Showing papers on "Larva published in 2017"

Carryover effects of larval exposure to different environmental bacteria drive adult trait variation in a mosquito vector

Abstract: Conditions experienced during larval development of holometabolous insects can affect adult traits, but whether differences in the bacterial communities of larval development sites contribute to variation in the ability of insect vectors to transmit human pathogens is unknown. We addressed this question in the mosquito Aedes aegypti, a major arbovirus vector breeding in both sylvatic and domestic habitats in Sub-Saharan Africa. Targeted metagenomics revealed differing bacterial communities in the water of natural breeding sites in Gabon. Experimental exposure to different native bacterial isolates during larval development resulted in significant differences in pupation rate and adult body size but not life span. Larval exposure to an Enterobacteriaceae isolate resulted in decreased antibacterial activity in adult hemolymph and reduced dengue virus dissemination titer. Together, these data provide the proof of concept that larval exposure to different bacteria can drive variation in adult traits underlying vectorial capacity. Our study establishes a functional link between larval ecology, environmental microbes, and adult phenotypic variation in a holometabolous insect vector.

Anopheles gambiae larvae mount stronger immune responses against bacterial infection than adults: evidence of adaptive decoupling in mosquitoes.

Abstract: The immune system of adult mosquitoes has received significant attention because of the ability of females to vector disease-causing pathogens while ingesting blood meals. However, few studies have focused on the immune system of larvae, which, we hypothesize, is highly robust due to the high density and diversity of microorganisms that larvae encounter in their aquatic environments and the strong selection pressures at work in the larval stage to ensure survival to reproductive maturity. Here, we surveyed a broad range of cellular and humoral immune parameters in larvae of the malaria mosquito, Anopheles gambiae, and compared their potency to that of newly-emerged adults and older adults. We found that larvae kill bacteria in their hemocoel with equal or greater efficiency compared to newly-emerged adults, and that antibacterial ability declines further with adult age, indicative of senescence. This phenotype correlates with more circulating hemocytes and a differing spatial arrangement of sessile hemocytes in larvae relative to adults, as well as with the individual hemocytes of adults carrying a greater phagocytic burden. The hemolymph of larvae also possesses markedly stronger antibacterial lytic and melanization activity than the hemolymph of adults. Finally, infection induces a stronger transcriptional upregulation of immunity genes in larvae than in adults, including differences in the immunity genes that are regulated. These results demonstrate that immunity is strongest in larvae and declines after metamorphosis and with adult age, and suggest that adaptive decoupling, or the independent evolution of larval and adult traits made possible by metamorphosis, has occurred in the mosquito lineage.

Metamorphosis is induced by food absence rather than a critical weight in the solitary bee, Osmia lignaria.

Abstract: Body size is an important phenotypic trait that correlates with performance and fitness. For determinate growing insects, body size variation is determined by growth rate and the mechanisms that stop growth at the end of juvenile growth. Endocrine mechanisms regulate growth cessation, and their relative timing along development shapes phenotypic variation in body size and development time. Larval insects are generally hypothesized to initiate metamorphosis once they attain a critical weight. However, the mechanisms underlying the critical weight have not been resolved even for well-studied insect species. More importantly, critical weights may or may not be generalizable across species. In this study, we characterized the developmental aspects of size regulation in the solitary bee, Osmia lignaria We demonstrate that starvation cues metamorphosis in O. lignaria and that a critical weight does not exist in this species. Larvae initiated pupation <24 h after food was absent. However, even larvae fed ad libitum eventually underwent metamorphosis, suggesting that some secondary mechanism regulates metamorphosis when provisions are not completely consumed. We show that metamorphosis could be induced by precocene treatment in the presence of food, which suggests that this decision is regulated through juvenile hormone signaling. Removing food at different larval masses produced a 10-fold difference in mass between smallest and largest adults. We discuss the implications of body size variation for insect species that are provided with a fixed quantity of provisions, including many bees which have economic value as pollinators.

Exogenous stress hormones alter energetic and nutrient costs of development and metamorphosis.

Abstract: Variation in environmental conditions during larval life stages can shape development during critical windows and have lasting effects on the adult organism. Changes in larval developmental rates in response to environmental conditions, for example, can trade off with growth to determine body size and condition at metamorphosis, which can affect adult survival and fecundity. However, it is unclear how use of energy and nutrients shape trade-offs across life-stage transitions because no studies have quantified these costs of larval development and metamorphosis. We used an experimental approach to manipulate physiological stress in larval amphibians, along with respirometry and 13C-breath testing to quantify the energetic and nutritional costs of development and metamorphosis. Central to larval developmental responses to environmental conditions is the hypothalamic-pituitary-adrenal/interrenal (HPA/I) axis, which regulates development, as well as energy homeostasis and stress responses across many taxa. Given these pleiotropic effects of HPA/I activity, manipulation of the HPA/I axis may provide insight into costs of metamorphosis. We measured the energetic and nutritional costs across the entire larval period and metamorphosis in a larval amphibian exposed to exogenous glucocorticoid (GC) hormones - the primary hormone secreted by the HPA/I axis. We measured metabolic rates and dry mass across larval ontogeny, and quantified lipid stores and nutrient oxidation via 13C-breath testing during metamorphosis, under control and GC-exposed conditions. Changes in dry mass match metamorphic states previously reported in the literature, but dynamics of metabolism were influenced by the transition from aquatic to terrestrial respiration. GC-treated larvae had lower dry mass, decreased fat stores and higher oxygen consumption during stages where controls were conserving energy. GC-treated larvae also oxidized greater amounts of 13C-labelled protein stores. These results provide evidence for a proximate cause of the physiological trade-off between larval growth and development, and provide insight into the energetic and nutrient costs that shape fitness trade-offs across life stages.

Development of Aedes albopictus (Diptera: Culicidae) Larvae Under Different Laboratory Conditions

Abstract: Critical to successful application of the sterile insect technique against Aedes albopictus (Skuse) is the development of an efficient and standardized rearing protocol to be employed in the mass production system. In this study, several life history traits of Ae. albopictus were analyzed to identify upper and lower thresholds of larval density and diet concentration. Survival to pupation, time to pupation, and sex ratio were evaluated under a range of larval densities (0.5-5 larvae/ml) and food levels (0.05-1.6 mg/larva/d) using two larval diets (one locally developed; one developed by the FAO/IAEA). The larvae reared at 28 °C, at a density of 2 larvae/ml and receiving a food dose equal to 0.6 mg/larva/d of a diet consisting of 50% tuna meal, 50% bovine liver powder (the FAO/IAEA diet), and, as an additive, 0.2 g of Vitamin Mix per 100 ml of diet solution, developed in 5 d and had 90% survival to the pupal stage. With this rearing regime male pupae production 24 h after the onset of pupation was the highest; these pupae were ∼94% male.

Pond drying cues and their effects on growth and metamorphosis in a fast developing amphibian

Abstract: The hydroperiod of breeding habitats imposes a strong selection on amphibians and pond-breeding species usually exhibit a high degree of plasticity in the duration of larval period. However, the potential for phenotypic plasticity in fast developing species was investigated only in a small number of anurans, and the specific response to environmental cues such as low water versus decreasing water level, as well as the effects of such cues on particular developmental stages, are even less understood. In this context, we investigated the plastic response to pond desiccation in a neotropical species (Ceratophrys stolzmanni) by raising tadpoles in three water level treatments: constant high, constant low, and decreasing. The growth rates were the highest reported for amphibian tadpoles (up to 0.3 g day−1) and the time to metamorphosis was short in all treatments, with the fastest developing tadpole metamorphosing in only 16 days after egg deposition. Individuals from the constant high water level treatment had a higher growth rate than those in the other two treatments, whereas decreasing and constant low water levels had similar effects on development, speeding up metamorphosis. In turn, this involved a cost as these tadpoles had a lower body size and mass at metamorphosis than the ones raised in constant high water levels. The final stages of metamorphosis, when tadpoles are the most vulnerable, were shorter in tadpoles exposed to a decreasing water level, allowing them to leave water quickly. Our experiment demonstrates that phenotypic plasticity is maintained even in environments devoid of permanent aquatic habitats. Ceratophryd tadpoles are able to shorten their developmental time when they perceive a risk of desiccation and react similarly to cues coming from the two unfavorable water conditions showing their adaptation to ephemeral and unpredictable breeding habitats.

Determination of the efficiency of diets for larval development in mass rearing Aedes aegypti (Diptera: Culicidae).

Abstract: Larval diet quality and rearing conditions have a direct and irreversible effect on adult traits. Therefore, the current study was carried out to optimize the larval diet for mass rearing of Aedes aegypti, for Sterile Insect Technique (SIT)-based applications in Sri Lanka. Five batches of 750 first instar larvae (L1) of Ae. aegypti were exposed to five different concentrations (2-10%) of International Atomic Energy Agency (IAEA) recommended the larval diet. Morphological development parameters of larva, pupa, and adult were detected at 24 h intervals along with selected growth parameters. Each experiment was replicated five times. General Linear Modeling along with Pearson's correlation analysis were used for statistical treatments. Significant differences (P < 0.05) among the larvae treated with different concentrations were found using General Linear Modeling in all the stages namely: total body length and the thoracic length of larvae; cephalothoracic length and width of pupae; thoracic length, thoracic width, abdominal length and the wing length of adults; along with pupation rate and success, sex ratio, adult success, fecundity and hatching rate of Ae. aegypti. The best quality adults can be produced at larval diet concentration of 10%. However, the 8% larval diet concentration was most suitable for adult male survival.

Decoupling of Behavioral Trait Correlation Across Life Stages in Two Holometabolous Insects

Abstract: Many animal behaviors have a genetic base, and behavioral traits often correlate with one another. In this study, we tested for a behavioral correlation between tonic immobility and walking distance in the larval and adult stages independently of two holometabolous insects. We confirmed a negative correlation of traits between strains in adults of both the species; however, we did not find it in larvae of either species. This suggests that the negative correlation between tonic immobility and walking is decoupled across life stages from larva to adult. In contrast, previous studies have reported that phenotypic correlations between behavioral traits are maintained from larvae to adults in hemimetabolous insects. In addition, our present results differ from previous results with holometabolous insects. Therefore, our results suggest that metamorphosis can change trade-offs between behavioral traits.

Asymmetrical Competition between Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) Coexisting in Breeding Sites

Abstract: Aedes aegypti and Culex quinquefasciatus are mosquito vectors for several tropical diseases that represent a current public health problem. The ecological requirements for each species are different, however, both species show high biological adaptability, which promotes their coexistence in the same breeding sites. The purpose of this study was to assess the effect of larval association between Ae. aegypti and Cx. quinquefasciatus under different laboratory conditions of food supply and temperature, and under field simulated conditions like peridomestic containers. Our findings showed that under field simulated conditions there was no asymmetrical competition in mixed cultures with the different Cx. quinquefasciatus/Ae. aegypti ratios tested. However, under laboratory conditions in which different doses of food supply were evaluated, it was observed that competition between the two species takes place. Larval coexistence under food scarcity conditions (0.95 mg/larva) showed that Ae. aegypti had a greater adult emergence than Cx. quinquefasciatus and was capable of depriving Cx. quinquefasciatus of the food needed to complete metamorphosis. In an intermediate dose of food (1.9 mg/larva), the dry weight of Cx. quinquefasciatus adults decreased, and their larval development time increased when Cx. quinquefasciatus/Ae. aegypti ratio was low. Also, a temperature effect was assessed demonstrating that Cx. quinquefasciatus was more vulnerable to changes in temperature. We suggest that Ae. aegypti is more successful in exploiting microhabitats when food is scarce, due to its scrape active feeding habitats and fast larval development times. Therefore, in conditions of food paucity both species will compete, and Ae. aegypti larvae will prevail.

Warmer temperature modifies effects of polybrominated diphenyl ethers on hormone profiles in leopard frog tadpoles (Lithobates pipiens).

Abstract: Amphibian populations have been declining, and climate change and exposure to environmental contaminants are thought to be involved. Higher water temperature accelerates larval development; however, its combined effects with contaminants and their influence on hormones during metamorphosis are poorly understood. The authors investigated changes in whole-body triiodothyronine (T3) and corticosterone concentrations in developing leopard frogs reared at 23 °C and 28 °C on diets with 0 ng g-1 , 6 ng g-1 , and 37 ng g-1 of a technical mixture of polybrominated diphenyl ethers (PBDE; DE-71) from 10 d to 44 d (premetamorphosis to late climax; Gosner Stages 28 to 46). Unlike controls, PBDE-exposed tadpoles (6 ng g-1 ) reared at 23 °C failed to show any increase in T3 concentrations throughout metamorphosis, and exposed tadpoles reared at 28 °C showed a lower peak at climax compared to controls. Corticosterone levels progressively increased throughout metamorphosis, but the levels were higher in PBDE-exposed tadpoles compared to controls at both temperatures. At the warmer temperature, corticosterone increase occurred earlier (at early climax) in controls and exposed tadpoles compared to tadpoles reared at the cooler temperature (late climax), coinciding with the faster development observed at 28 °C. Tadpoles reared at 28 °C were longer and developed faster than tadpoles reared at 23 °C. At both temperatures, PBDE exposure decreased T3 and increased corticosterone concentrations, which can potentially impair developing tadpoles. Environ Toxicol Chem 2017;36:120-127. © 2016 SETAC.

Potential of entomopathogenic nematodes of the genus Heterorhabditis for the control of Stomoxys calcitrans (Diptera: Muscidae).

Abstract: The present study verified the pathogenic potential of entomopathogenic nematodes (EPNs) of the genus Heterorhabditis (Heterorhabditis bacteriophora, isolate HP88 and Heterorhabditis baujardi isolate LPP7) to immature stages of Stomoxys calcitrans in the laboratory. All EPN concentrations of the H. bacteriophora HP88 strain caused mean larval mortality greater than 90% after four days. Higher concentrations of the H. baujardi LPP7 isolate (≥50 EPNs/larva) eliminated more than 70% of larvae after six days with the concentration 200 EPNs/larva reaching mortality levels of 93.3%. The larval mortality at all concentrations of EPNs (25, 50, 100, 150, and 200 EPNs/larva) for both strains was significant (p<0.05) when compared to the respective control groups. Concentrations of H. bacteriophora HP88 yielded an LC50 of 0.36 EPN/larva and LC90 of 29.1; while H. baujardi LPP7 yielded an LC50 of 39.85 and LC90 of 239.18. H. bacteriophora HP88 provided greater inhibition of the emergence of adults when compared to the response obtained with H. baujardi LPP7. EPNs did not cause considerable mortality when applied directly to pupae. The set of observed results suggests that the EPNs of the genus Heterorhabditis, isolates HP88 and LPP7, are a promising alternative in the control of the stable fly.

Developmental morphology of granular skin glands in pre-metamorphic egg-eating poison frogs

Abstract: Parents in many taxa, including insects, molluscs, fish, snakes, and amphibians provision chemical defences, such as peptides, steroids, or alkaloids to their offspring to reduce the risk of predation. In most cases, those defences are transferred to offspring in the egg and gradually diminish throughout the larval period. Adult poison frogs sequester alkaloid-based defences from arthropod prey in granular skin glands. In at least one poison frog, Oophaga pumilio, mother frogs intermittently feed tadpoles until metamorphosis with nutritive eggs containing those alkaloid-based defences. However, alkaloids are not detected in tadpoles until they reach the middle stages of larval development. Here, we investigate the histology of a developmental series of O. pumilio tadpoles to determine whether their ontogenetic alkaloid profile coincides with granular gland development. Our findings suggest that alkaloid sequestration in tadpoles is delineated by the differentiation of rudimentary granular skin glands in epithelial tissue. The timing of differentiation of granular glands in this species coincides with other anurans. Thus, provisioning of chemical defences to offspring is likely constrained by developmental timing of derived structures that can effectively store those toxic or noxious compounds.

Parasitismo en huevos de araña Achaearanea tepidariorum (Koch) (Aranea: Theridiidae) en Costa Rica

Abstract: Two new records of parasites of the eggs of the spider Achaearanea te­pidariorum are reported: an undescribed species of a microhymenopteran, Baeus sp. (Scelionidae) and a neuropteran, Mantispa viridis (Mantispidae). Three populations of the spider were studied, of which the one on the campus of Universidad de Costa Rica was highly infested: 63.85 per cent of the to­ tal egg sacs collected were parasitized, about 48 per cent by Baeus sp. and about 15 per cent by the mantispid. In M. viridis one larva develops in every egg sac, utilizing nearly all the eggs present. On the other hand, Baeus sp. has one larva developing per egg, parasitizing almost 80 per cent of the eggs present in each saco This means that of all the eggs produced by A. tepidariorum , less than 50 per cent complete their normal development. Two egg sacs were found evidently parasitized by both species, which means that some of the eggs eaten by the mantispid larva had already been parasitized by the wasp. Apparently M. viridis has a definite advantage in this competitive relationship for an identical source of food, but as shown here this is not the case in nature, due probably to the relatively large size of the neu­ ropteran. In many cases the mantispid is probably detected and captured by the female spider while approaching or leaving the egg sac, a problem not faced by the minute wasps. The adults of M. viridis feed actively on small insects... and live ap­ proximately five days under laboratory conditions. Those of Baeus sp. apparently do not feed (on sugar solutions). The males live one or two days, the females between five and seven days (one female lived 14 days in the laboratory).

The wasp larva's last supper: 100 million years of evolutionary stasis in the larval development of rhopalosomatid wasps (Hymenoptera: Rhopalosomatidae)

Abstract: . Rhopalosomatidae are an unusual family of wasps (Hymenoptera: Aculeata) comprising less than 100 species found in the tropics and subtropics of all continents except Europe and Antarctica. Whereas some species resemble nocturnal Ichneumonidae, others might be mistaken for spider wasps or different groups of brachypterous Hymenoptera. Despite their varied morphology, all members of the family supposedly develop as larval ectoparasitoids of crickets (Orthoptera: Grylloidea). Here, we report on the first record of a fossil rhopalosomatid larva which was discovered in mid-Cretaceous amber from northern Myanmar (Burma). The larva is attached to the lateral side of a cricket between the metafemur and the abdomen, impacting the natural position of the hind leg, exactly as documented for modern species. Additionally, the larval gestalt is strikingly similar to those of extant forms. These observations imply that this behavioral specialization, e.g., host association and positioning on host, likely evolved in the stem of the family at least 100 million years ago.

Effects of crowding on larval diapause and adult body size in Monochamus alternatus alternatus (Coleoptera: Cerambycidae)

Abstract: To determine the effect of larval crowding on induction of diapause in Monochamus alternatus alternatus Hope (Coleoptera: Cerambycidae), newly hatched larvae were inoculated singly (density 1) or in pairs (density 2) on Pinus thunbergii Parlatore (Pinaceae) bolts and reared at 25 °C and 16 light:8 dark hour photoperiod Adults emerged at density 1 and 2 between 75 and 139 days after the inoculation About 150 days after larval inoculation, dissection of pine bolts indicated the incidence of larval diapause was greater at density 1 (0536) than at density 2 (0222), indicating inversely density-dependent induction of diapause For both larval densities, the probability of entering diapause increased as bark surface area per larva (a proxy for per capita amount of food available) increased, showing that diapause induction can be explained by the amount of food available per larva Adults that emerged at density 1 were heavier than those at density 2 When diapause and nondiapause insects occurred in the same pine bolts, six heavy adults had experienced diapause whereas three heavy adults had not, indicating that bark surface area affected the induction of diapause indirectly through larval interaction The relationship between two different manners of density-dependent diapause induction and food supply is discussed

The larval sensilla on the antennae and mouthparts of five species of Cossidae (Lepidoptera)

Abstract: Most species in the family Cossidae can migrate from one host to a new one in later larval instars, which is different from other bark- and wood-boring insects. In this study, we selected Eogystia ...

Obligate planktotrophy in the Götte’s larva of Stylochus ellipticus (Platyhelminthes)

Abstract: Polyclad flatworms are a diverse and emerging model system for developmental biologists, yet development remains poorly understood for many species. One limitation of polyclads as a model system has been the lack of reliable methods for culturing planktotrophic polyclad larvae to metamorphosis. There are conflicting statements in the literature about which types of polyclad larvae require food to complete development. We developed simple methods for rearing planktotrophic flatworms to metamorphosis and tested the effects of food type and concentration on their development. The flatworm Stylochus ellipticus develops from small (~65 μm) eggs into an obligately planktotrophic Gotte’s larva. In this species, development to metamorphosis requires high concentrations (50,000 cells/ml) of the unicellular alga Rhodomonas lens as a food source. High concentrations of two other algal species (Dunaliella tertiolecta and Isochrysis galbana) were successfully ingested by larvae but failed to result in developm...

Chemical defence of turnip sawfly larvae against Japanese tree frogs

Abstract: Larvae of the turnip sawfly Athalia rosae (Hymenoptera: Tenthredinidae) are known to defend themselves using chemicals against predators such as ants, wasps and birds. However, only a few studies have tested the effectiveness of such chemical defences under field conditions. In a Japanese farm, a tree frog Hyla japonica (Anura: Hylidae) was observed to attack an A. rosae larva, but spit out the larva immediately after taking it into its mouth. To clarify how A. rosae larvae defend themselves against frogs, we quantitatively investigated how H. japonica attacked A. rosae larvae and palatable caterpillars of Pieris rapae (Lepidoptera: Pieridae) under field conditions. We experimentally placed an A. rosae larva or a P. rapae larva in front of tree frogs on the crop leaves. Frogs attacked both A. rosae and P. rapae larvae. However, the rate of predation by frogs was different between A. rosae and P. rapae larvae: 75% of frogs rejected A. rosae larvae, whereas 100% of frogs ate P. rapae larvae . Athalia rosae larvae attacked by frogs released their haemolymph (containing defensive chemicals) from the injured parts of their bodies. These results suggest that A. rosae larvae can chemically defend themselves against frogs in field conditions.

Influences of habitat and arthropod density on parasitism in two co-occurring host taxa

Abstract: Habitat attributes are known to influence infectious diseases such as those caused by parasites, but most studies have only considered single host and (or) parasite taxa, making it difficult to assess which features may be of general importance and to predict how alterations could affect disease dynamics. We examined infection with trematode (flatworm) parasites in two commonly co-occurring host taxa (larval amphibians and larval odonates (dragonflies and damselflies)) to investigate links with landscape-level features, including agricultural activity. We also assessed pond community composition with respect to the abundance and richness of aquatic arthropods known to prey upon tadpoles and (or) free-swimming trematode infectious stages. Larval amphibians from agricultural sites were most likely to be parasitized but had lower infection intensities, and infected hosts were positively associated with increasing distance to the nearest forest habitat, but negatively with road distance. The opposite was obse...

Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

Abstract: Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

Insecticidal effect of the ethanol extract of Baccharis dracunculifolia (Asterales: Asteraceae)

Abstract: Insecticides from plants have been studied as an alternative in agricultural production and in vector control of human diseases. The use of botanical insecticides may cause mortality in different stages, slow growth, infertile adults and decrease in viability of insect eggs. This study aimed to analyze the insecticidal potential of ethanol extract of Baccharis dracunculifolia DC, on Spodoptera frugiperda Smith, 1797 (Noctuidae) and Aedes aegypti L., 1762 (Culicidae). The botanical material was collected and prepared on February 8th, 2011 on the Fazenda Escola Tres Barras (20°33’37.44043" S - 54°32'10.3824" W), Campo Grande, MS. The ethanol extract was prepared from dried leaves obtained of adult plants in a vegetative state at the Chemistry Laboratory of Anhanguera University-Uniderp. The experiments of biological activities were conducted at the Entomology Laboratory of the Catholic University Don Bosco, in a controlled environment with an average temperature of 25 oC and photoperiod 12 hr. Experiments with S. frugiperda were conducted from August to October 2014. The collection of A. aegypti eggs was made in January 2014 and the treatments were done from March 10th to 17th, 2014. In the development of S. frugiperda the extract caused effect on caterpillars subjected to treatment at one and 10 days. The larval stage proved to be longer at both ages and pupal weight reduced at 10 days, as well as increased mortality at one day, when incorporated concentration 0.2 % into diet. The variables studied were mortality, larval duration, pupal weight, number and viability of the eggs. The bioassay used A. aedes third instar, 25 larvae per concentration, at four replicates. Parameters analysed for sublethal doses were pupal and larval, mortality, length larval and young (larva + pupa) the ethanol extract at concentrations 0.5 mg.mL-1 and 0.25 mg.mL-1. The extract resulted in deleterious effect on the development of caterpillars undergoing treatment in larvae of one and 10 days of age, the larval stage stretching, lower pupal weight in caterpillars 10 days and higher mortality in the group with one day of life. It did not interfere with the viability of eggs. In the life cycle of A. aegypti, the extract of B. dracuncufolia at the studied concentrations caused delay in the development of larval and pupal stages, and inhibited the emergence of adults in 85 % and 70 %. In laboratory conditions it can be said that the ethanol extract of B. dracunculifolia has a potential insecticide effect for both species of insects.

Effects of light quality and intensity on the growth, survival and metamorphosis of Haliotis discus hannai Ino larvae

Abstract: Light is a key environmental factor that influences the growth, culture and survival of aquatic organisms. This study examined the effects of different light qualities (red, orange, white, blue and green light) and intensities (5 μmol m−2 s−1, 15 μmol m−2 s−1 and 40 μmol m−2 s−1) on the hatching and metamorphosis of larva of Haliotis discus hannai Ino and the growth and survival of juveniles. It was found that under blue and green light, the hatching success rate and metamorphosis of larva were significantly higher than those for any other light quality (P 0.05). Therefore, selecting blue and green light and controlling the light intensity to 5–15 μmol m−2 s−1 during fingerling reproduction of abalone should increase the hatching success rate of larva and the yield per water body.

Early exposure to predation risk carries over metamorphosis in two distantly related freshwater insects

Abstract: 1. Predation and competition play a central role in ecological communities, and it is increasingly recognised that animals use early warning cues to reduce the impact of these antagonistic interactions. 2. Strategies to avoid risk can occur during embryo development through plasticity in egg hatching time. This strategy, and its associated costs and carryover effects on adults are little understood in insects. In this study, these are explored in two distantly related freshwater insects: the damselfly Ischnura elegans and the mosquito Aedes albopictus. 3. As predicted, damselfly eggs hatched earlier in response to larval predators cues, a treatment that also affected adult size. Risk cues did not affect mosquito egg hatching time, but they did affect larval development time in a sex-dependent manner. 4. The results suggest that responses aimed at avoiding risks can be triggered during the egg stage, and although they can vary dramatically among species, they are likely to be widespread in insects. Early warning responses can be particularly important to understand the ecology of aquatic insects, some of them global vectors of human diseases. (Resume d'auteur)

Bird droppings on chestnut leaves or sawfly larvae: DNA barcodes verify the occurrence of the archaic Megaxyela togashii (Hymenoptera, Xyelidae) in Hokkaido, Japan.

Abstract: We made a molecular phylogenetic analysis using mitochondrial cytochrome oxidase subunit 1 (COI) gene sequences for ten unidentified Megaxyela larvae from Hokkaido, Honshu and Shikoku, Japan, and 15 identified adults of four Megaxyela , one Macroxyela and three Xyela species. It revealed that all larvae belonged to M. togashii Shinohara, 1992, which showed rather large intraspecific genetic variability even among the individuals from the same population. This is the first distribution record of M. togashii from Hokkaido. Megaxyela togashii is a univoltine species with a very short larval feeding period, only nine days in one rearing experiment from egg to larval maturation. The larva is a solitary, external leaf-feeder on Juglans ailanthifolia , resting curled around the central leaf vein at the apex of a leaflet, and may resemble the excrement of birds. The prepupa overwinters in an earthen cell whose wall is made only of soil, neither parchment-like nor containing fiber. The mature larva is described and several life traits are discussed.