An illustrated identification key to early instar larvae of forensically important Muscidae (Diptera) of the western Palaearctic region

There is a significant gap in the availability of comprehensive identification keys for the early larval stages of forensically important fly species. While well-documented identification keys exist for the third instar larvae, particularly for the Calliphoridae, Muscidae and Sarcophagidae families, there is a notable scarcity of keys for the first, except Calliphoridae, and the second instar larvae, with no such resources available for muscid species. The second instar larvae suffer the most from the lack of morphological descriptions and available identification keys. The Muscidae is one of the most frequently reported dipteran families of forensic importance colonising animal cadavers and human corpses. Nevertheless, descriptions of the morphology of their early instars remain scarce and limited to only a few species, thus their larval identification is challenging or impossible. Considering the numerous challenges associated with studying small-sized entomological material, we tested whether it is feasible to identify muscid flies to the species or at least genus level based predominantly on the details of the cephaloskeleton. To overcome the obstacle of observing details of small sclerites, especially their shapes and interconnections, we effectively employed confocal laser scanning microscopy (CLSM) as a supplementary method for light microscopy (LM). This study provides an identification key for first and second instar larvae of forensically important muscid species from the western Palaearctic (Europe, North Africa, Middle East). The proposed key primarily utilises details of the cephaloskeleton with only addition of external morphology.

Odour-mediated oviposition site selection in Aedes aegypti depends on aquatic stage and density

BACKGROUND

Olfaction plays an important role in the selection and assessment of oviposition sites by mosquitoes. Volatile organic compounds (VOCs) associated with potential breeding sites affect the behaviour of gravid mosquitoes, with VOCs from aquatic stages of conspecific mosquitoes influencing and regulating oviposition. The purpose of this study was to conduct a systematic analysis of the behavioural response of gravid Aedes aegypti to conspecific aquatic stage-conditioned water, to identify the associated bioactive VOCs and to determine how blends of these VOCs regulate oviposition site selection and stimulate egg-laying.

METHODS

Using a multi-choice olfactory oviposition assay, controlling for other sensory modalities, the responses of individual females to water conditioned with different densities of conspecific aquatic stages were assessed. The conditioned water samples from the most preferred density of each aquatic stage were subsequently compared to each other using the same oviposition assay and analysed using an analysis of variance (ANOVA) followed by a Tukey post-hoc test. Using combined gas chromatography and electroantennographic detection or mass spectrometry, bioactive VOCs from the preferred density of each aquatic stage were identified. Synthetic blends were prepared based on the identified ratios of bioactive VOCs in the aquatic stages, and then tested to determine the oviposition choice of Ae. aegypti in a dose-dependent manner, against a solvent control, using a dual-choice assay. This dataset was analysed using nominal logistic regression followed by an odds ratio comparison.

RESULTS

Gravid Ae. aegypti responded stage- and density-dependently to water conditioned with eggs, second- and fourth-instar larvae, and pupal exuviae, but not to water conditioned with pupae alone. Multi-choice assays demonstrated that gravid mosquitoes preferred to oviposit in water conditioned with fourth-instar larvae, over the other aquatic stage-conditioned water. Gravid Ae. aegypti were attracted, and generally stimulated, to oviposit in a dose-dependent manner to the individual identified synthetic odour blends for the different aquatic stages.

CONCLUSIONS

Intraspecific VOCs regulate oviposition site selection in Ae. aegypti in a stage- and density-dependent manner. We discuss the need for further studies to evaluate the identified synthetic blends to modulate the odour-mediated oviposition of Ae. aegypti under field conditions.

Pintomyia evansi (Diptera: Psychodidae) larvae susceptibility to hydrated lime under laboratory conditions

This study evaluated the effect of Calcium hydroxide (Ca(OH)₂ Mg(OH)₂) on third stages Pi. evansi larvae mortality under experimental laboratory conditions. Three treatments containing a mixture of phlebotomine natural breeding soil (substrate) and Calcium hydroxide at different concentrations were used: Treatment 1 (T1), 1 kg of substrate mixed with 56.2 g of lime; Treatment 2 (T2), 1 kg of substrate mixed with 62.5 g of lime; and Treatment 3 (T3), 1 kg of substrate mixed with 70 g of lime. in addition, a sample of substrate without lime was used as a control for each treatment. The mortality in T1 was 1% at 24 h and 12% at 48 h, reaching a maximum of 56% at 72 h of exposure. For T2, mortality was progressive, starting with 12% at 12 h, 36% at 24 h, 52% at 48 h, and 100% at 72 h; while T3 showed mortality percentages of 94% and 100% between 12 and 24 h of exposure. Therefore, T3 was the most effective to according to the Kaplan-Meier survival analysis. This study showed that treatments over 62 g of Calcium hydroxide per 1 kg of substrate offer a starting point for immature stage control under laboratory conditions. With these results, we propose to evaluate the cost-effectiveness and feasibility of the application, of the latter concentration, under field conditions in urban environments for its application in vector control programs.

On the Andean genus Leschenius (Coleoptera: Curculionidae: Entiminae): Updated phylogeny, with a new species from Ecuador, discovery of males, and larval description of the potato weevil Leschenius vulcanorum

The weevil genus Leschenius del Río (Curculionidae: Entiminae: Naupactini) is distributed in the northern Andes, in Colombia and Ecuador. Among its species, L. vulcanorum stands out as an important pest of potatoes in its parthenogenetic form, which is known as "tiroteador de la papa". In this study, the adult male and the larval stage (first and mature larvae) of L. vulcanorun are described and illustrated for the first time. A description of the male of Leschenius bifurcatus is also provided. A new bisexual species was discovered, Leschenius ventrilingulatus sp. nov., and is described from Ecuador. An updated phylogenetic analysis was performed, including the new species, with results indicating a sister group relationship between L. ventrilingulatus and L. vulcanorum. They can be distinguished because the former is usually of smaller size and is covered by denser and thicker setae, has shorter antennae, a subcylindrical shape of the pronotum, shorter elytra (about 1.5×longer than wide at base), the female has ventrite 4 with a posterior rounded projection, and posterior margin of ventrite 5 subacute, not excavated. This paper also includes lectotype designations, a revised key to all known species of Leschenius, habitus photos of males and females, illustrations of genitalia, and a distribution map.

Description of the Third-Stage Larva and Puparium of Platycheirus (Carposcalis) chalconota (Philippi) (Diptera: Syrphidae) with New Information About the Trophic Interactions and Larval Habitats

In this study, the third-stage larva and puparium of the copper-backed fly, Platycheirus (Carposcalis) chalconota (Philippi, 1865) are fully described using stereomicroscopy and scanning electron microscopy from material collected in peach orchards of central-west Argentina. The immature stages of P. chalconota were compared with the third-stage larva and puparium of the best-studied species in the genus Platycheirus scutatus (Meigen, 1822); as well as with the only known Carposcalis immature stages description available for the Neotropical region namely Platycheirus stegnus (Say, 1829). New data on trophic interactions and larval habitats are given: P. chalconota larvae were found feeding on the aphid's species Uroleucon sonchi (Linnaeus, 1767) (large sow thistle aphid) and Hyperomyzus lactucae (Linnaeus, 1758) (blackcurrant-sow thistle aphid) in low vegetation as Sonchus oleraceus (common sow thistle); the species was also found feeding on Myzus persicae (Sulzer, 1776) (green peach aphid) in high vegetation as Prunus persicae (L.) Stokes (Peach trees). The third larval stage and puparium of P. chalconota are described and illustrated for the first time improving substantially the knowledge about the immature stages and natural history of Neotropical Platycheirus, constituting also a baseline for future comparative morphological studies. Despite the efficiency of P. chalconota in the biological control of pests has not been assessed, we think that relevant data presented here can be used in pest management of peach orchards and suggest P. chalconota as an excellent candidate for future studies on the life cycle, prey consumption, efficiency, artificial rearing, and its potential importance as pollinators of Peach crops.

The Dung Beetle Oxyomus of Taiwan (Coleoptera: Scarabaeidae): Review of the Fauna, a New Species and its Larva Associated by DNA Barcoding

The Taiwanese fauna of the dung beetle genus Oxyomus Dejean, 1833 (Coleoptera: Scarabaeidae: Aphodiinae) is reviewed based on museum specimens and newly collected material. Four species, all endemic to Taiwan, are recognized, one of which is newly described here: O. alligator sp. nov. Remaining species are diagnosed, compared with similar relatives from outside of Taiwan, and their distribution is mapped. We show that Taiwanese Oxyomus species form three distinct morphological groups, similar to species from Japan, SE Asia and Malay Archipelago, respectively, indicating a possible composite origin of Taiwanese fauna. The species occur in submontane and montane forests at altitudes of 700-2550 m including the secondary Cryptomeria ones. Available data confirm their association with dung of various forest mammals (monkeys, muntjacs and serows), although the discovery of larvae in sifted forest leaf litter may indicate they can also develop in nutrient-rich substrate around the dung. The larva of O. alligator sp. nov. is described in detail, based on the larval specimens associated with adults by DNA barcodes. Larvae of Oxyomus alligator sp. nov. are similar to those of the European O. sylvestris (Scopoli, 1763), with important differences only found on maxilla and abdominal apex.

A comprehensive review and call for studies on firefly larvae

BACKGROUND

Fireflies (Coleoptera: Lampyridae) are commonly recognized by adult traits, such as a soft exoskeleton, lanterns and associated glow and flash patterns, but their larval stage is far less appreciated. However, fireflies spend most of their lives as larvae, and adults of most species rely solely on resources previously obtained. Therefore, studying the immature stages is imperative towards a comprehensive understanding of fireflies. This paper reviews and indicates key gaps in the biology of firefly larvae based on available literature.

METHODOLOGY

We reviewed the literature on firefly larvae to identify key issues and important taxonomic, geographic, and subject biases and gaps.

RESULTS

We found 376 papers that included information on firefly larvae. Only 139 species in 47 genera across eight of eleven lampyrid subfamilies have been studied during larval stages. These numbers reveal a staggering gap, since 94% of species and over half of the genera of fireflies were never studied in a crucial stage of their life cycle. Most studies on firefly larvae focus on two subfamilies (Luciolinae and Lampyrinae) in four zoogeographic regions (Sino-Japanese, Oriental, Nearctic, and Palearctic), whereas the other subfamilies and regions remain largely unstudied. These studies mainly dealt with morphology and behavior, other subjects remaining greatly understudied by comparison, including habitats, life cycle, physiology and interactions.

CONCLUSIONS

Together, these literature biases and gaps highlight how little is known about firefly larvae, and warmly invite basic and applied research, in the field and in the lab, to overcome these limitations and improve our understanding of firefly biology to better preserve them.

Efficacy of a new oral chewable tablet containing sarolaner, moxidectin and pyrantel (Simparica Trio™) against induced ascarid infections in dogs

BACKGROUND

Ascarid infections are among the most prevalent intestinal parasitic infections occurring in dogs around the world, with Toxocara canis and Toxascaris leonina commonly observed. Toxocara canis can cause considerable disease in dogs and humans, and year-round prophylactic treatment and control in dogs is recommended. Elimination of immature stages of these parasites before egg-laying will reduce environmental contamination and the risk of infection for both dogs and humans. Studies were conducted to evaluate the efficacy of a novel, oral chewable tablet containing sarolaner, moxidectin and pyrantel (Simparica Trio™) against induced immature adult (L₅) and adult T. canis, and adult T. leonina infections in dogs.

METHODS

Six negative-controlled, masked, randomized laboratory studies were conducted. Two studies each evaluated efficacy against immature adult (L₅) T. canis, adult T. canis, and adult T. leonina. Sixteen to 40 dogs were included in each study. Dogs experimentally infected with the target parasite were dosed once on Day 0 with either placebo tablets or Simparica Trio™ tablets to provide minimum dosages of 1.2 mg/kg sarolaner, 24 µg/kg moxidectin and 5.0 mg/kg pyrantel (as pamoate salt). Efficacy was based on the number of worms recovered at necropsy 7-10 days after treatment compared to placebo control.

RESULTS

Based on geometric mean worm counts, efficacy of the sarolaner + moxidectin + pyrantel combination was ≥ 95.2% against immature adult T. canis, ≥ 97.3% against adult T. canis, and ≥ 89.7% against adult T. leonina. There were no treatment-related adverse events in any study.

CONCLUSIONS

These studies confirm the efficacy of a single dose of a new oral chewable tablet containing sarolaner, moxidectin and pyrantel (Simparica Trio™) against immature adult and adult T. canis, and adult T. leonina infections in dogs.

Efficacy of Simparica Trio™, a novel chewable tablet containing sarolaner, moxidectin and pyrantel, against induced hookworm infections in dogs

Background

Ancylostomatids (‘hookworms’) are among the most important zoonotic nematode parasites infecting dogs worldwide. Ancylostoma caninum and Uncinaria stenocephala are two of the most common hookworm species that infect dogs. Both immature and adult stages of hookworms are voracious blood feeders and can cause death in young dogs before infection can be detected by routine fecal examination. Hence, treatment of both immature and adult stages of hookworms will decrease the risk of important clinical disease in the dog as well as the environmental contamination caused by egg-laying adults, which should reduce the risk of infection for both dogs and humans. The studies presented here were conducted to evaluate the efficacy of a novel, oral chewable tablet containing sarolaner, moxidectin and pyrantel (Simparica Trio™), against induced larval (L₄), immature adult (L₅) and adult A. caninum, and adult U. stenocephala infections in dogs.

Methods

Eight negative-controlled, masked, randomized laboratory studies were conducted. Two separate studies were conducted against each of the target parasites and stages. Sixteen or 18 purpose bred dogs, 8 or 9 in each of the two treatment groups, were included in each study. Dogs experimentally infected with the target parasite were dosed once on Day 0 with either placebo tablets or Simparica Trio™ tablets to provide minimum dosages of 1.2 mg/kg sarolaner, 24 µg/kg moxidectin and 5.0 mg/kg pyrantel (as pamoate salt). Timing of dosing relative to parasite inoculation allowed for efficacy to be evaluated primarily against the target parasite stage. Worm counts were conducted 7 or 8 days after treatments during necropsy. Efficacy was based on the number of worms recovered at necropsy compared to placebo control.

Results

Based on geometric mean worm counts, efficacy of Simparica Trio™ was ≥ 98.4% against L₄ larval stage of A. caninum, ≥ 99.8% against immature adult (L₅) A. caninum, and 100% against adult A. caninum and adult U. stenocephala.

Conclusions

These studies confirm the efficacy of a single oral dose of a novel, chewable tablet containing sarolaner, moxidectin and pyrantel (Simparica Trio™) against L₄ larval and immature adult (L₅) A. caninum, and adult A. caninum and U. stenocephala infections in dogs.

Occurrence and predictive utility of isochronal, equiproportional, and other types of development among arthropods

In isochronal (ICD) and equiproportional development (EPD), the proportion of total immature (egg, larval, and/or juvenile) development spent in each stage (developmental proportion) does not vary among stages or temperatures, respectively. ICD and EPD have mainly been reported in copepods, and whether they occur in other arthropods is not known. If they did, then rearing studies could be simplified because the durations of later developmental stages could be predicted based on those of earlier ones. The goal of this study was to test whether different taxa have ICD, EPD, or an alternative development type in which stage-specific proportions depend on temperature, termed 'variable proportional' development (VPD), and also how well each development type allowed later-stage durations to be predicted from earlier ones. Data for 71 arthropods (arachnids, copepod and decapod crustaceans, and insects) were tested, and most (85.9%) species were concluded to have VPD, meaning that ICD and EPD do not occur generally. However, EPD predicted later-stage durations comparably well to VPD (within 19-23%), and thus may still be useful. Interestingly, some species showed a 'mixed' form of development, where some stages' developmental proportions varied with temperature while those of others did not, which should be further investigated.

A cross-sectional survey of Aedes aegypti immature abundance in urban and rural household containers in central Colombia

Background

Aedes aegypti, the major vector of dengue, breeds in domestic water containers. The development of immature mosquitoes in such containers is influenced by various environmental, ecological and socioeconomic factors. Urban and rural disparities in water storage practices and water source supply may affect mosquito immature abundance and, potentially, dengue risk. We evaluated the effect of water and container characteristics on A. aegypti immature abundance in urban and rural areas. Data were collected in the wet season of 2011 in central Colombia from 36 urban and 35 rural containers, which were either mosquito-positive or negative. Immature mosquitoes were identified to species. Data on water and container characteristics were collected from all containers.

Results

A total of 1452 Aedes pupae and larvae were collected of which 81% were A. aegypti and 19% A. fluviatilis. Aedes aegypti immatures were found in both urban and rural sites. However, the mean number of A. aegypti pupae was five times higher in containers in the urban sites compared to those in the rural sites. One of the important factors associated with A. aegypti infestation was frequency of container washing. Monthly-washed or never-washed containers were both about four times more likely to be infested than those washed every week. There were no significant differences between urban and rural sites in frequency of washing containers. Aedes aegypti immature infestation was positively associated with total dissolved solids, but negatively associated with dissolved oxygen. Water temperature, total dissolved solids, ammonia, nitrate, and organic matter were significantly higher in urban than in rural containers, which might explain urban-rural differences in breeding of A. aegypti. However, many of these factors vary substantially between studies and in their degree of association with vector breeding, therefore they may not be reliable indices for vector control interventions.

Conclusions

Although containers in urban areas were more likely to be infested with A. aegypti, rural containers still provide suitable habitats for A. aegypti. Containers that are washed more frequent are less likely to produce A. aegypti. These results highlight the importance of container washing as an effective vector control tool in both urban and rural areas. In addition, alternative designs of the highly productive washbasins should continue to be explored. To control diseases such as dengue, Zika and chikungunya, effective vector breeding site control must be implemented in addition to other interventions.

Inhibitory activity of Beauveria bassiana and Trichoderma spp. on the insect pests Xylotrechus arvicola (Coleoptera: Cerambycidae) and Acanthoscelides obtectus (Coleoptera: Chrisomelidae: Bruchinae)

Xylotrechus arvicola is an important pest in vineyards (Vitis vinifera) in the main Iberian wine-producing regions, and Acanthoscelides obtectus causes severe post-harvest losses in the common bean (Phaseolus vulgaris). Under laboratory conditions with a spray tower, the susceptibility of the immature stages of X. arvicola and A. obtectus against the entomopathogenic fungi Beauveria bassiana and four strains of Trichoderma spp. was evaluated. Both insect pests T. harzianum and B. bassiana showed a good inhibitory activity, accumulating an inhibition on the eggs of values above 85 and 82%, respectively. T. atroviride and T. citrinoviride had a lower inhibitory activity, with inhibition values of 74.1 and 73.3% respectively. These fungi can be considered a highly effective tool for the control during the immature stages of these species.

Muscidae (Diptera) of forensic importance-an identification key to third instar larvae of the western Palaearctic region and a catalogue of the muscid carrion community

The Muscidae is one of the main dipteran families recognized as important for medico-legal purposes. Although an association of adult flies with decomposing human and animal bodies is documented for about 200 taxa worldwide, cadavers and carrion represents a breeding habitat for considerably fewer species. Species that do colonize dead human bodies can do so under diverse environmental conditions and, under certain circumstances, Muscidae may be the only colonizers of a body. Because of difficulties in identification, many studies have identified immature and/or adult muscids only to the genus or family level. This lack of detailed species-level identifications hinders detailed investigation of their medico-legal usefulness in carrion succession-oriented experiments. Identification to species level of third instars of Muscidae of forensic importance and the utility of larval morphological characters for taxonomic purposes were subjected to an in-depth revision. A combination of characters allowing for the discrimination of third instar muscids from other forensically important dipterans is proposed. An identification key for third instar larvae, which covers the full set of cadaver-colonising species of Muscidae from the western Palaearctic (Europe, North Africa, Middle East), is provided. This key will facilitate more detailed and species-specific knowledge of the occurrence of Muscidae in forensic entomology experiments and real cases. The carrion-visiting Muscidae worldwide are catalogued, and those species breeding in animal carrion and dead human bodies are briefly discussed with regard to their forensic importance.

Description of the Terrestrial Larva of Parosca latipalpis (Macquart) (Diptera: Tabanidae) from Southern Chile

The terrestrial larva of the austral horsefly, Parosca latipalpis (Macquart), identified by molecular techniques, is described. The larva of P. latipalpis resembles Scaptia auriflua (Donovan), Copidapha vicina (Taylor), Myioscaptia muscula (English), and Osca lata (Guérin-Meneville) in many morphological characters, as well as in their terrestrial habitats. Some characters that are shared between these species are unique among Tabanidae and provide evidence of their monophyletic origin, suggesting a typical Gondwanaland group. Larvae of P. latipalpis were found 2-3 cm below of the soil surface and associated with larvae of Coleoptera, Lepidoptera, and Diptera in southern Chile.

Miltefosine lipid nanocapsules: Intersection of drug repurposing and nanotechnology for single dose oral treatment of pre-patent schistosomiasis mansoni

A dual drug repurposing/nanotechnological approach was used to develop an alternative oral treatment for schistosomiasis mansoni using miltefosine (MFS), an anticancer alkylphosphocholine, and lipid nanocapsules (LNCs) as oral nanovectors. We demonstrated earlier that MFS possesses significant activity against different developmental stages of Schistosoma mansoni in the mouse model using 5 successive 20mg/kg/day oral doses. Moreover, an effective single dose (20mg/kg) oral treatment against the adult stage of S. mansoni in mice was developed using LNCs, particularly modified with CTAB, a positive charge imparting agent (MFS-LNC-CTAB(+)), or oleic acid as membrane permeabilizer (MFS-LNC-OA). Efficacy enhancement involved, at least in part, targeting of the worm tegument with MFS-LNCs as a new therapeutic entity. As the tegument surface charge and composition may differ in pre-patent stages of the parasite, it was of importance in the present study to assess the efficacy of a single oral dose of the two MFS-LNC formulations against invasive and immature stages for potential advantage relative to praziquantel. Results indicated potent schistosomicidal effects against both invasive and immature stages of S. mansoni in infected mice, efficacy being both formulation and developmental stage dependent. This was indicated by the significant reduction in the total worm burden of the invasive stage by 91.6% and 76.8% and the immature stage by 82.7% and 96.7% for MFS-LNC-CTAB+ and MFS-LNC-OA, respectively. Histopathological findings indicated amelioration of hepatic pathology with regression of the granulomatous inflammatory reaction and reduction in granulomas number and size, verifying marked improvement in architecture of hepatic lobules. From a clinical perspective, MFS-LNCs offer potential as an alternative single oral dose nanomedicine with a wide therapeutic profile for the mass chemotherapy of schistosomiasis mansoni.

Immature stages and ecology of two species of the South African genus Stripsipher Gory & Percheron, 1833 (Coleoptera, Scarabaeidae, Cetoniinae, Trichiini)

Based on the study of newly accessible type material, Stripsipher drakensbergi Ricchiardi, 1998, is demoted to a junior synonym of Stripsipher jansoni Péringuey, 1908. The genus Stripsipher Gory & Percheron, 1833, thus, currently includes 12 species, but for none of these are larval stages and/or pupae currently known. The immature stages of Stripsipher orientalis Ricchiardi, 2008 and Stripsipher jansoni are described here for the first time and updated observations on distribution and ecology of both species are provided. Morphological affinities of Stripsipher with other Trichiini larvae are presented and the main diagnostic differences discussed. The larvae of both species are very similar to those of other representatives of the tribe Trichiini, with key differences found on the epipharynx. Based on the morphology of larvae and adults, it is suggested that Stripsipher is a member of the clade composed of Valgini, Trichiini and Cryptodontini.