Larval Ecology Research Articles

Evidence of density-dependent cannibalism in the diet of wild Atlantic bluefin tuna larvae (Thunnus thynnus) of the Balearic Sea (NW-Mediterranean)

The heavy exploitation rates of Atlantic bluefin tuna (ABFT) during the nineties propitiated research into the larval ecology of ABFT and its associated species. The transition from a planktivorous to a piscivorous diet is considered a major bottleneck in the survival of ABFT larvae observed in aquaculture experiments. Although larval piscivory was reported in the Gulf of Mexico (GOM), the most important spawning grounds of this species in the W Atlantic, trophic studies have not been able to reveal piscivory in Mediterranean ABFT larvae. This study analyzes the trophic behavior of Mediterranean ABFT larvae by stomach content analysis. The results show that more than 90% of the larvae had at least one prey in their stomachs. The diet shifted from copepods and cladocerans to gastropod larvae in pre-flexion stages and to ABFT larvae in post-flexion stages. This is the first time that cannibalism is reported for wild ABFT larvae from the Mediterranean Sea. Intracohort cannibalistic feeding was observed when the requisite density-dependent processes aligned, namely the spatio/temporal overlap of a wide range of ABFT larval cohorts of different size class. Moreover, stomach contents of ABFT larvae revealed the ingestion of microplastic fibres. Whether these plastic contaminants were passively or actively ingested, they may affect the condition of larvae. The presence of microplastic strands in fish larvae undoubtedly raises concern because its impact on the survival of ABFT larvae still remains uncertain and is open to scientific experimentation.

Broadening the tools for studying sand fly breeding habitats: A novel molecular approach for the detection of phlebotomine larval DNA in soil substrates

Phlebotomine sand flies constitute a group of haematophagous insects of great medical and veterinary importance. Despite the significant knowledge on the biology and behavior of adult sand flies in the wild, there is little information available on the ecology of their larval stages due to difficulties of detecting them in the soil. So far, investigations on sand fly breeding sites have been based on methods to catch emerging adults or on microscopic examination of the soil for the presence of immatures, neither of which is very precise or efficient for studying immatures in the field. Thus, there is a need for a better method to detect, identify and quantify immatures in soil samples. To address this issue we developed a novel molecular genetic approach for the detection of sand fly larval DNA within soil samples. Different numbers of live larvae of Phlebotomus papatasi and P. tobbi (alone or in combination), were mixed with soil and analyzed to identify and quantify the sand flies. By modifying already existing soil DNA extraction protocols in combination with a real-time PCR using species-specific primers, we successfully detected as little as one larva/40 ml of soil. We could also distinguish the two species of sand flies. This method should be very useful for increasing our knowledge of sand fly larval ecology in the field, and thus help develop more efficient, targeted control strategies against Phlebotomus sand flies.

Bacterial microbiota assemblage in Aedes albopictus mosquitoes and its impacts on larval development.

Interactions between bacterial microbiota and mosquitoes play an important role in mosquitoes' capacity to transmit pathogens. However, microbiota assemblages within mosquitoes and the impact of microbiota in environments on mosquito development and survival remain unclear. This study examined microbiota assemblages and the effects of aquatic environment microbiota on the larval development of the Aedes albopictus mosquito, an important dengue virus vector. Life table studies have found that reducing bacterial load in natural aquatic habitats through water filtering and treatment with antibiotics significantly reduced the larva-to-adult emergence rate. This finding was consistent in two types of larval habitats examined-discarded tires and flowerpots, suggesting that bacteria play a crucial role in larval development. Pyrosequencing of the bacterial 16S rRNA gene was used to determine the diversity of bacterial communities in larval habitats and the resulting numbers of mosquitoes under both laboratory and field conditions. The microbiota profiling identified common shared bacteria among samples from different years; further studies are needed to determine whether these bacteria represent a core microbiota. The highest microbiota diversity was found in aquatic habitats, followed by mosquito larvae, and the lowest in adult mosquitoes. Mosquito larvae ingested their bacterial microbiota and nutrients from aquatic habitats of high microbiota diversity. Taken together, the results support the observation that Ae. albopictus larvae are able to utilize diverse bacteria from aquatic habitats and that live bacteria from aquatic habitats play an important role in larval mosquito development and survival. These findings provide new insights into bacteria's role in mosquito larval ecology.

Detecting the elusive cost of parasites on fig seed production

Mutualisms provide essential ecosystem functions such as pollination and contribute considerably to global biodiversity. However, they are also exploited by parasites that remove resources and thus impose costs on one or both of the mutualistic partners. The fig/pollinator interaction is a classic obligate mutualism; it is pantropical and involves >750 Ficus species and their host-specific pollinating wasps (family Agaonidae). Figs also host parasites of the mutualism that should consume pollinators or seeds, depending on their larval ecology. We collected data from a large crop of figs on Ficus glandifera var. brachysyce in a Sulawesi rainforest with an unusually high number of Eukoebelea sp. parasites. We found that these parasites have a significant negative correlation with fig seed production as well as with pollinator offspring production. Eukoebelea wasps form the basal genus in subfamily Sycophaginae (Chalcidoidea) and their larval biology is considered unknown. Our analysis suggests that they feed as flower gallers and impose direct costs on the fig tree, but a strategy including the consumption of pollinator larvae cannot be ruled out. We also present baseline data on the composition of the fig wasp community associated with F. glandifera var brachysyce and light trap catch data.

Larval development, metabolism and diet are possible key factors explaining the decline of the threatenedDytiscus latissimus

AbstractIn Western Europe, the diving beetleDytiscus latissimus(Coleoptera: Dytiscidae) has become rare and went extinct in several countries during the last century. This study investigated whether larval development rate, metabolism and feeding ecology differ betweenD. latissimusand the congenericD. lapponicusto explore factors explaining its decline.During instar I andII,D. latissimuslarvae developed faster and gained more weight thanD. lapponicuslarvae. In accordance,D. latissimuslarvae had higher oxygen consumption rates thanD. lapponicuslarvae, which signifies a greater energy expenditure.Food preference tests showed thatD. latissimuslarvae strongly prefer caddisfly larvae (Trichoptera: Limnephilidae) with early instars being obligatory dependent on caddisfly larvae for their development. Only instarIIIlarvae readily fed on alternative prey items. In contrast,D. lapponicuslarvae had a broader diet and even rejected caddisfly larvae.Based on field observations, availability of caddisfly larvae strongly declined before the end of the larval development ofD. latissimus, suggesting that time constraints on food availability limit completion of larval development.Our results suggest that food limitation during (early) larval stages is a possible bottle‐neck for this species, potentially explaining its disappearance from former localities. Promoting caddisfly larvae in the vicinity ofD. latissimusoviposition sites, may possibly safeguard the present distribution ofD. latissimusand support the species recovery. Although more research is needed, promoting leaf litter in shores may be beneficial to the shredding caddisfly larvae and in turn for their predatorD. latissimus.

New and poorly known Meligethes Stephens from China, with bionomical data on some species (Coleoptera: Nitidulidae: Meligethinae).

Meligethes (Odonthogethes) trapezithorax sp. n., M. (O.) tricuspidatus sp. n., and M. (O.) luteomaculatus sp. n. are described from Hubei Province, China, based on a series of recently collected specimens. The new species appear morphologically closely related to M. (O.) brassicogethoides Audisio, Sabatelli Jelínek, 2015 from Yunnan [M. (O.) trapezithorax sp. n.], M. (O.) occultus Audisio, Sabatelli Jelínek, 2015 from Yunnan [M. (O.) tricuspidatus sp. n.], as well as M. (O.) pallidoelytrorum Chen Kirejtshuk, 2013 from Sichuan and M. (O.) simulator Audisio, Sabatelli Jelínek, 2015 from Shaanxi and Gansu [M. (O.) luteomaculatus sp. n.]. The new species clearly differ from their closely related taxa by details of body shape and color, and the distinct shape of the male and/or female genitalia. The previously unknown male of the rare and localized M. (M.) elytralis Audisio, Sabatelli Jelínek, 2015 from Sichuan is described for the first time, and new distributional data of other Chinese species of the genus are presented, including M. (M.) semenovi Kirejtshuk, 1979 from Hubei, M. (M.) macrofemoratus Liu, Yang, Huang, Jelínek Audisio, 2016 from Hubei, M. (M.) auropilosus Liu,Yang, Huang, Jelínek Audisio, 2016 from Hubei, M. (O.) flavicollis Reitter, 1873 from Chongqing, M. (O.) wagneri Rebmann, 1956 from Shaanxi, M. (O.) pectoralis Rebmann, 1956 from Guizhou, and M. (O.) pseudopectoralis Audisio, Sabatelli Jelínek, 2015 from Sichuan. Meligethes (M.) cinereoargenteus is moved from the Meligethes nepalensis species group to the Meligethes auripilis species group. Additional data on geographic distribution and larval ecology of other species in the genus are also reported. An updated species checklist of the genus Meligethes is presented.

Larval breeding habitats and ecological factors influence the species composition of mosquito (Diptera : Culicidae) in the parks of Dhaka city, Bangladesh

Mosquito larval ecology is prerequisite for determining the larval abundance and species assemblage in mosquito control program. The study explored the association of five mosquito species with their breeding habitat diversity and species distribution in three selected parks from May to October, 2015. A total of 3217 mosquito larvae were reported from six breeding habitats, namely tree hole, leaf axils, water bottle, tire, drain and coconut shell. The frequency of the three species (Ae. aegypti, Ae. albopictus and Ar. subalbatus) coexistence was higher in tree holes (82.4%) than that of the other coexisting species. Pearson Chi-square result revealed that the association of species was significantly dependent on the breeding habitats. ANOVA further suggested that mosquito density varied across habitats where among the highest density of Cx. quinquefasciatus (3.87 ± 0.22) found in drain, followed by both Ae. albopictus (2.02 ± 0.17) and Ar. subalbatus (0.50 ± 0.09) in tree holes and Ae. aegypti (1.25 ± 0.23) in coconut shell. Cx. tritaeniorhynchus occurred in drain with the least observed density (0.03 ± 0.01). CCA results suggested that Aedes species were likely preferred to oviposit in shaded habitats where pH was associated with Ae. albopictus and dissolved oxygen was with Ae. aegypti and Ar. subalbatus. Culex species were positively associated with the habitats characterizing muddy bottom and emerging vegetation but not with any of the physico-chemical parameters. These findings concluded that ecological factors influence mosquito species to favor their breeding habitats can be helpful in controlling targeted vector species as well as the mosquito borne diseases.Bangladesh J. Zool. 45(2): 111-122, 2017

Quantitative species-level ecology of reef fish larvae via metabarcoding.

The larval pool of coral reef fish has a crucial role in the dynamics of adult fish populations. However, large-scale species-level monitoring of species-rich larval pools has been technically impractical. Here, we use high-throughput metabarcoding to study larval ecology in the Gulf of Aqaba, a region that is inhabited by >500 reef fish species. We analysed 9,933 larvae from 383 samples that were stratified over sites, depth and time. Metagenomic DNA extracted from pooled larvae was matched to a mitochondrial cytochrome c oxidase subunit I barcode database compiled for 77% of known fish species within this region. This yielded species-level reconstruction of the larval community, allowing robust estimation of larval spatio-temporal distributions. We found significant correlations between species abundance in the larval pool and in local adult assemblages, suggesting a major role for larval supply in determining local adult densities. We documented larval flux of species whose adults were never documented in the region, suggesting environmental filtering as the reason for the absence of these species. Larvae of several deep-sea fishes were found in shallow waters, supporting their dispersal over shallow bathymetries, potentially allowing Lessepsian migration into the Mediterranean Sea. Our method is applicable to any larval community and could assist coral reef conservation and fishery management efforts.

Paradigm shifts in community ecology: Open versus closed units, challenges and limits of connectivity studies

AbstractDue to the presence of the complex life cycles involving a benthic adult and a pelagic larval phase, the study of benthic community dynamics cannot ignore investigations of the processes occurring in the water column. Current investigations focus mainly on larval dispersal from an evolutionary and a biogeographic perspective, taking into account also population connectivity, conservation planning and coastal management. In the present paper we underline the need to improve knowledge of the main traits of marine invertebrate life cycles, highlighting the limits and challenges of current approaches. Firstly, we summarized the changing approaches within community studies, following the paradigm shifts found in recent marine ecological research, from supply‐side ecology to connectivity, and involving the concepts of open and closed populations. Secondly, we analysed the main larval traits influencing dispersal, paying particular attention to pelagic larval duration in light of the few available data for connectivity studies. The difficulty in estimating many of the main traits of larval ecology make numerical simulation fundamental for a better understanding of the relationship between propagule dispersal and seawater dynamics, both being highly variable. We conclude that some essential biological information is still lacking for the proper integration of the modeling approaches. Thus it is necessary to further investigate the life‐cycle traits and physiological and ecological characteristics of each species, an approach known as autecology or natural history. All too frequently modern ecologists ignore such reductionist approaches, although they are essential for a full understanding of processes, such as connectivity and metapopulation dynamics.

The significance of climate in the pollinator dynamics of a tropical agroforestry system

Even though many globally important tropical agroforestry crops are partially or completely dependent on insect pollination, the conditions influencing pollinator abundance in these systems are often incompletely understood. This is particularly the case for cocoa midges (Diptera: Ceratopogonidae), which are essential for cocoa pollination and thus yield, but agro-ecological management frequently neglects them. We report the first assessment of cocoa midge population dynamics from two Caribbean countries across a full year, and relate this to seasonal climate variables.We used static suction traps along transects to sample insects monthly, from six cocoa farms across three Caribbean islands, with a particular focus on known pollinators of cocoa. A total of over 87,000 insects were captured, including more than 1800 cocoa midges. Midges were present in all months of the survey and on all sites, but typically comprised less than 2% of the total insects caught. At least twelve different species of cocoa midges were identified from this survey. The previous month’s rainfall positively predicted cocoa midge absolute abundance and further analysis also revealed a relationship between rainfall and relative midge abundance. In particular, during drought periods, midge numbers were very low, consistent with their larval ecology. Humidity and mean daily maximum and minimum temperatures did not relate to midge abundance. Rainfall negatively influenced the Shannon-Weaver index. The findings highlight the possible threat of droughts to cocoa pollination services and the importance of proactive farm management to support them.

Diet composition and feeding habits of larval Pacific bluefin tuna Thunnus orientalis in the Sea of Japan: integrated morphological and metagenetic analysis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 583:211-226 (2017) - DOI: https://doi.org/10.3354/meps12341 Diet composition and feeding habits of larval Pacific bluefin tuna Thunnus orientalis in the Sea of Japan: integrated morphological and metagenetic analysis Taketoshi Kodama1,*, Junya Hirai2,7, Saori Tamura1, Takashi Takahashi3, Yosuke Tanaka4,8, Taiki Ishihara5, Atsushi Tawa5, Haruyuki Morimoto1, Seiji Ohshimo5,6 1Japan Sea National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Suido-cho, Chuo, Niigata 951-8121, Japan 2National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency, Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan 3Joetsu Environmental Science Center, Shimo-monzen, Joetsu, Niigata 942-0063, Japan 4Amami Laboratory, Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Sakiyamahara, Hyo, Setouchi-cho, Oshima, Kagoshima 894-2414, Japan 5National Research Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency, Orido, Shimizu, Shizuoka 424-8633, Japan 6Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Taira-machi, Nagasaki 851-2213, Japan 7Present address: Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8564, Japan 8Present address: Tohoku National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Sakiyama, Miyako, Iwate 027-0097, Japan *Corresponding author: takekodama@affrc.go.jp ABSTRACT: Diet compositions of larval Pacific bluefin tuna (PBT) Thunnus orientalis caught in the Sea of Japan during the summers of 2011-2015 were investigated using both microscopic (n = 149) and metagenetic (n = 120) methods to determine the species’ prey and feeding habits. The microscopic analysis revealed that prey abundance in gut contents ranged from 0-10 ind. larva-1 (mean ± SD: 0.89 ± 1.5 ind. larva-1, including larvae with empty guts), which was low, similar to levels for larval bluefin tunas in other seas except the Mediterranean. The cladoceran family Podonidae (Podon spp. and Evadne spp.) represented the most abundant prey (0.73 ± 1.4 ind. larva-1) observed microscopically. Metagenetic analysis of the 18S V9 region detected a taxonomically wide range of prey. In addition to Podonidae, morphologically unidentified taxa were detected as major prey, including Copepoda (Paracalanus parvus s.l. and Labidocera sp.), Appendicularia (Oikopleura spp.), and Doliolida (Doliolum sp.). Compared with plankton communities in the sea, the proportions of Oikopleura spp. and Podonidae in the guts of the larvae were high, indicating that PBT larvae fed on them selectively. Although copepods were abundant in the sea, PBT larvae only consumed a small number of them. The ability of copepods to escape predation is higher than that of Oikopleura spp. and Podonidae, and the guts of the PBT larvae generally contained a low number of copepods considering their abundance and size in the region. This study successfully characterized the prey of PBT larvae in the Sea of Japan, and showed that they were unable to exploit the abundance of copepods, a fact which may lead to high larval mortality. KEY WORDS: Pacific bluefin tuna · Larval feeding habits · Larval trophic ecology · Diet composition · Zooplankton · 18S rDNA · Metagenomics · Trophic selectivity Full text in pdf format Supplementary material PreviousNextCite this article as: Kodama T, Hirai J, Tamura S, Takahashi T and others (2017) Diet composition and feeding habits of larval Pacific bluefin tuna Thunnus orientalis in the Sea of Japan: integrated morphological and metagenetic analysis. Mar Ecol Prog Ser 583:211-226. https://doi.org/10.3354/meps12341 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 583. Online publication date: November 16, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

The acute thermal respiratory response is unique among species in a guild of larval anuran amphibians—Implications for energy economy in a warmer future

Climate change is bringing about increased temperatures of amphibian habitats throughout the world, where ectothermic larvae will experience elevated respiratory (metabolic) energy demands. We compared the acute, thermal respiratory response (“TRR”) of four species of sympatric larval amphibians (Lithobates sphenocephalus, L. catesbeianus, Scaphiopus holbrookii, and Hyla chrysoscelis) to determine species-specific differences in the rate at which metabolic energy requirements increase with temperature. The TRR, the slope of the relationship between respiration rate and temperature within critical thermal limits, varied significantly among species such that the absolute, per capita change in metabolic energy requirement as temperature increased was greater for L. sphenocephalus and L. catesbeianus than for H. chrysoscelis and S. holbrookii. This was also reflected in the temperature coefficients (Q10,18.5–25.5), which ranged from 1.77 (S. holbrookii) to 2.70 (L. sphenocephalus) for per capita respiration rates. Our results suggest that L. sphenocephalus and L. catesbeianus will experience a more rapid increase in energetic requirements as temperature increases relative to the other species, possibly magnifying their influences on the resource pool. There is a critical paucity of information on the metabolic responses of most larval amphibians across a range of temperatures, despite that this relationship dictates the magnitude of the priority investment of assimilated energy in respiration, thus shaping the energetic economy of the individual. A broader knowledge of species-specific TRRs, combined with research to determine thermal acclimatory or adaptive potentials over chronic time scales, will provide a framework for evaluating whether asymmetric, climate-mediated differences in energetic demands among species could ultimately influence larval amphibian ecology in a warmer future.

Larval Ecology of Some Lower Michigan Black Flies (Diptera: Simuliidae) With Keys to the Immature Stages

Larval Ecology of Some Lower Michigan Black Flies (Diptera: Simuliidae) With Keys to the Immature Stages

Larval assemblages of large saproxylic cerambycids in Iberian oak forests: wood quality and host preference shape resource partitioning

AbstractOak open woodlands are widespread in southwestern Iberia and present outstanding ecological, biodiversity and socio‐economic values. Evergreen species (holm and cork oaks) are prevalent but deciduous oaks may be also locally important. Three large xylophagous cerambycids are associated to these oaks, Cerambyx welensii (Cw), C. cerdo (Cc) and Prinobius myardi (Pm). Like other saproxylic insects, these cerambycids are essential to the nutrient cycle, wood degradation and tree hollow formation, significantly contributing to biodiversity in oak forests. These cerambycids may also potentially colonise healthy living trees and become harmful or pest species. Factors driving their larval ecology are almost unknown, especially in oak forests harbouring mixed populations living in sympatry. Wood samples (n = 500 bolts) from 348 colonised trees were examined during 2011–2016 across the Extremadura region (41,634 km2). Bolts were measured, scored into five wood quality classes, dissected, and all target cerambycids were collected, measured, reared and taxonomically identified. We then determined species‐specific prevalence, niche breadth, niche overlap, age structure and population density depending on wood quality, host preference, tree part, wood size, altitude and sun exposure. Wood quality and host preference were major factors segregating interspecific resource partitioning. Cw was prevalent on cork oak decayed wood, and Pm on holm oak degraded wood. Host tree part was involved in Cerambyx larval niche segregation, with Cw prevalent in the fork/branches and Cc in the trunk/base. Pm was never found inhabiting deciduous oaks. Our results may be useful to improve sustainable forest management practices in Iberian oak open woodlands.

Larval cycle, ecology and distribution of the red mangrove crab ( Ucides occidentalis ) in the Gulf of Guayaquil, Ecuador: understanding multiple impacts on fishery sustainability

Larval cycle, ecology and distribution of the red mangrove crab ( Ucides occidentalis ) in the Gulf of Guayaquil, Ecuador: understanding multiple impacts on fishery sustainability

Evidence for complex life cycle constraints on salamander body form diversification

Metazoans display a tremendous diversity of developmental patterns, including complex life cycles composed of morphologically disparate stages. In this regard, the evolution of life cycle complexity promotes phenotypic diversity. However, correlations between life cycle stages can constrain the evolution of some structures and functions. Despite the potential macroevolutionary consequences, few studies have tested the impacts of life cycle evolution on broad-scale patterns of trait diversification. Here we show that larval and adult salamanders with a simple, aquatic-only (paedomorphic) life cycle had an increased rate of vertebral column and body form diversification compared to lineages with a complex, aquatic-terrestrial (biphasic) life cycle. These differences in life cycle complexity explain the variations in vertebral number and adult body form better than larval ecology. In addition, we found that lineages with a simple terrestrial-only (direct developing) life cycle also had a higher rate of adult body form evolution than biphasic lineages, but still 10-fold lower than aquatic-only lineages. Our analyses demonstrate that prominent shifts in phenotypic evolution can follow long-term transitions in life cycle complexity, which may reflect underlying stage-dependent constraints.

Urbanization is a main driver for the larval ecology of Aedes mosquitoes in arbovirus-endemic settings in south-eastern Côte d'Ivoire.

BackgroundFailure in detecting naturally occurring breeding sites of Aedes mosquitoes can bias the conclusions drawn from field studies, and hence, negatively affect intervention outcomes. We characterized the habitats of immature Aedes mosquitoes and explored species dynamics along a rural-to-urban gradient in a West Africa setting where yellow fever and dengue co-exist.MethodologyBetween January 2013 and October 2014, we collected immature Aedes mosquitoes in water containers in rural, suburban, and urban areas of south-eastern Côte d’Ivoire, using standardized sampling procedures. Immature mosquitoes were reared in the laboratory and adult specimens identified at species level.Principal findingsWe collected 6,159, 14,347, and 22,974 Aedes mosquitoes belonging to 17, 8, and 3 different species in rural, suburban, and urban environments, respectively. Ae. aegypti was the predominant species throughout, with a particularly high abundance in urban areas (99.374%). Eleven Aedes larval species not previously sampled in similar settings of Côte d’Ivoire were identified: Ae. albopictus, Ae. angustus, Ae. apicoargenteus, Ae. argenteopunctatus, Ae. haworthi, Ae. lilii, Ae. longipalpis, Ae. opok, Ae. palpalis, Ae. stokesi, and Ae. unilineatus. Aedes breeding site positivity was associated with study area, container type, shade, detritus, water turbidity, geographic location, season, and the presence of predators. We found proportionally more positive breeding sites in urban (2,136/3,374, 63.3%), compared to suburban (1,428/3,069, 46.5%) and rural areas (738/2,423, 30.5%). In the urban setting, the predominant breeding sites were industrial containers (e.g., tires and discarded containers). In suburban areas, containers made of traditional materials (e.g., clay pots) were most frequently encountered. In rural areas, natural containers (e.g., tree holes and bamboos) were common and represented 22.1% (163/738) of all Aedes-positive containers, hosting 18.7% of the Aedes fauna. The predatory mosquito species Culex tigripes was commonly sampled, while Toxorhynchites and Eretmapodites were mostly collected in rural areas.Conclusions/significanceIn Côte d’Ivoire, urbanization is associated with high abundance of Aedes larvae and a predominance of artificial containers as breeding sites, mostly colonized by Ae. aegypti in urban areas. Natural containers are still common in rural areas harboring several Aedes species and, therefore, limiting the impact of systematic removal of discarded containers on the control of arbovirus diseases.

Characterization and productivity profiles of Aedes aegypti (L.) breeding habitats across rural and urban landscapes in western and coastal Kenya

BackgroundAedes aegypti, the principal vector for dengue and other emerging arboviruses, breeds preferentially in various man-made and natural container habitats. In the absence of vaccine, epidemiological surveillance and vector control remain the best practices for preventing dengue outbreaks. Effective vector control depends on a good understanding of larval and adult vector ecology of which little is known in Kenya. In the current study, we sought to characterize breeding habitats and establish container productivity profiles of Ae. aegypti in rural and urban sites in western and coastal Kenya.MethodsTwenty sentinel houses in each of four study sites (in western and coastal Kenya) were assessed for immature mosquito infestation once a month for a period of 24 months (June 2014 to May 2016). All water-holding containers in and around the households were inspected for Ae. aegypti larvae and pupae.ResultsCollections were made from a total of 22,144 container visits: Chulaimbo (7575) and Kisumu (8003) in the west, and from Msambweni (3199) and Ukunda (3367) on the coast. Of these, only 4–5.6% were positive for Ae. aegypti immatures. In all four sites, significantly more positive containers were located outdoors than indoors. A total of 17,537 Ae. aegypti immatures were sampled from 10 container types. The most important habitat types were buckets, drums, tires, and pots, which produced over 75% of all the pupae. Key outdoor containers in the coast were buckets, drums and tires, which accounted for 82% of the pupae, while pots and tires were the only key containers in the western region producing 70% of the pupae. Drums, buckets and pots were the key indoor containers, producing nearly all of the pupae in the coastal sites. No pupae were collected indoors in the western region. The coastal region produced significantly more Ae. aegypti immatures than the western region both inside and outside the sentinel houses.ConclusionsThese results indicate that productive Ae. aegypti larval habitats are abundant outdoors and that only a few containers produce a majority of the pupae. Although the numbers were lower, productive habitats were detected within households. Targeting source reduction efforts towards these productive containers both inside and outside homes is likely to be a cost-effective way to reduce arboviral transmission in these regions.

Phylogeography in Nassarius mud snails: Complex patterns in congeneric species.

One major goal for phylogeographical studies is to elucidate respective roles of multiple evolutionary and ecological forces that shape the current distribution patterns. In marine and coastal ecosystems, it has been generated a common realization that species with enormous population size and pelagic larval stages can disperse across broad geographical scales, leading to weak or even no phylogeographical structure across large geographical scales. However, the violation of such realization has been frequently reported, and it remains largely unexplored on mechanisms responsible for various phylogeographical patterns observed in different species at varied geographical scales. Here, we used a species-rich genus Nassarius to assess and compare phylogeographical patterns in congeneric species, and discuss causes and consequences underlying varied phylogeographical patterns. Interestingly, we observed complex phylogeographical patterns both within single species and across multiple species, and multiple analyses showed varied levels of genetic heterogeneity among sites within and across species. Available evidence suggests that related species with similar biological characteristics may not be necessary to result in consistent phylogeographical patterns. Multiple factors, including larval ecology, interactions between dispersal and natural selection, and human activity-mediated dispersal, can partially explain the complex patterns observed in this study. Deep investigations should be performed on these factors, particularly their respective roles in determining evolutionary/ecological processes to form phylogeographical patterns in species with high dispersal capacities in marine and coastal ecosystems.

Larval shell morphology of Inoceramus pictus: all suspicions confirmed

Inoceramids were eurytopic bivalves and have a wide application as biostratigraphic index fossils in the Upper Cretaceous. Their paleoecology, however, is far from being understood. Here the prodissoconch of Inoceramus pictus is described. It was found in an upper Cenomanian shallow water methane-seep deposit in the Tropic Shale, southern Utah, USA. The larval shell consists of a small prodissoconch-1 and a large prodissoconch-2. The shell morphology indicates a planktotrophic larval phase with wide dispersal potential, and which confirms previous hypotheses of inoceramid larval ecology. Comparison with other inoceramid prodissoconchs shows that larval shell morphology cannot generally explain dispersal, and that more factors must have played a role in the distribution of species.