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Several studies have shown that group feeding by immature insects enhances larval performance through feeding facilitation. However, the benefits of this behavior have not been studied for species that hatch off from their host plant. For these taxa, group feeding may enhance recruitment of newly emerging larvae and may improve larval performance through feeding facilitation. I conducted laboratory experiments with the European chrysomelid Chrysolina aurichalcea asclepiadis (Villa) (Coleoptera: Chrysomelidae: Chrysomelinae), whose larvae hatch on the ground near their host plant [ Vincetoxicum (Apocynaceae)] and feed in groups during early instars, to determine whether cues associated with larval feeding enhance neonate establishment and determine whether feeding in groups improves larval performance. Neonates located shoots infested with larvae more often than when confined to shoots with leaves that were undamaged or mechanically damaged. When provided a choice, neonates preferred shoots infested with 10 larvae to non-infested shoots and shoots with one or five larvae. In the larval performance test, group feeding did not improve survival, but larvae completed larval development about 2 days faster when larvae were raised in groups of 10 compared to isolated larvae. However, larval group size negatively affected the size of emerging adults. The results of this study indicate that the main benefit of group feeding is to young C. a. asclepiadis larvae and this benefit diminishes over development due to competition of mature larvae. [ABSTRACT FROM AUTHOR]

Background: The ability to withstand thermal stress is considered to be of crucial importance for individual fitness and species' survival. Thus, organisms need to employ effective mechanisms to ensure survival under stressful thermal conditions, among which phenotypic plasticity is considered a particularly quick and effective one. Methodology/Principal Findings: In a series of experiments we here investigate phenotypic adjustment in temperature stress resistance following environmental manipulations in the butterfly Bicyclus anynana. Cooler compared to warmer acclimation temperatures generally increased cold but decreased heat stress resistance and vice versa. In contrast, shorttime hardening responses revealed more complex patterns, with, e.g., cold stress resistance being highest at intermediate hardening temperatures. Adult food stress had a negative effect on heat but not on cold stress resistance. Additionally, larval feeding treatment showed interactive effects with adult feeding for heat but not for cold stress resistance, indicating that nitrogenous larval resources may set an upper limit to performance under heat stress. In contrast to expectations, cold resistance slightly increased during the first eight days of adult life. Light cycle had marginal effects on temperature stress resistance only, with cold resistance tending to be higher during daytime and thus active periods. Conclusions/Significance: Our results highlight that temperature-induced plasticity provides an effective tool to quickly and strongly modulate temperature stress resistance, and that such responses are readily reversible. However, resistance traits are not only affected by ambient temperature, but also by, e.g., food availability and age, making their measurement challenging. The latter effects are largely underexplored and deserve more future attention. Owing to their magnitude, plastic responses in thermal tolerance should be incorporated into models trying to forecast effects of global change on extant biodiversity. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effects of host plants such as tobacco, cowpea, Chinese cabbage, and sweet potato on Spodoptera litura's larvae susceptibility on five insecticides including chlorfenapyr, phoxim, and fenvalerate. It says that the susceptibility of the larvae on host plants to insecticides was determined under laboratory condition. Results show that larvae raised on sweet potato has demonstrated to be the most susceptible to all insecticides.

The article studies the larval settlement behavior in six species of gregarious ascidians in relation to adult distribution. The results indicate differences in habitat orientation of the species. The effects of light and orientation on larval settlement behavior is examined. An observation on the effect of tunic extracts on the geotactic behavior of the species is presented. The adult orientation pattern that emerged from comparing aggregation level and the overall abundance of each species is discussed.

The article discusses a study which investigated the combined effects of predicted ocean acidification and global warming on the larvae of the cold-eurythermal spider crab Hyas araneus in a southernmost around Helgoland and a northernmost at Svalbard. The study examined larval development time, growth and carbon/nitrogen ratio in the larval stages Zoea I, II and Megalopa. The study observed permanent differences in instar duration between both populations in all stages. Also noted is the role of enhanced carbon dioxide levels in the duration of larval development and growth.

This experiment has been conducted to evaluate the viability of Angiostrongylus vasorum L1 under different conditions of temperature and humidity. In order to assess the viability, fox faecal pellets containing first stage larvae (L1) were exposed to relative humidity (RH) 95% and 75%, and to different temperatures (5°C, 18°C) and at fluctuating conditions ranging from −5°C to +5°C. Moreover, larval viability under outdoor conditions in April was also observed. Survival of the larvae was strongly influenced by temperature; however, humidity did not show any significant influence on viability. In controlled condition, 100% of the larvae were found motile and active; whereas, around 14% and 19% of the larvae kept at 5°C remained viable at RH 95% and RH 75%, respectively after 78 h. All of the larvae kept at 18°C died after 66 h. In outdoor condition, larval survivability reduced to 18% after 66 h, and in fluctuation temperature viable larvae were observed in both control and experimental conditions (15%) after 78 h. [ABSTRACT FROM AUTHOR]

Abstract: The aquaculture of bivalve molluscs has attained a considerable level of production but it is not enough to cover the demand of worldwide consumers. In the development of this sector, hatcheries play an important role, as suppliers of competent spat of different bivalves, including species with an aquaculture based on natural extraction present. Besides, these installations may help in the recovery of exhausted natural beds and in the obtaining of populations under genetic selection. Unfortunately, the disease outbreaks caused by bacterial pathogens are frequent, with the loss of complete batches, compromising the regular production and the economic viability of the industry. There are many descriptive studies about these outbreaks, but only a few focused on the control of microbiota. The particularities of bivalve aquaculture in hatchery must be taken into account to design methods of control. A common environment is shared by larvae and bacteria, including both beneficial and potentially pathogenic. The filter-feeding behaviour of larvae increases the strong influence of these populations. The classical treatments are directed toward to the complete elimination of bacteria from culture seawater. That objective is unfeasible, because the cultures are not axenic, and undesirable, since some bacteria enhance larval development. Taking into account these considerations, the most promising alternative is the use of probiotic bacteria. In this review we summarize the scientific literature about this subject, considering the particularities of bivalve larval cultures and the need to adapt the concept of probiotic and the strategies to use in marine bivalve hatcheries. [ABSTRACT FROM AUTHOR]

The present study evaluates whether larval density and aquatic exposure to the insecticide carbaryl influenced susceptibility to terrestrial exposure of carbaryl through effects on juvenile feeding ability, growth, and survival with metamorphs of American toads (Bufo americanus). Tadpoles were reared in outdoor mesocosms, and individuals were brought into the lab at metamorphosis for terrestrial exposure studies. The present study indicated that feeding and survival of toads after metamorphosis was not affected by earlier aquatic or subsequent terrestrial exposure; therefore, the impacts of short-lived insecticides may be most significant to aquatic, larval stages. Environ. Toxicol. Chem. 2010;29:2323-2327. © 2010 SETAC [ABSTRACT FROM AUTHOR]

Methods Mosquito aquatic stages were collected in domestic and peri-domestic areas, and epidemic risk indexes (Breteau, Container) were calculated for each prospected location. Adult female mosquitoes were captured by human landing catches, while larvae were sampled by inspecting artificial and natural breeding sites in randomly selected premises. Results Seventy-eight adults Aedes albopictus were collected in Bangui and Bayanga. Mosquito biting rate and abundance were, respectively, 0.33–1.70 bites/human/hour and 14.6% in Bangui and 0.04–0.16 and 0.4% in Bayanga. Larval sampling revealed a large diversity of water container harbouring the species in Bangui, Bayanga, Nola and Salo including unused containers, old tires, vehicle carcasses, buckets, barrels and stem of bamboo. The epidemic risk indices were erratic according to the location, ranging between 1.5–27.6 for Breteau and 1.3–47.1 for Container. Conclusion This is the first record of Ae. albopictus in two bioclimatic zones of CAR This observation emphasizes the need to further investigate its potential impact on dengue and chikungunya viruses transmission regarding their recent emergences in Africa (Côte d’Ivoire, Senegal, Mali, Somalia, Gabon, Cape Verde Islands). [ABSTRACT FROM AUTHOR]

The behavior of the ubiquitous estuarine planktotrophic spionid polychaete larvae Polydora ciliata was studied. We describe ontogenetic changes in morphology, swimming speed and feeding rates and have developed a simple swimming model using low Reynolds number hydrodynamics. In the model we assumed that the ciliary swimming apparatus is primarily composed of the prototroch and secondarily by the telotroch. The model predicted swimming speeds and feeding rates that corresponded well with the measured speeds and rates. Applying empirical data to the model, we were able to explain the profound decrease in specific feeding rates and the observed increase in the difference between upward and downward swimming speeds with larval size. We estimated a critical larval length above which the buoyancy-corrected weight of the larva exceeds the propulsion force generated by the ciliary swimming apparatus and thus forces the larva to the bottom. This modeled critical larval length corresponded to approximately 1 mm, at which, according to the literature, competence for metamorphosis and no more length increase is observed. These findings may have general implications for all planktivorous polychaete larvae that feed without trailing threads. We observed bell shaped particle retention spectra with a minimum prey size of approximately 4μm, equivalent spherical diameter, and we found that an ontogenetic increase in maximum prey size add to a reduction in intra-specific food competition in the various larval stages. In a grazing experiment using natural seawater, ciliates were cleared approximately 50% more efficiently than similar sized dinoflagellates. The prey sizes retainable for P. ciliata larvae covers the microplankton fraction and includes non-motile as well as motile prey items, which is why the larvae are trophically positioned among the copepods and dinoflagellates. Not only do larval morphology and behavior govern larval feeding, prey behavior also influences the feeding efficiency of Polydora ciliata. [ABSTRACT FROM AUTHOR]

Abstract: Research to quantify the potency of larval excretion/secretion from Lucilia sericata using liquid culture assays has produced contradictory results. In this study, viable counting was used to investigate the effectiveness of excretion/secretion against three marker bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli) and the effects of varying growing conditions in assays. Results demonstrate that factors such as number of larvae, species of bacteria and addition of nutrient influence its antibacterial potency. Therefore a standardised method should be employed for liquid culture assays when investigating the antibacterial activity of larval excretion/secretion from L. sericata. [ABSTRACT FROM AUTHOR]

The fourth instar larva and pupa of Forcipomyia (Phytohelea) bromelicola (Lutz) are redescribed and illustrated, and compared with immatures of F. (P.) musae Clastrier and Delecolle and F. (P.) dominicana de Meillon and Wirth. Both life stages were photographed using scanning electron microscopy and phase-contrast light microscopy. The immatures were collected from bromeliads in Florida, USA. [ABSTRACT FROM AUTHOR]

Abstract: Sublethal effects of toxicants can upset normal behavioural responses to predators, leading to increased predation. For example, sensory capabilities can be impaired by toxicants, leading to difficulty in detecting predators or other threats. Alteration of locomotor abilities by pollutants can also explain the difficulty of tadpoles to escape from predators. Here we assess the effects of a nitrogenous fertilizer on the response to predators shown by anuran tadpoles. In a first experiment, we chronically exposed Iberian painted frog (Discoglossus galganoi) and spadefoot toad (Pelobates cultripes) tadpoles to environmentally relevant concentrations of ammonium nitrate. After the exposure, we tested tadpoles’ ability to avoid predation by the red crayfish (Procambarus clarkii). In a second experiment, we analysed the escape behaviour of P. cultripes tadpoles as a function of ammonium nitrate exposure and presence of predatory crayfishes. Tadpoles of both species that were exposed to ammonium nitrate were consumed by crayfishes faster than controls (mean time of predation: Dg controls=18.03h, 90.3mgN-NO3NH4/L=7.48h; Pc controls=16.12h, 90.3mgN-NO3NH4/L=9.46h). Control larval P. cultripes showed specific anti-predator escape responses, whereas those exposed to the fertilizer did not. We demonstrate, for the first time in amphibians, how nitrogenous fertilizers can affect larval defensive behaviours, and thereby increase the risk of predation. Our results emphasize the importance of considering environmental stresses on the ecotoxicological studies with amphibians. [Copyright &y& Elsevier]

Summary: Genetic programs, environmental factors, and electrical activity interact to drive the maturation of the brain. Although the cascade of transcription factors that leads to specification of the serotonergic phenotype has been well characterized, its interactions with electrical activity are not known. Here we show that spontaneous calcium spike activity in the hindbrain of developing Xenopus laevis larvae modulates the specification of serotonergic neurons via regulation of expression of the Lmx1b transcription factor. Activity acts downstream of Nkx2.2 but upstream of Lmx1b, leading to regulation of the serotonergic phenotype. Using global manipulation of activity and targeted alteration of Lmx1b expression, we also demonstrate that changes in the number of serotonergic neurons change larval swimming behavior. The results link activity-dependent regulation of a transcription factor to transmitter specification and altered behavior. [ABSTRACT FROM AUTHOR]

The article presents a study that examines the effects of biofilm and conspecific settlers, separately and in combination, on subsequent primary and secondary settlement of co-existing Perna Perna and Mytilus Galloprovincials in South Africa. It states that the study was conducted at two coastal sites in South Africa, wherein spatial replication of the experiments were conducted. Several experimental treatments were conducted including biofilm, settler, and one control treatment for the course of 5 preparatory days to examine the indigenous settlers' behavioural responses. Results show that both biofilm and conspecific presence have positive effects on settlements and that it provides new understanding for small-scale settlement patterns and influence large-scale ecological processes.

Abstract: We investigated planktonic larval transport processes along an axially symmetric mid-ocean ridge with characteristics similar to that of the East Pacific Rise (EPR) segment at 9–10°N. The hydrodynamic basis for this study is a primitive equation model implemented in two dimensions (depth and across-ridge), forced at the open boundaries to provide suitably realistic simulation of currents observed on the EPR ridge crest from May to November 1999. Three-dimensional trajectories of numerical larvae are computed assuming homogeneity in currents in the along-ridge direction. Larval dispersal fluctuates significantly in time. Transport distance decreases systematically with height above the bottom where numerical larvae are less subject to strong currents along the flanks of the ridge. The probability that the simulated larvae will be located near the ridge crest at settlement depends strongly on their behavioral characteristics (vertical position in the water column during the larval stage) and the length of their precompetency period. [Copyright &y& Elsevier]

The rising prevalence of complex disease suggests that alterations to the human environment are increasing the proportion of individuals who exceed a threshold of liability. This might be due either to a global shift in the population mean of underlying contributing traits, or to increased variance of such underlying endophenotypes (such as body weight). To contrast these quantitative genetic mechanisms with respect to weight gain, we have quantified the effect of dietary perturbation on metabolic traits in 146 inbred lines of Drosophila melanogaster and show that genotype-by-diet interactions are pervasive. For several metabolic traits, genotype-by-diet interactions account for far more variance (between 12 and 17%) than diet alone (1-2%), and in some cases have as large an effect as genetics alone (11-23%). Substantial dew point effects were also observed. Larval foraging behavior was found to be a quantitative trait exhibiting significant genetic variation for path length (P = 0.0004). Metabolic and fitness traits exhibited a complex correlation structure, and there was evidence of selection minimizing weight under laboratory conditions. In addition, a high fat diet significantly increases population variance in metabolic phenotypes, suggesting decreased robustness in the face of dietary perturbation. Changes in metabolic trait mean and variance in response to diet indicates that shifts in both population mean and variance in underlying traits could contribute to increases in complex disease. [ABSTRACT FROM AUTHOR]

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This study investigated the effect of different light intensities on first feeding of chub mackerel Scomber japonicus larvae. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (60 larvae/l) into twelve 30-l aquaria under light intensities of 0, 100, 200, 500 and 1000 lx, with three replicate aquaria per treatment. Temperature was maintained at 20°C and salinity was 35 psu. Larvae were fed the rotifer Brachionus rotundiformis at a density of five rotifers/ml. Feeding incidence was measured as the percentage of larvae with prey in the digestive tract. Feeding intensity was evaluated as the number of prey in the digestive tract of the larvae. Larvae fed in darkness (0 lx) had significantly lower (P<0.05) feeding incidence (13±0.05% larvae with prey) and feeding intensity (1.00±0.05 rotifers per larva) than those larvae fed at 100 (30±0.07%, 1.17±0.09 rotifers per larva), 200 (43±0.08%, 1.24±0.11 rotifers larvae-1), 500 (53±0.08%, 1.48±0.14 rotifers per larva) and 1000 lx (60±0.08%, 1.38±0.13 rotifers per larva). The feeding incidence of S. japonicus larvae increased with light intensity while feeding intensity showed no significant difference (P>0.05) between light treatments. [ABSTRACT FROM AUTHOR]

The introduced spider crab Pyromaia tuberculata was collected from Korea in 2005 and it was ovigerous. After hatching, larvae were reared in the laboratory at 20°C. The larval stage of the species consists of two zoeal and one megalopal stages. The larvae of the Korean species differ somewhat from those from New Zealand described by Webber and Wear (1981; N Z J Mar Freshwat Res. 15:331-383) and from Brazil described by Fransozo and Negreiros-Fransozo (1997; Crustaceana. 70:304-323.) in the setal presence of the antennule, the maxillule, the maxilla and the maxillipeds, and the abdomen. It is found that Fransozo and Negreiros-Fransozo have overlooked some setae on the basis of the zoeal maxillipeds and that re-examination of their larvae is needed. Also, it is found that the Inachoididae is heterogeneous based on the zoeal morphology because two distinct groups exist in the family. [ABSTRACT FROM AUTHOR]

Background: The potential to adapt to a changing climate depends in part upon the standing genetic variation present in wild populations. In corals, the dispersive larval phase is particularly vulnerable to the effects of environmental stress. Larval survival and response to stress during dispersal and settlement will play a key role in the persistence of coral populations. Methodology/Principal Findings: To test the hypothesis that larval transcription profiles reflect location-specific responses to thermal stress, symbiont-free gametes from three to four colonies of the scleractinian coral Montastraea faveolata were collected from Florida and Mexico, fertilized, and raised under mean and elevated (up 1 to 2°C above summer mean) temperatures. These locations have been shown to exchange larvae frequently enough to prevent significant differentiation of neutral loci. Differences among 1,310 unigenes were simultaneously characterized using custom cDNA microarrays, allowing investigation of gene expression patterns among larvae generated from wild populations under stress. Results show both conserved and location-specific variation in key processes including apoptosis, cell structuring, adhesion and development, energy and protein metabolism, and response to stress, in embryos of a reef-building coral. Conclusions/Significance: These results provide first insights into location-specific variation in gene expression in the face of gene flow, and support the hypothesis that coral host genomes may house adaptive potential needed to deal with changing environmental conditions. [ABSTRACT FROM AUTHOR]

Free-swimming larvae of tropical corals go through a critical life-phase when they return from the open ocean to select a suitable settlement substrate. During the planktonic phase of their life cycle, the behaviours of small coral larvae (,1 mm) that influence settlement success are difficult to observe in situ and are therefore largely unknown. Here, we show that coral larvae respond to acoustic cues that may facilitate detection of habitat from large distances and from upcurrent of preferred settlement locations. Using in situ choice chambers, we found that settling coral larvae were attracted to reef sounds, produced mainly by fish and crustaceans, which we broadcast underwater using loudspeakers. Our discovery that coral larvae can detect and respond to sound is the first description of an auditory response in the invertebrate phylum Cnidaria, which includes jellyfish, anemones, and hydroids as well as corals. If, like settlement-stage reef fish and crustaceans, coral larvae use reef noise as a cue for orientation, the alleviation of noise pollution in the marine environment may gain further urgency. [ABSTRACT FROM AUTHOR]

The growth and survival of larvae can be significantly enhanced through close association with patches of high prey concentration. However, the taxis and kinesis responses used by larvae to locate and maintain residence in micro-patches remains poorly understood. In this study, the behavioral responses of Pacific cod ( Gadus macrocephalus) and walleye pollock ( Theragra chalcogramma) larvae (45–100 dph) to light, prey scent, and prey were examined. Both species displayed an ontogenetic shift in response to a horizontal light gradient, with small larvae (11–13 mm SL) exhibiting a positive phototaxis and large larvae (23–32 mm SL) exhibiting a negative phototaxis. Whether this reversal is related to ontogenetically appropriate foraging cues or some other aspect of the environment remains to be determined. Neither species displayed significant behavioral responsiveness to the introduction of olfactory prey cues at either size. The aggregating (taxis) response of large larvae to introduction of live prey was stronger than that of small larvae, possibly due to increased reaction distances and encounter rates. In addition, both species exhibited a kinesis response of reducing the frequency of swimming bouts in response to introduction of live prey. These results suggest that the scale of prey patchiness and the physical factors that determine patch encounter rates are a significant determinant of larval growth and survival in the early feeding stages of marine fishes. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the larval behavior that regulates nearshore retention and offshore migration in productive upwelling regions. It found that larvae of nine more taxa were prevalent as early stage larvae and later stages were uncommon, which indicated that larvae migrated offshore. It determined that larvae of taxa that occurred nearshore in high concentrations resided below a shallow Ekman layer of seaward-flowing surface waters, while most larvae of the other taxa occurred closer to the surface. It concluded that larvae retention may be more widespread in upwelling regions.

Darkness serves as a stimulus for vertebrate photoreceptors; they are actively depolarized in the dark and hyperpolarize in the light. Here, we show that larval zebrafish essentially turn off their visual system at night when they are not active. Electroretinograms recorded from larval zebrafish show large differences between day and night; the responses are normal in amplitude throughout the day but are almost absent after several hours of darkness at night. Behavioral testing also shows that larval zebrafish become unresponsive to visual stimuli at night. This phenomenon is largely circadian driven as fish show similar dramatic changes in visual responsiveness when maintained in continuous darkness, although light exposure at night partially restores the responses. Visual responsiveness is decreased at night by at least two mechanisms: photoreceptor outer segment activity decreases and synaptic ribbons in cone pedicles disassemble. [ABSTRACT FROM AUTHOR]

Predation among aquatic invertebrate predators can have important effects on patterns of exclusion and coexistence in aquatic habitats, especially if these predators also act as intraguild predators. Such patterns may be explained by variation in predator foraging mode and in the extent and overlap of habitat use. Predaceous diving beetles (Coleoptera: Dytiscidae) are abundant in isolated bodies of water and are effective predators on many aquatic organisms, including other dytiscids. The under-investigated role of hunting behavior and habitat use in altering outcomes of predation under different plant densities may offer insights into patterns of coexistence among larval dytiscids. I performed experiments that quantified behavior of larvae of three common genera of dytiscids that share common prey and then measured predation among genera in the presence or absence of aquatic plants. Behavioral analyses concluded that there were significant differences in foraging modes, with Dytiscus primarily exhibiting sit-and-wait tactics, Graphoderus engaging in active, open water searching, and Rhantus displaying combinations of these behaviors. Predation among larvae was common and occurred when predators were larger than the prey, with no indication of prey preference. Incidence of predation among generic combinations depended on the presence of plants and appeared to be related to behavioral differences among genera. The presence or absence of plants and differences in larval behavior may help to mitigate predation by reducing negative interactions in natural aquatic systems. These results have implications for IGP interactions and may be one of the explanations for the observed richness of this group of predators within aquatic habitats. [ABSTRACT FROM AUTHOR]

Dual-choice behavioral assays and electrophysiological tip-recording technique were used to investigate the taste adaptation of different diet-experienced fifth instar larvae of Helicoverpa armigera to azadirachtin. The behavior test showed that the larvae reared with normal artificial diets were highly deterred by azadirachtin. However, the larvae reared with the artificial diets containing low concentration of azadirachtin showed insensitivity to azadirachtin. The electrophysiological tests showed that there was a changed responsiveness in the deterrent neuron responding to azadirachtin in the lateral sensilla styloconica of different diet-experienced larvae. It indicated that there was a taste adaptation to azadirachtin in different diet-experienced larvae of H. armigera and this taste adaptation was correlated with desensitization of related taste neurons. [ABSTRACT FROM AUTHOR]

Abstract: The postfeeding larval stage in blow flies is generally an irreversible condition when the fully grown third instar larvae stop feeding and give no response towards food. The larvae of most species then disperse away from their feeding medium and pupariate. There are several cases reported about the use of postfeeding larvae as forensic evidence. It is a matter of common observation that the postfeeding stage can be reached earlier than the expected time if food becomes unavailable. However, no information is available on whether postfeeding stage induced by scarcity of food is also irreversible. Similarly, the minimum period of development required by the larvae of different blow flies species to enable their survival as postfeeding larvae and pupariation in the absence of food is unknown. It was observed during the present studies that the larvae of two Chrysomya species must feed for at least 35h at 28°C in order to be capable of reaching the postfeeding stage and subsequent pupariation. Duration of the starvation period required to induce postfeeding behavior decreases with increasing age of larvae. In the case of Chrysomya megacephala, 35, 45, 55 and 65h old larvae attained irreversible postfeeding stage after 30, 20, 12 and 2h of starvation, respectively. Similarly, larvae of Chrysomya rufifacies that were 35, 45, 55 and 60h old attained irreversible postfeeding stage after 25, 16, 6 and 2h of starvation, respectively. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the relative importance of larval recruitment in a strong and persistent region where there is limitation in recruitment. It mentions that larvae are considered to be highly vulnerable to offshore transport in upwelling regions where there is infrequent wind relaxation and downswelling events. The study was conducted through determining the recruitment process for 5 years at an open embayment. Results of the study are also presented with the recommendation that comprehensive studies on the behavioral and physical processes connected with larval recruitment should be undertaken.

Prey animals often encounter situations that hinder their ability to conduct normal fitness-enhancing behaviors. Mating and foraging are frequently interrupted by predator vigilance and avoidance, and antipredator behavior. Many caddisfly larvae build protective cases that are carried with them throughout the aquatic life cycle. However, they are still vulnerable to predation, yet it is unknown the extent caddisflies use chemical cues for predator recognition and avoidance. We exposed larval caddisfly Hesperophylax occidentalis (Banks, 1908) to predatory, conspecific, and heterospecific chemical cues to determine if caddisfly larvae can use chemical stimuli alone for predator recognition and avoidance. Exposure to predator and injured conspecific chemicals elicited significant decreases in activity, while exposure to injured and uninjured heterospecific chemicals yielded no significant change in activity. The extended latency to move following exposure to predator kairomones indicates larval caddisflies utilize chemical cues for predator recognition and avoidance, and a similar decrease in movement associated with exposure to injured conspecifics suggests the presence of a chemical alarm cue. [ABSTRACT FROM AUTHOR]

The main objective was to develop an artificial diet for two flat-headed borers, Capnodis tenebrionis L. and C. carbonaria Klug. (Coleoptera: Buprestidae), which are severe pests of stonefruit plantations in the Mediterranean basin. The effect of proteins from various sources, percentage of cortex tissue in the diet and diet structure on larval growth and survival were investigated. The most successful diet contained 2.8% casein and 4.6% dry brewer's yeast as the protein source. For complete larval development and successful pupation it is essential to include cortex tissue from the host plant in the diet. Mean larval development time was shortened by 10-12 days when reared on a diet containing 20% cortex tissue compared with rearing on diet containing 10% cortex tissue. Two different diet structures were required, a viscous matrix for the first and second instar larvae and drier crumbly diet, which allows the larvae to move within the diet, for older larvae. At 28°C on the artificial diet C. tenebrionis and C. carbonaria completed their development in 2-2.5 months compared to the 6-11 months recorded in Israeli orchards. C. tenebrionis successfully completed two generations on the artificial diet. [ABSTRACT FROM AUTHOR]

Olive fruit flies [Bactrocera oleae (Gmelin)] occur at densities in California that can result in intraspecific larval competition within infested fruit. Larval B. oleae densities tracked in the field at six location were found to be highly variable and related to the proportion of fruit infested and adult densities. Egg and larval distribution within the field was generally aggregated early in the season and trended toward random and uniform as the season progressed. To determine whether B. oleae experienced fitness consequences at a range of larval densities observed in the field, olive fruits were infested with one, two, four, and six eggs, and larval and pupal developmental time, pupal weight, and pupal yield were compared. At the highest egg density, all measures of performance were negatively impacted, resulting in fewer and lighter pupae that took longer to pupate and emerge as adults, and even when only two larvae was present per olive, resulting pupae were significantly smaller. Density did not impact the sex ratio of the resulting flies or survive to adults. As field surveys showed, larval densities ranged from 1 to 11 B. oleae per fruit at some sites, and our results suggest that, at high densities, B. oleae do experience competition for larval resources. The impact of intraspecific larval competition North American in field populations of B. oleae is unknown, but the potential for competition is present. [ABSTRACT FROM AUTHOR]

The role of behavior, especially vertical migration, is recognized as a critical component of realistic models of larval fish dispersion. Unfortunately, our understanding of these behaviors lags well behind our ability to construct three-dimensional flow-field models. Previous field studies of vertical behavior of larval Pacific cod ( Gadus macrocephalus) were limited to small, preflexion stages (≤11 mm SL) in a narrow range of thermal conditions. To develop a more complete picture of larval behavior, we examined the effects of ontogeny, temperature, and light on vertical responses of larval Pacific cod in experimental columns. While eggs were strictly demersal, yolk-sac larvae displayed a strong surface orientation as early as 1 day post hatch (∼ 5 mm SL). Consistent with field observations, small preflexion larvae (<10 mm SL) showed no response to varying light levels. However, there was a direct effect of temperature on larval behavior: Pacific cod larvae exhibited a stronger surface orientation at 4°C than at 8°C. The behavior of larger, postflexion larvae (>15 mm SL) in experimental columns was consistent with a diel vertical migration and independent of water temperature: fish were more widely distributed in the column, and median positions were consistently deeper at higher light levels. These laboratory observations are combined with observations from discrete-depth (MOCNESS) sampling in the Gulf of Alaska to characterize the vertical distribution of larval Pacific cod and contrast ontogenetic patterns with walleye pollock ( Theragra chalcogramma). The vertical movements of larval Pacific cod described here will be applied in the development of dispersal projections from Gulf of Alaska spawning grounds. [ABSTRACT FROM AUTHOR]

The European green crab (Carcinus maenas) is invasive on the U.S. West Coast. This study uses a high-resolution circulation model to determine the likelihood that green crab larvae spawned in Willapa Bay, Washington could be retained by circulation and behavior long enough to reach maturity and resettle within the bay. A particle-tracking method (the "diffusive Lagrangian return map") is presented that makes it possible to track the dispersion of hundreds of thousands of model larvae-each subject to three-dimensional advection, vertical turbulent diffusion, and imposed vertical migration behavior-over their full 30-50 days development time with modest computational resources. Larvae spawned in summer show significant retention (5-40%) in the southern and western portions of the bay, including the Stackpole shoals near the mouth, the area most likely to be colonized by late-stage megalopae arriving from the coastal ocean. Larvae spawned in spring show much less retention throughout the bay because of (1) increased flushing caused by increased river input relative to summer conditions and (2) longer development times caused by lower water temperatures. The role of larval swimming behavior is secondary to hydrodynamics in setting these spatial and seasonal patterns of retention. [ABSTRACT FROM AUTHOR]

Effects of maize ( Zea mays L.) volatiles induced by larvae of the Asian corn borer, Ostrinia furnacalis (Guenée), on the orientation behaviors of Asian corn borer larvae and oviposition of the females were investigated. Nineteen volatile chemicals, with terpenes being the major components, were identified from maize plants attacked by third instar Asian corn borer larvae. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses revealed some electroantennographic differences between female and male Asian corn borer antennae in response to larvae-induced maize volatiles; female responded to ( E)-2-hexenal, nonanal, ( Z)-3-hexen-1-ol and three unknown compounds while the male only responded to ( E)-2-hexenal, nonanal and one unknown compound. In laboratory orientation bioassays, Asian corn borer neonate larvae were attracted to extracts collected from Asian corn borer-damaged plants as well as to synthetic farnesene, but were repelled by ( Z)-3-hexen-1-ol. In laboratory oviposition bioassays, gravid females laid fewer eggs on plants damaged by larvae than on mechanically damaged plants or undamaged plants. Adult Asian corn borer females deposited fewer eggs on wax paper treated with ( E)-2-hexenal or ( Z)-3-hexen-1-ol than on wax paper treated with hexane (control). The results suggest that Asian corn borer can affect the behaviors of conspecific larvae and adults by changing host plant volatiles. [ABSTRACT FROM AUTHOR]

To determine if larval crabs alter their horizontal swimming behavior in response to biochemical cues in the water, fiddler crab (Uca pugnax) and blue crab (Callinectes sapidus) megalopae were video recorded in a laminar-flow flume while putative cues were introduced and allowed to establish a gradient in the flow field. Changes in horizontal orientation, distribution, and swimming velocity were observed for six different cue treatments. Overall results show that crab megalopae can detect biochemical cues in ambient water and that they adjust their horizontal swimming behavior in response to these cues. The dominant response was a change in swimming velocity in the presence of a cue. While this response may affect the dynamics of larval patches, it is not clear if swimming in the horizontal plane has a substantial effect on the spatial aggregation of the larvae in the field. [ABSTRACT FROM AUTHOR]

Two subspecies of the papilionid butterfly Byasa alcinous, B. a. bradanus and B. a. alcinous, have varying degrees of larval aggregation. Early instar larvae of ssp. bradanus always occur in aggregations. To determine the functions of larval aggregation in this subspecies, we examined the effects of leaf toughness on larval performance when caterpillars were reared alone and in aggregations. Newly hatched larvae were reared either individually or in groups of 10 and were fed either tough or tender leaves of Aristolochia debilis. When fed tough leaves, more gregarious larvae survived the first instar. This difference between solitary and aggregated larvae did not occur when caterpillars were fed soft leaves. The effects of aggregation on larval weight and duration were not significant between leaf-toughness treatments. Larval aggregation of B. a. bradanus improves larval survivorship in early instars that use host plants with tough leaves. [ABSTRACT FROM AUTHOR]

The article focuses on the study of red drum Sciaenops ocellatus larvae's swimming performance and its importance in evaluating the potential of the species to migrate and survive. It also discusses the comparison of the swimming performance between wild-caught and laboratory-reared larvae by measuring their critical swimming speed (Ucrit). The result of the study showed that the Ucrit of such species increases within two phases, wherein there was a rapid improvement in the first phase and a slower improvement in the second phase. The importance of determining the swimming ability of Sciaenops ocellatus larvae is also discussed, including its impact on the capacity to evade predators and control dispersal.

The article analyzes the distribution of larval phenotypic plasticity in sea urchin to provide insights into the phenomenon. It investigates the phenotypic plasticity and growth dynamics to the larvae of two echinoid species with contrasting larval forms. Furthermore, it examines the arm growth of echinopleteus of the sympatric species Heliocidaris tuberculata who develop short postal arms and low postoral arm length and midline body length towards dissenting food regimes. Moreover, it discusses the hypothesis concerning the larvae with long arms and the idea regarding the arm length irrespective of food conditions.

Abstract   Coccinella magnifica Redtenbacher lives only in close contact with species of the Formica rufa group. Laboratory experiments were set up to determine how this species may be adapted to living with ants by comparing its behaviour with that of the closely related Coccinella septempunctata L. Eggs and larvae of C. magnifica placed on the foraging trails of ants were bitten significantly less often by the ants than those of C. septempunctata. However, the ants responded similarly to the adults of both species. For these two species, the presence of ants resulted in a significant decrease in predation efficiency. However, C. magnifica was more efficient at catching aphids in the presence of ants than C. septempunctata. The behaviour of this myrmecophilous species is discussed by taking into account that it is a generalist in terms of prey specificity. [ABSTRACT FROM AUTHOR]

Abstract  We performed a computational analysis employing a cellular automata model to investigate the larval dispersal behavior of blowflies. The spatially discrete model developed here, incorporates simple behavioral rules in local interactions to produce the large-scale patterns observed in the larval dispersal process. We were able to find parameter ranges that could simulate the required experimental dispersal patterns in the study. In particular, oscillations, initially explained as a response to larval aggregation, could be explained by the combination of different mechanisms acting during the dispersal process. Peaks have characterized the interaction between dispersing larvae, but as a function of time. Then, the number of larvae decreased as a result of the pupation process, and neighborhood interaction became stingy. [ABSTRACT FROM AUTHOR]

1. Variables affecting species at the ends of trophic chains may modify the success of members with which they do not directly interact. The majority of such examples involve three trophic levels, but hyperparasitoids provide an excellent opportunity to examine four-level relationships. 2. The gregarious hyperparasitoid Aprostocetus sp. (Hymenoptera: Eulophidae) commonly attacks the primary parasitoid Alabagrus texanus (Hymenoptera: Braconidae), by far the commonest parasitoid of the moth Herpetogramma theseusalis (Lepidoptera: Crambidae). 3. Larvae of this moth feed on ferns of two families, sensitive fern Onoclea sensibilis (Dryopteridaceae) and marsh fern Thelypteris palustris (Thelypteridaceae), in the study area, an old field in Maine, U.S.A. 4. I test the hypotheses that the ferns indirectly affect the reproductive success of the hyperparasitoids and that the ferns produce similar effects at intermediate links. 5. The moths experienced similar success on the two ferns, and the primary parasitoid performed similarly on moths reared from both ferns. The hyperparasitoid parasitized similar proportions of the primary parasitoid from moths that fed on sensitive fern and marsh fern. 6. However, hyperparasitoid broods on primary parasitoids from moths feeding on marsh fern contained approximately one-third more offspring, whose individuals were significantly larger than those from sensitive fern, even though their hosts’ sizes did not differ significantly. 7. An indirect effect, related to the primary producers, thus strongly affected Trophic Level 4 in the absence of a significant effect at intermediate levels. To the best of my knowledge, this relationship has not been previously reported in a multi-year or field-based study of a natural system. [ABSTRACT FROM AUTHOR]

Although it has clearly been demonstrated in previous studies that honeybees inspect their worker brood in a non-random fashion, it is still unclear which signals and cues worker bees use to monitor the nutritional state of their brood. Here we show that worker bees can recognize and quantify the larval food present in a brood cell olfactorily and identify potential mechanical signals produced by the brood. There is no evidence for additional chemical hunger signals produced by the larvae. However, the pattern of movement of larvae within their cells changes with their nutritional state and might provide additional information to nurse bees. [ABSTRACT FROM AUTHOR]

Perfluorooctane sulfonic acid (PFOS) is a persistent and ubiquitous environmental contaminant that has been detected in organisms worldwide. Here, we evaluate whether long-term (1 and 4months) exposure to PFOS contamination affects the behavioural performance of freshwater larvae of the damselfly Enallagma cyathigerum (Insecta: Odonata). Our results show reduced behavioural performance with increasing PFOS concentration. In 1month exposed larvae, no observed effect concentrations (NOECs) were 100μg/L for general activity. In 4months exposed larvae, NOECs were 10μg/L, for each behavioural trait, except swimming acceleration of male larvae where the NOEC was 100μg/L. When faced with PFOS concentrations above the NOEC, E. cyathigerum larvae were less active, less capable to escape a simulated predator attack and less efficient in foraging. Together, our results show that damselfly larvae suffer reduced survival-related behavioural performance. [Copyright &y& Elsevier]

Abstract: The widespread development of anthelmintic resistance and high cost of the conventional anthelmintic drugs, has limited the control of gastrointestinal nematode parasites of sheep and goats and hence led to evaluation of medicinal plants as an alternative source of anthelmintics. In the current study, in vitro ovicidal and larvicidal activity of the leaves and fruits of the aqueous and hydro-alcoholic extracts of Maesa lanceolata and aerial parts of Plectranthus punctatus were evaluated on the egg and larvae of Haemonchus contortus using egg hatch assay and larval development test. All extracts of plants tested have shown complete inhibition of egg hatching at or below 1mg/ml. ED50 for egg hatch inhibition ranged from 0.11 to 0.29mg/ml, for both the aqueous and hydro-alcoholic extracts of Plectranthus punctatus and Maesa lanceolata. All extracts have shown dose dependent inhibition of larval development with variable results. The complete inhibition (100%) at the maximum concentration tested (50mg/ml) was obtained only for hydro-alcoholic extract of the fruits of Maesa lanceolata and the lowest inhibition (50.33%) was recorded for the hydro-alcoholic extract of the leaves of the same plant. The overall findings of the present study has shown that Plectranthus punctatus and Maesa lanceolata contain possible anthelmintic compounds and further evaluation of different extracts and fractions of these plants should be carried out. [Copyright &y& Elsevier]

Factors responsible for ontogenetic habitat shifts were examined using larvae of the Indian red admiral butterfly, Vanessa indica (Herbst) (Lepidoptera: Nymphalidae). The larvae of V. indica fold leaves of China ramie, Boehmeria nipononivea Koidz. (Urticaceae), to form shelters that also serve as food. When constructing shelters, old larvae (usually third instar or older) frequently cut trenches at the bases of the leaves, whereas younger larvae do not. This trenching behaviour reduces the force required to fold large ramie leaves. Young larvae used small apical leaves as shelter sites. Once larvae were capable of cutting trenches, they moved proximally on the host plant and used middle leaves that either had completed or were about to complete expansion. Results of bioassays revealed that, for young larvae, apical and middle leaves did not differ in food quality. In contrast, for older larvae, the quality of middle leaves was higher than that of apical leaves. These observations suggest that young larvae decrease the risk of predation during shelter construction by using apical leaves that are relatively easy to fold, and that old larvae employ trenching to decrease the duration of leaf folding and improve growth rate by using middle leaves that are of high quality. Thus, the facilitation of leaf-folding by trenching is considered to reduce the necessity of using apical leaves, and the acquisition of the trenching ability triggers an ontogenetic shift in the selection of larval shelter sites. [ABSTRACT FROM AUTHOR]

Studies on the avoidance behavior of aquatic organisms to contaminants have confirmed that such behavior can be relevant in field situations. However, almost all toxicity tests involve the forced exposure of organisms to toxicants. In particular, despite the importance of Chironomus riparius Meigen larvae in sediment toxicity testing, only a few studies on avoidance behavior have been performed. This study investigated the ability of different life stages of C. riparius, including ovipositing females, first-, second-, and fourth-instar larvae, to avoid copper-contaminated environments. Ovipositing females were given a choice between a control and copper solution (1.3 mg Cu l- 1). First-instar larvae were provided with a choice between a control and a copper (2.0 mg Cu l- 1)-spiked sediment. Both second- and fourth-instars were exposed to a copper gradient (0.38-3.4 mg Cu l- 1) in a flow-through system. None of the life stages avoided copper, even though the highest concentrations caused lethal effects on midges. The avoidance behavior of C. riparius is not a sensitive endpoint to assess copper sublethal toxicity. [ABSTRACT FROM AUTHOR]

The article focuses on the transplantation of rootworm larvae to potential hosts for the development of western corn rootworm. A rootworm-resistant and a giant foxtail grassy weed species were chosen as hosts for infestation. Inorder to facilitate the larval movement, the Tullgren funnel was used. The two hosts had created an impact on the reproduction of beetles. The larvae that feasted first on a giant foxtail and later switched to the rootworm-resistant host had more survival ratio than those who exclusively reared on the rootworm-resistant transgenic maize.

The simplest animal eyes are eyespots composed of two cells only: a photoreceptor and a shading pigment cell. They resemble Darwin’s ‘proto-eyes’, considered to be the first eyes to appear in animal evolution. Eyespots cannot form images but enable the animal to sense the direction of light. They are characteristic for the zooplankton larvae of marine invertebrates and are thought to mediate larval swimming towards the light. Phototaxis of invertebrate larvae contributes to the vertical migration of marine plankton, which is thought to represent the biggest biomass transport on Earth. Yet, despite its ecological and evolutionary importance, the mechanism by which eyespots regulate phototaxis is poorly understood. Here we show how simple eyespots in marine zooplankton mediate phototactic swimming, using the marine annelid Platynereis dumerilii as a model. We find that the selective illumination of one eyespot changes the beating of adjacent cilia by direct cholinergic innervation resulting in locally reduced water flow. Computer simulations of larval swimming show that these local effects are sufficient to direct the helical swimming trajectories towards the light. The computer model also shows that axial rotation of the larval body is essential for phototaxis and that helical swimming increases the precision of navigation. These results provide, to our knowledge, the first mechanistic understanding of phototaxis in a marine zooplankton larva and show how simple eyespots regulate it. We propose that the underlying direct coupling of light sensing and ciliary locomotor control was a principal feature of the proto-eye and an important landmark in the evolution of animal eyes. [ABSTRACT FROM AUTHOR]