Larval Condition Research Articles

Life-shortening Wolbachia infection reduces population growth of Aedes aegypti

Wolbachia bacteria are being introduced into natural populations of vector mosquitoes, with the goal of reducing the transmission of human diseases such as Zika and dengue fever. The successful establishment of Wolbachia infection is largely dependent on the effects of Wolbachia infection to host fitness, but the effects of Wolbachia infection on the individual life-history traits of immature mosquitoes can vary. Here, the effects of life-shortening Wolbachia (wMelPop) on population growth of infected individuals were evaluated by measuring larval survival, developmental time and adult size of Aedes aegypti in intra- (infected or uninfected only) and inter-group (mixed with infected and uninfected) larval competition assays. At low larval density conditions, the population growth of wMelPop infected and uninfected individuals was similar. At high larval densities, wMelPop infected individuals had a significantly reduced population growth rate relative to uninfected individuals, regardless of competition type. We discuss the results in relation to the invasion of the wMelPop Wolbachia infection into naturally uninfected populations.

Maternally induced intraclutch cannibalism: an adaptive response to predation risk?

Theory on condition-dependent risk-taking indicates that when prey are in poor condition, their anti-predator responses should be weak. However, variation in responses resulting from differences in condition is generally considered an incidental by-product of organisms living in a heterogeneous environment. Using Leptinotarsadecemlineata beetles and stinkbug (Podisusmaculiventris) predators, we hypothesised that in response to predation risk, parents improve larval nutritional condition and expression of anti-predator responses by promoting intraclutch cannibalism. We showed that mothers experiencing predation risk increase production of unviable trophic eggs, which assures provisioning of an egg meal to the newly hatched offspring. Next, we experimentally demonstrated that egg cannibalism reduces L.decemlineata vulnerability to predation by improving larval nutritional condition and expression of anti-predator responses. Intraclutch cannibalism in herbivorous insects might be a ubiquitous strategy, aimed to overcome the dual challenge of feeding on protein-limited diets while living under constant predation threat.

Effect of larval growth conditions on adult body mass and long-distance flight endurance in a wood-boring beetle: Do smaller beetles fly better?

The tropical fig borer, Batocera rufomaculata De Geer, is a large beetle that is a pest on a number of fruit trees, including fig and mango. Adults feed on the leaves and twigs and females lay their eggs under the bark of the tree. The larvae bore into the tree trunk, causing substantial damage that may lead to the collapse and death of the host tree. We studied how larval development under inferior feeding conditions (experienced during development in dying trees) affects flight endurance in the adult insect. We grew larvae either in their natural host or on sawdust enriched with stale fig tree twigs. Flight endurance of the adults was measured using a custom-built flight-mill. Beetles emerging from the natural host were significantly larger but flew shorter distances than beetles reared on less favourable substrates. There was no difference in the allometric slope of wing area with body mass between the beetles groups; however flight muscle mass scaled with total body mass with an exponent significantly lower than 1.0. Hence, smaller beetles had proportionally larger flight muscles. These findings suggest that beetles that developed smaller as a result from poor nutritional conditions in deteriorating hosts, are better equipped to fly longer distances in search of a new host tree.

Oogenesis and reproductive investment of Atlantic herring are functions of not only present but long-ago environmental influences as well

Following general life history theory, immediate reproductive investment (egg mass × fecundity/body mass) in oviparous teleosts is a consequence of both present and past environmental influences. This clarification questions the frequent use of season-independent (general) fecundity formulas in marine fish recruitment studies based on body metrics only. Here we test the underlying assumption of no lag effect on gametogenesis in the planktivorous, determinate-fecundity Atlantic herring (Clupea harengus) displaying large plasticity in egg mass and fecundity, examining Norwegian summer-autumn spawning herring (NASH), North Sea autumn-spawning herring (NSAH), and Norwegian spring-spawning herring (NSSH). No prior reproductive information existed for NASH. Compared with the 1960s, recent reproductive investment had dropped markedly, especially for NSAH, likely reflecting long-term changes in zooplankton biography and productivity. As egg mass was characteristically small for autumn spawners, although large for spring spawners (cf. different larval feeding conditions), fecundity was the most dynamic factor within reproductive investment. For the data-rich NSSH, we showed evidence that transient, major declines in zooplankton abundance resulted in low fecundity over several subsequent seasons, even if Fulton's condition factor (K) turned high. Temporal trends in Kslope (K on total length) were, however, informative. These results clarify that fecundity is defined by (i) dynamics of primary (standing stock) oocytes and (ii) down-regulation of secondary oocytes, both processes intimately linked to environmental conditions but operating at different timescales. Thus, general fecundity formulas typically understate interannual variability in actual fecundity. We therefore argue for the use of segmented fecundity formulas linked to dedicated monitoring programs.

Anti-drift nano-stickers made of graphene oxide for targeted pesticide delivery and crop pest control

Pesticide plays an important role in the agricultural production, however more than 90% of pesticide goes non-target. Present study, uses reduced graphene oxide for controlled and targeted pesticide delivery, as it can bind drug until native larval gut condition appears. Graphene oxide is not reported for pesticide delivery and here with reference to graphene oxide ∼400% pesticide loading (w/w) is observed. The graphene oxide is decorated with copper selenide, which have photothermal and photocatalytic property. Photothermal property complements with graphene oxide in pesticide delivery, which may control diurnal pest. The photocatalytic property aid in programmed pesticide residue degradation in the offsite. This nano-carrier shows drift resistance in addition to targeted release, which enhanced larval mortality by >35%.

Regional climate on the breeding grounds predicts variation in the natal origin of monarch butterflies overwintering in Mexico over 38years.

Addressing population declines of migratory insects requires linking populations across different portions of the annual cycle and understanding the effects of variation in weather and climate on productivity, recruitment, and patterns of long-distance movement. We used stable H and C isotopes and geospatial modeling to estimate the natal origin of monarch butterflies (Danaus plexippus) in eastern North America using over 1000 monarchs collected over almost four decades at Mexican overwintering colonies. Multinomial regression was used to ascertain which climate-related factors best-predicted temporal variation in natal origin across six breeding regions. The region producing the largest proportion of overwintering monarchs was the US Midwest (mean annual proportion=0.38; 95% CI: 0.36-0.41) followed by the north-central (0.17; 0.14-0.18), northeast (0.15; 0.11-0.16), northwest (0.12; 0.12-0.16), southwest (0.11; 0.08-0.12), and southeast (0.08; 0.07-0.11) regions. There was no evidence of directional shifts in the relative contributions of different natal regions over time, which suggests these regions are comprising the same relative proportion of the overwintering population in recent years as in the mid-1970s. Instead, interannual variation in the proportion of monarchs from each region covaried with climate, as measured by the Southern Oscillation Index and regional-specific daily maximum temperature and precipitation, which together likely dictate larval development rates and food plant condition. Our results provide the first robust long-term analysis of predictors of the natal origins of monarchs overwintering in Mexico. Conservation efforts on the breeding grounds focused on the Midwest region will likely have the greatest benefit to eastern North American migratory monarchs, but the population will likely remain sensitive to regional and stochastic weather patterns.

Coupling suitable prey field to in situ fish larval condition and abundance in a subtropical estuary

Survival of fish larvae is influenced by the suitability of the prey field and its variability in time and space. Relationships among food quality, quantity and recruitment have been explored in temperate ecosystems where spawning and secondary production are strongly seasonal, but for subtropical estuaries the mechanisms responsible for larval survival remain poorly identified. This study evaluated the nutritional condition (feeding incidence and AARS activity) and abundance of a multi-specific assemblage of fish larvae from a subtropical estuary in South America (Solís Grande, Uruguay) during the fish reproductive season; and related both variables to prey abundance, composition, size and fatty acids content. The larval assemblage was composed of 13 species belonging to different functional groups and composition varied seasonally. Contrary to expectations larval condition did not match an increase in prey quality. Food availability was high throughout the study period, although significant changes existed in the size and taxonomic structure of the prey assemblage. The temporal succession of complementary factors - temperature, prey composition, abundance and quality - promoted a wide window of opportunity for larvae, where quality seemed to have compensated quantity. Such combination of factors could allow an extended larval survival along the spawning season. These findings underline the importance of a better understanding of subtropical estuaries as nursery areas.

Combined effects of elevated pCO2, temperature, and starvation stress on larvae of a large tropical marine fish

Ocean acidification and other environmental changes pose an ecological challenge to marine organisms globally. Although the youngest life stages of these organism are likely to be most affected, a limited number of studies of larval fishes have investigated the effects of combined stressors. We conducted two experiments on larval cobia (Rachycentron canadum) raised under combinations of elevated pCO2 and increased temperature or starvation stress. Larvae responded to individual CO2, temperature, and rationing treatments, and there was a negative effect of elevated pCO2 on starvation resistance, but few synergistic effects of combined stressors. Elevated pCO2 (1700–2100 μatm pCO2) caused a transient but significant reduction in larval standard length (SL), growth rate, and development rate, while warmer temperature (32 vs. 27 °C) caused a consistent increase in SL, development rate, and swimming ability. Larval condition (RNA:DNA ratio) was unaffected by elevated pCO2 although larvae fed a 25% ration had significantly reduced SL, growth rate, and development rate. Under complete feeding cessation, larvae in elevated-pCO2 seawater demonstrated lower starvation resistance, indicating that acidification may increase starvation risk in a patchy marine environment. Overall, our results indicate that larval cobia are resistant to any major direct impact of combined elevated pCO2 and temperature or rationing stress.

Feeding, somatic condition and survival of sand lance Ammodytes sp. larvae in Mutsu Bay, Japan

To clarify the recruitment process of sand lance Ammodytes sp., we investigated larval condition factor, relative gut fullness (%GF), prey abundance and oceanographic structure in Mutsu Bay, Japan, during 1999–2001. Ammodytes sp. larvae, which were collected by horizontal hauls of Motoda nets and a ring net at depths of 1, 10, 20, 30 and 40 m, were mainly distributed at 10–30 m. Larvae at the first feeding time until 12 mm in body length (BL) fed predominantly on copepod nauplii, whereas large larvae with BL of 12.1–14.0 mm fed on a mixture of copepod nauplii, copepodites and appendicularians from late February to April. A path analysis showed that difference in water density between 35- and 5-m depths negatively affected naupliar abundance at 10–30-m depth (standardised path coefficient β = −0.71, p = 0.005 for 3.3–8.0-mm BL larvae and β = −0.78, p < 0.001 for 8.1–12.0-mm BL larvae). Naupliar abundance positively affected the %GF of Ammodytes sp. larvae (β = 0.75, p < 0.001 for 3.3–8.0-mm BL larvae and β = 0.66, p < 0.001 for 8.1–12.0-mm BL larvae), whereas it was negatively affected by water temperature (β = −0.45, p = 0.008 for 3.3–8.0-mm BL larvae and β = −0.56, p = 0.002 for 8.1–12.0-mm BL larvae), and the temperature effect was weak compared with that of naupliar abundance. In turn, %GF positively affected larval somatic weight (β = 0.91, p < 0.001 for 6.0-mm BL larvae and β = 0.70, p = 0.005 for 10.0-mm BL larvae). The recruitment failure in 1999 was likely caused by a reduced condition factor, which resulted from low naupliar abundance. In contrast, the abundance of nauplii and Oithona similis copepodites was high in 2000 and 2001. It is possible that the higher recruitment success in 2001 was because of the higher water temperatures in Mutsu Bay, sustaining faster growth of the larvae than in 2000 under the high-prey abundance conditions.

Regional productivity predicts individual growth and recruitment of rockfishes in a northern California upwelling system

AbstractRecruitment of marine fishes is largely determined by biological and environmental factors acting on early‐life stages. Subtle changes in larval condition in response to their environment can result in order‐of‐magnitude differences in year‐class‐strength. Overlap of larval production and favorable feeding conditions drives recruitment for many temperate marine fishes, but challenges associated with studying marine larvae have made it difficult to assess how environmental processes act on individual larvae to affect their growth and survival. We conducted a 2‐yr study in an upwelling system to assess the influence of regional productivity, temperature, and larval condition in explaining growth in rockfishes (Sebastes spp.). We employed otolith microstructure and satellite imagery to measure initial larval growth and estimate the productivity and temperature experienced by individuals to determine their relative importance in subsequent growth at metamorphosis. We compared model performance using indexed environmental conditions scaled over three different regions. In both years, net primary productivity explained the most variation in pre‐metamorphic growth relative to temperature and initial growth. This relationship was consistent across spatial regions, although model fit was highest using indices scaled to the south continental shelf region. Recent settlement, juvenile recruitment, and individual growth were significantly higher in a year when productivity bloomed earlier and individual larvae experienced higher levels of productivity. Thus, this link between regional scale productivity, growth, and subsequent year‐class strength supports the hypothesis that large‐scale oceanographic processes stimulating upwelling and secondary production are primary drivers of larval growth and recruitment in rockfishes.

Adaptation to divergent larval diets in the medfly, Ceratitis capitata.

Variation in diet can influence the timing of major life‐history events and can drive population diversification and ultimately speciation. Proximate responses of life histories to diet have been well studied. However, there are scant experimental data on how organisms adapt to divergent diets over the longer term. We focused on this omission by testing the responses of a global pest, the Mediterranean fruitfly, to divergent selection on larval diets of different nutritional profiles. Tests conducted before and after 30 generations of nutritional selection revealed a complex interplay between the effects of novel larval dietary conditions on both plastic and evolved responses. There were proximate‐only responses to the larval diet in adult male courtship and the frequency of copulation. Males on higher calorie larval diets consistently engaged in more bouts of energetic courtship. In contrast, following selection, larval development time, and egg to adult survival showed evidence of evolved divergence between diet regimes. Adult body size showed evidence for adaptation, with flies being significantly heavier when reared on their “own” diet. The results show the multifaceted responses of individuals to dietary selection and are important in understanding the extreme generalism exhibited by the medfly.

Condition of larval Spanish mackerel Scomberomorus maculatus in relation to the Deepwater Horizon oil spill

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 558:143-152 (2016) - DOI: https://doi.org/10.3354/meps11880 Condition of larval Spanish mackerel Scomberomorus maculatus in relation to the Deepwater Horizon oil spill J. T. Ransom1,2, J. E. Filbrun1,3, F. J. Hernandez Jr.1,* 1Division of Coastal Sciences, University of Southern Mississippi, 703 East Beach Road, Ocean Springs, Mississippi 39564, USA 2Benzie Conservation District, 280 South Benzie Blvd, Beulah, Michigan 49517, USA 3Department of Biology, 100 East University, Southern Arkansas University, Magnolia, Arkansas 71753, USA *Corresponding author: frank.hernandez@usm.edu ABSTRACT: The Deepwater Horizon oil spill (DWHOS) coincided with the pelagic larval stages of many valued commercial and recreational fishes in the northern Gulf of Mexico. Larval fish survival and eventual recruitment into adult populations may have been impacted directly through toxicity or indirectly through changes in the planktonic food web caused by the release of oil and chemical dispersants during the DWHOS event. Using samples from a long-term ichthyoplankton survey off the coast of Alabama, USA, in a region impacted by the DWHOS, the abundance and condition of larval Spanish mackerel Scomberomorus maculatus were compared during summer months in years before (2007-2009), during (2010) and after (2011) the DWHOS. Changes in larval quality were examined using morphometric and weight-based body condition indices, whereas potential trophic impacts were quantified using stable C and N isotopes. Larval abundance did not differ across years. However, larvae were in better body condition during the DWHOS period relative to before the spill. Larvae had generally similar isotopic values through time. Thus, larval Spanish mackerel body condition was largely resilient to the harmful effects of the DWHOS. Responses to the DWHOS are likely taxon-specific, as the resiliency of larval Spanish mackerel starkly contrast the response of another managed species (red snapper) during the same period. KEY WORDS: Deepwater Horizon · Gulf of Mexico · Spanish mackerel · Larval condition Full text in pdf format PreviousNextCite this article as: Ransom JT, Filbrun JE, Hernandez FJ Jr (2016) Condition of larval Spanish mackerel Scomberomorus maculatus in relation to the Deepwater Horizon oil spill. Mar Ecol Prog Ser 558:143-152. https://doi.org/10.3354/meps11880 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 558. Online publication date: October 25, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Role of Recruitment Processes in Structuring Coralligenous Benthic Assemblages in the Northern Adriatic Continental Shelf.

Coralligenous biogenic reefs are among the most diverse marine habitats in the Mediterranean Sea. The northern Adriatic mesophotic coralligenous outcrops host very rich and diverse epibenthic assemblages. Several studies quantified the low temporal variability and high spatial heterogeneity of these habitats, while processes driving structuring and differentiation are still poorly understood. To shed light on these processes, temporal and spatial patterns of colonisation were investigated using travertine tiles deployed on three coralligenous outcrops, corresponding to the main typologies of benthic assemblages described in previous studies. Three years after deployment, assemblages colonising travertine tiles resembled the differentiation among sites revealed by the natural assemblages in terms of major ecological groups. Processes structuring and maintaining species diversity have been explored. Pioneer species with high reproduction rate, long distance larval dispersal and fast growth (e.g. the serpulid polychaete Spirobranchus triqueter and the bivalve Anomia ephippium), were the most abundant in the early stages of recruitment on the two outcrops further away from the coast and with lower sedimentation. Their success may vary according to larval availability and environmental conditions (e.g., sedimentation rates). At these sites early-stage lasted 10–12 months, during which even species from natural substrates began colonising tiles by settlement of planktonic propagules (e.g., encrusting calcareous Rhodophyta) and lateral encroachment (e.g., sponges and ascidians). On coastal outcrop, exposed to a higher sedimentation rates, tiles were colonised by fast-growing algal turfs. Resilience of northern Adriatic coralligenous assemblages, and maintenance of their diversity, appeared largely entrusted to asexual reproduction. Exploring the mechanisms that underlie the formation and maintenance of the species diversity is crucial to improve our understanding of ecological processes and to implement appropriate conservation strategies of the Adriatic coralligenous reefs.

Prophylactic effect ofHaslea ostreariaculture supernatant containing the pigment marennine to stabilize bivalve hatchery production

This paper explores the possibility of using the supernatant of Haslea ostrearia culture containing marennine, a natural microalgal pigment, as an antimicrobial in bivalve hatcheries. The blue mussel Mytilus edulis and the scallop Placopecten magellanicus were used as model animals, and the pathogenic marine bacteria Vibrio splendidus was used to induce larval mortality. The hypothesis tested was that V. splendidus pathogenicity in larval rearings can be controlled by using marennine-containing culture supernatants. The effect of three marennine concentrations was tested on a larval rearing over 20 days for M. edulis and 9 days for P. magellanicus. At a low dose (0.1 mg L-1), survival and physiological condition were both higher than in the control. In bacterial challenges, larvae were exposed to V. splendidus for 72 h, with or without marennine. The bacterial challenge caused significant mortality when compared to controls, while the marennine-treated larvae showed significantly higher survival. Results show that marennine is an interesting molecule for pathogen control in hatcheries as it is active at low concentrations and significantly enhanced larval survival and physiological condition. -- Keywords : Bivalve hatcheries ; microalgal by-products ; Haslea ostrearia ; Mytilus edulis ; Placopecten magellanicus ; Vibrio splendidus.

Autonomy and integration in complex parasite life cycles.

Complex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

Effects of larval versus adult density conditions on reproduction and behavior of a leaf beetle

Population density is an important social environmental factor influencing various life history traits of individuals in many species. In how far density also affects behavioral traits, and particularly at which life stage during ontogeny the adult behavioral phenotype is shaped, has been rarely examined, especially in holometabolous insects. We tested the effects of larval versus adult density on development, reproductive success, and the adult behavioral phenotype of a non-social beetle, Phaedon cochleariae. Therefore, we reared individuals either constantly isolated, in groups, or switched them to the other rearing density condition after metamorphosis. We expected beneficial consequences on the growth and reproduction of isolated individuals because these individuals did not have to compete for food and resting sites. The development time was significantly influenced by the larval density with isolated larvae developing faster than group-reared individuals. Furthermore, the reproductive success was higher for individuals kept isolated as larvae, regardless of the adult density, pointing to a silver spoon effect (i.e., persisting fitness advantage based on favorable, less competitive early conditions). Three behavioral dimensions were found in adult beetles, boldness, activity, and exploration. Adult boldness behavior and activity were influenced by either larval or adult density conditions in dependence of the context and/or sex. Thus, the present study highlights the major influence of the experienced larval density on adult reproductive success and demonstrates the high complexity in which the behavioral phenotype of a holometabolous insect is shaped by a social environmental factor. We investigated the effects of keeping larvae and/or adults either isolated or in a group on the adult reproduction and behavior of a leaf beetle. This study was performed to understand which life stage has a stronger impact on the adult phenotype in an organism that undergoes a metamorphosis. We found that the larval stage was most decisive for the adult reproductive success, with isolated larvae laying more eggs as adults than individuals kept in groups. Furthermore, adult boldness and activity behavior were shaped by larval and adult density conditions differently between females and males. These results demonstrate that both larval and adult experience can be involved in shaping the adult behavioral phenotype of a holometabolous insect.

Condition of larval red snapper (Lutjanus campechanus) relative to environmental variability and the Deepwater Horizon oil spill

The Deepwater Horizon oil spill (DWHOS) spatially and temporally overlapped with the spawning of many fish species, including Red Snapper, one of the most economically important reef fish in the Gulf of Mexico. To investigate potential impacts of the DWHOS on larval Red Snapper, data from a long-term ichthyoplankton survey off the coast of Alabama were used to examine: (1) larval abundances among pre-impact (2007–2009), impact (2010), and post-impact (2011, 2013) periods; (2) proxies for larval condition (size-adjusted morphometric relationships and dry weight) among the same periods; and (3) the effects of background environmental variation on larval condition. We found that larval Red Snapper were in poorer body condition during 2010, 2011, and 2013 as compared to the 2007–2009 period, a trend that was strongly (and negatively) related to variation in Mobile Bay freshwater discharge. However, larvae collected during and after 2010 were in relatively poor condition even after accounting for variation in freshwater discharge and other environmental variables. By contrast, no differences in larval abundance were detected during these survey years. Taken together, larval supply did not change relative to the timing of the DWHOS, but larval condition was negatively impacted. Even small changes in condition can affect larval survival, so these trends may have consequences for recruitment of larvae to juvenile and adult life stages.

Larval food quantity affects the capacity of adult mosquitoes to transmit human malaria.

Adult traits of holometabolous insects are shaped by conditions experienced during larval development, which might impact interactions between adult insect hosts and parasites. However, the ecology of larval insects that vector disease remains poorly understood. Here, we used Anopheles stephensi mosquitoes and the human malaria parasite Plasmodium falciparum, to investigate whether larval conditions affect the capacity of adult mosquitoes to transmit malaria. We reared larvae in two groups; one group received a standard laboratory rearing diet, whereas the other received a reduced diet. Emerging adult females were then provided an infectious blood meal. We assessed mosquito longevity, parasite development rate and prevalence of infectious mosquitoes over time. Reduced larval food led to increased adult mortality and caused a delay in parasite development and a slowing in the rate at which parasites invaded the mosquito salivary glands, extending the time it took for mosquitoes to become infectious. Together, these effects increased transmission potential of mosquitoes in the high food regime by 260–330%. Such effects have not, to our knowledge, been shown previously for human malaria and highlight the importance of improving knowledge of larval ecology to better understand vector-borne disease transmission dynamics.

Effects of culture conditions on larval growth and survival of stalked barnacles ( Pollicipes pollicipes )

Pollicipes pollicipes (Crustacea: Scalpelliformes) is a highly prized food in Portugal and Spain and consequently a species of considerable interest to aquaculture. Surprisingly, however, larval culture conditions for this barnacle have not been optimized. This study investigated the effects of temperature, diet, photoperiod and salinity on the growth and survival of P. pollicipes larvae. Temperature had a significant effect on specific growth rate (2.6–5.9% total width per day, from 11 to 24°C), reducing mean development time to the cyprid from 25 days at 11 °C to 10 days at 24°C, although this was accompanied by a significant increase in mortality to over 90% above 22°C. Mid-range temperatures (15–20°C) maximized total survival (19–31% respectively). Algal diets of Tetraselmis suecica, T. suecica/Skeletonema marinoi and S. marinoi/Isochrysis galbana did not affect specific growth rate significantly, but survival (on average 39% in 15 days) and the proportion of high-quality healthy cyprids was significantly higher on the latter two diets (11–15% of initial number of larvae). Photoperiod did not significantly affect the survival, although specific growth rate was significantly higher at 24:0 and 16:8 L:D. Salinity (20–40 g L−1 range) did not affect growth and survival significantly. The best growth and survival were accomplished using rearing temperatures of 15–20°C, daily feeding with T. suecica/S. marinoi or I. galbana/S. marinoi and a photoperiod of 24:0 L:D.

Chemical parameters and bacterial communities associated with larval habitats of Anopheles, Culex and Aedes mosquitoes (Diptera: Culicidae) in western Kenya

AbstractAquatic larval habitat conditions influence the development, fitness and vectorial capacity of mosquitoes. In turn, human activities can influence these conditions and shape mosquito vector distribution, thus affecting pathogen circulation and transmission. We measured environmental factors (chemical and microbial) in mosquito larval habitats and evaluated their potential as predictors for the occurrence of different mosquito species in an arbovirus and malaria endemic region of western Kenya. We found significantly greater proportions ofAedes aegyptimosquito larvae in ammonium and phosphate rich habitats, suggesting that fertilizer usage could potentially increase aquatic habitat suitability andAedesvectored disease transmission.Anopheles gambiaelarval habitats correlated significantly with higher temperatures. However, none of theCulexspecies’ habitats correlated with investigated variables, indicating greater larval plasticity compared toAedesorAnopheles. Profiling of bacterial communities by 16S rRNA pyrosequencing revealed Proteobacteria, Bacterioidetes and Firmicutes as the major bacteria phyla present in mosquito aquatic microhabitats. Although there were no correlations between microbiota composition or diversity and larval species abundance, the dominant genera of microbes detected in larval habitats were reported in larval and adult mid-guts, suggesting that bacteria acquired from the larval habitats are transmitted to adult stages. This study identified the chemical and bacterial composition of aquatic microhabitats that are conducive to the development of different mosquito vectors in western Kenya. This information can inform potential vector control strategies by assessing management of breeding sites based on likely exposure to fertilizer, light and bacterial fauna.