae collected from Nan Province, Northern Thailand. It is characterized by the medium-long cerci in the female, enlarged hind basitarsus, and broad ventral plate with its posterior margin not deeply concave in the male, arborescent pupal gill with 42-56 filaments in the pupa and smaller number of primary rays of the labral fan (30-33) in the larva. This is the fifth species of the subgenus Asiosimulium, the second smallest among 10 subgenera in the Oriental Region. Taxonomic notes are given to distinguish this new species from the three known species from Thailand and one from Nepal.

Uptake of heavy metals and arsenic in black soldier fly (Hermetia illucens) larvae grown on seaweed-enriched media

BACKGROUND

The black soldier fly (Hermetia illucens) is one of the most promising insect species for use in animal feed. However, studies investigating feed and food safety aspects of using black soldier fly as feed are scarce. In this study, we fed black soldier fly larvae feeding media enriched with seaweed, which contains naturally high concentrations of heavy metals and arsenic. The aim of this study was to investigate the potential transfer of such undesirable substances from the feeding media to the larvae.

RESULTS

The larvae accumulated cadmium, lead, mercury and arsenic. Concentrations of these elements in the larvae increased when more seaweed was added to the feeding media. The highest retention was seen for cadmium (up to 93%) and the lowest for total arsenic (up to 22%). When seaweed inclusion exceeded 20% in the media, this resulted in larval concentrations of cadmium and total arsenic above the current European Union maximum levels for these elements in complete feed.

CONCLUSION

Our results confirm that insect larvae can accumulate heavy metals and arsenic when present in the feeding media. A broader understanding of the occurrence of these undesirable substances in processed larvae products is needed to assess feed and food safety. © 2017 Society of Chemical Industry.

A New Anthropophilic Species of Simulium (Trichodagmia) (Diptera: Simuliidae) From Amazonia: Morphology, Chromosomes, and DNA Sequences

The black fly Simulium (Trichodagmia) hirtipupa Lutz (Diptera: Simuliidae) is widely distributed in southern Brazil, with one report from Amapá state in the northern region of Brazilian Amazonia. Morphological comparison of northern and southern populations revealed differences in all life stages, corroborated by chromosomal and molecular analyses, and indicated that the population previously identified as S. hirtipupa from Amapá state represents an undescribed species. This new species is described based on all life stages above the egg, and its chromosomal and molecular divergence from S. hirtipupa is highlighted. Simulium criniferum n. sp. can be diagnosed by the deeply concave male ventral plate with a prominent median projection bearing a ventral keel; female anal lobe in lateral view with a broadly rounded, distal membranous area about as long as wide; pupa with a boot-shaped cocoon bearing a minutely bubbled surface, cephalic plate and thorax with abundant hair-like tubercles, and gill of 12 translucent filaments with darkly sclerotized, acuminate tips; and larva with the body cuticle bearing spiniform setae, abdomen truncated posteriorly, and gill histoblast in situ with the filament tips directed ventrally. Chromosomally, the new species has five unique fixed inversions and uniquely shares three additional fixed inversions with its nearest relative, S. hirtipupa. Partial COI sequences indicate a genetic distance of ~9% between the new species and S. hirtipupa. Females of the new species are anthropophilic.

Morphology and Polytene Chromosomes of a New Species of Simulium (Trichodagmia) (Diptera: Simuliidae) from the Espinhaço Mountains of Brazil

The species richness of black flies in the Simulium (Trichodagmia) orbitale (Diptera: Simuliidae) species group is greatest in southern Brazil, where 9 of 19 species are found. A new species in the S. orbitale group was collected during a survey of black flies in Minas Gerais state, Brazil, in the Espinhaço Mountains, an area rich in endemic taxa. The new species is morphologically similar to Simulium guianense Wise (Diptera: Simuliidae), the main vector of the causal agent of onchocerciasis in Brazil and Venezuela. It can be identified in the male by the unpatterned scutum and slightly concave ventral plate with a prominent median projection, in the female by the bilobate anal lobe, in the pupa by the 12 slender gill filaments with nonsclerotized apices, branching in a rake-like pattern, and in the larva by the elongated abdominal segments V-VIII and ventrolaterally lobulate segment IX. The polytene chromosomes have one unique fixed inversion in the IS arm, relative to all other Brazilian members of the group, confirming the morphological evidence of a distinct species.

Hierarchical dynamics influence the distribution of immature black flies (Diptera: Simuliidae)

Adult black flies (Simuliidae) are medically important insects and they are the sole vector of Onchocerca volvulus. Immature black flies are major components of aquatic macroinvertebrate assemblages in streams and play a vital role in nutrient dynamics. In this study, we examined effect of hierarchical dynamics (spatio-temporal pattern) on the distribution of immature black flies in South Indian streams. The sampling was done in streams of Western Ghats, South India. A total of 16 species belong to two subgenera: Simulium (10 species) and Gowmphostilbia (6 species) of Simulium were observed. Alpha diversity indices were analyzed, which indicate the abundance and species richness between sampling sites. Non-parametric analysis recognized the key environmental variables including latitude and stream order. Subsequently, the monsoon influences the larval assemblages and its association was high in leaf litter as revealed through statistical analyses. Although the members of the immature black fly assemblage with different environmental factors, they are very closely related to spatial and temporal organization and secondarily with other factors prevailing in streams.

Genetic Diversity and Identification of Palearctic Black Flies in the Subgenus Wilhelmia (Diptera: Simuliidae)

Accurate species identifications are the essential first step in understanding the medical, economic, and ecological importance of black flies. The utility of DNA barcoding based on cytochrome c oxidase subunit 1 (COI) sequences was evaluated for identifying six common species of Palearctic black flies in the subgenus Wilhelmia, including several that are virulent pests. Chromosomally identified larvae from Turkey and Germany and COI sequences in GenBank were analyzed. Intraspecific genetic divergence was 0.7-3.5% (mean 1.6%), whereas interspecific genetic divergence was 2.7-16.9%. On the basis of COI barcodes, the six nominal species of Simulium (Wilhelmia) were clustered in three distinct clades with high levels of genetic divergence, using maximum likelihood and Bayesian analyses. All specimens of Simulium equinum (L.), Simulium pseudequinum Séguy, and Simulium paraequinum Puri were correctly identified. However, >75% of identifications were ambiguous for Simulium lineatum (Meigen) and Simulium turgaicum Rubtsov (Meigen) because of overlapping intra- and interspecific divergence of the two species and Simulium balcanicum (Enderlein), all three of which are chromosomally similar and nearly isomorphic. Phylogenetic evaluation showed that S. balcanicum, S. equinum, S. pseudequinum, and S. paraequinum were monophyletic, with high bootstrap and posterior probability values, but it also showed that S. lineatum and S. turgaicum were paraphyletic, each clustering in two distinct groups, suggesting the presence of cryptic taxa. Although DNA barcoding provided a partial means of identification and indications of additional biodiversity, other molecular markers are needed to clarify the limits of all pest species of the subgenus Wilhelmia.

Nutritional composition of black soldier fly (Hermetia illucens) prepupae reared on different organic waste substrates

BACKGROUND

Black soldier fly larvae are converters of organic waste into edible biomass, of which the composition may depend on the substrate. In this study, larvae were grown on four substrates: chicken feed, vegetable waste, biogas digestate, and restaurant waste. Samples of prepupae and substrates were freeze-dried and proximate, amino acid, fatty acid and mineral analyses were performed.

RESULTS

Protein content of prepupae varied between 399 and 431 g kg^-1 dry matter (DM) among treatments. Differences in amino acid profile of prepupae were small. On the other hand, the ether extract (EE) and ash contents differed substantially. Prepupae reared on digestate were low in EE and high in ash (218 and 197 g kg^-1 DM, respectively) compared to those reared on vegetable waste (371 and 96 g kg^-1 DM, respectively), chicken feed (336 and 100 g kg^-1 DM, respectively) and restaurant waste (386 and 27 g kg^-1 DM, respectively). Prepupal fatty acid profiles were characterised by high levels of C12:0 in all treatments.

CONCLUSION

Since protein content and quality were high and comparable for prepupae reared on different substrates, black soldier fly could be an interesting protein source for animal feeds. However, differences in EE and ash content as a function of substrate should be considered. © 2016 Society of Chemical Industry.

Two New Species of Simulium (Gomphostilbia) (Diptera: Simuliidae) From Flores, Indonesia

Two new species, Simulium (Gomphostilbia) sunapii and S. (G.) rangatense, are described based on adults, pupae, and mature larvae from Flores, in the eastern part of the Sunda Archipelago, Indonesia. Simulium (G.) sunapii sp. nov. is placed in the S. asakoae species-group, representing the easternmost geographical record for the group in this archipelago. It is characterized by a small number of male upper-eye large facets in eight or nine vertical columns and 12 horizontal rows. Simulium (G.) rangatense sp. nov. is placed in the S. ceylonicum species-group and is characterized by the pupal gill with six filaments. This new species, together with two related species of the S. ceylonicum species-group in Flores, suggests the species radiation of this species-group might have been accompanied by a reduction of the number of pupal gill filaments from eight to four through six. Taxonomic notes are provided to distinguish these two new species from related species.

Influences of chromium and cadmium on the development of black soldier fly larvae

The black soldier fly Hermetia illucens is a good candidate for waste management. The harvested insects are rich in protein and have the potential to be used in animal feed. However, people are wary about heavy metals in waste. Therefore, it is necessary to understand how the uptake of heavy metals could affect H. illucens and where and to what extent metals are accumulated by the black soldier fly. Based on these considerations, developmental parameters were investigated in the different life stages of H. illucens fed an increasing concentration gradient of cadmium (Cd) and chromium (Cr); additionally, Cd and Cr distribution in the body parts of H. illucens at the different life stages was monitored. We found that Cd and Cr have no effects on larvae survival and eclosion rate, but they do have effects on larvae duration and pupation rate. Both Cd and Cr were transferred into larvae, prepupae, and pupae. While the concentrations of Cd in larvae and prepupae were much higher than that in their diets, the opposite case was observed with Cr. The concentrations of Cd and Cr in H. illucens decreased in later development stages. In individual larva and prepupa, Cd and Cr were mainly included in the body and not in the integument. In the pupa, the puparium contained higher Cd and Cr concentrations than the pupa body. The distribution of Cd and Cr in the different life stages and body parts may present a potential strategy for how H. illucens tolerate and remove heavy metal stress.

Species diversity of black flies (Diptera: Simuliidae) in Oriental region and molecular phylogeny of the subgenus Gomphostilbia members

BACKGROUND & OBJECTIVES

Black flies (Diptera: Simuliidae) are ecologically and medically important insects. Female adults of black flies are the solitary vectors of river blindness (onchocerciasis) and their larvae play a vital role in stream ecosystem. This study examined the distribution of black flies in the Oriental region and analyzed the phylogenetic relationship of the subgenus Gomphostilbia members based on two molecular loci.

METHODS

The distribution data of black fly species in different countries of Oriental region were obtained from world black flies geographic inventory. The two gene sequences, COI and ITS1 were used to study the phylogenetic relationships of the members of subgenus Gomphostilbia members.

RESULTS

The distribution analysis revealed that out of the 16 subgenera in the genus Simulium Latreille s., the species-level diversity of three subgenera (Gomphostilbia, Nevermannia and Simulium) contributes about thrice of total black fly species diversity. The highest diversity of species was found in the subgenus Simulium. The strict consensus of Tree analysis using New Technology (TNT) and Maximum Likelihood (ML) recovered similar topolo- gies for Gomphostilbia members and they formed as monophyly. The overall sequence identities of the 19 species of subgenus Gomphostilbia were high and shared 55-60% similarity.

INTERPRETATION & CONCLUSION

Results of this study highlighted that eight subgenera of Simulium Latreille s. str are commonly distributed in different parts of Oriental region. Among these the subgenera of Simulium, Gomphostilbia and Nevermannia are most common with high diversity in China, Pakistan, Thailand and Vietnam. The phylogenetic analysis of Gomphostilbia members demonstrates the inter-specific divergence, indicating the centre of origin (India) or the recipient of ancestral migrant lineages in Oriental region.

Simulium maleewongae, a New Species of Simulium (Gomphostilbia) (Diptera: Simuliidae) From Thailand

Simulium (Gomphostilbia) maleewongae sp. nov. is described based on the adult males and females, their pupal exuviae, and larvae from Thailand. This new species is placed in the Simulium gombakense species-group of Simulium (Gomphostilbia). It is characterized by the female cibarium with a cup-like appendage, male ventral plate deeply depressed ventromedially, pupal gill composed of an inflated structure and eight slender filaments, cone-shaped pupal terminal hooks, and cocoon with an anterodorsal projection. Taxonomic notes are given to separate this new species from 10 other species of the same species-group known from China, India, Malaysia, Thailand, Nepal, and Vietnam. Keys to identify all 11 species of the S. gombakense species-group are provided for females, males, pupae, and larvae.

Comments on the association of immatures of Hemerodromia (Diptera, Empididae) and Simulium (Diptera, Simuliidae), and first record of this association in the Atlantic Forest (Brazil)

Larvae of Empididae (Diptera) prey on black fly immatures and its pupae can be collected from pupal cases of Simuliidae (Diptera). The aim of our work was to report the second record of association between immatures of Empididae and Simuliidae in the Neotropical Region and the first for the Atlantic Forest (Rio de Janeiro, Brazil). We collected 4982 pupae and exuviae of Simulium Latreille, (Diptera, Simuliidae) and found three with a pupa of Hemerodromia Meigen (Diptera, Empididae) inside. This shows that the use of black flies cocoons by dance flies occurs at extremely low frequencies, which might explain why this association is so rarely recorded. Our results are relevant for a better comprehension of the predator-prey relationship between these families.

Three Taxa in One: Cryptic Diversity in the Black Fly Simulium nobile (Diptera: Simuliidae) in Southeast Asia

We access the molecular diversity of the black fly Simulium nobile De Mejiere, using the universal cytochrome c oxidase subunit I (COI) barcoding gene, across its distributional range in Southeast Asia. Our phylogenetic analyses recovered three well-supported mitochondrial lineages of S. nobile, suggesting the presence of cryptic species. Lineage A is composed of a population from Sabah, East Malaysia (Borneo); lineage B represents the type population from Java, Indonesia; and lineage C includes populations from the mainland of Southeast Asia (Peninsular Malaysia and Thailand). The genetic variation of lineage C on the mainland is greater than that of lineages A and B on the islands of Borneo and Java. Our study highlights the value of a molecular approach in assessing species status of simuliids in geographically distinct regions.

A New Species of Simulium (Gomphostilbia) (Diptera: Simuliidae) From Kalimantan, Indonesia, With Keys to Identify 19 Bornean Species of the Subgenus Gomphostilbia

A new simuliid species, Simulium kalimantanense sp. nov., is described on the basis of females, males, pupae, and mature larvae from East Kalimantan, Indonesia, and is assigned to the Simulium banauense species-group of Simulium (Gomphostilbia). This new species has close similarities to S alienigenum Takaoka from the Philippines, in many characters including the adult antennal color pattern and pupal gill with four long filaments arranged in two pairs each bearing a long stalk, but is distinguished from the latter in the female by the longer sensory vesicle and in the pupa by the gill with an elongate common basal stalk. Simulium kalimantanense sp. nov. is the first member of the S. banauense group in Borneo, and marks the most southerly distribution of the group. Keys to identify 19 Bornean species of the subgenus Gomphostilbia are provided.

Distribution pattern of black fly (Diptera: Simuliidae) assemblages along an altitudinal gradient in Peninsular Malaysia

BACKGROUND

Preimaginal black flies (Diptera: Simuliidae) are important components of the stream ecosystem. However, there has been limited research undertaken on the vertical distribution of preimaginal black flies and their associated ecological factors. Stream conditions are generally variable along the altitudinal gradient. Therefore, we conducted an in-depth entomological survey to investigate the simuliid distribution pattern along an altitudinal gradient in Peninsular Malaysia.

METHODS

A total of 432 collections were performed in this study (24 samplings at each of 18 fixed-streams at monthly intervals) from February 2012 to January 2014. Larvae and pupae attached on aquatic substrates such as grasses, leaves and stems, twigs, plant roots and rocks were collected by hand using fine forceps. Stream depth (m), width (m), velocity (m/s), water temperature (°C), acidity (pH), conductivity (mS/cm) and dissolved oxygen (mg/L) were measured at the time of each collection.

RESULTS

A total of 35 black fly species were recorded in the present study. The most frequently collected species were Simulium tani (31.7%) and S. whartoni (21.5%), while the relatively common species were Simulium sp. (nr. feuerborni) (16.2%), S. decuplum (15.5%), S. angulistylum (14.8%), S. bishopi (13.2%) and S. izuae (11.8%). Total estimated species richness ranged between 39.8 and 41.3, which yielded more than 80% of sampling efficiency. Six simuliid species were distributed below 500 m, whereas eight species were distributed above 1400 m. Simulium sp. (nr. feuerborni) and S. asakoae were found from middle to high altitudes (711-1813 m). Simulium whartoni, S. brevipar and S. bishopi were distributed widely from low to high altitudes (159-1813 m). Regression analysis between species richness and PCs revealed that the species richness was significantly associated with wider, deeper and faster streams at low altitude, normal water temperature (23-25 °C), low conductivity, higher discharge, more canopy cover and riparian vegetation and with larger streambed particles (F = 20.8, df = 1, 422, P < 0.001). Forward logistic regression indicated four species were significantly related to the stream variables (S. whartoni, Simulium sp. (nr. feuerborni), S. tani and S. angulistylum). Canonical correspondence analysis indicated that the temperature, stream size and discharge were the most important factors contributing to the separation of the stream sites from different altitude and hence are the predictors for the distribution of black fly species assemblages.

CONCLUSIONS

This study has provided insight into the distribution pattern of preimaginal black fly assemblages along an altitudinal gradient in Peninsular Malaysia. This study could deepen our knowledge on the ecology and biology of the specialised taxa in response to environmental changes.

An adaptive kernel smoothing method for classifying Austrosimulium tillyardianum (Diptera: Simuliidae) larval instars

In insects, the frequency distribution of the measurements of sclerotized body parts is generally used to classify larval instars and is characterized by a multimodal overlap between instar stages. Nonparametric methods with fixed bandwidths, such as histograms, have significant limitations when used to fit this type of distribution, making it difficult to identify divisions between instars. Fixed bandwidths have also been chosen somewhat subjectively in the past, which is another problem. In this study, we describe an adaptive kernel smoothing method to differentiate instars based on discontinuities in the growth rates of sclerotized insect body parts. From Brooks' rule, we derived a new standard for assessing the quality of instar classification and a bandwidth selector that more accurately reflects the distributed character of specific variables. We used this method to classify the larvae of Austrosimulium tillyardianum (Diptera: Simuliidae) based on five different measurements. Based on head capsule width and head capsule length, the larvae were separated into nine instars. Based on head capsule postoccipital width and mandible length, the larvae were separated into 8 instars and 10 instars, respectively. No reasonable solution was found for antennal segment 3 length. Separation of the larvae into nine instars using head capsule width or head capsule length was most robust and agreed with Crosby's growth rule. By strengthening the distributed character of the separation variable through the use of variable bandwidths, the adaptive kernel smoothing method could identify divisions between instars more effectively and accurately than previous methods.

Cryptic biodiversity in the cytogenome of bird-biting blackflies in North Africa

Bird-biting blackflies in the Simulium (Eusimulium) aureum group (Diptera: Simuliidae) are widespread vectors of Leucocytozoon and Trypanosoma parasites. The polytene chromosomes of 619 larvae of the three nominal members of the S. aureum group in North Africa were evaluated cytogenetically for cryptic biodiversity. Seven chromosomal segregates were discovered among 29 populations in Algeria and Morocco. This diversity was based primarily on two chromosomal inversions, which have assumed unique roles in different lineages, including sex linkage, fixation, loss and autosomal polymorphism. Reproductive isolation was demonstrated for six of the seven segregates, doubling the number of species known in the area. Four species were linked with existing names: (a) Simulium mellah Giudicelli & Bouzidi, which is known only from North African high-salinity habitats; (b) Simulium petricolum (Rivosecchi), which is tentatively conspecific with continental European populations; (c) Simulium rubzovianum (Sherban) and its synonym Simulium latinum (Rubtsov), which is widely distributed from North Africa across Europe into Western Asia, and (d) Simulium velutinum (Santos Abreu) and its new synonym Simulium tenerificum Crosskey, which is restricted to North Africa and the Canary Islands. Of the remaining entities, two are new species precinctive to North Africa and one, known only from Morocco, is of undetermined taxonomic status.

Mortality Patterns of Simulium vittatum Larvae (Diptera: Simuliidae) Following Exposure to Insecticidal Proteins Produced by Bacillus thuringiensis var. israelensis

Products containing insecticidal crystalline proteins (ICPs) produced by Bacillus thuringiensis var. israelensis (Bti ICPs) are used to suppress vector and nuisance populations of black flies. The efficacy of an application of these products is often determined by a posttreatment evaluation of larval mortality. Larvae are typically removed from the substrate at some point in time after application of the product and mortality is determined. The time necessary for the effects of Bti ICPs to cause morality in exposed larvae can vary, and there is little consensus on how long operators should wait before evaluating larval mortality. This study was conducted to provide more information to larvicide applicators when performing posttreatment evaluations. Simulium vittatum larvae were exposed to Bti ICPs under controlled conditions and the mortality was monitored over time. Larvae exposed to operational concentrations of ICPs exhibited maximum mortality, approximately 87%, after 4 h. Exposure of larvae to 1/3 of that concentration resulted in similar mortality; however, the maximum mortality was not reached until 8 h postexposure. Additional experiments revealed that maximum mortality and time to maximum mortality can also be affected by components in the larval medium. Larval mortality was compared between larvae exposed to Bti ICPs in moderately hard water, medium containing 50 parts per million (ppm) of kaolinite, and medium containing 50 ppm of cellulose. The clay material had no significant effect on larval mortality or time to achieve maximum mortality. When cellulose was present in the medium, the time to maximum mortality was increased 50% and overall mortality was reduced by more than 40%.

Notes on facultative predation in Prosimulium larvae (Diptera: Simuliidae) in alpine and subalpine streams in Colorado

Although it is widely accepted that black fly larvae employ filter feeding as their primary mode of nutrient intake, other forms of food acquisition, such as predation, may be more prevalent than previously realized. It has been suggested that environments where particulate matter is low, such as high-elevation seasonal streams, may drive predatory behavior in black fly larvae. Relatively little is known about the frequency at which larvae prey on other organisms or if predation may be obligate in some species. In order to supplement the idea that larval black fly predation may be a common method of feeding under certain conditions, a preliminary survey of predation by Prosimulium larvae was conducted in order to assess predation frequency at high-elevation sites (> 3,200 m) in the Colorado Rocky Mountains. Larvae were sampled from alpine and subalpine locations, and their gut content analysis revealed evidence of facultative predation and possible cannibalism. Evidence of predation was observed in all but 1 Prosimulium species collected. Predation frequency was highest in the North Fork Snake River headwater location, a small tributary stream of the Snake River in central Colorado. This survey suggests that further inquiry into predatory behavior of black fly larvae should be conducted to determine the mechanisms, behavior, and ecological impact of this understudied feeding strategy.

Two new Species of Simulium (Simulium) (Diptera: Simuliidae) From Mount Murud, Sarawak, Malaysia

Two new species of black flies, Simulium (Simulium) murudense and Simulium (Simulium) cheedhangi, are described on the basis of females, males, pupae, and larvae collected in Mount Murud, Sarawak, Malaysia. Both species belong to the Simulium melanopus Edwards species group. S. (S.) murudense sp. nov. is distinguished from most known species by a combination of the haired basal portion of the radial vein and the darkened fore coxae, and S. (S.) cheedhangi sp. nov. is characterized in the female by having a medium-sized claw tooth and in the pupa by six somewhat inflated gill filaments. Notes are given on the S. melanopus species-group in Sarawak and Sabah.

[Contribution to the black fly fauna of the tribes Nevermanniini and Wilhelmiini (Diptera: Simuliidae) of the Sakha Republik (Yakutia)]

In this paper, the data on fauna of Nevermanniini and Wilhelmiini tribes (Diptera: Simuliidae) were analyzed. All the accessible literature sources, institute collections and new materials recently collected in Yakutia were examined. Regional fauna was supplemented by two species: Schoenbaueria dendrofila (Patrusheva, 1962) and S. furculata Shewell, 1952, the latter being new for the Russian fauna also. The distribution of five more species from Simuliidae family was clarified. Processing of the collected material proved that 10 species previously registered in Yakutia can still be found in the region.

A new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Malaysia, with keys to 32 species of the Simulium ceylonicum species-group

Simulium (Gomphostilbia) leparense sp. nov. is described from females, males, and pupae collected from Peninsular Malaysia. This new species is assigned to the ceylonicum species-group of the subgenus Gomphostilbia, and is characterized by the female and male scuta covered with dark-brown short hairs, smaller number of male upper-eye facets, presence of shiny paired spots on the male abdominal segments 2-8, and absence of grapnel-shaped hooklets on the pupal abdominal segment 9. The male and pupa of S. capillatum Takaoka, which was originally described from larvae collected from Sarawak and Sabah, are described for the first time. Keys to identify all 32 species of the Simulium ceylonicum species-group including 27 species from other countries are provided for females, males, pupae, and mature larvae.

DNA barcoding distinguishes pest species of the black fly genus Cnephia (Diptera: Simuliidae)

Accurate species identification is essential for cost-effective pest control strategies. We tested the utility of COI barcodes for identifying members of the black fly genus Cnephia Enderlein (Diptera: Simuliidae). Our efforts focus on four Nearctic Cnephia species-Cnephia dacotensis (Dyar & Shannon), Cnephia eremities Shewell, Cnephia ornithophilia (Davies, Peterson & Wood), and Cnephia pecuarum (Riley)--the latter two being current or potential targets of biological control programs. We also analyzed one Palearctic species, Cnephia pallipes (Fries). Although Cnephia adults can be identified anatomically to species, control programs target the larval stage, which is difficult or impossible to distinguish morphologically. By using neighbor-joining, maximum parsimony, and Bayesian methods, we found that COI barcodes successfully identified three Nearctic Cnephia species, but not C. pecuarum. The Palearctic C. pallipes was also successfully identified. Despite nonmonophyly of C. pecuarum, we show that data from COI barcoding, in combination with geographical and ecological information, can be used to distinguish all four Nearctic species. Finally, we discussed 1) possible reasons for paraphyly in C. pecuarum, 2) topological concordance to previously reported chromosomal dendrograms, and 3) evolution of diverse feeding strategies within the genus Cnephia.

Description of a new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Cameron's Highlands, Peninsular Malaysia, with keys to 18 species of the Simulium asakoae species-group

Simulium (Comphostilbia) izuae sp. nov. is described from female, male, pupal, and larval specimens collected from Cameron's Highlands, Peninsular Malaysia. This new species is placed in the asakoae species-group of the subgenus Gomphostilbia. The pupa of this new species is characterized by the gill with eight long filaments arranged as (3 + 3) + 2 filaments, of which the ventral pair of filaments is borne on a stalk that is always shorter than the common basal stalk. Taxonomic notes to distinguish this new species from five other Malaysian species and 12 other species of the asakoae species-group from other countries are given. Keys to identify all 18 species of the asakoae species-group are also provided for females, males, pupae, and mature larvae.

Simulium (Asiosimulium) furvum, a new species of black fly (Diptera: Simuliidae) from Thailand

Simulium (Asiosimulium) furvum sp. nov. (Diptera: Simuliidae) is described from female, male, pupal, and larval specimens collected from Maewa National Park, Lampang Province, Thailand. This new species represents the fourth member of the subgenus Asiosimulium Takaoka & Chochoote, one of two small black fly subgenera endemic in the Oriental Region. It is characterized by a pear-shaped spermatheca in the female; a ventral plate in the male with a laterally compressed median keel directed ventrally and with a deep notch posteromedially, and aedeagal membrane with stout spines; and by 22 gill filaments in the pupa. Taxonomic notes are provided to separate this new species from three known species, Simulium (Asiosimulium) oblongum Takaoka & Choochote and Simulium (Asiosimulium) wanchaii Takaoka & Choochote, both from Thailand, and Simulium (Asiosimulium) suchitrae Takaoka from Nepal.

Influence of water physicochemical characteristics on Simuliidae (Diptera) prevalence in some streams of Meghalaya, India

BACKGROUND & OBJECTIVES

Simuliids (Diptera) are one of the medically important biting insects group and have worldwide distribution. Their immature stages proliferate in fast flowing river or stream water and have been considered as important ecological indicator.

METHODS

Aquatic stages of simuliids were collected and speciated from 16 different fresh water rivers and streams. Water flow rate was determined and water samples were analysed for various water variables such as water temperature, pH, dissolved oxygen concentration (DOC), dissolved oxygen saturation (DOS), conductivity, total dissolved solute (TDS), turbidity, resistivity and salinity. Linear regression was used to determine relationship between simuliid density and water variables, whereas multiple regression was used to determine the fitness for the presence of simuliid species. Principal component analysis (PCA) was used to determine the water parameters association with simuliid distribution.

RESULTS

Total 565 specimens comprising of three species namely, Simulium (S) barraudi Puri, S. (S) striatum Brunetti, and S. (S) himalayense Puri were recorded in the present study. Simulium barraudi was the most abundant (56.8%) and its density was high (χ2 = 289.3; df = 2; p <0.0001) as compared to the others. The average population size of each species was 188.3, whereas Simpson and Shannon-Wiener diversity indices were 0.4466 and 1.306 respectively. Linear regression showed that simuliid density was associated with the water flow rate. Principal component analysis indicated that the water parameters accounted for 42.25% variation along D1 axis, while 24.1% variation along D2 axis. Atleast two principal components have eigenvalue >1 and accounted for 32.6% of variation.

INTERPRETATION & CONCLUSION

Our study provides new information on simuliid species association with breeding water parameters in a little studied region of high biological interest. Turbidity, water flow and pH are important water parameters affecting the simuliid species prevalence. Each simuliid species preferred different sets of physicochemical parameters of breeding habitat, which are specific to that particular species. Therefore, simuliid species community as a whole cannot be considered as a suitable indicator of the streams water quality. In addition to describing simuliids, the information provided herein will be useful for the conservation of aquatic ecology and environment in Meghalaya state of India.

The relationship between water temperature and the development cycle beginning and duration in three black fly species

Understanding environmental factors affecting the timing and rate of animal development, as well as the factors that cause their effects, is of great importance. The purpose of this study was to establish the relationship between the onset and duration of the development from egg to pupal stage and water temperature in three black fly (Diptera: Simuliidae) species: Simulium (Simulium) reptans (Linnaeus 1758), Simulium (Byssodon) maculatum (Meigen 1804), Simulium (Boophthora) erythrocephalum (De Geer 1776). The study was based on surveys conducted between April and June of 1998-2010. The water temperature on the day of larval eclosion had no statistically significant impact on the beginning of development in any of the three species studied. The date when water temperature in the river reaches a certain value is important to the initiation of development in some black fly species. The present study revealed that the most important dates to the beginning of development of S. reptans black flies are when water temperature rises above 5° C, 7° C, and 10° C, while pivotal dates to the development of S. maculatum are when water temperature exceeds 4° C and 10° C. Water temperature most often exceeds the value important to the start of the development of these black fly species during March and April. The findings of the present study show that the hatching time of the two black fly species is also related to the mean water temperature in March and April. There were no statistically significant relations established between certain temperature dates and the beginning of larval development in S. erythrocephalum. Significant relations (p < 0.01) were found to exist between the duration of the development cycle from the first instar larva to pupa and the mean water temperature during the development period in S. reptans (r = -0.84; y = 53.088e(-0.0806x), R(2) = 0.70), S. maculatum (r = -0.82; y = 186.48e(-0.1123x), R(2) = 0.69) and S. erythrocephalum (r = -0.83; y = 58.768e(-0.0652x), R(2) = 0.70). The present study showed that the duration of development from the first instar larva to pupa in all the three black fly species studied was shorter when water temperatures during the development period were higher and longer when water temperatures were lower. The devised model of dependence between the duration of the studied black fly species' development and water temperature was verified experimentally.

The thermal constant of the onchocerciasis vector Simulium damnosum s.l. in West Africa

The minimum water temperature for development (t(0)) and the thermal constant (K) for the development of immature stages of Simulium damnosum s.l. (Diptera: Simuliidae) in West Africa were estimated as 20.1 °C and 93 day-degrees, respectively, based on analyses of published data on development rates of eggs, larvae and pupae at different water temperatures (24.0 °C and 31.5 °C). Thus, at a constant water temperature of 30.0 °C (approximately 10 °C above t(0)), adult flies would emerge about 9 days after oviposition. Analysis of a dataset probably restricted to S. damnosum s.s., but for which the temperature for the egg stage varied, revealed a much lower t(0) (16.3 °C) and a much higher K (181 day-degrees), suggesting that the insects' thermal relations may be cytoform-specific. The results will aid control decisions and predictions of possible effects of climate change on sizes and geographic distributions of populations of onchocerciasis vectors in West Africa.

The effect of seston on mortality of Simulium vittatum (Diptera: Simuliidae) from insecticidal proteins produced by Bacillus thuringiensis subsp. israelensis

Water was collected from a site on the Susquehanna River in eastern Pennsylvania, where less-than-optimal black fly larval mortality had been occasionally observed after treatment with Bacillus thuringiensis subsp. israelensis de Barjac insecticidal crystalline proteins (Bti ICPs). A series of experiments was conducted with Simulium vittatum Zetterstedt larvae to determine the water related factors responsible for the impaired response to Bti ICPs (Vectobac 12S, strain AM 65-52). Seston in the water impaired the effectiveness of the ICPs, whereas the dissolved substances had no impact on larval mortality. Individual components of the seston then were exposed to the larvae followed by exposure to Bti ICPs. Exposure of larvae to selected minerals and nutritive organic material before ICP exposure resulted in no significant decrease in mortality. Exposure of larvae to silicon dioxide, cellulose, viable diatoms, and purified diatom frustules before Bti ICP exposure resulted in significant reductions in mortality. Exposure of larvae to purified diatom frustules from Cyclotella meneghiniana Kützing resulted in the most severe impairment of mortality after Bti ICP exposure. It is postulated that frustule-induced impairment of feeding behavior is responsible for the impairment of larval mortality.

Seasonal occurrence of black flies (Diptera: Simuliidae) in a desert stream receiving trout farm effluent

The distribution and abundance of black flies (Diptera: Simuliidae) in a small desert stream were influenced by environmental changes caused by recharge of water supply storage basins and an aquaculture operation. Simulium virgatum was the most abundant benthic insect collected in Whitewater Canyon (Riverside County, CA) after April; however, it was never found in trout farm effluent where the ammonium-nitrogen concentration was > 0.25 mg/liter. S. virgatum densities downstream of the input of water from the Colorado River aqueduct were lower than at other sampling sites in the Whitewater River. Simulium tescorum, an especially anthropophilic black fly, was most abundant during February and March, was not collected from late spring through early autumn, and was found only in the highly enriched, less variable flow of trout farm effluent. The mean concentrations of ammonium nitrogen and nitrate nitrogen in the trout farm effluent nearly 1 km from the fish holding ponds were ten and two times, respectively, the ambient levels in the Whitewater River upstream of the effluent discharge point. A combination of factors probably contributed to the presence of S. tescorum in the trout farm effluent including homogenization of the flow regime, enrichment of larval resources, and the development of riparian vegetation that provided oviposition and attachment sites.

[First description of the Prosimulium candicans Rubzov, 1956 males (Diptera: Simuliidae)]

First description of the previously unknown Prosimulium candicans males is given. Belonging of this species to the genus Prosimulium Roubaud, 1906 rather than to the genus Taeniopterna Enderlein, 1925 is confirmed.

Mechanistic approach to understanding the toxicity of the azole fungicide triadimefon to a nontarget aquatic insect and implications for exposure assessment

Mechanistic and stereoselective based in vitro metabolism assays were utlilized to gain insight into the toxic mode of action of the 1,2,4-triazole fungicide, triadimefon, with black fly (Diptera: Simuliidae) larvae. Based on results from enzyme inhibitor studies, the metabolism of triadimefon in black fly larvae microsomes was found to occur predominantly via an oxidative P450-mediated pathway; triadimenol was formed via the stereoselective reduction of the prochiral carbonyl group of triadimefon. The relatively minor contribution of carbonyl reduction suggests that triadimefon may inhibit ecdysone 20-monooxygenase and disrupt insect molting hormone biosynthesis. 48-h LC50 tests for triadimefon and triadimenol with black fly larvae yielded median values (with 95% confidence intervals) of 6.1 (5.8-6.4) and 22.3 (20.3-24.1) mg/L respectively. The exposure of black fly larvae to sublethal concentrations of triadimefon resulted in increased microsomal P450 activity and affected the microsomal rates of both triadimefon depletion and triadimenol formation. In contrast to trout, black fly larvae produced a higher fraction of the more toxic triadimenol stereoisomers, which may explain in part why triadimefon exhibited a significantly greater toxicity with black fly larvae than trout. These results illustrate that while LC50 tests conducted with commercial triadimenol would presumably expose each organism to the same relative abundance of the four triadimenol stereoisomers, LC50 tests with triadimefon ultimately expose each organism to a unique set of triadimenol stereoisomers depending upon the organism's stereoselective metabolism.

Larval ontogeny and morphological variations of Psaroniocompsa incrustata (Lutz) (Diptera: Simuliidae) in the State of Rio Grande do Norte, Northeastern Brazil

Psaroniocompsa incrustata (Lutz) is an antropophilic species widely distributed in Central and South America. It is the vector of Onchocerca volvulus in a Brazilian focus and has been considered a plague in several areas of this country. The objective of this study was to determine the number of larval instars and to describe the morphological variations and teratologies of a population of P. incrustata from the Pium river, Rio Grande do Norte State. The number of larval instars was determined measuring the head capsule lateral length of 3,164 larvae. The larval instars were determined using the measurement frequency distribution, Student's t-test, the Dyar and Crosby growth rules. Eight larval instars were determined for P. incrustata. A high rate of teratologies (9.6%) in the hypostomium and variations in the lateral serrations and the latero-mandibular process were found.

Elimination of the Djodji form of the blackfly Simulium sanctipauli sensu stricto as a result of larviciding by the WHO Onchocerciasis Control Programme in West Africa

Cytotaxonomic identifications of larvae of members of the Simulium damnosum Theobald (Diptera: Simuliidae) complex collected in forest zones of southeast Ghana and southwest Togo between 1977 and 1996 showed that the Djodji form of Simulium sanctipauli Vajime & Dunbar, a vector of onchocerciasis, was eliminated in 1988 by larvicide operations conducted by the World Health Organization (WHO) Onchocerciasis Control Programme (OCP) in West Africa. No members of the form were identified amongst 997 larvae collected up to 8 years after systematic control operations began in February 1988. The results are discussed in relation to estimates of the numbers of samples required to certify elimination and the possibility that other members of the S. damnosum complex were also eliminated by the OCP.

[Morphology of the blackfly species group macropyga of the genus Prosimulium roubaud, 1906, and re-establishment of the generic name Taeniopterna Enderlein, 1925 for this group (Diptera: Simuliidae)]

The genus Taeniopterna with the types species Melusina macropyga Lundstrom, 1911 was proposed by Enderlein in 1925. Later this taxon was considered as the species group macropyga in the genus Prosimulium Roubaud, 1906 by many authors (Rubzov, 1956; Crosskey et Howard, 1997; Adler et al., 2004, and others). However, differences between this group and the remaining species of Prosimulium s. str. (species group hirtipes/mixtum) seem to be not lesser, than those between other genera (or subgenera) of the tribe Prosimuliini (in our sense), namely Helodon Enderlein, 1921, Urosimulium Contini, 1963, Parahelodon Peterson, 1970, and Distosimulium Peterson, 1970. Taeniopterna differs from other genera of Prosimuliini by the following characters. Imago differs from all other genera in having shortened proboscic (1.5 times shorter than clypeus, while in other genera it is of the same length with clypeus). It differs from all genera except Helodon in having relatively prolonged and lightly pointed distally wings (in other genera wings are wide and rounded distally). Male differs from all other genera of the tribe, except Urosimulium, in having narrow frons between the eyes. It differs from the Urosimulium male by conic gonostyles (in Urosimulium gonostyles bear the large heel). Female differs from all other genera of tribe by very small spermatheca (1/3-1/5 of the lenght of the branch of genital fork (while in other genera spermatheca is equal or longer, than the branch of genital fork) and by the absence of serration on maxillae and mandibles. Female also differs from other genera of the tribe, except Prosimulium, by very long hypogynal valves and by missing or very small and pressed basal tooth of claws (in Helodon, Urosimulium, Parahelodon, and Distosimulium hypogynal valves are short and rounded, basal tooth of claws is moderate or large and put aside). It differs from Prosimulium by smaller head (more narrow than thorax, while in Prosimulium head is near equal by width with thorax) and by absence of sclerotization on the medial edges of hypogynal valves. Larva differs from all other genera of the tribe, except Prosimulium, in having long dorsoventral projections of wide sclerotized band of prothorax (in other genera this band is narrow and without projections). It differs from Prosimulium by another pattern of the hypostomal teeth. Pupa differs from all other genera of the tribe, except Distosimulium, by cocoon covering all the pupal body (in other genera cocoon covers only posterior part of the pupal body). It differs from Distosimulium by long and strong caudal thorns (in Distosimulium caudal thorns are of moderate length and more thin). These and some other characters give the base for the proposition to consider the species group macropyga as a a separate genus Taeniopterna Enderlein, 1925. A list of Taeniopterna species is given.

[Some ecological aspects of larvivorous fish existing in Cayo Santa María, Cuba]

One thousand and three hundred twenty one fish from Cyprinodon variegatus, Gambusia punticulata, Fundulus grandis saguanus. Cubanichthys cubensis y Girardinus metallicus were collected for the purpose of locating and identifying fish of interest in the control of mosquito larvae in Cayo Santa Maria, Villa Clara province. Ecological indexes such as diversity (H') and equity (J') were estimated through a program named BIODIVERSITY Pro v2 and also the contents in the stomach of 341 specimens (25,81%) of the total was analyzed. The most abundant and distributed species in all the sampled sites was C. variegatus followed by G puncticulata. The number of fish of these species showed a differential gradient going from West to East: upward for C. variegatus and downward for G. puncticulata (X2 = 150,60, p< 0,001), being the latter the species that most equitably used the food resources (J' = 0,92) since it consumed 6 of them for food. These indigenous fish that are abundant in natural reservoirs should be taken into account for integrated control plans aimed at mosquito, gnat and horsefly breeding sites found in these locations.