Post-settlement abundance, condition, and survival in a climate-stressed population of Pacific cod

The Pacific cod (Gadus macrocephalus) fishery recently collapsed in the Gulf of Alaska after a series of marine heatwaves that began in 2014. To gauge the likelihood of population recovery following these extreme warming events, we investigate potential thermal stress on age-0 cohorts through a comprehensive analysis of juvenile cod abundance, condition, growth, and survival data collected from 15 years of beach seine surveys. Abundance was strongly negatively related to ocean temperature during the egg and larval phase (winter/spring), but age-0 cod were larger in the early summer following warm winter/spring temperatures. Body condition indices suggest that warm summers may improve energetic reserves prior to the first winter; however, there was no summer temperature effect on post-settlement growth or survival. Spatial differences in abundance, condition, or growth were not detected, and density-dependent effects were either weak or positive. While the positive effects of increased summer temperatures on juvenile condition may benefit overwintering survival, they cannot compensate for high pre-settlement mortality from warming winter/spring temperatures. We conclude the critical thermal bottleneck for juvenile abundance occurs pre-settlement.

Evolution of diverse host infection mechanisms delineates an adaptive radiation of lampsiline freshwater mussels centered on their larval ecology

North American watersheds contain a high diversity of freshwater mussels (Unionoida). During the long-lived, benthic phase of their life cycle, up to 40 species can co-occur in a single riffle and there is typically little evidence for major differences in their feeding ecology or microhabitat partitioning. In contrast, their brief parasitic larval phase involves the infection of a wide diversity of fish hosts and female mussels have evolved a spectrum of adaptations for infecting host fish with their offspring. Many species use a passive broadcast strategy: placing high numbers of larvae in the water column and relying on chance encounters with potential hosts. Many other species, including most members of the Lampsilini, have a proactive strategy that entails the use of prey-mimetic lures to change the behavior of the hosts, i.e., eliciting a feeding response through which they become infected. Two main lure types are collectively produced: mantle tissue lures (on the female’s body) and brood lures, containing infective larvae, that are released into the external environment. In this study, we used a phylogenomic approach (ddRAD-seq) to place the diversity of infection strategies used by 54 North American lampsiline mussels into an evolutionary context. Ancestral state reconstruction recovered evidence for the early evolution of mantle lures in this clade, with brood lures and broadcast infection strategies both being independently derived twice. The most common infection strategy, occurring in our largest ingroup clade, is a mixed one in which mimetic mantle lures are apparently the predominant infection mechanism, but gravid females also release simple, non-mimetic brood lures at the end of the season. This mixed infection strategy clade shows some evidence of an increase in diversification rate and most members use centrarchids (Micropterus & Lepomis spp.) as their predominant fish hosts. Broad linkage between infection strategies and predominant fish host genera is also seen in other lampsiline clades: worm-like mantle lures of Toxolasma spp. with sunfish (Lepomis spp.); insect larvae-like brood lures (Ptychobranchus spp.), or mantle lures (Medionidus spp., Obovaria spp.), or mantle lures combined with host capture (Epioblasma spp.) with a spectrum of darter (Etheostoma & Percina spp.) and sculpin (Cottus spp.) hosts, and tethered brood lures (Hamiota spp.) with bass (Micropterus spp.). Our phylogenetic results confirm that discrete lampsiline mussel clades exhibit considerable specialization in the primary fish host clades their larvae parasitize, and in the host infection strategies they employ to do so. They are also consistent with the hypothesis that larval resource partitioning of fish hosts is an important factor in maintaining species diversity in mussel assemblages. We conclude that, taking their larval ecology and host-infection mechanisms into account, lampsiline mussels may be legitimately viewed as an adaptive radiation.

Ontogenetic niche specialisation of the spider crab Libinia ferreirae associated with the medusa Lychnorhiza lucerna

Symbiotic relationships in marine environments are not fixed and can change throughout the animal’s life. This study investigated the ontogeny of symbiosis of the spider crab Libinia ferreirae with the host medusa Lychnorhiza lucerna. We described the type of relationship, the temporal correlation among species and food habits. More than 50% of the sampled crabs were symbionts, most in early life stages. The highest number of crabs found in a single medusa was 11. Symbiosis was observed throughout most of the year but was more evident in warm periods. The crab has many benefits in this relationship with a medusa. One is the use of food resources captured by the medusa, primarily copepods. Since the crab steals the medusa's food, it is a kleptoparasitic relationship. There is a niche partition between symbiont and the free-living crabs as they occupy different habitats and use nonoverlapping food resources. Previous research reported that symbiosis first developed during the crab’s last larval phase (megalopa) when crab and medusa are in the same habitat. Observation of the crab's behaviour shows that symbiosis occurs when the crab can grab to the medusa when the host touches the sea bottom. The crab also took advantage of water currents, releasing itself from the substrate and then drifting towards the medusa. The symbiotic relationship that crabs have with the medusa provides then with a nursery, food resources, shelter, dispersion, and decreased competition with free-living adult crabs, all essential for the crab's survival.

Efficacy of Two Predatory Coccinellid Specie Feeding on Different Desities of Bemisia Tabaci (Homoptera : Aleyrodidae) Nymphs in The Laboratory

Aseries of experiments were conducted laborators of biollogical control in the postgraduate laboratory at the Al-Mussaib Technical College, AL-Furat Al-Awsat Technical University-Iraq in 2020, The larval and adult phase of Hippodamia variegate and Coccinella Septempunctata.L were reard on different densities of Bemisia tabaci nymphs to reveae theis predation and the effect on this longevity too: The average number of predation whitefly nymphs per day from each age larvae and adults of the thirteen-spoted ladybird H. variegate and the seven- spoted ladybird C. Septempunctata. L was in direct proportion to the increase in the density of the whitefly nymphs supplied for it daily, The highest average of thirteen point ladybird larvae was (48.60) at density (64) nymphs/whitefly at the first larval phase. While the lowest rate of first-stage larvae was (6.40) at density (2) nymphs/whitefly for the same larval phase, while the highest average of fourth-stage larvae was (131.20) at density (64) nymphs/whitefly. While the lowest average of the fourth larvae phase was (39.20) at density (8) nymphs/whitefly, As for the seven- spoted ladybird, the highest average of first-phase larvae reached (53.80) at density (64) nymphs/whitefly, while the lowest average of first-phase larvae reached (5.40) at density (2) nymphs/whitefly for the same larval phase. While the highest average of fourth phase larvae was (160.40) at density (64) nymph/whitefly, while the lowest average of fourth phase larvae was (46.00) at density (4) nymph/whitefly. The number of whitefly nymphs preyed by the thirteen- spoted ladybird H. variegate is less than the number of whitefly nymphs preyed by the seven- spoted ladybird C. Septempunctata. L. The daily average of predation for male predation ladybirds understudy for whitefly nymphs is less than the daily average for females with significant differences.

Dynamics of Toxorhynchites splendens population in the Larval phase at a rubber plantation in Banjarbaru, South Kalimantan, Indonesia

Muhamat, Hadisusanto S, Umniyati SR, Soesilohadi RCH. 2021. Dynamics of Toxorhynchites splendens population in the Larval phase at a rubber plantation in Banjarbaru, South Kalimantan, Indonesia. Biodiversitas 22: 4915-4922. This study aims to describe a water-filled rubber sap bowl as a habitat for larval Toxorhynchites splendens. The research used a quota drive count method, taking the first 10 rubber sap bowls found in the study area: (i) with larval Tx. splendens, (ii) with other mosquito larvae, (iii) with water but without mosquito larvae, and (iv) without water. The number of larval Tx. splendens was calculated based on the developmental phase and other mosquito larvae present in each bowl. Environmental factors, such as temperature and humidity, rainfall, wind velocity, and duration of irradiation were the additional data. The results of this study showed that the average frequency of On average, over 20% of bowls contained larval Tx. splendens, and the percentage increased in high rainfall. During low rainfall in August and September, Tx. splendens used water-filled rubber sap bowls as breeding places. This study concludes that Tx. splendens can make use of water-filled rubber sap bowls as places for breeding. Each rubber sap bowl contained one or more individuals of instar larvae 2, and the number decreased as the developmental phase continued because of the limited volume of water in the bowl, cannibalism, and the number of other mosquito larvae as prey.

Do Sand Smelt (Atherina presbyter Cuvier, 1829) Larvae Discriminate among Conspecifics Using Different Sensory Cues?

The ability of shoaling fish to recognise and differentiate between potential groupmates may affect their fitness and survival. Fish are capable of social recognition and multiple sensory cues mediate the recognition mechanisms. This has been comprehensively studied for juvenile and adult freshwater species. However, the recognition ability and mechanisms intervening during the larval phase of marine species are yet poorly understood. Fish larvae are capable of discriminating conspecifics from heterospecifics based on chemical and/or visual cues, but whether this recognition occurs at finer scales, such as discerning among conspecifics of different reefs, is yet understudied. Here, we tested the hypothesis that larvae of a marine fish species, the sand smelt (Atherina presbyter Cuvier, 1829), are able to recognise and associate with conspecifics of their natal reef versus conspecifics of a non-natal reef based on three sensory modalities—chemical, visual, and chemical and visual simultaneously. Results do not support our hypothesis, but still provide evidence of group cohesion and indicate large differences in the relative importance of the different senses when associating with conspecifics, with visual cues playing a more important role than chemical cues alone.

Low winter precipitation, but not warm autumns and springs, threatens mountain butterflies in middle-high mountains

Low-elevation mountains represent unique model systems to study species endangered by climate warming, such as subalpine and alpine species of butterflies. We aimed to test the effect of climate variables experienced by Erebia butterflies during their development on adult abundances and phenology, targeting the key climate factors determining the population dynamics of mountain insects. We analysed data from a long-term monitoring of adults of two subalpine and alpine butterfly species, Erebia epiphron and E. sudetica (Nymphalidae: Satyrinae) in the Jeseník Mts and Krkonoše Mts (Czech Republic). Our data revealed consistent patterns in their responses to climatic conditions. Lower precipitation (i.e., less snow cover) experienced by overwintering larvae decreases subsequent adult abundances. Conversely, warmer autumns and warmer and drier springs during the active larval phase increase adult abundances and lead to earlier onset and extended duration of the flight season. The population trends of these mountain butterflies are stable or even increasing. On the background of generally increasing temperatures within the mountain ranges, population stability indicates dynamic equilibrium of positive and detrimental consequences of climate warming among different life history stages. These contradictory effects warn against simplistic predictions of climate change consequences on mountain species based only on predicted increases in average temperature. Microclimate variability may facilitate the survival of mountain insect populations, however the availability of suitable habitats will strongly depend on the management of mountain grasslands.

Hydatid Disease of the Liver Presenting as Spontaneous Cutaneous Fistula

Hydatid cyst (HD) disease is a parasitic infection produced by cysts containing the Echinococcus granulosus larval phase. Patients with HC are typically asymptomatic until incidentally diagnosed or when complications occur. A rare presentation of liver HC is spontaneous cutaneous fistualization; we report a 63- year-old female patient admitted in the hospital in 2019 (Al-Thora General Hospital, Ibb, Yemen) with an infected cutaneous fistula induced by a ruptured HC. The patient underwent laparotomy and partial cystectomy with excision of the fistula tract. The main purpose of this report is for physicians to consider this diagnosis when they face an unusual cutaneous fistula near HC common involved organs, especially in areas where the prevalence of this disease is high. We also briefly discuss the management and outcome of this disease. Keywords: Case Report; Complications; Cutaneous Fistula; Echinococcosis; Liver; Surgery.

Lethal and Sublethal Effects of Insecticides Used in Cotton on Harmonia Axyridis

The agriculture industry seeks to reconcile control tactics for pest management, necessitating studies of lethal and sublethal effects of insecticides on natural enemies. The effect of six insecticides with diverse modes of action—ethiprole, etofenprox, lambda-cyhalothrin, lambda-cyhalothrin + chlorantraniliprole, pymetrozine, and thiamethoxam + chlorantraniliprole—were evaluated after spraying on eggs, third-instar larvae, pupae, and adults of Harmonia axyridis , a generalist predator in cotton crops. Ethiprole was the only one that had no lethal effect on the predator at any stage of its development; however, it caused sublethal effects when applied to eggs (shortening of the larval phase and lower reproduction). Lambda-cyhalothrin caused high predator mortality after exposure at all stages. Due to the high compatibility between the ladybug H. axyridis and ethiprole, this compound is recommended for use in cotton integrated pest management programs. The other insecticides were harmful in lethal or sublethal tests, and further work in semifield and field conditions is required to confirm if they reduce H. axyridis populations.

Genetic Diversity and Population Structure of the Antarctic Toothfish, Dissostichus mawsoni, Using Mitochondrial and Microsatellite DNA Markers

The Antarctic toothfish, Dissostichus mawsoni, serves as a valuable fishery resource around the Antarctic Continent since 1997, managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Although delineating genetic or stock structure of populations is crucial for improving fishery management of this species, its number of genetic populations and genetic diversity levels remain ambiguous. In the present study, we assessed the population genetic and phylogeographic structure of the Antarctic toothfish across 20 geographic localities spanning from Subareas 88 (88.1, 88.2, and 88.3) to Subareas 58 (58.4 and 58.5) by using mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and 16S rRNA (16S) sequences and seven nuclear microsatellite loci. MtDNA revealed a low level of polymorphism (h = 0.571, π = 0.0006) with 40 haplotypes in 392 individuals, connected only by 1–5 mutational steps, which is indicative of shallow evolutionary history. Microsatellites showed a range of allelic richness (AR) from 6.328 (88.3 RB3) to 7.274 (88.3 RB6) within populations. Overall genetic diversity was generally higher in Subareas 58 than in Subareas 88, suggesting that effective population size (NE) is larger in Subareas 58. The results of population analyses using microsatellites suggest that the sampled populations are likely to comprise a well-admixed single gene pool (i.e., one genetic stock), perhaps due to high contemporary gene flow occurring during the prolonged larval phase of this fish. However, given weak, but significant microsatellite differentiation found in six population-pairs, the possibility of existence of multiple genetic populations could not be completely excluded. The mtDNA AMOVA suggests a genetic break between the Subareas 88 and 58 groups (FCT = 0.011, P = 0.004). Moreover, mtDNA genetic distances (FST) between populations were proportionally greater as geographic distances increase. The patterns of isolation by distance (IBD) shown only in mtDNA, but not in microsatellites might suggest that population differentiation or divergence processes underwent faster in mtDNA than microsatellites, due to its NE being only one-quarter of nuclear DNA. Temporal stability in the genetic structure of D. mawsoni is also indicated by the results of no genetic differentiation between juveniles and adults. The findings of this study will help to design effective stock management strategies for this valuable fishery resource. We suggest that a long-term genetic monitoring is needed to understand the population structure and dynamics of toothfish in response to ongoing climate changes.