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Phototaxis is a well-studied insect behaviour described as rigid and stereotyped. Larval response to light can be assessed by a fast and highly repetitive assay like a half-dark/half-illuminated plate. Drosophila melanogaster Meigen (Diptera: Drosophilidae) mutants can be used to study the response of larvae to sensory stimuli. Adults of the ebony mutant show behavioural deficits such as abnormal circadian rhythms and severe defects in vision, whereas the tan mutants show a slight deficiency in vision. We analysed the response of D. melanogaster mutant larvae for N-ß-alanyl derivatives metabolism (ebony and tan) to determine whether they also show abnormal phototactic behaviour. Our results showed that ebony larvae exhibited a random response to light, whereas tan larvae showed a similar response to wild-type larvae. To assess if N-ß-alanyl derivatives metabolism might be involved in the response of larvae to light, we fed them with N-ß-alanyldopamine (NBAD), N-ß-alanylhistamine (carcinine) or dopamine. NBAD restored the wt response in ebony larvae, whereas carcinine and DA produced no effect. These results suggest, for the first time, that NBAD might act as a neuroactive compound involved in the phototactic response of the D. melanogaster larvae. [ABSTRACT FROM AUTHOR]

As a factor controlling the vertical distribution of larvae, changes in phototaxis, geotaxis, and sinking velocity concerning larval development in the snow crab (Chionoecetes opilio), a relatively shallower water species, and red snow crab (Chionoecetes japonicus), a relatively deeper water species, were investigated using laboratory-raised individuals. We also measured carapace width and carapace length in all larval stages and the length of the spines seen in the zoeal stages. The phototaxis of the zoeae of both species was strongly positive immediately after hatching, but it gradually changed to neutral. Megalopal phototaxis changed from strongly negative to neutral. The geotaxis of both species was strongly negative only for a few days after hatching, and the red snow crab exhibited stronger negative geotaxis than the snow crab. The sinking velocity of the red snow crab was slower than the snow crab just after hatching but faster in the megalopal stage. Red snow crab showed a greater tendency to float immediately after hatching (stronger negative geotaxis, slower sinking rate), compared to snow crab, and sink more easily in the megalopal stage (faster sinking speed). This might be because the red snow crab hatches and settles at deeper areas than the snow crab. Red snow crab larvae had larger carapace sizes and shorter spine lengths (at the zoeal stages) than the snow crab, which is indicative of adaptations that increase starvation tolerance for longer larval periods and reduce the energy costs of swimming for longer distances (i.e., greater hatching depth) after hatching. [ABSTRACT FROM AUTHOR]

Vertical migration of marine larvae may drastically affect their dispersal, especially if they are spawned in the deep sea. Previous studies have shown that the planktonic larvae of the cold-water coral Lophelia pertusa in still water swim upwards at a speed of ca. 0.5 mm s-1 during a pre-competency period of 3–5 weeks. This behavioral trait is thought to benefit dispersion of larvae as it promotes near surface drift in relatively strong currents. In the ocean however, larvae regularly encounter turbulent water movements potentially impeding their swimming ability. With no apparent stabilizing mechanism, it may be expected that the body orientation of these larvae, and consequently their directed swimming, is sensitive to perturbation by external forces. We investigated the effects of turbulence on vertical swimming of pre-competent L. pertusa larvae by exposing them to relevant turbulence intensities within a grid-stirred tank. Larval movement and water flow were simultaneously recorded, allowing for analysis of individual larval swimming velocities. We showed that the upwards directed swimming speed generally decreased with increasing turbulence, dropping to non-significant in turbulence levels occurring near ocean boundaries. Our results do however suggest that L. pertusa larvae maintain their upwards directed swimming, albeit at reduced speed, in a major part of the water column, thus allowing them to spend part of their planktonic phase in the uppermost ocean layer. This new insight into the behavior of L. pertusa larvae in their natural environment strengthens the notion of the species as one with strong potential for long-distance dispersal. Such information is important for the understanding of L. pertusa population connectivity, and vital when developing tools for modelling of larval transport.

Mosquitoes are the important carriers of disease-causing pathogens responsible for serious health effects in humans. The vector control management mainly focuses on synthetic insecticides and their overuse creates resistance in mosquitoes. Henceforth, there is a need to develop insecticides that are effective and help in overcoming resistance development in mosquitoes. An attempt is made here to bring effective management of larval mosquitoes with herbal-based preparations since it is eco-friendly and causes no ill effects on humans. In this study, aqueous and solvent extracts of Acorus calamus leaves were tested for their anti-mosquito activity against third instar larvae of Aedes aegypti and Culex quinquefasciatus. Among the tested extracts, the crude hexane leaf extract of A. calamus showed the highest percentage of mortality with LC50 of 151.86 ppm and LC90 of 536.36 ppm against A. aegypti and LC50 of 174.70 ppm and LC90 of 696.73 ppm against C. quinquefasciatus. The treatment showed significant changes in the larval morphology such as damaged body parts, enlarged mid-gut, and lesions on the thoracic region. Similarly, histopathological analysis of treated larvae after 24 hours of treatment was observed with dislocations of cells, augmented nucleus, and ruptured epithelial cells. GC-MS analysis of the effective crude hexane leaf extract of A. calamus showed the presence of asarone to the level of 50.18% and that could have been thought to be insecticidal in nature which is probably responsible for the effective larval anti-mosquito activity. [ABSTRACT FROM AUTHOR]

Larval supply determines year-class strength of fisheries and complex ecological interactions among adults of benthic marine species. In upwelling regions, a latitudinal cline in the intensity and persistence of upwelling is thought to affect larval advection and recruitment, thereby regulating the intensity of interactions in adult populations and communities. We tested this hypothesis by determining the monthly cross-shelf abundances of nearshore benthic crustacean larvae throughout development during the peak upwelling season for 7 years in a region of intermittent upwelling and high recruitment (45°N). We tested whether larvae were found farther offshore during upwelling conditions, and we compared their interspecific cross-shelf distributions to previous results from a region of strong, persistent upwelling (38°N). We also compared larval abundances across the 2 upwelling regions for 1 year. Most species were retained nearshore, regardless of intra- and inter-annual variations in the intensity of upwelling. In both upwelling regions, larvae of each species consistently occurred at different distances from the shore. Further, there were no differences in nearshore larval abundance across upwelling regions for all but 1 larval stage of 1 species. Thus, latitudinal variations in the intensity and persistence of upwelling do not appear to affect larval survival, providing further evidence that nearshore processes may be a primary determinant of larval delivery to the rocky intertidal across these regions. © Inter-Research 2014.

The majority of marine species maintain genetic connectivity through pelagic propagules, with pelagic duration hypothesized to limit dispersal potential. This dissertation investigates the geographic scale of genetic connectivity when pelagic duration is likely not limiting. I analyzed mtDNA sequences and microsatellites to determine patterns of genetic structure across the geographic distributions of three lobster species: Panulirus penicillatus (Red Sea to the East Pacific Ocean), P. interruptus (sub-tropical East Pacific), and P. marginatus (Hawaiian endemic). At the broadest spatial scale, significant genetic discontinuities for P. penicillatus correspond to provincial biogeographic boundaries, including putative species-level disjunction across the East Pacific Barrier. On a smaller scale, novel kinship analyses combined with traditional F-statistics indicate that larval behavior and oceanographic processes result in localized recruitment for P. interruptus. Geographic scales of connectivity differ by location and species, even in Hawai‘i, where P. marginatus and P. penicillatus co-occur. These findings indicate the combined effects of geography, ocean currents, and biology overcome extremely long pelagic periods and result in variable degrees of genetic connectivity.

The maintenance of marine populations depends on the completion of larval migrations between adult and larval habitats, but the ability of microscopic larvae to regulate their movements in such a dynamic environment has been debated. Using a comparative hypothesis testing approach and intensive hourly sampling throughout the water column, we determined the ability of larvae of 6 species with different swimming abilities (2 gastropods, 2 crabs, 2 fishes) to overcome strong tidal mixing during spring tides and regulate their vertical, and hence, horizontal position, in opposing depth-stratified currents in the upper Hudson River estuary, USA. The vertical distributions of nonmotile eggs and swimming larvae generally differed, suggesting that larvae regulated depth. Eggs were passively mixed by tidal currents, but larvae typically aggregated in stratified portions of the water column, which fostered retention in the upper estuary. However, the capacity to regulate depth depended on swimming ability and the degree of mixing. In a predominantly mixed tidal environment upstream, mixing overcame most larvae when current velocities were maximal during mid-ebb or mid-flood tides; tidal vertical migrations were not evident for any species, and diel vertical migrations were apparent for only 1 species. In a partially stratified water column downstream, diel vertical migrations were apparent for larvae of 3 of 4 invertebrate species, and tidal vertical migrations were apparent for the 2 fish species. The presence of all larval stages showed that all species regulated depth sufficiently well to remain in the upper estuary. Regardless of swimming ability, larvae were retained in the estuary by occurring near the level of no net motion, even without completing tidal vertical migrations. Continuous profiling of larvae and hydrodynamics is necessary to reveal the ability of larvae to regulate depth in tidal mixing and recruit to adult populations. © Inter-Research 2013.

Dispersal, retention, and population connectivity are impacted by current regime and the behaviors that drive larval distribution, so understanding both is key to informing restoration of native species like the Olympia oyster (Ostrea lurida) across its range in western North America. This study explores the relationships between several factors (temperature, [chl a], larval size, tidal stage, and estimated current speed) and Olympia oyster larval vertical distributions in Fidalgo Bay (48.4828, − 122.5811), a shallow, tidally flushed bay in the Salish Sea. Olympia oyster larvae collected from four depths over the tidal cycle from July 11–14, 2017, were ~ 20% deeper near slack tide and shallower during the faster parts of both ebb and flood, with a threshold for this transition around an estimated 25 cm s−1. This pattern does not suggest tidally timed migrations as has been shown in another population of Olympia oysters, nor can this pattern be totally explained by passive processes. Larvae did not cluster at depths with specific temperatures or [chl a] but there was a difference in larval size between surface and bottom waters, with older, larger larvae more common at the bottom. Fidalgo Bay does not exhibit two-way flow or strong vertical shear, so vertical distribution of larvae likely has little effect on transport in this system but might in other similarly shallow habitat areas with higher stratification that are target restoration sites in the Salish Sea. These results add to the growing number of studies that show location-specific differences in larval vertical distribution and behavior within taxa and underscore the importance of integrating local hydrodynamics into predictions of bivalve larval transport. [ABSTRACT FROM AUTHOR]

Temporal variability of the genetic structure and connectivity patterns of the blue and red shrimp Aristeus antennatus in the seven most important fishing grounds of the Western Mediterranean Sea, were assessed using twelve microsatellite loci during 2 consecutive years (2016 and 2017), in a total of 1403 adult individuals. A high level of geographical connectivity among groups was observed in the two studied years. In fact, no significant geographical differentiation was found in 2016 (FST = 0.0018, p > 0.05), whereas it was indicated in 2017 (FST = 0.0025, p < 0.05). This small divergence in 2017 was not attributed to the distance among locations nor to the effect of the Ibiza Channel. Significant allele frequency changes were found at local level between the 2 years (FCT = 0.0006, p < 0.05), mainly due to Blanes' fishing ground. Larval dispersal from the North to the South through the main superficial current supports the high level of connectivity pattern found. The temporal genetic instability detected in the Blanes' fishing ground could be explained by oceanographic temporary features. Our findings evidence only one biological unit in the study region and establish the baseline for an inter-federal management plan of A. antennatus. [ABSTRACT FROM AUTHOR]

The estuarine mud crab Panopeus herbstii navigates a complex, but structured, hydrodynamic environment throughout its life history. The effects of hydrodynamic cues associated with turbulent flows on larval behavior are relatively well understood in the context of selective tidal stream transport (STST) phenomena during the dispersed (pelagic) larval stages preceding benthic settlement. In contrast, the potential relevance of hydrodynamic cues associated with spatiotemporally persistent flow features, which are typical of estuarine regions of enhanced productivity such as fronts and clines, remains much less certain. To investigate the behavioral relevance of persistent hydrodynamic cues, larval assays were conducted in a flume system that uses a laminar slot jet to produce steady fluid shear layers. Further, to ascertain whether or not the spatial orientation of the shear layers relative to gravity significantly affected larval behavior, assays were conducted in upwelling, downwelling, and horizontal shear flows, corresponding to the direction of the bulk flow produced by the jet. The flow was quantified using particle image velocimetry (PIV) and tuned to produce ecologically-relevant hydrodynamic conditions for larval assays. Changes in larval swimming kinematics show a distinct response to shear flows in all orientations relative to no-flow conditions, and the macro effect of these changes is to enhance depth-keeping and induce area-restricted search behaviors. Furthermore, the specifics of larval behavioral responses depend on the directional orientation of the shear flow, and the statistical properties of the strength of the hydrodynamic cue (vorticity) eliciting these responses are also shown to be shear flow orientation-specific. Orientation-specific hydrodynamic sensitivity and behavioral response strategies in the presence of persistent hydrodynamic cues may enable larvae to effectively forage and sample to locate and exploit nearby resource patches, while also inducing dispersal trajectories toward favorable benthic settlement habitats through depth-regulation and effective STST. In this regard, hydrodynamic cues associated with spatiotemporally persistent flow features are likely fundamental drivers of decapod crab larvae behavior and may act as another mechanism of larval patchiness by directly impacting finescale population distributions and resultant dispersal trajectories.

Abstract Background A common life cycle pattern in benthic-dwelling taxa in the ocean is an obligate pre-competent dispersal period of microscopic propagules followed by their entry into a competent period, during which they are capable of transitioning back to the sea floor at settlement. The behavior of larvae during their competent periods varies: some taxa are characterized by discriminating larvae that will only accept high quality habitat in which to settle, whereas larvae from other taxa may initially be discriminating, but will become increasingly ‘desperate’ to settle as they age. Larvae in this latter class, if they fail to encounter optimal settlement habitat, are observed to accept increasingly sub-optimal habitat as their competent period progresses. Results Here we show that a brief exposure of competent sand dollar larvae (Dendraster excentricus) to a high intensity of turbulent shear shifts larvae into less discriminating settlement behavior. Specifically, turbulence-exposed larvae will settle in response to a wider variety of settlement cues, and will do so more rapidly than will their unexposed siblings. We also report that turbulence causes larvae to sink to the bottom in greater numbers, presumably increasing their exposure to cues on the substrate. Conclusions We conclude that fundamental aspects of larval life history and habitat selection are sensitive to short term environmental exposure. We discuss these findings in the context of how larvae might more generally utilize transient features of their environment to make key life history decisions. Such a perspective has implications for issues as diverse as aquaculture, population recovery following disturbance, and the sensitivity and response of marine organisms to climate change.

Larvae are considered to be highly susceptible to offshore transport, thereby limiting recruitment in productive upwelling regions, except in the recirculation features that form in the lee of headlands. We show that 19 of 20 taxa of nearshore crustaceans were at least as common on the open coast as they were in the lee of a headland in a recruitment-limited region characterized by strong upwelling. Nine of these taxa occurred in high concentrations throughout development, indicating that larvae completed development nearshore in a coastal boundary layer of reduced Ekman transport. Larvae of 9 more taxa were prevalent as early stage larvae, and later stages were uncommon, indicating that larvae migrated offshore. The relative abundance of larval stages largely matched the vertical distributions of larvae in this study and a previous cross-shelf survey at this site, indicating that larval behavior plays a substantial role in determining whether larvae complete development nearshore or migrate offshore later in development. Larvae of taxa that occurred nearshore in high concentrations throughout development resided below a shallow Ekman layer of seaward-flowing surface waters, whereas most larvae of the other taxa occurred closer to the surface. Whether larvae undertook ontogenetic and diel vertical migrations also appeared to determine whether they were retained nearshore. Thus larval retention may be more widespread in upwelling regions than is widely believed, and the cause of recruitment limitation along upwelling coasts needs to be determined to further advance our understanding of the connectivity, dynamics and structure of coastal populations. © Inter-Research 2010.

Behavioral responses to environmental factors at the planktonic larval stage can have a crucial influence on habitat selection and therefore adult distributions in many benthic organisms. Reef-building corals show strong patterns of zonation across depth or underwater topography, with different suites of species aggregating in different light environments. One potential mechanism driving this pattern is the response of free-swimming larvae to light. However, there is little experimental support for this hypothesis; in particular, there are few direct and quantitative observations of larval behavior in response to light. Here, we analyzed the swimming behavior of larvae of the common reef coral Acropora tenuis under various light conditions. Larvae exhibited a step-down photophobic response, i.e. a marked decrease in swimming speed, in response to a rapid attenuation (step-down) of light intensity. Observations of larvae under different wavelengths indicated that only the loss of blue light (wavelengths between 400 and 500 nm) produced a significant response. Mathematical simulations of this step-down photophobic response indicate that larvae will aggregate in the lighter areas of two-dimensional large rectangular fields. These results suggest that the step-down photophobic response of coral larvae may play an important role in determining where larval settle on the reef. [ABSTRACT FROM AUTHOR]

The ability of miniscule larvae to control their fate and replenish populations in dynamic marine environments has been a long-running topic of debate of central importance for managing resources and understanding the ecology and evolution of life in the sea. Larvae are considered to be highly susceptible to offshore transport in productive upwelling regions, thereby increasing dispersal, limiting onshore recruitment, and reducing the intensity of community interactions. We show that 45 species of nearshore crustaceans were not transported far offshore in a recruitment-limited region characterized by strong upwelling. To the contrary, 92% of these larvae remained within 6 km from shore in high densities throughout development along two transects sampled four times during the peak upwelling season. Larvae of most species remained nearshore by remaining below a shallow Ekman layer of seaward-flowing surface waters throughout development. Larvae of other species migrated farther offshore by occurring closer to the surface early in development. Postlarvae evidently returned to nearshore adult habitats either by descending to shoreward-flowing upwelled waters or rising to the sea surface where they can be transported shoreward by wind relaxation events or internal waves. Thus wind-driven offshore transport should not limit recruitment, even in strong upwelling regions, and larvae are more likely to recruit closer to natal populations than is widely believed. This study poses a new challenge to determine the true cause and extent of recruitment limitation for a more diverse array of species along upwelling coasts, and thus to further advance our understanding of the connectivity, dynamics, and structure of coastal populations.

Planktonic larvae of many marine organisms have been known to cycle in abundance according to lunar phases. It is unknown, however, if these cycles are caused by timed release of larvae by the adults in accordance with lunar cues or if predation pressure on the larvae varies across the lunar cycle. Larvae of some invertebrate taxa are capable of predator detection and avoidance, suggesting that predation on meroplankton is lower than dispersal models predict. This study tracked lunar cycling of decapod larvae from Oct. 6, 2008 to Nov. 13, 2008 in Moorea, French Polynesia. Predator avoidance capabilities of the larvae and relative predation pressure during each phase of the moon were also tested in a laboratory setting. Larval abundances on the reef were highest during the new moon period and lowest during quarter and full moons, suggesting predation does affect lunar abundance cycling. Decapod megalops stage larvae were found to be capable of predator avoidance but younger stage zoeas were not. Predation pressure was also found to correlate directly with light intensity. Results of this study suggest predation does affects larval population cycling, however it is possible that both predation and larval release timing play a role in shaping larval abundances and dispersal.

Abstract Background Cannibalism has been observed in a wide range of animal taxa and its importance in persistence and stability of populations has been documented. In anopheline malaria vectors the inter-instar cannibalism between fourth- and first-instar larvae (L4-L1) has been shown in several species, while intra-instar cannibalism remains poorly investigated. In this study we tested the occurrence of intra-instar cannibalism within larvae of second-, third- and fourth-instar (L2, L3 and L4) of Anopheles gambiae (s.s.) and An. stephensi. Experiments were set up under laboratory conditions and the effects of larval density, duration of the contact period among larvae and the presence of an older larva (i.e. a potential cannibal of bigger size) on cannibalism rate were analysed. Cannibalism was assessed by computing the number of missing larvae after 24 and 48 h from the beginning of the experiments and further documented by records with a GoPro videocamera. Results Intra-instar cannibalism was observed in all larval instars of both species with higher frequency in An. gambiae (s.s.) than in An. stephensi. In both species the total number of cannibalistic events increased from 0–24 to 0–48 h. The density affected the cannibalism rate, but its effect was related to the larval instar and to the presence of older larvae. Interestingly, the lower cannibalism rate between L4 larvae was observed at the highest density and the cannibalism rate between L3 larvae decreased when one L4 was added. Conclusions The present study provides experimental evidence of intra-instar cannibalism in the malaria vectors An. gambiae (s.s.) and An. stephensi and highlights the possible occurrence of complex interactions between all larval instars potentially present in the breeding sites. We hypothesize that the high density and the presence of a potential cannibal of bigger size could affect the readiness to attack conspecifics, resulting into low risk larval behavior and lower cannibalism rate. The understanding of cannibalistic behavior and the factors affecting it is of utmost importance for malaria vectors, as nutrition during larval development can strongly affect the fitness of adult female mosquitoes and ultimately their vector ability.

The selection of suitable host plants for larval development is critical for most herbivorous insects. In this study, we examined host plant preferences of larvae of the Epistrophus white morpho butterfly, Morpho epistrophus argentinus (H. Fruhstorfer), a specialized butterfly that oviposits on a few plant species. In many species, the selection of host plant species for larvae development is under the control of ovipositing females and the role of larvae in host selection is minimal. Through field observations, we characterized larval host plant use in coastal woodland patches of its southernmost distribution range at eastern Buenos Aires, Argentina. All sampled M.e. argentinus larvaegroups (n = 40) were found on Scutia buxifolia trees, although the number of larval groups did not correlate with cover of this plant at patch scale. To further examine host plant preferences we performed translocation experiments and feeding choice assays. M.e. argentinus larvae translocated to unsuitable host plants had a shorter residence time than those translocated to suitable (i.e. control) hosts. Choice assays also indicated strong feeding preferences of wild larvae for S. buxifolia leaves. Our results highlight the high degree of host specificity of this butterfly, and reveal that host preference of growing larvae matches that of ovipositing females.

Triphenyl phosphate (TPhP) is an organophosphate flame retardant that is frequently detected in the environments. TPhP exposure is known to cause developmental toxicity. However, the underlying molecular mechanisms remain underestimated. In the present study, zebrafish embryos were acutely exposed to 0, 4 and 100 μg/L TPhP until 144 h post-fertilization. Profiles of differentially expressed proteins were constructed using a shotgun proteomic. With the input of differential proteins, principal component analysis suggested different protein expression profiles for 4 and 100 μg/L TPhP. Gene ontology and KEGG pathway analyses further found that effects of TPhP at 4 μg/L targeted phagosome and lysosome activity, while 100 μg/L TPhP mainly affected carbohydrate metabolism, muscular contraction and phagosome. Based on proteomic data, diverse bioassays were employed to ascertain the effects of TPhP on specific proteins and pathways. At gene and protein levels, expressions of critical visual proteins were significantly changed by TPhP exposure, including retinoschisin 1a, opsins and crystallins, implying the impairment of ocular development and function. TPhP exposure at 100 μg/L also altered the abundances of diverse muscular proteins and disordered the assembly of muscle fibers. Effects of TPhP on visual development and motor activity may be combined to disturb larval swimming behavior. In summary, current results provided mechanistic clues to the developmental toxicities of TPhP. Future works are inspired to broaden the toxicological knowledge of TPhP based on current proteomic results. Image 1 • TPhP at 4 μg/L targeted phagosome and lysosome activities in zebrafish larvae. • TPhP at 100 μg/L affected carbohydrate metabolism, muscle contraction and lysosome. • Expressions of critical visual proteins were disturbed, implying ocular toxicity. • Assembly of muscle fibers was disordered by 100 μg/L TPhP. • Toxic mechanisms of TPhP varied as a function of exposure concentrations. [ABSTRACT FROM AUTHOR]

This article describes early development of the climbing perch Anabas testudineus in relation to its buoyancy dynamics. Main patterns of the ontogeny during the first 140 h of development are described. The climbing perch is characterized by positive buoyancy of eggs and early larvae not usually found in other freshwater fish. This allows the fish development close to the surface of the water and is enabled by a large oil globule in the yolk. The data on the spatial orientation of the larva body, their vertical distribution in the water column, the beginning of exogenous feeding and locomotion, and the fright reaction of the larvae at different ages are presented. The most significant changes in the behavior of the climbing perch larvae are associated with changing the shape of the yolk sac, beginning to function as a provisional hydrostatic organ from about the 80s hour of development. [ABSTRACT FROM AUTHOR]

Ustiloxin A is a cyclopeptide mycotoxin originally isolated from rice false smut balls (FSBs) that formed in rice spikelets infected by the fungal pathogen Ustilaginoidea virens. Studies have shown that ustiloxin A was toxic to animals, but the toxicological evidence is still lacking. To reveal the negative influence of ustiloxin A on model organism, zebrafish were selected and exposed to ustiloxin A at concentrations of 0, 0.25, 2.5 or 25 μM from 2 h post-fertilization (hpf) to 144 hpf. The hatching rates of embryos in the 25 μM exposure group was 12.85% less than the control group at 96 hpf. Meanwhile, exposure to 0.25, 2.5 or 25 μM ustiloxin A resulted in a distinct dose-dependent increase in mortality rate of embryos at 96 hpf. We also found that exposed to ustiloxin A could cause some other damages on zebrafish larvae, such as growth delay and increased heart rate. In addition, the athletic behavior of zebrafish larvae exposed to ustiloxin A at 25 μM was dramatically different with that of control. Transcriptome sequencing showed that abundances of 339 transcripts (125 up-regulated and 214 down-regulated) were significantly altered in larvae exposed to 25 μM of ustiloxin A. Several of the crucial genes were validated by RT-qPCR. This is the first report on the toxicologic study of ustiloxins against model organism zebrafish. Results suggested that ustiloxins have become a potential danger for food security. • Ustiloxin A causes growth inhibition and developmental damage on early life zebrafish. • The athletic behavior of zebrafish larvae exposed to ustiloxin A is dramatically different to that of control. • Ustiloxin A is likely to be an important influencing factor for food security. [ABSTRACT FROM AUTHOR]

Biophysical models are well-used tools for predicting the dispersal of marine larvae. Larval behavior has been shown to influence dispersal, but how to incorporate behavior effectively within dispersal models remains a challenge. Mechanisms of behavior are often derived from laboratory-based studies and therefore, may not reflect behavior in situ. Here, using state-of-the-art models, we explore the movements that larvae must undertake to achieve the vertical distribution patterns observed in nature. Results suggest that behaviors are not consistent with those described under the tidally synchronized vertical migration (TVM) hypothesis. Instead, we show (i) a need for swimming speed and direction to vary over the tidal cycle and (ii) that, in some instances, larval swimming cannot explain observed vertical patterns. We argue that current methods of behavioral parameterization are limited in their capacity to replicate in situ observations of vertical distribution, which may cause dispersal error to propagate over time, due to advective differences over depth and demonstrate an alternative to laboratory-based behavioral parameterization that encompasses the range of environmental cues that may be acting on planktic organisms. [ABSTRACT FROM AUTHOR]

Triadimefon (TDF) is a triazole fungicide extensively used in agriculture that has been found as a pollutant in numerous water sources. In mammals, it inhibits monoamine uptake through binding to the dopamine transporter, with a mechanism of action similar to cocaine, resulting in higher levels of dopamine at the synapse. Dopamine is a neurotransmitter involved in a broad spectrum of processes such as locomotion, cognition, reward, and mental disorders. In this work we have studied, for the first time, the effects of TDF on behavior of both larval and adult zebrafish and its connection with changes in the dopaminergic and serotonergic systems. We evaluated the acute exposure of 5 dpf larvae to different concentrations of TDF, ranging from 5 mg/L to 35 mg/L. The lowest concentration does not alter neither locomotor activity nor dopamine levels but produced changes in the expression of two genes, tyrosine hydroxylase 1 (th1) and dopamine transporter (dat). Besides, it induced a reduction in extracellular serotonin and had an anxiolytic-like effect, supported by a decrease in cortisol production. On the other hand, a high concentration of TDF produced a dose-dependent reduction in locomotion, which was reversed or enhanced by D1 (SCH-23390) or D2 (Haloperidol) dopamine receptor antagonists, respectively. Using in vivo electrochemistry, we show that these changes could be associated with higher levels of dopamine in the brain. Thus, in adult zebrafish, though not in larvae, TDF exposure increases locomotor activity, anxiety and aggressiveness, which coincides with the behaviors observed in mammals. • TDF decreases locomotor activity in a dose dependent manner. • TDF diminishes anxiety-like behavior and cortisol levels in zebrafish larvae. • Behavioral effects exerted by TDF are related to changes in the extracellular levels of dopamine and serotonin. • TDF exerts opposing effects on the behavior of larvae and adult zebrafish. [ABSTRACT FROM AUTHOR]

Monopterus cuchia is a fresh water eel widely distributed in Nepal, Myanmar, Pakistan but predominantly available in Bangladesh and North East Region of India. The population of the species has been declined in its natural habitat to a great extend due to various environmental and anthropogenic factors. So far no report was available regarding artificial propagation of the species M. cuchia, especially from India. Hence it is necessary to develop an induced breeding protocol by standardized doses of synthetic hormone for artificial propagation of the fish. Thus, an experiment was set up for induced breeding of the species using synthetic hormone, Gonopro-FH. After hormonal administration (Gonopro-FH), brooders were released into specially prepared ponds and spawning was natural and spontaneous. During the period of analysis, fecundity of M. cuchia was calculated as 924 eggs (length= 78cm, weight= 344 gms). Induced breeding was successful using Gonopro-FH and the final dosage was 1ml/kg body weight to the female along with 0.3ml/kg body weight to the male. Final fertilization percentage was 75-80% and hatching percentage was 80-85%. [ABSTRACT FROM AUTHOR]

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• The mean weighted depth (centroids) of the early life stages occurred below the pycnocline. • Both distance of centroid from pycnocline and vertical ranges differed among stages and sites. • High late zoea and megalopa abundances agreed with the reported winter reproductive season. • Increased abundances of late zoea and megalopa at flood tides suggest onshore transport. In recent decades, the distribution of the very abundant squat lobster, Munida gregaria , a key species in the Beagle Channel and southernmost Patagonian waters, has widened towards lower latitudes. The general objective of this study was to assess how early life stages of this species cope with changes in environmental conditions at sites within its northern distribution in the Chilean Patagonia. In particular, we were interested in determining: (i) whether the various developmental stages of M. gregaria inhabited different mean depth ranges, (ii) whether diel vertical migrations were present in all stages and, (iii) if they occurred, whether these migrations were modified at sites with contrasting environmental conditions. The study consisted of high-frequency (every 3 h) observations over 30-h periods at each hydrographic and stratified sampling site of a springtime oceanographic cruise. Our results showed slight variations in preferences for hydrographic characteristics among stages, differences in their relative abundance in each sampling zone, and fluctuations in the mean weight by depth of distribution among sites. However, larval behavior showed certain similarities: the abundance and vertical distribution of most stages seemed to fluctuate with the semidiurnal tides, apparently not following the day-night cycle. For all stages, the weighted mean depth (centroids) was located below the pycnocline, although the mean distance from it and vertical displacement ranges differed among stages. Late zoea and megalopa were the most abundant stages, increasing in abundance at flood tides, in agreement with the previously reported winter reproductive season and the hypothesis of inshore-offshore ontogenetic movement of plankton stages for this species, which predicts that inshore transport should occur at this time of year. In summary, our results suggest that ontogenetic changes in vertical distribution and migrations and their respective deviations at each location constitute a flexible behavior that may facilitate dispersal towards new habitats and enhance the species' chances of survival under changing environmental conditions. [ABSTRACT FROM AUTHOR]

Environmental pollutants, such as insecticides, can alter the equilibrium of aquatic ecosystems, particularly those closely located to human occupations. The use of such anthropogenic compounds frequently results in the selection of resistant individuals. However, how the underlying insecticide resistance mechanisms interplay with the abilities of the resistant individuals to cope with other environmental challenges (e.g., predators) has not received adequate attention. Here, we evaluated whether resistance to pyrethroid insecticides in larvae of the yellow fever mosquito, Aedes aegypti (Diptera: Culicidae), would affect their abilities to survive other environmental challenges. We assessed the susceptibilities of the pyrethroid-resistant larvae to other insecticides (i.e., the oxadiazine indoxacarb and juvenile hormone mimic pyriproxyfen) and determined the activities of potential detoxification enzymes. Finally, we also recorded potential alterations in larva swimming behavior in the presence of predators, such as the water bug Belostoma anurum (Hemiptera: Belostomatidae). Our results revealed that high pyrethroid resistance was associated with moderate resistance to the other two insecticides. Furthermore, this multiple resistance was associated with higher detoxification activity by glutathione-S-transferases and general esterases. Interestingly, in comparison with insecticide-susceptible larvae, the pyrethroid-resistant larvae not only swam for longer periods and distances, but also took longer to be captured by B. anurum nymphs. Collectively, our findings revealed increased abilities to survive natural environmental challenges (e.g., predatory attacks) in mosquito larvae that express physiological and behavioral changes associated with multiple resistance to insecticides. Unlabelled Image • Larvae of Aedes aegypti were resistant to pyrethroids and other insecticide compounds. • Multiple insecticide resistance was associated with higher enzymatic activities. • Insecticide-resistant larvae are more mobile than insecticide-susceptible larvae. • Insecticide-resistant larvae spent more time on the deeper regions of water column. • Insecticide-resistant larvae survived better the Belostoma anurum predatory attacks. [ABSTRACT FROM AUTHOR]

Predation is the main source of mortality during the larval stage of marine fishes. Previous work has shown a correlation between measures of performance related to predator evasion and fatty acid (FA) composition of marine fish larvae, and that the latter can be influenced by both larval diet and maternally-derived nutrition (yolk). This study aimed to determine the relationships between FA composition of eggs, FA composition of the larval body, and predator evasion performance of southern flounder, Paralichthys lethostigma. Larvae hatched from eggs differing in FA composition were reared under common garden conditions to 15 and 35 days posthatching (dph) when measurements of routine swimming and responsiveness to a simulated looming predator were made. Larval responsiveness to the predatory stimulus was positively correlated with the FA ratios DHA: ARA and DHA: EPA in whole larvae at 15 and 35 dph, respectively. The amount of omega-3 docosapentaenoic acid (22:5(n-3)) in the egg was correlated, though not significantly, with the amount of DHA in the larval body at 15 dph (r = −0.51, P = 0.052), and was significantly correlated with the amount of DHA in the larval body at 35 dph (r = −0.62, P = 0.031). These results provide evidence of metabolic programming in southern flounder, and suggest that maternally derived nutrients indirectly influence larval mortality in the wild. • Fatty acid composition of larvae is correlated with predator evasion success. • Ratios of EFAs in the larval body significantly correlated with larval quality. • Maternally-derived nutrients influence larval body fatty acid composition. • Maternal diet may influence larval mortality by predation in the wild. [ABSTRACT FROM AUTHOR]

Abstract The habenula (Hb) plays important roles in emotion-related behaviors. Besides receiving inputs from the limbic system and basal ganglia, Hb also gets inputs from multiple sensory modalities. Sensory responses of Hb neurons in zebrafish are asymmetrical: the left dorsal Hb and right dorsal Hb (dHb) preferentially respond to visual and olfactory stimuli, respectively, implying different functions of the left and right dHb. While visual responses of the left dHb (L-dHb) have been implicated in light-preference behavior, the significance of olfactory responses of the right dHb (R-dHb) remains under-examined. It was reported that the R-dHb can gate innate attraction to a bile salt. However, considering a broad range of odors that R-dHb respond to, it is of interest to examine the role of R-dHb in other olfactory behaviors, especially food seeking, which is essential for animals' survival. Here, using in vivo whole-cell recording and calcium imaging, we first characterized food extract-evoked responses of Hb neurons. Responsive neurons preferentially locate in the R- but not L-dHb and exhibit either ON- (~ 87%) or OFF-type responses (~ 13%). Interestingly, this right-to-left asymmetry of olfactory responses converts into a ventral-to-dorsal pattern in the interpeduncular nucleus (IPN), a main downstream target of Hb. Combining behavior assay, we further found that genetic dysfunction or lesion of the R-dHb and its corresponding downstream ventral IPN (V-IPN) impair the food seeking-associated increase of swimming activity. Thus, our study indicates that the asymmetrical olfactory response in the R-dHb to V-IPN pathway plays an important role in food-seeking behavior of zebrafish larvae. Graphical abstract Unlabelled Image Highlights • Olfactorily responsive neurons preferentially locate in the right (R) but not left dorsal habenula (dHb). • This right-to-left Hb asymmetry converts to a ventral-to-dorsal pattern in the downstream interpeduncular nucleus (IPN). • Loss-of-function of either the R-dHb or ventral IPN (V-IPN) impairs food-seeking associated increase of swimming activity. • Asymmetrical olfactory responses in the R-dHb to V-IPN pathway are important for food-seeking behavior of larval zebrafish. [ABSTRACT FROM AUTHOR]

Abstract Broad applications and exposure to the fungicide maneb can lead to toxicity in non-target organisms. Maneb is also associated with neurogenerative diseases such as Parkinson's disease (PD). The objectives of this study were to determine the acute toxicity of maneb to zebrafish by measuring mitochondrial bioenergetics, locomotor activity, and the expression of genes related to the oxidative damage response, as well as those related to dopamine signaling due to its association with PD. Zebrafish embryos at 6 h post-fertilization (hpf) were exposed to either solvent control (0.1% DMSO, v / v), or one dose of 0.1, 0.5, 1.0 and 10.0 µM maneb for 96 h. Maneb was moderately toxic to zebrafish embryos, and had a 96-h LC 50 value of 4.29 μM (~ 1.14 mg/L). Maneb induced a dose-dependent increase in mortality, decreased hatching rate, and increased notochord deformity rate at both 1.0 and 10.0 µM after 72 and 96 h. Total body length was also significantly reduced with 1.0 µM maneb. A 50–60% decrease in mean basal oxygen consumption rate was also observed in embryos following a 24 hpf exposure to 10.0 µM maneb but oligomycin-induced ATP production and FCCP-induced maximum respiration remained unaffected. No change was detected in the expression levels of genes associated with oxidative stress (sod1 and sod2), nor those related to dopamine synthesis (th1), dopamine transporter (dat) , dopamine receptors (drd1 , drd2a , drd3 , and drd4b). Thus, modifying the expression of these transcripts may not be a mechanism for maneb-induced developmental toxicity in zebrafish. To assess the potential for neurotoxicity, a dark photokinesis assay was conducted in larvae following 7 d exposure to 0.1, 0.5 and 1.0 μM maneb. Larvae exposed to 0.5 and 1.0 μM maneb showed signs related to hypoactivity, and this reduced activity is hypothesized to be associated with notochord defects as this deformity was prevalent at higher concentrations of maneb. Overall, these data demonstrate that maneb negatively affects embryonic development (i.e. notochord development), affects basal oxygen consumption rates of embryos, and induces hypoactivity in larval fish. This study improves understanding regarding the developmental neurotoxicity of the fungicide maneb to zebrafish. Graphical abstract fx1 Highlights • Developmental neurotoxicity of the fungicide maneb in zebrafish embryos was studied. • Mitochondrial bioenergetics, gene expression, and larval behavior were assessed. • Maneb induced lethality, developmental defects, and notochord deformity at ≥ 1.0 μM. • Exposure to 10.0 μM maneb decreased basal respiration of embryos at 24 h. • Maneb induced hypoactivity in larvae following 7 days exposure to 0.5 and 1.0 μM. [ABSTRACT FROM AUTHOR]

• Karenia brevis exposure had lethal and sublethal impacts on stage-1 stone crab larvae. • Larval survivorship was reduced at medium and high concentrations of K. brevis. • Larval vertical swimming was altered following K. brevis exposure. The dinoflagellate Karenia brevis causes harmful algal blooms commonly referred to as red tides that are prevalent along Florida's gulf coast. Severe blooms often cause fish kills, turbid water, and hypoxic events all of which can negatively impact local fisheries. The stone crab, Menippe mercenaria, is a ˜$25 million per year fishery that occurs primarily along Florida's gulf coast. On the west Florida shelf, red tides occur from fall through spring, although severe blooms can occur during the summer. During the summer, stone crabs are reproductive and release larvae that are transported offshore where K. brevis blooms originate. This study determined the effects of K. brevis exposure on the survivorship, vertical swimming behavior, and oxygen consumption of stage-1 larval stone crabs. Survivorship was determined by exposing larvae to high (> 1 × 106 cells L−1) and medium (˜1 × 105 cells L−1) K. brevis concentrations for 96-hrs and were compared to controls that had no algae present. Larval swimming behavior (i.e., geotaxis) and oxygen consumption were monitored after 6-hr exposure to K. brevis. After 96-hrs of exposure, mortality was 100% and 30% for larvae in the high and medium concentrations of K. brevis , respectively, relative to the control. Larval swimming behavior was reversed in the K. brevis treatment; however oxygen consumption rates did not differ among treatments. These results suggest that severe blooms during the summer may reduce larval supply and serve as a potential bottleneck for new individuals recruiting into the fishery in years following a K. brevis bloom. [ABSTRACT FROM AUTHOR]

The bilaterally symmetrical, feeding larval stage is an ancestral condition in echinoderms. However, many echinoderms have evolved abbreviated development and form a pentamerous juvenile without a feeding larva. Abbreviated development with a non-feeding vitellaria larva is found in five families of brittle stars, but very little is known about this type of development. In this study, the external anatomy, ciliary bands, neurons, and muscles were examined in the development of the brooded vitellaria larva of Ophioplocus esmarki. The external morphology throughout development shows typical vitellaria features, including morphogenetic movements to set up the vitellaria body plan, an anterior preoral lobe, a posterior lobe, transverse ciliary bands, and development of juvenile structures on the mid-ventral side. An early population of neurons forms at the base of the preoral lobe at the pre-vitellaria stage after the initial formation of the coelomic cavities. These early neurons may be homologous to the apical neurons that develop in echinoderms with feeding larval forms. Neurons form close to the ciliary bands, but the vitellaria larva lacks the tracts of neurons associated with the ciliary bands found in echinoderms with feeding larvae. Additional neurons form in association with the axial complex and persist into the juvenile stage. Juvenile nerves and muscles form with pentamerous symmetry in the late vitellaria stage in a manner similar to their development within the late ophiopluteus larva. Even though O. esmarki is a brooding brittle star, its developmental sequence retains the general vitellaria shape and structure; however, the vitellaria larvae are unable to swim in the water column. [ABSTRACT FROM AUTHOR]

Adaptive autotomy is the self-amputation of an appendage in response to external stimuli that benefits survival. Variation in the ease of appendage removal among populations suggests that autotomy performance is under selection, evolves, or is phenotypically plastic, although the latter has never been experimentally tested. We model an autotomy threshold that optimally balances how the benefits of surviving predator attack versus the costs of losing an appendage vary with predator presence. We test for functional plasticity in autotomy threshold in the caudal lamellae of Enallagma damselfly larvae by experimentally manipulating non-lethal cues from predatory dragonfly larvae. Predator cues lead to functional plastic responses in the form of smaller lamellar joints that required lower peak breaking force. This is the first experimental demonstration of functional plasticity in autotomy to cues from a grasping predator, a novel form of indirect predator effects on prey, realized through plasticity in morphological traits that govern the autotomy threshold. This supports the model of optimized autotomy performance and provides a novel explanation for variation in performance among populations under different predator conditions. Plastic autotomy responses that mitigate costs in the face of variation in mortality risks might be a form of inducible defense. [ABSTRACT FROM AUTHOR]

In this study, we aimed to investigate the effect of the two main active cannabinoids extracted from cannabis: Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on two distinct behavioral models of induced neuro-hyperactivity. We have taken advantage of two previously developed zebrafish models of neuro-hyperactivity: a chemically induced pentylenetetrazole model and a genetic model caused by loss-of-function mutations in the GABA receptor subunit alpha 1 (GABRA1−/−). Both CBD and THC have a significant effect on the behavioral changes induced by both models. Importantly, we have also shown that when applied together at different ratios of THC to CBD (1:1, 1:5, and 1:10), there was a synergistic effect at a ratio of 1:1. This was particularly important for the genetically induced neuro-hyperactivity as it brought the concentrations of THC and CBD required to oppose the induced behavioral changes to levels that had much less of an effect on baseline larval behavior. The results of this study help to validate the ability of THC and CBD to oppose neuro-hyperactivity linked to seizure modalities. Additionally, it appears that individually, each cannabinoid may be more effective against the chemically induced model than against the GABRA1 −/− transgenic model. However, when applied together, the concentration of each compound required to oppose the GABRA1 −/− light-induced activity was lowered. This is of particular interest since the use of cannabinoids as therapeutics can be dampened by their side-effect profile. Reducing the level of each cannabinoid required may help to prevent off target effects that lead to side effects. Additionally, this study provides a validation of the complimentary nature of the two zebrafish models and sets a platform for future work with cannabinoids, particularly in the context of neuro-hyperactivity disorders such as epilepsy. [ABSTRACT FROM AUTHOR]

Highlights • Zebrafish (F0) were chronically exposed to a realistic environmental PCB/PBDE mixture via diet. • Molecular and behavioral analyses were performed from F0 to F4 generation. • Environmental PCB/PBDE mixture does not alter behavior in F0 exposed fish. • Gene transcription and behavior are altered in unexposed offspring in F1 to F4 generations. • These results suggest a combination of multi- and transgenerational effects of an environmental PCB/PBDE mixture. Abstract Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants extensively used during the 20th century and still present in aquatic environments despite their ban. Effects of exposure to these compounds over generations are poorly documented. Therefore, our aims were to characterize behavioral responses and underlying molecular mechanisms in zebrafish exposed to an environmentally relevant mixture of PCBs and PBDEs as well as in four unexposed offspring generations. Zebrafish (F0) were chronically exposed from the first meal onward to a diet spiked with a mixture containing 22 PCB and 7 PBDE congeners in proportions and concentrations reflecting environmental situations (ΣPCBs = 1991 and ΣPBDEs = 411 ng/g). Four offspring generations (F1 to F4) were obtained from this F0 and were not further exposed. Behavior was assessed at both larval and adult stages. Mechanisms related to behavioral defects (habenula maturation and c-fos transcription) and methylation (dnmts transcription) were monitored in larvae. Exposed adult F0 as well as F1 and F3 adults displayed no behavioral change while F2 expressed anxiety-like behavior. Larval behavior was also disrupted, i.e. hyperactive after light to dark transition in F1 or hypoactive in F2, F3 and F4. Behavioral disruptions may be related to defect in habenula maturation (observed in F1) and change in c-fos transcription (observed in F1 and F2). Transcription of the gene encoding DNA methyltransferase (dnmt3ba) was also modified in all generations. Our results lead us to hypothesize that chronic dietary exposure to an environmentally relevant mixture of PCB and PBDE triggers multigenerational and transgenerational molecular and behavioral disruptions in a vertebrate model. [ABSTRACT FROM AUTHOR]

Laboratory experiments were conducted to determine larval movement of the spotted wing drosophila (Drosophila suzukii Matsumura). Movement of larvae outside of the wild blueberry fruit (Vaccinium angustifolium Aiton) can occur after exhausting fruit food resources pri- or to completion of development or just prior to pupation. We found that when provided a choice larvae select moist compared to dry environments both in plastic arenas providing only filter paper for shelter and in a soil filled petri dishes. Movement was usually limited to less than 7.5 cm in the soil from a release point. An exponential decay model suggests that only 0.1% of a larval population will move as far as 17.5 cm. Results of our study suggest that while larvae move readily, they have minimal ability to avoid localized xeric soil micro-climatic conditions through movement. However, they will select less stressful moist soil environments. [ABSTRACT FROM AUTHOR]

Gibberellic acid (GA3) is usually used as a plant growth regulator to enhance the quality and quantity of crop yield. Moreover, GA3 may also affect insects and other herbivores that rely on a particular plant for their living. Hence, in the present study the defensive mechanisms of Helicoverpa armigera (Hübner) fed on the diet contating GA3 have been considered. The larvae fed with GA3 significantly exhibited cellular and humoral inhibitory responses such as, reduced nodule formation and phenoloxidase activity. Antioxidant system was also affected; the lowest activity of peroxidase, catalase, superoxide dismutase, ascorbate peroxidise, glucose-6-phosphate dehydrogenase, and glutathione S-transferases was observed in control larvae while the highest activity was found in those larvae that were provided with a diet containing 800 µg/g GA3. The metabolites like triglyceride, glycogen, and cholesterol were reduced compared to the control. It is concluded that the use of plant growth regulators like GA3 not only does benefit plants for their growth and yield, but also can somehow help plants to withstand the impact of herbivores. Hence, studies covering direct field collected insects from crop plants treated with PGRs would be beneficial for further studies. [ABSTRACT FROM AUTHOR]

Specific scope: This Standard describes a diagnostic protocol for Dacus ciliatus. It should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols. Specific approval and amendment: Approved in 2018–09. [ABSTRACT FROM AUTHOR]

Abstract In the present scenario, solid waste management (SWM) has become one of the main concerns for urban waste managers in the developing world. This article reviews the recent trends and technologies associated with the process of composting. Utilization of black soldier fly (BSF) larvae can be one of the rapid methods for treatment of biodegradable wastes. A detailed review of the literature indicated that more importance is to be given on the pre-processing of Municipal Solid Waste (MSW) which includes segregation of biodegradables, inerts, metals for preparing the requisite substrate for application of the suitable technology. In developing countries, major emphasis should be given on curtailing the environmental and health impacts caused due to improper management of MSW and for developing some innovative as well as economically feasible systems for proper handling of MSW. BSF can transform the biodegradable wastes into biofuels and byproducts at a minimal cost. The utilization of BSF for treating various organic waste (OW) has been thoroughly studied and discussed in detail. The salient observations on the factors affecting the growth of BSF larvae as well as comprehensive analysis of patents on breeding and utilization of BSF are also presented in this paper. The present review also assesses the potential of various rapid composting techniques and advocates about the planning and development of real-scale treatment systems by the researchers, environmental planners and policy makers to eradicate the problem of solid wastes. Graphical abstract Image 1 Highlights • Critically reviewed various types of composting system. • Identified gaps in conventional composting practices. • Growth and survival of Black Soldier Fly (BSF) critically reviewed. • Utilization of BSF proved to be beneficial for rapid composting of organic waste. • Exploitation of BSF have huge potential for further research and improvement. [ABSTRACT FROM AUTHOR]

As global temperatures rise, thermal limits play an increasingly important role in determining the persistence and spread of invasive species. Gypsy moth (Lymantria dispar L. Lepidoptera: Erebidae) in North America provides an ideal system for studying the effect of high temperatures on invasive species performance. Here, we used fluctuating temperature regimes and exposed gypsy moth at specific points in development (first–fourth instar, pupa) to cycles of favorable (22–28°C) or high-temperature treatments (30–36°C, 32–38°C, 34–40°C) for either 2 or 7 d. We measured survival, growth, and prolonged effects of exposure on development time and pupal mass. Survival generally decreased as the experimental temperature treatment and duration of exposure increased for all instars and pupae, with a narrow threshold for lethal effects. In response to increasing temperature and magnified by longer exposure times, growth abruptly declined for third instars and development time increased for pupae. For those surviving the 2-d exposure treatment, development time to pupation increased for all instars, but we did not find consistent effects on final pupal mass. These negative effects of high temperature provide important data on the susceptibility of gypsy moth to heat at different points in development. This work improves our understanding of thermal limits to growth and development in gypsy moth and can aid in determining invasion potential under current and future climates. [ABSTRACT FROM AUTHOR]

Abstract The objectives of this study were to compare the biological responses in developing zebrafish to two organophosphate insecticides, chlorpyrifos (CPF) and diazinon (DZN). Zebrafish embryos were exposed to either solvent control (0.1% DMSO, v/v), or one dose of 0.1, 1.0, 10.0 and 25.0 μM CPF, as well as one dose of 0.1, 1.0, 10.0 and 100.0 μM DZN for 96 h. CPF at 10.0 and 25.0 μM caused 70–80% and 100% mortality in embryos after 96 h exposure, whereas embryos treated with 10.0 and 100.0 μM DZN showed 30–40% and 70–80% lethality. CPF at 10.0 μM significantly decreased cumulative hatching rate, whereas hatching rate was significantly reduced in embryos treated with 100.0 μM DZN. Spinal lordosis was primarily observed in larvae exposed to 1.0 and 10.0 μM CPF, whereas pericardial edema was mainly detected with 10.0 and 100.0 μM DZN exposure. Embryo exposed to 1.0, 10.0 and 25.0 μM CPF exhibited no mitochondrial dysfunction; exposure to 100.0 μM DZN significantly inhibited mitochondrial bioenergetics. To determine if CPF and DZN affected larval activity, dark photokinesis response was assessed in larvae following 7 days exposure to 0.1 and 1.0 μM CPF, as well as to 0.1 1.0, and 10.0 μM DZN. Larvae exposed to 1.0 μM CPF showed hypoactivity, whereas the activity in the dark was not overtly changed in larvae exposed to DZN. In summary, CPF showed higher developmental toxicity compared to DZN. Moreover, based on the types of morphological deformities noted, as well as differences in locomotor activity, we conclude that OPs have unique chemical-specific modes of action that can result in varied biological responses during early development. Graphical abstract Unlabelled Image Highlights • Neurotoxic effects of chlorpyrifos and diazinon in zebrafish embryos were studied. • Chlorpyrifos at ≥1.0 μM exhibited a dose-dependent fashion in spinal lordosis. • Exposure to ≥10.0 μM diazinon showed a dose-dependent manner in pericardial edema. • Exposure to 100.0 μM diazinon impaired mitochondrial bioenergetics of embryos. • Larvae exposed to 1.0 μM chlorpyrifos displayed hypoactivity after 7 days exposure. [ABSTRACT FROM AUTHOR]

Exogenous stimuli modify larval behaviors and mediate an individual's vertical position in the water column. Larvae (stages-1, -3 and -5) of the commercially important Florida stone crab, Menippe mercenaria, were used to determine if (i) individuals elicited a response to gravity (geotaxis), hydrostatic pressure and light, (ii) those responses underlie depth regulation and (iii) those responses change during larval development. All larval stages were negatively buoyant. Stages-1 and -3 larvae elicited a negative geotaxis that promoted upward swimming, while stage-5 larvae elicited behaviors that would position individuals at depth. During relative increases in pressure all larval stages tested swam up, while pressure decreases resulted in downward movement. Light intensities that mimicked an angular light distribution resulted in a negative phototaxis among all stages with stages-1 and -3 larvae being more sensitive than stage-5 larvae. These results indicate that the responses to exogenous stimuli in stone crab larvae function as a negative feedback mechanism for depth maintenance and change throughout ontogeny. The responses observed in stages-1 and -3 larvae suggest an overall shallower distribution while the shift in the sensitivity and orientation in stage-5 larvae likely positions individuals deeper in the water column, where sublittoral flow will facilitate transport toward settlement habitats. [ABSTRACT FROM AUTHOR]

Propolyssenia gen. nov. with Propolyssenia wohltmanni sp. nov., based on larva, and Eothrombium fortesambiense sp. nov. based on active postlarval form, are described from Baltic amber. The new genus shares some characters with the extant Polydiscia and Lassenia. The new species are among the three fossil amber representatives of Tanaupodidae known to date. The present-day fauna of Tanaupodidae is revisited. [ABSTRACT FROM AUTHOR]

Pesticides, in particular insecticides, can be very beneficial but have also been found to have harmful side effects on non-target insects. Butterflies play an important role in ecosystems, are well monitored and are recognised as good indicators of environmental health. The amount of information already known about butterfly ecology and the increased availability of genomes make them a very valuable model for the study of non-target effects of pesticide usage. The effects of pesticides are not simply linear, but complex through their interactions with a large variety of biotic and abiotic factors. Furthermore, these effects manifest themselves at a variety of levels, from the molecular to metapopulation level. Research should therefore aim to dissect these complex effects at a number of levels, but as we discuss in this review, this is seldom if ever done in butterflies. We suggest that in order dissect the complex effects of pesticides on butterflies we need to integrate detailed molecular studies, including characterising sequence variability of relevant target genes, with more classical evolutionary ecology; from direct toxicity tests on individual larvae in the laboratory to field studies that consider the potentiation of pesticides by ecologically relevant environmental biotic and abiotic stressors. Such integration would better inform population-level responses across broad geographical scales and provide more in-depth information about the non-target impacts of pesticides. [ABSTRACT FROM AUTHOR]

The hydrocarbon phenanthrene is an organic compound commonly found in the environment. In aquatic ecosystems, it is highly toxic to organisms, although little is known about its effects on sediment-dwelling organisms. The purpose of this study was to evaluate phenanthrene effects on biochemical, histological, and ontogenetic levels in larvae of the sediment-dwelling invertebrate Chironomus sancticaroli at acute and chronic exposure. Lethal concentrations were estimated and toxicity (acute-96 h and chronic- 8 d) tests were performed at phenanthrene concentrations from 0.12 to 1.2 mg L −1 . At acute and chronic exposure, we evaluated acetylcholinesterase (AChE), alpha esterase (EST-α), and beta esterase (EST-β) activities as well as histological alterations. In the assays with chronic exposure, effects on larval development were estimated using antennae length (instar estimative) and body length (growth estimative). The EST-α showed a significantly increased activity after 48 h at acute exposure to high concentrations of phenanthrene, while EST-β activity was increased after 48 and 72 h at acute exposure at higher concentrations and at 0.12 mg L −1 at chronic exposure. At acute exposure, the midgut showed alterations such as brush border disruption, gastric caeca regression, and lumen area reduction; the fat body showed nuclear alteration in the trophocytes, while the Malpighian tubules showed brush border reduction and the salivary glands were subject to cytoplasm vacuolation. At chronic exposure, the same alterations were observed, in addition to vacuolar coalescence in the trophocytes of the fat body. Regarding larval development, a reduction of body length was observed with increasing phenanthrene concentrations. Similarly, molting was delayed; in the control group, all larvae were in the fourth instar, while at higher phenanthrene concentrations, larvae were predominantly in the third instar. Phenanthrene had toxic effects on this chironomid, indicating risks for natural populations. [ABSTRACT FROM AUTHOR]

Abstract Larvae of water scavenger beetles are found in all types of aquatic and semi-aquatic environments and play an important role in the structure of these communities. Despite their diversity, morphological characters that allow the identification of larvae at species level are usually inconspicuous. In this paper we analyze the head capsule and mouthparts chaetotaxy of hydrophilid larvae belonging to the tribe Berosini, with the purpose of identifying variations on the external sensory organs that may be used for species delimitations. We focus on two species of Berosus Leach (Berosus festivus Berg, 1885 and Berosus patruelis Berg, 1885) and compare larval structures within Berosus and among other genera of Berosini. We include morphometric characters together with detailed illustrations of all characters, SEM images of selected structures and micrographs of a sensory organ present on the inner margin of the first antennomere which is a novelty within larval Coleoptera. Our analysis shows that the number, shape, relative position and organization of sensilla, especially those of labroclypeus and mouthparts, provide diagnostic characters for the separation of Berosus species. Also, we found a new set of characters derived from chaetotaxy that supports current phylogenetic relationships within the tribe Berosini. Most of these chaetic characters are associated with structures that have undergone strong modifications as adaptation to a benthic lifestyle in the clade Berosus + Hemiosus. [ABSTRACT FROM AUTHOR]

Abstract The available data on the biology of the water scavenger beetle genus Protosternum Sharp, 1890 (Hydrophilidae: Sphaeridiinae: Protosternini) are summarized, indicating an obligate association of Protosternum beetles with banana plants (Musaceae): they inhabit decaying tissues of old banana stems in which adult feeding, larval development and pupation takes place. Second and third instar larvae and pupa of the Taiwanese-endemic P. abnormale (Orchymont, 1913) are described in detail, based on field-collected specimens associated with co-occurring adults by cox1 DNA barcodes. Larvae are unique in the Hydrophiloidea by having strongly asymmetrical mouthparts with a large basal bifid tooth on the right mandible, indicating a specialized prey preference. Putative larval synapomorphies of the Protosternini are revealed, based on the comparison of the Protosternum larva with that of Sphaerocetum. Taxonomic status of P. abnormale is revealed to be confused by previous authors due to the absence of male specimens and is clarified here. Two new species are described based on specimens previously misidentified as P. abnormale : P. malayanum sp. nov. from Sumatra and Peninsular Malaysia, and P. hainanense sp. nov. from Hainan. [ABSTRACT FROM AUTHOR]

The article discusses the project to assess the natural removal rate of honeybee colonies with regard to the brood development observed byphoto assessments and laboratory larval tests conducted in 2014-2015. It discusses the assessment of side effects of plant protection products on honeybees in the official risk assessment procedure experimental data will always be apparently evaluated alongside untreated control data.

Immature stages of insects are generally susceptive to their natural enemies, but many species developed defensive and evasive mechanisms to circumvent predation. Gregarious larvae of the noctuid moth Dyops cf. cuprescens feed on leaves of young Cecropia pachystachya shrubs colonized by Azteca ants. Ants avoid contact with larval clusters, retreating to the nest when larvae are moving near the stems. Provoked encounters revealed that Dyops caterpillars present several specialized behaviors to avoid and overcome ant attacks, such as fleeing to under leaf, jumping off the leaf, curling and wriggling vigorously the anterior portion of the body, spitting droplets of oral fluids, or killing ants by pouncing them. These mechanisms allow the caterpillars to overcome ant attacks and consume leaves of ant-colonized plants. By feeding on a heavily protected plant, larvae can enjoy not only a competitor-free plant, but possibly also the enemy-free space created by the aggressive ants.