Composition,Seasonal Dynamics,and Long-Term Fluctuations in the Density of Pelagic Polychaetes in Amurskii Bay,Sea of Japan

This is the first survey of the composition and seasonal density dynamics of the pelagic polychaete larvae in Amurskii Bay. This is a summary of the results of two years of observations (1996–1998). The larvae of 14 polychaete families have been recorded. The greatest number of species have been found in the family Spionidae. The most common were the larvae of Harmothoe imbricata (family Polynoidae) and Paraprionospio sp. (family Spionidae). The larvae of polychaetes have been found in plankton throughout the year and have two density peaks. The first peak was due to the spawning of H. imbricata; the second one was provided by representatives of several species of the family Spionidae, mostly Paraprionospio sp., Polydora ciliata, and P. caeca.     

Invertebrate infestation on eggs and hatchlings of the loggerhead turtle, Caretta caretta, in Dalaman, Turkey

The damage caused by some invertebrates to the eggs and hatchlings of loggerhead turtles, Caretta caretta, was investigated during the summer of 2002 on Dalaman beach, Turkey. The specimens, identified to family or genus levels, from nine families representing seven orders were recorded as infesting nests of loggerhead turtles. The heaviest impacts on loggerhead turtle nests was made by Pimelia sp. (Tenebrionidae, Coleoptera). Twenty-four (36.3%) out of 66 intact loggerhead hatched nests were affected by these larvae. Larval damage by Pimelia sp. was recorded in 188 (10.6%) out of 1773 eggs, but only in two (0.28%) hatchlings. The results show that fewer insects were in the nest the further from vegetation and therefore the relocation of nests from the water's edge to further inland close to vegetation may increase the infestation rate of the eggs.     

Parasitism,seasonality, and diversity of trombiculid mites (Trombidiformes: Parasitengona,Trombiculidae) infesting bats (Chiroptera) in Poland

The study aims to ascertain the diversity of trombiculid species associated with Chiroptera in Poland, and for the first time in the case of research on Central European Trombiculidae, we use both DNA and morphology in an integrative taxonomic approach to determine species identities of trombiculids. The research was carried out from 2015 to 2019. In total, 2725 larvae were collected from 300 specimens of bats belonging to 11 species. Deutonymphs were obtained through laboratory rearing of larvae; few larvae and deutonymphs were collected also from bats' daily roosts. The presence of trombiculid larvae on hosts was observed between July and April of the following year, with the highest numbers recorded in autumn, during bat swarming. Male bats were infested more often than females (16.4 vs. 6.6%). The highest infestation rate was recorded for Barbastella barbastellus, Myotis nattereri and Plecotus auritus, and the highest prevalence of chiggers (>?30%) for Myotis bechsteinii and P. auritus. The larvae found on bats occupied the areas with free access to the host’s skin: auricles, tragus, and snout. Morphological identification of specimens to the species level was hindered by the mosaic distribution of diagnostic traits. Morphological analyses indicated the presence of Leptotrombidium russicum and Leptotrombidium spp. in the examined material, whereas molecular analyses additionally suggested three other potential species assigned to the same genus based on the assessed scope of intrageneric variation (ASAP method). We argue that the identification of the parasitic larvae (chiggers) using morphological characters does not address the question of actual species boundaries, which, in turn, affects the inferences about host specificity and host range.

     

The effects of pollen consumption of transgenic Bt maize on the common swallowtail, Papilio machaon L. (Lepidoptera, Papilionidae)

Effects of exposure to maize pollen of event Bt176 (cultivar “Navares”) on the larvae of the European common swallowtail (Papilio machaon L.) were studied in the laboratory. First instar larvae were exposed to different pollen densities applied to leaf disks of Pastinaca sativa L. for 48 h. Pollen densities applied in this study were in the range recorded from the field. Larvae which were exposed to higher Bt maize pollen densities consumed more pollen and had a lower survival rate. The LD₅₀ with regard to larvae surviving to adulthood was 13.72 pollen grains consumed by first-instar larva. Uptake of Bt maize pollen led to a reduced plant consumption, to a lower body weight, and to a longer development time of larvae. Effects on pupal weight and duration of the pupal period were present but less pronounced and smaller than effects on larvae. Larvae having consumed Bt-maize pollen as first instars had a lower body weight as adult females and smaller forewings as adult males. We conclude that possible effects of Bt maize on European butterflies and moths must be evaluated more rigorously before Bt maize should be cultivated over large areas.     

Distribution,abundance and diversity of macrozoobenthos in Aiba Reservoir,Iwo, Nigeria

Spatial and seasonal variation in macrozoobenthic composition, abundance and diversity in Aiba Reservoir were investigated bimonthy between June 2004 and April 2005 using a van Veen grab. A depauperate fauna of nine taxa was recorded. Generally, larger numbers of taxa were recorded during the dry season than in the wet season. Melanoides tuberculata and chironomid larvae dominated the macrozoobenthos and showed wide spatial distribution. Diversity and evenness were lower during the wet season than in the dry season, when densities of the major species were low. Melanoides tuberculata and chironomid larvae were recorded from maximum depths of 3.9 m and 2.6 m, respectively. Both taxa were also recorded from all substrate texture types, regardless of the amount of macrophyte material present. The benthic fauna is characterised as being poor in terms of density, taxonomic richness and diversity     

First records of the parasite Symbiocladius rhithrogenae (Zavrel, 1924) (Diptera: Chironomidae) in several streams of Rila Mountain,Bulgaria

Parasite stages of Symbiocladius rhithrogenae (Zavrel, 1924) (Diptera: Chironomidae) were found in several streams from the Rila Mountain. A total of 19 sites (18 from the Iskar River and one from the Struma River catchments) were sampled, from which the parasite was recorded only in four (Levi Iskar, Rilska, Malyovishka and Cherni Iskar Rivers). Both pupa and larvae of S. rhithrogenae were found attached only to mayfly larvae of the genus Rhithrogena Eaton, 1881, while other Heptageniidae species were ignored. This specialisation could be connected to an overlap between the seasonal cycles of the parasite and its host. We discussed the bioindicative potential of S. rhithrogenae.     

Occurrence of Gobiidae larvae in a tropical Brazilian estuary,with particular emphasis on the use of size classes to categorize species guilds

The structure and seasonal dynamics of larvae of the Gobiidae family in the Mucuri Estuary (Bahia, Brazil) were studied for nine consecutive years. Sampling was conducted at three stations in the lower estuary channel, between 2002 and 2010, in relation to season, day and night and tidal variations. A total of 5802 Gobiidae larvae, representing 15 taxa (12 species and three morphotypes), were collected in the Mucuri Estuary during this time. The highest mean ± s.d. density of fish larvae, 54·7 ± 79·8 larvae 100 m^?3, was recorded during the flood tide and night sampling. Ctenogobius boleosoma was the most abundant species (68%), being dominant in the rainy and dry seasons and had a long reproductive period. This species was classed as a marine estuarine‐opportunist because it was observed at high frequencies and active larvae entering the estuary between 6·1 and 12·0 mm standard length (L_S). Gobionellus oceanicus, second in abundance (12%), occurred only in later larval stages but did not use the estuary as a preferred location for spawning, being classed a marine estuarine dependent. Microgobius carri (11%) was represented in all L_S classes and was resident in the estuary for spawning, remaining there throughout their life cycle. The other species were considered rare due to their low densities and could not be classified in any guild.     

The period of occurrence,density, and distribution of larvae of three commercial crab species in Peter the Great Bay,Sea of Japan

Based on materials from plankton surveys carried out in 2004–2009, the period of occurrence, density, and distribution of larvae of three commercial species of crabs in the Peter the Great bay and adjacent areas of Sea of Japan were studied. The larvae of the horsehair crab Erimacrus isenbeckii (Brandt, 1848) occurred in the plankton from mid-March to early June, within the range of water temperature from −1 to 10.8°C. The larvae of the helmet crab Telmessus cheiragonus (Tilesius, 1812) appeared in the plankton in mid-April and occurred to the end of June within the temperature range from 2.8 to 13.0°C. The larvae of the snow crab Chionoecetes opilio (O. Fabricius, 1788) appeared in the plankton in mid-April as well, but some individuals sporadically occurred until early August. All the species of crabs produced one generation of larvae for their reproduction season. The terms of larval stay in plankton depended on water temperature and the duration of the pelagic period increased in colder years. In that area, the larvae of C. opilio were the most abundant (up to 41 ind./m³) and the zoea density of horsehair and helmet crabs was significantly lower (no more than 2 ind./m³). The larvae of C. opilio occurred over the entire area of the Peter the Great bay; the greatest aggregations of their early stages were observed in its southwestern open part. The maximum density of E. isenbeckii zoea was recorded in the south of the Amursky bay and in the Posyet bay. Individual larvae of T. cheiragonus occurred in the Posyet bay and in the southern part of the Amursky and Ussuriisky bays. The late-stage larvae of all crab species were concentrated in areas of the coastal circulation.     

Biology and life table studies of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae), influenced by different larval diets

Development, survivorship, pupal weight, oviposition, and life table parameters of the oriental tobacco budworm, Helicoverpa assulta Guenée, were evaluated in the laboratory on an artificial diet, pepper (Capsicum frutescens L.), and tobacco (Nicotiana tobacum L.). We found that the average developmental time of immature stages was longest on tobacco (36.2 d), intermediate on pepper (34.4 d), and shortest on artificial diet (33.5 d). Immature survival from egg to pupa varied from 31% on tobacco, 43% on pepper, and 74% on artificial diet. Pupal weight ranged from 197.4 mg/pupa on tobacco, 233.1 mg/pupa on pepper and 253.4 mg/pupa on artificial diet. The average numbers of eggs laid by adults reared as larvae on the artificial diet, pepper, or tobacco were 614, 421 and 334 eggs/female, respectively. Numbers of remaining eggs in ovaries of the adult females reared as larvae on the artificial diet, pepper, or tobacco were 16, 26, and 42 eggs/female, respectively. The longevity of adult females developed from larvae reared on the three diets was not significantly different, whereas the longevity of male adults from the larvae reared on artificial diet was longer (16.8 d) than that for males reared on tobacco (13.8 d) and pepper (13.3 d). The intrinsic, finite, gross, and net rates of increase were highest for females reared as larvae on artificial diet, lowest for females emerging from larvae reared on tobacco, and intermediate for females emerging from larvae reared on pepper. Generation times and doubling time of H. assulta were shortest for larvae fed artificial diet, intermediate from larvae reared on pepper, and longest from larvae reared on tobacco. We concluded that the artificial diet was the most suitable larval diet of H. assulta followed by pepper, and tobacco.     

Parasitism of lizards by immature stages of the blacklegged tick,Ixodes scapularis (Acari,Ixodidae)

From 1982–1985 and 1993–1999, a total of 309 individual reptiles, mostly lizards and snakes, belonging to 12 species (American alligator, six lizard species, five snake species) was captured on St. Catherine's Island, Liberty County, Georgia, USA, and examined for ticks. Three lizard species, the broad-headed skink Eumeces laticeps, southeastern 5-lined skink Eumeces inexpectatus, and eastern glass lizard Ophisaurus ventralis, were severely infested with larvae and nymphs of the blacklegged tick, Ixodes scapularis. Ticks were not found on any of the other reptile species. Overall, 80% of 65 E. inexpectatus examined were parasitized by a mean intensity of 21.5larvae and 88% were parasitized by a mean intensity of 4.8 nymphs. Corresponding figures for E. laticeps (n=56) were 93% and 51.3 for larvae and 89% and 7.4 for nymphs, and for O. ventralis (n=3) were 67% and 22.5 for larvae and 100% and 21.3 for nymphs. Larvae and nymphs attached along the lateral grooves of O. ventralis. Nymphs attached mainly behind the ears and in the foreleg axillae whereas larvae mainly attached to these sites and on the hindlegs in Eumeces spp. Seasonally, both larvae and nymphs were recorded on lizards from April through October. A unimodal larval peak was recorded in May or June. Seasonal data for nymphs did not reveal any distinct peaks but small bimodal peaks in mean intensities may have occurred (one in early summer, the other in late summer)suggesting that some ticks complete their life cycle in one year, and others in two years, on St. Catherine's Island. Potential epidemiological consequences of these findings with respect to Lyme disease in the southeastern United States are briefly addressed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Biological notes on a fungus-growing ant, Trachymyrmex cf. zeteki (Hymenoptera, Formicidae, Attini) attacked by a diverse community of parasitoid wasps (Hymenoptera, Diapriidae)

A number of wasps in the family Diapriidae, subfamily Diapriinae (Proctotrupoidea), are parasitoids that specialize on ant larvae. These wasps are abundant and diverse in the Neotropics, but little is known about their biology. We studied parasitism rates by an array of diapriine wasps that attack the larvae of fungus-growing ants, Trachymyrmex cf. zeteki, in a single population (near Gamboa, Panamá). Relatively little is known about the biology and natural history of these ants, so we also present data on colony size and nest architecture. We excavated 136 colonies in central Panamá from June to September 2006, and 20 nests from July 2009. We reared six wasp morphotypes; two of them in the genus Mimopriella Masner and Garcia, one Oxypria Kieffer, two Szelenyiopria Fabritius and one Acanthopria Ashmead. The mean intensity of larval parasitism per ant colony was 33.9% (2006), and its prevalence across all ant populations was 27.2% (2006 and 2009). Parasitism rates were not positively correlated with host colony size. A single case of super-parasitism was documented in which two Oxypria males were reared from the same host larva.     

Xylophagous entomofauna in branches of oaks (Quercus spp.) and its significance for oak health in the Karst region of Slovenia

Samples of dying branches from 121 trees of Quercus pubescens, Q. cerris, and Q. petraea were taken from 102 sites in Seslerio autumnalis-Quercetum petraeae and Ostryo-Quercetum pubescentis forests. After nine months’ rearing in eclectors, branches were cut to 20-cm sections, and signs of infestation as well as larvae and adult insects were noted. We analysed 395 sections of branches from Q. pubescens, 125 sections from Q. cerris, and 85 sections from Q. petraea. We found 44 adult insects: 45% were from the Cerambycidae family (Callimus angulatus ssp. angulatus, Poecilium alni, and Exocentrus adspersus), 18% were from the Scolytinae subfamily (Scolytus intricatus, Xyleborus dispar), 4% from the Buprestidae family (Coraebus florentinus), 4.5% from the Cleridae family (Tilloidea unifasciata), and 28.5% from other families. In addition, 145 larvae were found: 50% from the Cerambycidae family, 39% from the Buprestidae family, 4% from the Scolytinae subfamily, and 7% from other families. Significant difference in the abundance of adult insects and larvae with regard to the diameter of branch sections and the host species were found. 78% of dying branches showed signs of infestation. Species of the Buprestidae, Scolytinae, and Cerambycidae represent important factors in the decline in oak vitality in the lower Karst region of Slovenia.     

Subsidies for production of Chironomus calligraphus larvae (Chironomidae,Diptera) in the laboratory

The objective of this study was to evaluate the effect of temperature, type of mineral substrate, and type and amount of feed on the growth of Chironomus calligraphus as a subsidy for the production of Chironomus larvae to feed the fish. Egg production was evaluated at 22, 25, and 28?°C on fine (0.074–0.210?mm), or silty sand (0.002–0.250?mm), and no mineral substrate as control. For larval production, 0.10, 0.20, and 0.30?mg/larvae of fish feed, poultry feed, or turkey manure were used as food. The highest number of egg masses was produced when mineral substrates and 25?°C were used, but the higher number of eggs/mass was registered in the control. Therefore, the total number of eggs and hatched larvae produced was the same in the presence or in the absence of mineral substrates (p?>?0.05). The best results for survival and growth were recorded for larvae reared with fish or poultry food. The increase in the amount of feed was correlated with weight gain only for larvae fed with poultry feed, with no reduction in survival.     

Laboratory rearing of Hydrochus japonicus (Coleoptera: Hydrochidae) suggests larvae live at the water bottom

The aquatic larvae of the family Hydrochidae (Coleoptera) have been considered ‘mystery larvae’, because ecological knowledge about them is lacking. We discovered that Hydrochidae larvae (Hydrochus japonicus Sharp) are benthic via laboratory rearing. The larvae have a terminal spiracular atrium, but we did not observe them breathing at the water surface. The larvae fed on Naididae worms that were collected from the same habitat.     

Predators,Parasites and Heterospecific Aggregations in Chrysomeline Larvae

Gregariousness is a common feature in aposematic insect prey and offers the additional benefit of enhancing the effectiveness of their toxic defences. Aggregations of the aposematic larvae of two species of leaf beetles, Paropsis atomaria and Paropsisterna variicollis, occur together on the same Eucalyptus trees over spring and summer. Conventionally, the colouration of these larvae is thought to provide aposematic protection against vertebrate predators, but supporting evidence is limited. We determine whether environmental preferences contribute to the heterospecific aggregations, and the potential costs for larvae of living in heterospecific aggregations. We surveyed natural aggregations of the larvae of both species in the field and recorded environmental variables of these aggregations. This revealed that heterospecific aggregations occurred more commonly at higher leaf temperatures, and in less visually conspicuous locations. Paropsis atomaria larvae were twice as likely to be found in heterospecific aggregations than Pa. variicollis. Next, we manipulated larval aggregations in the field to investigate the survival and gregarious behaviour of larvae in heterospecific aggregations. The gregarious behaviour of both species of larvae did not differ between heterospecific and monospecific aggregations. Further, the survival of larvae did not significantly differ between heterospecific and monospecific aggregations. We suggest that the preference for P. atomaria larvae to aggregate with Pa. variicollis at higher leaf temperature results in the observed heterospecific aggregations, with a potential benefit of lowerer parasitoidism rates for P. atomaria.     

Neural correlates of settlement in veliger larvae of the gastropod,Crepidula fornicata

Settlement behavior of molluscan veliger larvae prior to metamorphosis requires cessation of swimming, accomplished by arrest of prototrochal cilia on the margin of the velum (the larval swimming organ). Ciliary arrest in larvae of gastropods is mediated by an action potential that occurs synchronously across the velum as a consequence of electrical coupling between the prototrochal ciliated cells. We developed a preparation for extracellular recording of such ciliary arrest spikes from intact swimming and crawling veliger larvae of the caenogastropod Crepidula fornicata, using a fine wire electrode. Ciliary arrest spike rates during bouts of substrate crawling were significantly higher than those recorded during preceding swimming periods in larvae that were competent for metamorphosis, but not in precompetent larvae. Spike rates were similar on clean polystyrene substrates, and on substrates that had been coated with a natural cue for metamorphosis (mucus from conspecific adults). We used immunohistochemical methods to localize neuromodulators that might regulate the function of velar cilia. Labeled terminals for serotonin, FMRFamide, and tyrosine hydroxylase (an enzyme for catecholamine synthesis) were located in positions consistent with modulatory effects on the prototrochal ciliated cells. Prototrochal ciliary arrest spike rates and beat frequencies were measured in isolated velar lobes from competent larvae, which were exposed to serotonin, FMRFamide, and dopamine (10^?5 mol L^?1). Serotonin abolished arrest spiking and increased beat frequency; dopamine also increased beat frequency, and FMRFamide depressed it. Competent larvae tested in a small static water column swam to the top of the column when exposed to serotonin, but occupied lower positions than controls when in the presence of dopamine and FMRFamide. The larval nervous system appears to regulate velar functions that are critical for settlement behavior, and is likely to do so by integrating different sensory modalities in an age‐dependent manner.     

Parasite-host associations and life cycles of spring-living water mites (Hydrachnidia, Acari) from Luxembourg

Larval water mites are parasites of various insect species. The main aim of the present study was to analyse the host range of spring dwelling water mites. The investigation focuses on seven spring sites in Luxembourg. Some 24 water mite species were recorded either from the benthos or as parasites attached to flying insects captured in emergence traps. For 20 mite species 35 host species from four Nematocera (Diptera) families were recorded. About 80% of the host species and over 90% of the host individuals were Chironomidae, the others were Limoniidae, Dixidae and Simuliidae. For all water mite species recorded we present the observed host spectrum and/or potential hosts as well as the intensity of parasitism and the phenology of the mites. For 10 mite species the hosts were previously unknown. For another ten species the known host spectrum can be confirmed and extended. The host spectrum ranged from one host species (e.g. for Sperchon insignis) to at least 10 host species (for Sperchon thienemanni, Ljania bipapillata), but the effective host range could not be definitively estimated due to the lack of corresponding data. The hypothesised host preference of the water mites, of which most are strictly confined to spring habitats, for similarly spring-preferring hosts could not be proven. The mean intensity of parasitism was highest for Thyas palustris (10.8 larvae/host) and lowest for Sperchon insignis and Hygrobates norvegicus (1.2 larvae per host for each). The hydryphantid mite Thyas palustris occurred at maximal intensity (41 larvae per host) and the two abdominal parasites Ljania bipapillata and Arrenurus fontinalis showed higher mean intensities than the thoracic parasites did. Larval water mites parasitising chironomids did not exhibit a preference for host sex. The phenology of the larval mite species was varied, some species were only present in samples early in the year and others exclusively in the summer. Another species showed two peaks of occurrence, springtime/early summer and late summer/autumn. In conclusion, the water mite larvae in the studied springs showed differences in host spectra and phenology but there are no clear evidences in both for host partitioning. Maybe, the relative low species diversity of water mites in individual springs and the low inter-specific competition for suitable hosts in combination with the high host abundances and species richness makes springs such favourable habitats for the mites.     

Specific Detection of Pacific Oyster (Crassostrea gigas) Larvae in Plankton Samples Using Nested Polymerase Chain Reaction

Management of sustainable Pacific oyster fisheries would be assisted by an early, rapid, and accurate means of detecting their planktonic larvae. Reported here is an approach, based on polymerase chain reaction (PCR), for the detection of Pacific oyster larvae in plankton samples. Species-specific primers were designed by comparing partial mitochondrial cytochrome oxidase subunit I (COI) sequences from Crassostrea gigas, with other members of the family Ostreidae including those of Crassostrea angulata. Assay specificity was empirically validated through screening DNA samples obtained from several species of oysters. The assay was specific as only C. gigas samples returned PCR-positive results. A nested PCR approach could consistently detect 5 or more D-hinge-stage larvae spiked into a background of about 146 mg of plankton. The assay does not require prior sorting of larvae. We conclude that the assay could be used to screen environmental and ballast water samples, although further specificity testing against local bivalve species is recommended in new locations.     

Influence of weeding regimes and pearl millet genotypes on parasitism of the Oriental armyworm, <Emphasis Type="Italic">Mythimna separata</Emphasis>

We studied the effect of four weeding regimes (weed free, one manual weeding, one manual weeding+atrazine, and a weedy check) on larval density and leaf defoliation in four pear millet genotypes by the larvae of Oriental armyworm, Mythimna separata. Data were also recorded on the extent of larval parasitism under different weeding regimes, and the parasitoids involved. The leaf damage and larval densities were lower in weed free plots as compared to the weedy plots. This was also reflected in grain yield, as maximum grain yield was recorded in weed-free plots as compared to the weedy plots. Seven parasitoids (Cotesia ruficrus, Metopius rufus, Sturmiopsis inferens, Palexorista solemnis, P. laxa, Carcelia sp., and the entomopathogenic nematode Neoplectana sp. were recorded from M. separata larvae, of which M. rufus, Carceliasp., and Neoplectanasp. were the most abundant. Parasitism by M. rufus was greater in plots with a weed cover and least in weed-free plots, while parasitsm by Carcelia sp. was lower in plots with one hand weeding than in weedy plots. Numerically, parasitism by Neopletana sp. was low in plots treated with atrazine, and maximum in plots weeded manually. Therefore, the minimum level of weeding, which does not affect the crop adversely should be undertaken to promote the biological control of M. separata in pearl millet.