Egg Oviposition Research Articles

Effect of egg weight and oviposition time on hatchability and post hatch performance of Japanese quail (Coturnix coturnix japonica)

A total of three hundred (300) Japanese quail eggs were used to study the effect of oviposition time and egg weight on hatchability and post-hatch performance. The eggs were grouped into two (2) of 150 eggs based on the oviposition time of Morning and Afternoon. The eggs in each group (150) were further sub-grouped based on the egg weights of 8 to10 grams designated as small sized and 10.1 to 12 grams designated as big size in a 2 x 2 factorial design trial of 4 treatments. Each treatment had seventy five (75) eggs each with three replicates. The four treatments groups were; Big Morning, Small Morning, Big Afternoon, Small Afternoon. Each treatment group was replicated three times with each replicates consisting of twenty-five (25) eggs. Hatchability parameters were determined during incubation period of 18 days. The quail chicks were fed ad-libitum and the post- hatch performance was studied for eight (8) weeks. The data generated were subjected to a one-way analysis of variance. Oviposition time and size of the egg significantly (p<0.05) affected the average hatch weight. The effect of interaction of oviposition time and egg size on post-hatch performance did not have any significant (p>0.05) influence. Oviposition time had a positive correlation (p<0.05) with egg weight, egg weight loss, percent egg weight loss and fertility percentage but negatively correlated with average hatch weight and hatchability percentage. Meanwhile egg size had a positive significant (p<0.01) correlation with average hatch weight. It was concluded that eggs ranging between 10.1 to 12 grams will produce higher hatch weight. However, setting of Japanese quail eggs ranging between 8 to 12 grams irrespective of oviposition time could not affect post-hatch performance of the chicks.

Resistance of Phaseolus vulgaris genotypes to Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae): categories and mechanisms

Information on Phaseolus vulgaris L. resistance categories and mechanisms to the Mexican bean weevil Zabrotes subfasciatus Boheman (Coleoptera: Chrysomelidae: Bruchinae) is important for breeding and subsequent commercialization of improved P. vulgaris genotypes. Using resistant genotypes in the bruchid beetles control may reduce insecticide applications, environmental risks, and production costs. Therefore, the objective of this study was to evaluate antixenosis and antibiosis of P. vulgaris genotypes to Z. subfasciatus and the relation of bromatological components on resistance. Free- and no-choice tests were carried out in a climate-controlled room (temperature 25 ± 1 °C, relative humidity 70 ± 10%, and 12:12 h light:dark photoperiod). Host selection for oviposition, total and viable numbers of eggs, emerged adults, egg to adult period (life cycle), adult longevity, and dry mass consumed of Z. subfasciatus were evaluated on 10 P. vulgaris genotypes. Bean samples of P. vulgaris genotypes were subjected to a bromatological analysis to determine possible resistance mechanisms. In the oviposition antixenosis, none of the P. vulgaris genotypes showed resistance to Z. subfasciatus. Contrastingly, the genotypes Raz 59, 173, 177, 179, 283, 284, 361, and 364 showed resistance in the categories of feeding antixenosis and/or antibiosis to Z. subfasciatus. On average, these genotypes reduced the number of emerged adults in 95.9%, the dry mass consumed in 88.3%, and increased the Z. subfasciatus life cycle in 40.3% compared to susceptible genotypes (IAC Alvorada and 178). Crude protein content in the resistant genotypes was on average 10.9% higher than in the susceptible genotypes. Some proteins, such as arcelin, have antibiotic effects on bruchid beetles, indicating that a higher protein content in resistant genotypes may have been one of the mechanisms responsible for antibiosis of these genotypes to Z. subfasciatus.

Cuidado maternal en Omaspides bistriata Boheman (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini)

Maternal care (subsociality): characterization of the different stages of maternal care and its efficiency as a strategy. Maternal care and larval development of Omaspides bistriata Boheman, 1862 (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini) are described; including characteristics and manner in which maternal care is given across the different stages of development of the specie (eggs, larvae, pupae and teneral adults). We report the oviposition of eggs, the duration to hatch the eggs, and the duration of larval period, pupal stage, and emergence. A life table and survival curve is presented covering all life stages. Changes in the behavior and feeding habits are also noted for the immatures and the attending mother.

Mortality of light brown apple moth egg masses in coastal California: Impact of resident Trichogramma parasitism and predation

Egg mortality of light brown apple moth (LBAM), Epiphyas postvittana (Walker), was studied during the early years of its discovery and establishment in California from 2008 to 11. Sentinel egg cards were used to quantify mortality by parasitoids and predators at an intensively monitored location in Santa Cruz to reveal seasonality, and at other sites in Santa Cruz and San Francisco to measure spatial variation and parasitoid species composition. In addition to egg mortality, egg mass use efficiency by Trichogramma parasitoids was also examined under field conditions. The egg parasitoids primarily consisted of three Trichogramma species, T. deion, T. fasciatum and T. platneri. Previously unknown to California, T. fasciatum was shown to displace the indigenous T. platneri over a two-year period as the predominant egg parasitoid attacking LBAM egg masses. Based on the number of parasitized eggs per sentinel egg card, it is argued that individual females of at least some Trichogramma species have the capacity to oviposit more than 50 eggs in the egg mass of a host, warranting further studies to document the egg mass use efficiency and oviposition traits of other trichogrammatids under field conditions. Although egg parasitism was limited to causing elevated mortality during the summer and fall only, egg predation occurred more consistently throughout the year and is likely to be of considerable significance in suppressing LBAM populations in California. Combined with the use of a Type II survivorship curve, the importance of using a temperature-dependent physiological time scale to quantify egg mortality is illustrated when sentinel hosts are exposed to natural enemies in the field for less than the entire duration of the ‘window of susceptibility’ to parasitism and predation.

Spatio‐temporal dynamics of Aedes aegypti and Aedes albopictus oviposition in an urban area of northeastern Brazil

The objective of this study was to analyse abundance and spatial distribution of Aedes aegypti and Aedes albopictus oviposition in the city of Natal-RN, 2016 to 2018. Three hundred and seven oviposition traps were installed covered the whole city and were monitored weekly from January 2016 to December 2018. To verify the abundance of the vector based on its location, the formation of oviposition clusters was studied using the Kernel statistics. Egg Density Index (EDI) and Oviposition Positivity Index (OPI) values were calculated. Temperature and humidity presented weak and very weak correlation, respectively, with the oviposition indicators. The median of oviposition positivity index (OPI) was 60.5%, and the egg density index (EDI) was 45.4 eggs/trap. The OPI (71.1%) was higher in the second quarter of the year. The areas with the most persistent oviposition are located in a continuous strip that extends from the extreme of the northern district and extends along the western district of the city. Also noteworthy is the proximity to the strategic points. The spatio-temporal distribution of oviposition revealed that there is spatial segregation and marked seasonality. Therefore, this study highlights the importance of maintaining surveillance targeting and control strategies focused on these areas, especially during the most important period of the year.

Lizard Embryos Prioritize Posthatching Energy Reserves over Increased Hatchling Body Size during Development

Embryonic development in oviparous organisms is fueled by maternally allocated yolk, and many organisms hatch before that energy store is used completely; the resultant leftover (residual) yolk is internalized and may support early posthatching life. However, embryos that use most, or all, of their yolk supply before hatching should hatch at a larger size than those that do not exhaust those energy reserves, which could also have benefits for posthatching growth and survival. To examine the trade-off between residual yolk and offspring size, we experimentally reduced yolk quantity at oviposition in lizard eggs (Amphibolurus muricatus) and then quantified offspring size and the amount of internalized residual yolk. This design enabled us to determine whether embryos (1) exhaust yolk supply during development (thereby maximizing neonatal size) or (2) reduce neonatal size by retaining yolk reserves at hatching. Our data support the latter scenario. Eggs from the yolk-reduced treatment produced smaller offspring with a proportion of residual yolk similar to that of offspring from unmanipulated eggs, suggesting that the fitness benefits of posthatching energy stores outweigh those of larger neonatal size.

JNK signaling regulates oviposition in the malaria vector Anopheles gambiae

The reproductive fitness of the Anopheles gambiae mosquito represents a promising target to prevent malaria transmission. The ecdysteroid hormone 20-hydroxyecdysone (20E), transferred from male to female during copulation, is key to An. gambiae reproductive success as it licenses females to oviposit eggs developed after blood feeding. Here we show that 20E-triggered oviposition in these mosquitoes is regulated by the stress- and immune-responsive c-Jun N-terminal kinase (JNK). The heads of mated females exhibit a transcriptional signature reminiscent of a JNK-dependent wounding response, while mating—or injection of virgins with exogenous 20E—selectively activates JNK in the same tissue. RNAi-mediated depletion of JNK pathway components inhibits oviposition in mated females, whereas JNK activation by silencing the JNK phosphatase puckered induces egg laying in virgins. Together, these data identify JNK as a potential conduit linking stress responses and reproductive success in the most important vector of malaria.

Intrinsic competition between two European egg parasitoids of the brown marmorated stink bug

AbstractFollowing the accidental introduction and spread of the invasive polyphagous agricultural pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), the two European egg parasitoids Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) have been investigated for inundative biological control. Since the competititve outcome between the two generalist parasitoids is difficult to predict, intrinsic competition was investigated with a time‐course development study. Both species readily oviposited in H. halys eggs containing eggs and early instar larvae of the competitor, but oviposition decreased when eggs contained late instar larvae and pupae. Ooencyrtus telenomicida offspring emergence from multiparasitized eggs was significantly lower than that from rearing controls, independent of the order of parasitization. Anastatus bifasciatus offspring emergence was not influenced by the presence of O. telenomicida when it parasitized as the first species, but emergence was decreased after oviposition in eggs containing O. telenomicida larvae and pupae. There was no indication that O. telenomicida can act as a facultative hyperparasitoid of A. bifasciatus. These results suggest that A. bifasciatus is the superior intrinsic competitor and no or minor negative implications for A. bifasciatus are expected if released in combination with O. telenomicida.

Adult feeding and host type modulate the life history traits of the capital breeder Zabrotes subfasciatus

AbstractIncome breeding animals support reproduction by the intake of energy and molecular building blocks during adulthood. Capital breeders, in contrast, fuel reproduction by the intake of materials during the larval stage. There exists, however, some controversy as to whether adult feeding in capital breeders actually increases fitness. We tested whether individuals feed as adults in the weevil Zabrotes subfasciatus Boheman, whether they equally accept carbohydrate‐ or nitrogen‐rich food (sugar or yeast), whether food ingestion varies with the available host type and whether feeding as adults alters life history traits. The hosts tested were three varieties of Phaseolus vulgaris, Carioca, Jalo, and Preto; Vigna unguiculata Frade; and Vicia faba. We also tested whether sugar ingestion affects life history traits differently in the presence of different host types. We found that Z. subfasciatus feed as adults and equally accept sugar and yeast, and food ingestion depends on host type. Sugar and yeast significantly promote oviposition of larger eggs on Carioca seeds and enhance adult emergence, and sugar ingestion increases longevity. Moreover, the insects avoid feeding when on V. faba seeds, on which they did not oviposit. Mean fitness values showed the following hierarchy: Carioca = Jalo > Frade > Preto > V. faba. These results show that the capital breeder Z. subfasciatus feed as adults, which increases life history traits and suggests the existence of a hierarchy of performance on different hosts, with the P. vulgaris varieties Carioca and Jalo offering the best conditions.

Exposure to Lead (Pb2+) Eliminates Avoidance of Pb-Treated Oviposition Substrates in a Dose-Dependent Manner in Female Vinegar Flies.

Female vinegar flies (Drosophila melanogaster) preferentially oviposit eggs on oviposition substrates that decrease larval foraging costs. We tested whether female D. melanogaster would avoid oviposition substrates containing lead (Pb2+), which could potentially decrease offspring fitness. Wild type D. melanogaster were reared on control or Pb-treated medium from egg stage to adulthood and tested for differences in oviposition substrate preference, fecundity (number of eggs laid) and Pb accumulation. Control females laid a significantly lower proportion of eggs on Pb-treated substrates than Pb-treated females. Pb-treated females laid significantly more eggs than control females. Pb-treated adults accumulated significantly more Pb than control-treated adults. These results indicate that Pb exposure disrupts normal oviposition avoidance behaviors, which could increase larval foraging costs for larval offspring. These factors could induce population declines and have cascading implications for the ecosystem.

The antischistosomal potential of GSK-J4, an H3K27 demethylase inhibitor: insights from molecular modeling, transcriptomics and in vitro assays

BackgroundSchistosomiasis chemotherapy is largely based on praziquantel (PZQ). Although PZQ is very safe and tolerable, it does not prevent reinfection and emerging resistance is a primary concern. Recent studies have shown that the targeting of epigenetic machinery in Schistosoma mansoni may result in severe alterations in parasite development, leading to death. This new route for drug discovery in schistosomiasis has focused on classes of histone deacetylases (HDACs) and histone acetyltransferases (HATs) as epigenetic drug targets. Schistosoma histone demethylases also seem to be important in the transition of cercariae into schistosomula, as well as sexual differentiation in adult worms.MethodsThe Target-Pathogen database and molecular docking assays were used to prioritize the druggability of S. mansoni histone demethylases. The transcription profile of Smp_03400 was re-analyzed using available databases. The effect of GSK-J4 inhibitor in schistosomula and adult worms’ motility/viability/oviposition was assessed by in vitro assays. Ultrastructural analysis was performed on adult worms exposed to GSK-J4 by scanning electron microscopy, while internal structures and muscle fiber integrity was investigated by confocal microscopy after Langeronʼs carmine or phalloidin staining.ResultsThe present evaluation of the potential druggability of 14 annotated S. mansoni demethylase enzymes identified the S. mansoni ortholog of human KDM6A/UTX (Smp_034000) as the most suitable druggable target. In silico analysis and molecular modeling indicated the potential for cofactor displacement by the chemical probe GSK-J4. Our re-analysis of transcriptomic data revealed that Smp_034000 expression peaks at 24 h in newly transformed schistosomula and 5-week-old adult worms. Moreover, this gene was highly expressed in the testes of mature male worms compared to the rest of the parasite body. In in vitro schistosome cultures, treatment with GSK-J4 produced striking effects on schistosomula mortality and adult worm motility and mortality, as well as egg oviposition, in a dose- and time-dependent manner. Unexpectedly, western blot assays did not demonstrate overall modulation of H3K27me3 levels in response to GSK-J4. Confocal and scanning electron microscopy revealed the loss of original features in muscle fibers and alterations in cell-cell contact following GSK-J4 treatment.ConclusionsGSK-J4 presents promising potential for antischistosomal control; however, the underlying mechanisms warrant further investigation.

Comprehensive and Durable Modulation of Growth, Development, Lifespan and Fecundity in Anopheles stephensi Following Larval Treatment With the Stress Signaling Molecule and Novel Antimalarial Abscisic Acid.

The larval environment of holometabolous insects determines many adult life history traits including, but not limited to, rate and success of development and adult lifespan and fecundity. The ancient stress signaling hormone abscisic acid (ABA), released by plants inundated with water and by leaf and root fragments in water, is likely ubiquitous in the mosquito larval environment and is well known for its wide ranging effects on invertebrate biology. Accordingly, ABA is a relevant stimulus and signal for mosquito development. In our studies, the addition of ABA at biologically relevant levels to larval rearing containers accelerated the time to pupation and increased death of A. stephensi pupae. We could not attribute these effects, however, to ABA-dependent changes in JH biosynthesis-associated gene expression, 20E titers or transcript patterns of insulin-like peptide genes. Adult females derived from ABA-treated larvae had reduced total protein content and significantly reduced post blood meal transcript expression of vitellogenin, effects that were consistent with variably reduced egg clutch sizes and oviposition success from the first through the third gonotrophic cycles. Adult female A. stephensi derived from ABA-treated larvae also exhibited reduced lifespans relative to controls. Collectively, these effects of ABA on A. stephensi life history traits are robust, durable and predictive of multiple impacts of an important malaria vector spreading to new malaria endemic regions.

Plant responses to butterfly oviposition partly explain preference\u2013performance relationships on different brassicaceous species

The preference–performance hypothesis (PPH) states that herbivorous female insects prefer to oviposit on those host plants that are best for their offspring. Yet, past attempts to show the adaptiveness of host selection decisions by herbivores often failed. Here, we tested the PPH by including often neglected oviposition-induced plant responses, and how they may affect both egg survival and larval weight. We used seven Brassicaceae species of which most are common hosts of two cabbage white butterfly species, the solitary Pieris rapae and gregarious P. brassicae. Brassicaceous species can respond to Pieris eggs with leaf necrosis, which can lower egg survival. Moreover, plant-mediated responses to eggs can affect larval performance. We show a positive correlation between P. brassicae preference and performance only when including the egg phase: 7-day-old caterpillars gained higher weight on those plant species which had received most eggs. Pieris eggs frequently induced necrosis in the tested plant species. Survival of clustered P. brassicae eggs was unaffected by the necrosis in most tested species and no relationship between P. brassicae egg survival and oviposition preference was found. Pieris rapae preferred to oviposit on plant species most frequently expressing necrosis although egg survival was lower on those plants. In contrast to the lower egg survival on plants expressing necrosis, larval biomass on these plants was higher than on plants without a necrosis. We conclude that egg survival is not a crucial factor for oviposition choices but rather egg-mediated responses affecting larval performance explained the preference–performance relationship of the two butterfly species.

Mathematical analysis of a spatio‐temporal model for the population ecology of anopheles mosquito

We propose a novel model for the population dynamics of mosquitoes by considering the dispersal states of female mosquitoes of oviposition's cycle and spatial variations. From the modeling perspective, a general functional form of eggs oviposition rate is used including the Malthusian, the Verhlust‐Pearl logistic, the Hassell, and the Maynard‐Smith‐Slatkin functions. From the theoretical and numerical perspectives, the study is done in two steps using the more realistic birth Maynard‐Smith‐Slatkin function. First, we consider an ordinary differential equations model and show that the mosquito‐free equilibrium (MFE) is globally asymptotically stable, whenever the basic offspring number is less than unity. Using a fluctuation argument, we prove that the unique mosquito‐persistent equilibrium (MPE) is globally attractive, whenever exceeds the unity. Moreover, the temporal model undergoes a Hopf bifurcation in the absence of density‐dependent mortality in the aquatic stage of mosquitoes. Second, the temporal model is extended into an advection‐reaction‐diffusion model in order to account for the movement of mosquitoes and their spatial source of heterogeneity. We establish the uniform persistence and the existence of at least one positive steady state whenever the spatial basic offspring number is greater than unity. Finally, for the case study of malaria vector agent (Anopheles mosquito), we construct a nonstandard finite difference scheme that is dynamically consistent with the features of the continuous model to illustrate our results, including the spatial heterogeneity of mosquito resources.

In vitro Assessment of Period of Oviposition and Hatching in Hyalomma anatolicum anatolicum

Hyalomma anatolicum anatolocum is one of the most important tick species in India (Geeverghese and Dhanda, 1987), which assumed noticeable importance because of its role as the major vector of the hemoprotozoan parasites. Besides, the role of Hyalomma species in transmitting the Crimean-Congo hemorrhagic fever (CCHF) virus in humans has been established in different countries (Karti et al., 2004). Ticks produce severe economic losses through blood-sucking and acting as vectors of pathogens and toxins. In India alone, the cost of tick and tick-borne diseases (TTBDs) in animals has been estimated to the tune of approx. Two thousand crores (Ghosh et al., 2007). Scanty literature is available pertaining to the life cycle of H. a. anatolicum in general and from Madhya Pradesh in particular. Therefore, the present study was designed to record the period of oviposition and hatching of eggs in H. a. anatolicum.

Oviposition site preference and reproductive ecology of Teratohyla midas (Anura: Centrolenidae) in the Colombian Amazon

ABSTRACTThe family Centrolenidae (Glass frogs) includes 157 species of anurans with a Neotropical distribution. Although glass frogs have been the subject of several studies encompassing various aspects of their biology, natural history data on their reproductive ecology is still scarce. One of the important aspects of reproductive ecology is the oviposition site since it can impact the reproductive success of a species. Herein, we provide detailed information on the reproductive ecology of a population of Teratohyla midas from the Colombian Amazon foothills and test whether this species shows a preference on substrate and height of oviposition site. We monitored a population using capture-mark-recapture of individuals identified by a photograph of their unique pattern of dorsal yellow spots. Wild-ID Software was used to corroborate if the dorsal pattern was different between individuals. Additionally, we monitored the presence of egg clutches, amplexus and oviposition behaviour. We observed 110 males and 5 females of T. midas, seen at an average height of 3.1 m ± 2.9 (0–17.8 m) from the ground. Likewise, we recorded the amplexus behaviour of two pairs for approximately 150 min. Once the oviposition happened, the male retreated, and the female covered the egg clutches for approximately 60 min. We observed 25 egg clutches with 60% being deposited in leaves of Selaginella sp and found at an average height of 2.9 ± 1.7 m (1.1–7.0 m). Thus, the selection of oviposition site was not random but mostly specific to one type of substrate. Furthermore, there was an overlap of the re-sampled median height distributions of active individuals and clutches, which suggests that oviposition does not occur at a preferred height within the vertical distribution of individuals. The information presented here is the first detailed record of reproductive ecology for this species and we hope to provide a basis to improve our knowledge on the biology of this species and other glass frogs.

Study on Oviposition and Hatching Period in Rhipicephalus(Boophilus) Microplus (Acari: Ixodidae) under Laboratory Conditions

Ticks are highly specialized distributed worldwide obligatehematophagous ectoparasites of mammals, birds, and reptiles. Amongst the species of ticks infecting cattle in India, Rhipicephalus microplus is the most widely distributed tick and established as the principal vectors of pathogens like Babesia and Anaplasma species (Ghosh and Nagar, 2014). Changes in the ovipositional and hatching pattern of these parasites are observed depending on the atmospheric conditions. Severalextrinsic factors Such as rainfall, temperature, humidity,floods, winds and physical damage affect the successful reproductive performance and survival of ixodid ticks after detachment from their hosts (Dipeolu, 1984). This study was aimed to evaluate the period of oviposition and hatching of eggs in engorged female ticks R.(B.) microplus collected from cattle in and around Indore.

A non‐pollinating moth inflicts higher seed predation than two co‐pollinators in an obligate pollination mutualism

1. Mutualisms are relationships of mutual exploitation, in which interacting species receive a net benefit from their association. In obligate pollination mutualisms (OPMs), female pollinators move pollen between the flowers of a single plant species and oviposit eggs within the female flowers that they visit.2. Competition between co‐occurring pollinator species is predicted to increase pollinator virulence, i.e. laying more eggs or consuming more seeds per fruit. Plants involved in OPMs frequently host various non‐pollinating seed parasites and parasitoids that may influence the outcome of the mutualism. Quantifying the prevalence of parasites and parasitoids and competition between pollinators is important for understanding the factors that influence OPM evolutionary stability.3. This study investigated the pollination mutualism occurring between the leaf flower plant, Breynia oblongifolia, and its co‐pollinating Epicephala moths. A third moth, Herpystis, also occurs in B. oblongifolia fruits as a non‐pollinating seed parasite.4. Breynia oblongifolia fruits were collected to quantify seed predation and compare seed predation costs between the three moth species. Results showed that the larvae of the two pollinator species consume similar numbers of seeds, and that adults deposit similar numbers of eggs per flower. As such, no evidence of increases in virulent behaviours was detected as a result of competition between co‐pollinators.5. By contrast, the seed parasite Herpystis consumed more seeds than either pollinator species, and fruit crops with a high proportion of Herpystis had significantly lower net seed production.6. This work adds to the growing understanding of the ecology and dynamics of plant–pollinator mutualisms.

First detection of ivermectin resistance in oesophagostomum dentatum in pigs

In 2016 suspected reduced ivermectin (IVM) efficacy in Oesophagostomum species in pigs was reported in England. Following this initial report, APHA raised awareness amongst private pig veterinary practitioners of the need to monitor the efficacy of the worm control on pig units. In 2017 another veterinary practitioner highlighted a potential in-field lack of IVM efficacy in treating Oesophagostomum species in sows on another breeder-finisher unit. In this trial, the efficacy of IVM against Oesophagostomum species worms has been investigated to determine whether suspected reduced efficacy (52% reduction in mean faecal egg count 14 days post ivermectin administration) on a mixed indoor and outdoor breeder-finisher pig farm in England reflected true IVM resistance under controlled experimental conditions. On days 0 and 40 of the trial, twenty helminth-naive pigs were artificially infected per os with 5000 Oesophagostomum L3 obtained from the farm under investigation. The pigs were allocated to treatment or control groups (n = 10 per group). Treatment group pigs received IVM (0.3 mg kg body weight) by sub-cutaneous injection as per manufacturer’s instructions on day 44. Control group animals were left untreated. Faecal worm egg counts were monitored throughout the trial from day 15 post infection to determine time to patency. On day 50 all pigs were euthanased to assess the worm burdens. Resistance to IVM was confirmed in Oesophagostomum dentatum based on the results of a faecal egg count reduction test (FECRT) and a controlled efficacy test (CET). Efficacy based on mean reduction in faecal egg count of IVM-treated pigs compared to untreated control pigs was 86%. Mean reduction in IVM-treated pig worm burdens was 5% against an adult worm population and 94% against an L3/L4 population. The apparent discrepancy between FECRT and CET efficacy results appears to be due to egg development and/or oviposition suppression in IVM-treated female worms. The detection of IVM resistance in Oesophagostomum species worms for the first time in UK pigs is particularly important considering the global situation where resistance to pyrantel, levamisole and benzimidazole anthelmintics in Oesophagostomum species in pigs have already been reported. The results also provide an opportunity to discuss the wider issue of anthelmintic usage and efficacy on pig farms and highlight the need for wider surveillance for the occurrence of anthelmintic resistance in pigs.

Bombyxin/Akt signaling in relation to the embryonic diapause process of the silkworm, Bombyx mori

Our previous study showed that phosphorylation of glycogen synthase kinase (GSK)-3β is related to the embryonic diapause process in Bombyx. However, the upstream signaling pathway was not clearly understood. In the present study, we examined bombyxin/Akt signaling in relation to the embryonic diapause process of B. mori. Results showed that GSK-3β phosphorylation stimulated by dechorionation was blocked by LY294002, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, indicating involvement of PI3K in GSK-3β phosphorylation in dechorionated eggs. Direct determination of Akt phosphorylation showed that dechorionation stimulated Akt phosphorylation. The Akt phosphorylation was blocked by LY294002. Temporal changes in Akt phosphorylation showed that different changing patterns exist between diapause and developing eggs. Relatively higher phosphorylation levels of Akt were detected between days 3 and 5 after oviposition in non-diapause eggs compared to those at the same stages in diapause eggs. Upon treatment with HCl, which prevents diapause initiation, Akt phosphorylation levels exhibited a later and much broader peak compared to diapause eggs. Examination of expression levels of the bombyxin-Z1 gene showed that in diapause eggs, a major peak occurred 1 day after oviposition, and its level then sharply decreased on day 2. However, in both non-diapause and HCl-treated eggs, a major broad peak was detected between days 1 and 4 after oviposition. These temporal changes in bombyxin-Z1 gene expression levels during embryonic stages coincided with changes in Akt phosphorylation, indicating that bombyxin-Z1 is likely an upstream signaling component for Akt phosphorylation. Taken together, our results indicated that PI3K/Akt is an upstream signaling pathway for GSK-3β phosphorylation and is associated with the diapause process of B. mori eggs. To our knowledge, this is the first study to demonstrate the potential correlation between bombyxin/Akt signaling and the embryonic diapause process.