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Simulium (Gomphostilbia) 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.
A new tick species belonging to the genus Dermacentor Koch, 1844, Dermacentor panamensis n. sp., is described. All stages of this species are similar to those of Dermacentor halli McIntosh, 1931, with which it was confused for a long time. Males of D. panamensis can be distinguished from those of D. halli by the following suite of characters: narrower conscutum, broader basis capituli, shorter dorsal cornua, narrower palpi, palpal segment III tapering to its apex, legs poorly ornate: ivory colored patches present only on dorsal aspects of leg segments (mostly on legs III and IV), and internal spur of coxae I narrower and more tapering. Females of D. panamensis can be distinguished from those of D. halli by the following suite of characters: narrower and less ornate scutum, broader basis capituli, shorter dorsal cornua, larger porose areas, narrower palpi, palpal segment III tapering to its apex, legs poorly ornate: ivory colored patches present only on dorsal aspects of leg segments (mostly on legs III and IV), and internal spur of coxae I narrower and more tapering. Nymphs of D. panamensis can be distinguished from those of D. halli by clear posterolateral projections of scutum and by absence of coxal “pore” on coxae I–IV, while larvae of D. panamensis can be distinguished from those of D. halli by shorter and less sharp lateral projections of basis capituli dorsally and slightly sharp anterior angle of basis capituli. D. panamensis is known from highlands of Costa Rica, Guatemala, Honduras, Nicaragua, and Panama where the adults were collected from porcupines and unidentified sloth and mouse while nymphs and larvae were found on various rodents and a bat.
This article describes morphological characteristics and the occurrence of Demodex gracilentus sp. nov., which was found in the striped field mouse Apodemus agrarius (Pallas, 1771) in the skin of vibrissae area. D. gracilentus occurred in 36.7% of the rodents examined. D. gracilentus is a relatively large representative of the genus (adult stages on average 292 µm in length), a slender, elongated body; characteristic feature of these mites are conical supracoxal spines on dorsal side of gnathosoma, palps with asymmetric, forked triple spines on palptarsus, and the presence of rhomboidal opisthosomal organ. So far, the occurrence of three specific representatives of the family Demodecidae has been demonstrated in A. agrarius: Demodex apodemi (Hirst, 1918) (=Demodex arvicolae apodemiHirst, 1918), Demodex agrariiBukva, 1994, and Demodex huttereriMertens, Lukoschus et Nutting, 1983. The first one is related to common hair follicles, especially in the skin of the head, while the next one inhabits the external auditory meatus, and the last one occurs in the meibomian glands of the eyelids.
Two hundred and ninety-one ticks (i.e., 185 larvae, 72 nymphs, and 34 adults) were removed from 153 small mammals comprising six species collected in Verdant Forest, Numa Forest, and Marble Canyon within Kootenay National Park, British Columbia, Canada. Morphological examination and molecular analyses (i.e., polymerase chain reaction-single-strand conformation polymorphism [PCR-SSCP] and DNA sequencing of the mitochondrial 16S rRNA gene) of the ticks revealed that most individuals were Ixodes angustus Neumann. All life cycle stages of J. angustus were found primarily on southern red-backed voles, Clethrionomys gapperi (Vigors). Two Dermacentor andersoni Stiles females were also found on these small mammals. The results of the molecular analyses also revealed that there were three 16S haplotypes of I. angustus and two 16S haplotypes of D. andersoni. A comparison of available sequence data suggests genetic divergence between I. angustus near the western and eastern limits of the species distributional range in North America. Additional studies are needed to determine whether there are genetic differences between I. angustus from North America, Japan, and Russia, and whether there is geographical variation in the ability of ticks to transmit pathogens to their mammalian hosts.
We evaluated the ecological and epidemiological aspects of the sand fly fauna in an area of the Atlantic Forest biome with records of visceral and cutaneous leishmaniasis. Sand fly collections at three different localities at the National Monument of Pontões Capixabas, State of Espírito Santo, Southeastern Brazil, were conducted by using two Centers of Disease Control and Prevention automatic light traps in the peridomiciliary environment and eight Centers of Disease Control and Prevention automatic light traps in the forested environment. Collections occurred during four consecutive nights within each of the months and locations: São Luiz (December 2009, May 2010, July 2010, and December 2010), Córrego Palmital de Baixo (September 2010 and October 2010), and Córrego São Bento (February 2011 and May 2011). We collected 21,138 sand flies belonging to 31 species and 14 genera. Of this total, 12,412 sand flies were captured in the peridomiciliary environment and 8,726 in the forested environment. All of the vector species, Lutzomyia longipalpis (=Lutzomyia longipalpis, sensu; Young and Duncan), Migonemyia migonei (=Lutzomyia migonei, sensu; Young and Duncan), and Nyssomyia intermedia (=Lutzomyia intermedia, sensu; Young and Duncan), occurred in significantly higher numbers in the peridomiciliary environment than compared with the forested environment. Our results highlight the importance of conservation in the forest remains of the National Monument of Pontões Capixabas, because of higher species richness and diversity. Furthermore, they indicate the epidemiological role of Lu. longipalpis as the vector of Leishmania infantum within the study area, and the no evident role of Mg. migonei.
Black soldier flies, Hermetia illucens L., are distributed throughout the temperate and tropic regions of the world and are known an established method for sustainably managing animal wastes. Colonies used to conduct research on the black soldier fly within the past 20 yr have predominately been established from eggs or larvae received from a colony originated from Bacon County, GA. Consequently, little is known about the phenotypic plasticity (i.e., development and waste conversion) across strains from different regions. This study compared the development of three strains of the black soldier fly (Texas; Guangzhou, China; and Wuhan, China) and their ability to reduce dry matter and associated nutrients in swine, dairy, and chicken manure. The Wuhan strain appeared to be more fit. Larvae from Wuhan needed 17.7–29.9% less time to reach the prepupal stage than those from Guangzhou or Texas, respectively. Larvae from Wuhan weighed 14.4–37.0% more than those from Guanghzhou or Texas, respectively. Larvae from the Wuhan strain reduced dry matter 46.0% (swine), 40.1% (dairy), and 48.4% (chicken) more than the Guangzhou strain and 6.9, 7.2, and 7.9% more than the Texas strain. This study demonstrates that phenotypic plasticity (e.g., development and waste conversion) varies across populations of black soldier flies and should be taken into account when selecting and establishing a population as a waste management agent in a given region of the world.
Landscape fragmentation often increases contact between humans, wildlife, and potential disease vectors. We examined how adult host-seeking mosquitoes respond to small-scale habitat differences within southern Great Plains cross-timber habitat mosaics in northern Oklahoma consisting of eastern red cedar (Juniperus virginianus L.) woodlands, mixed-deciduous woodlands, and adjacent grasslands. Mosquitoes responded most markedly to an overall grassland-woodland habitat gradient, with species separating by habitat based largely on tree density. Differences in abundance of host-seeking females occurred at fine spatial scales, sometimes varying dramatically over distances as little as 200 m when tree density changed abruptly. Tree type was not as important as tree density, although the West Nile virus vector Culex tarsalis Coquillett showed a greater affinity for areas containing eastern red cedar than for deciduous woodlands. The invasive Aedes albopictus Skuse showed equal affinity for both tree types. Conversion of grassland habitats in the Great Plains to more vegetated environments associated with humans (towns and homesteads) and the invasion of grasslands by eastern red cedar may change the species composition of mosquito, bird, and mammal assemblages and potentially alter arbovirus exposure for humans.
Competitive interactions between mosquitoes Aedes aegypti (L.) and Aedes albopictus (Skuse) may depend on environmental conditions. Pesticides may alleviate density-dependent competition for limited food, and a differential species response to sublethal concentrations may modify interspecific competition. We tested the hypothesis that exposure to malathion alters interspecific resource competition between these two species. In the absence of malathion, Ae. aegypti survivorship and per capita rate of population change were negatively affected by increasing densities of Ae. albopictus. However, the asymmetrical negative effect of Ae. albopictus on Ae. aegypti was eliminated in the presence of malathion. In addition, the presence of malathion resulted in shorter development time compared with the controls. The relative importance of pesticide-mediated coexistence in nature has not been evaluated, so its role in mediating coexistence is unclear; however, these findings underscore the potential of environmental concentrations of malathion, and perhaps other pesticides to facilitate coexistence between species.
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 neighborjoining, 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.
VECTOR CONTROL, PEST MANAGEMENT, RESISTANCE, REPELLENTS
Pyriproxyfen, a juvenile hormone analog insect growth regulator (IGR), is a recommended insecticide for the control of container-inhabiting mosquitoes. The effects of eight container substrates (three plastics, wood, tire rubber, clay pot, concrete, and glass) were studied on reduction of bio-efficacy of pyriproxyfen for Aedes albopictus (Skuse) in the laboratory. Insect growth regulator-bioassay of third instars showed significant increase of LC50 with some substrates compared with control probably because of pyriproxyfen adsorption to the substrate. The LC50 for the control substrate (glass mug) was 0.029 µg/ liter. In comparison to the control, LC50 increased 150.1 times with tire rubber (4.354 µg/liter) and 8–10 times with wood and high-density polyethylene plastic containers. Slight increases of LC50 were detected for clay pots, polypropylene, and polystyrene plastics (1.9–2.7 times). Pyriproxyfen efficacy with concrete substrate was higher than with glass containers, which might be caused by high pH. The pH of water with wood (5.6) and concrete (9.8) substrates differed from the other substrates tested (6.3–7.1). There was no pupal mortality at pH 5–11 without pyriproxyfen; however, interaction of pH (5–11) with pyriproxyfen (0.05 µg/liter) showed additive effects at both low and high pH values. Different substrates have variable impacts on pyriproxyfen efficacy, which might be associated with the failure of larval control strategies for the container mosquitoes under certain field conditions.
The essential oil from aerial parts of Ruta chalepensis L. (Sapindales: Rutaceae) was obtained by hydrodistillation, and its chemical profile was identified using gas chromatography and gas chromatography-mass spectrometry. Compounds, 2-undecanone (43.2%), 2-nonanone (27.9%), and 2-nonyl acetate (10.6%) were the major constituents of the oil. Biting deterrent activity of R. chalepensis essential oil at 10 and 50 µg/cm2, 2-undecanone at 8.5 µg/cm2, 2-nonanone at 9 µg/cm2, and 2-nonyl acetate at 9.3 µg/cm2 was similar to DEET (N, N-diethyl-meta-toluamide) at 4.8 µg/cm2, against Aedes aegypti L. Biting deterrent activity of R. chalepensis oil at 50 µg/cm2 against Anopheles quadrimaculatus Say was statistically similar to DEET at 4.8 µg/cm2, whereas the activity was lower in the other compounds tested. In cloth patch assay, R. chalepensis essential oil was effective at 187 µg/cm2, whereas 2-undecanone was effective at 108.9 µg/cm2 against Ae. aegypti. In larval bioassays, 2-undecanone showed similar toxicity whereas toxicity of R. chalepensis essential oil and 2-nonanone was higher at 24-h posttreatment at the LD50 in An. quadrimaculatus than Ae. aegypti. This study revealed that R. chalepensis essential oil and its major compounds were active biting deterrents against Ae. aegypti at higher application rates whereas only the essential oil showed activity similar to DEET against An. quadrimaculatus. 2-undecanone was the most active compound in in vivo repellency bioassay against Ae. aegypti. Chemical composition of R. chalepensis essential oil varies because of plant production and harvest practices, and the activity level of the essential oil may depend on the source of the sample.
The selection of insecticide resistance in malaria vectors has the potential to compromise any insecticide-based malaria vector control program. To ensure that transmission-interrupting tools remain effective, and their choice is evidence based, insecticide surveillance and monitoring is essential. This study assessed and compared the residual efficacy of an organophosphate insecticide pirimiphos methyl (ACTELLIC 300 CS, 0-2-diethylamino-6-methylpyrimidin-4-yl 0, 0-dimethylphosphorothioate) at 1 g/m2 and the pyrethroid deltamethrin (K-Othrine WG 250, (S)-α-cyano-3phenoxybenzyl (IR, 3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate) at 20 mg/m2 for indoor residual spraying on cement and mud-rendered walls inside houses. Insecticide susceptibility profiles of local malaria vectors were also assessed using World Health Organization standard protocols. The residual efficacy of ACTELLIC 300 CS on cement and mud walls lasted for 5 mo on both surfaces, with complete mortality of Anopheles gambiae sensu stricto Giles (Kisumu strain) (Diptera: Culicidae) in cone assays. By 8 mo, the average residual effect of ACTELLIC 300 CS remained much better on cement walls than on mud walls but not significantly different from deltamethrin-treated cement walls. Anopheles funestus sensu stricto Giles was resistant to 0.05% deltamethrin and 0.01% bendiocarb but remained completely susceptible to 5% malathion and 4% dichlorodiphenyltrichloroethane. The duplicated P450 genes, CYP6P9a and CYP6P9b, were found to be highly overexpressed in deltamethrin-resistant An. funestus s.s as compared with bendiocarbresistant individuals. Pirimiphos methyl CS is recommended for intra-domiciliary spraying for malaria control and could replace dichlorodiphenyltrichloroethane within the context of an insecticide resistance management strategy.
Ixodes scapularis Say, 1821 larvae were fed on mice and allowed to molt under laboratory conditions. A liquid chromatography—tandem mass spectrometry-based proteomic study was conducted to identify the type of mammalian proteins present in the derived nymphal ticks at different time intervals after molting. Albumin was present for 85 d; transferrin was present for 29 d; and, more importantly, hemoglobin remained detectable for up to 309 d postmolting. Peptides of actin, keratin, and tubulin are highly similar between mouse and tick, and therefore, unambiguous assignment of these proteins to different species was not possible. Establishing a time line for the persistence of hemoglobin, one of the most abundant blood proteins, at detectable levels in ticks after the bloodmeal and molting advances our efforts to use this protein to identify the host species.
Following the 2009 and 2010 dengue-1 (DENV-1) outbreaks in Key West, FL, we used Florida Aedes aegypti (L.) mosquitoes and DENV-1 isolated from Key West in 2010 to test the hypothesis that if the 2009 and 2010 DENV-1 genome sequences are similar, then vertical transmission of DENV-1 from infected Ae. aegypti female mosquitoes to their eggs could have served as an interepidemic reservoir between outbreaks. We also investigated the ability of Florida Aedes albopictus (Skuse) mosquitoes to vertically transmit DENV-1. In addition, we determined the rates of infection and dissemination of these Florida mosquito species for DENV-1 and the effect of DENV-1 infection on oviposition success and number of mosquito eggs laid by females. Vertical transmission of DENV-1 was documented, with rates of 11.11% (2 out of 18) for Ae. albopictus and 8.33% (3 out of 36) for Ae. aegypti. Approximately 93% (111 out of 119) of Ae. aegypti that fed on DENV-1 in blood became infected, and 80% (89 out of 111) of infections were disseminated. Similarly, 93% of Ae. albopictus became infected (53 out of 57), and 85% (45 out of 53) of infections were disseminated. No significant differences were detected in numbers of eggs laid by either species after imbibing DENV-1 in blood, suggesting little cost of infection on number of eggs laid. Our results demonstrate that Florida Ae. aegypti and Ae. albopictus mosquitoes are competent vectors for DENV-1, whose maintenance between the 2009 and 2010 Key West outbreaks may have been facilitated by vertical transmission.
Entomological surveys were conducted in the malaria-endemic southwestern region of Tajikistan to establish which species of Anopheles may be responsible for malaria transmission. The head—thorax portions of 2,213 wild-caught Anopheles females—Anopheles superpictus Grassi (n = 1,292), Anopheles pulcherrimus Theobald (n = 376), Anopheles hyrcanus (Pallas) (n = 544), and Anopheles claviger (Meigen) (Diptera: Culicidae) (n = 1)—were tested for the presence of Plasmodium sporozoites using enzyme-linked immunosorbent assays. Four females of An. superpictus (three captured when landing on humans and one resting indoors) and one female of An. hyrcanus (captured when landing on a human indoors) were positive for Plasmodium vivax (Haemosporida: Plasmodiidae) VK-210. The infected females of An. superpictus were captured in the Hamadoni and Yovon districts of the Khatlon province, and the single infected female of An. hyrcanus was captured in the Jilikul district of the Khatlon province.
The spatial heterogeneity of West Nile virus (WNV) activity in Sutter County, CA, as measured by mosquito infection rates, was associated with spatial variation in the prevalence of Culex blood feeding on competent passeriform hosts. Overall, 42 vertebrate host species (31 avian, 11 mammal) were identified from 601 blood-fed Culex tarsalis Coquillett and 151 blood-fed Culex pipiens L. complex females using sequences of the cytochrome c oxidase I gene and the Barcode of Life Data Systems database. WNV infection rates were low at sites where the primary vector, Cx. tarsalis, fed frequently on domestic cattle or incompetent galliform birds and high when females fed frequently on American Robins, American Crows, and Yellow-billed Magpies. Opportunistic host selection by Cx. tarsalis in combination with spatial variation in the presence of highly competent corvid hosts appeared to determine the distribution of WNV activity in rural Sutter County, CA.
Philip M. Armstrong, John F. Anderson, Ary Farajollahi, Sean P. Healy, Isik Unlu, Taryn N. Crepeau, Randy Gaugler, Dina M. Fonseca, Theodore G. Andreadis
The Asian tiger mosquito, Aedes albopictus (Skuse), is an invasive species and a major pest problem in urban and suburban locales in New Jersey. To assess its potential role as an arbovirus vector, we sampled Ae. albopictus from two New Jersey counties over a 3-yr period and estimated the prevalence of virus infection by Vero cell culture and reverse transcription-polymerase chain reaction assays. Three virus isolates were obtained from 34,567 field-collected Ae. albopictus, and all were identified as Cache Valley virus by molecular methods. Ae. albopictus (N = 3,138), collected in Mercer County from late July through early September 2011, also were retested for West Nile virus (WNV) by reverse transcription-polymerase chain reaction, and all were negative. These results corroborate previous findings showing that Ae. albopictus may occasionally acquire Cache Valley virus, a deerassociated arbovirus, in nature. In contrast, we did not detect WNV infection in Ae. albopictus despite concurrent WNV amplification in this region.
Canine heartworm is one of the most serious infections primarily affecting domestic dogs but will also infect cats and wild canids. To evaluate the potential of mosquitoes as vectors of dog heartworm, Dirofilaria immitis (Leidy) in San Joaquin County, CA, we collected mosquitoes in 2011 and analyzed for infection with heartworm by using polymerase chain reaction. Of 3,000 mosquito pools (total number of specimens = 36,554), D. immitis DNA was detected in 97 pools of seven species, and the overall minimum infection rate (MIR) for all mosquito species was 2.69: Culex pipiens L. (n = 40; MIR = 3.66), Culex tarsalis Coquillett (n = 25; MIR = 1.89), Culiseta incidens (Thomson) (n = 11; MIR = 2.81), Aedes vexans (Meigen) (n = 7; MIR = 2.18), Aedes melanimon Dyar (n = 5; MIR = 4.64), Culex erythrothorax Dyar (n = 5; MIR = 3.96), and Culiseta inornata (Williston) (n = 4; MIR = 2.65). Cx. pipiens and Cx. tarsalis had the highest number of D. immitis infections and collectively accounted for 67% of all positive pools. Ae. melanimon, Ae. vexans, and Cx. erythrothorax were found to be infected with D. immitis only in rural and agriculture areas, whereas infections in other species were identified in rural and agriculture areas, and urban and residential settings. The majority of positive pools were identified from June through November and peaked during August through October. This is the first report of D. immitis infection in Ae. melanimon, Cx. erythrothorax, Cx. tarsalis, Cs. incidens, and Cs. inornata. The frequent detection of D. immitis in field-collected Cx. pipiens and Cx. tarsalis in concert with their seasonal abundance and widespread distribution suggest a central role for these species in dog heartworm transmission. Other species, including Ae. vexans, Ae. melanimon, Cs. incidens, Cs. inornata, and Cx. erythrothorax, may play a secondary role in transmission.
The medically important sand fly Lutzomyia shannoni (Dyar 1929) was collected at eight different sites: seven within the southeastern United States and one in the state of Quintana Roo, Mexico. A canonical discriminant analysis was conducted on 40 female L. shannoni specimens from each of the eight collection sites (n = 320) using 49 morphological characters. Four L. shannoni specimens from each of the eight collection sites (n = 32) were sent to the Barcode of Life Data systems where a 654-base pair segment of the cytochrome c oxidase subunit 1 (CO1) genetic marker was sequenced from each sand fly. Phylogeny estimation based on the COI segments, in addition to genetic distance, divergence, and differentiation values were calculated. Results of both the morphometric and molecular analyses indicate that the species has undergone divergence when examined between the taxa of the United States and Quintana Roo, Mexico. Although purely speculative, the arid or semiarid expanse from southern Texas to Mexico City could be an allopatric barrier that has impeded migration and hence gene flow, resulting in different morphology and genetic makeup between the two purported populations. A high degree of intragroup variability was noted in the Quintana Roo sand flies.
Ticks are common on horses, but there is a dearth of contemporary data on infestation prevalence, predominant species, and tick-borne disease agents important in this host. To determine the species of ticks most common on horses and the prevalence of equine exposure to and infection with tick-borne disease agents, ticks and blood samples were collected from 73 horses during May, June, and July of 2010. Adult ticks were identified to species, and antibodies to Ehrlichia spp., Anaplasma spp., and Borrelia burgdorferi were identified using indirect fluorescence antibody assay, a commercial point-of-care enzyme-linked immunosorbent assay, or both. In total, 1,721 ticks were recovered at the majority (85%) of equid examinations. Amblyomma americanum (L.) was the most common tick collected (1,598 out of 1,721; 92.9%) followed by Dermacentor variabilis (Say, 1821) (85 out of 1,721; 4.9%) and Amblyomma maculatum Koch, 1844 (36 out of 1,721; 2.1%); single specimens of Ixodes scapularis Say, 1821 and Dermacentor albipictus (Packard, 1869) were also identified. Antibodies reactive to Ehrlichia spp. were found in 18 out of 73 (24.7%) of horses tested, and were more commonly identified in horses with moderate or high tick infestations than those with low tick infestations (P < 0.001). These data support A. americanum as the most common tick species infesting horses in central Oklahoma from May through July and suggest horses are also commonly exposed to an Ehrlichia sp.
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