Artificial heat waves induce species-specific plastic responses on reproduction of two spider mite predators

Climate change models predict that the frequency, intensity and duration of heat waves will increase in the next decades. Heat waves can have profound impact on the reproduction of biocontrol agents ranging from postponing oviposition to manipulating offspring quantity via egg number and quality via egg size. Such species-specific responses of biocontrol agents to heat stress may also affect their success in controlling the target pest. Here, we evaluated the predation and reproductive performance of the two spider mite predators Phytoseiulus persimilis and Neoseiulus womersleyi exposed to simulated mild, moderate and extreme heat wave conditions over three days. Irrespective of heat wave conditions, all N. womersleyi females survived, whereas 12% of the P. persimilis females died. Both species responded to heat stress via plastic modifications resulting in increased predation rates and smaller egg sizes. Significantly more P. persimilis females postponed oviposition during the experimental phase than N. womersleyi. The deposited egg number of Phytoseiulus persimilis was not affected by heat wave conditions. On the contrary, the reproductive output of N. womersleyi was a function of temperature, i.e., the higher the temperature, the higher the number of deposited eggs. These findings indicate that P. persimilis is more heat sensitive in relation to reproduction than N. womersleyi. However, further investigations of heat wave effects on other fitness-related traits and their consequences at population level are needed to find out whether N. womersleyi is an alternative or supplement to P. persimilis as spider mite control agent under heat waves.

Observation on the reproductive behavior and embryo of the daisy’s ricefish, Oryzias woworae in laboratory condition

Oryzias woworae is an endemic ricefish from Muna Island, Southeast Sulawesi, traded as an ornamental fish. Information on the biology of these fish is very lacking, including their reproductive. These fish also face the threat of population decreasing in the wild. The research aimed to examine the spawning behavior and embryonic of O. woworae as the basis for aquaculture. Fish spawning was carried out using 1 male: 1 female ratio, which was repeated three times. The observed spawning behavior was pre-spawning, mating process, egg number, and morphology. Behavioral observations were carried out for five days of spawning. Observation of embryos was carried out to see the stages of embryo development until hatching. The results obtained on pre-spawning behavior were changes in body color and blackened fins in males, which did not occur in female fish. Males actively swim by approaching their dorsal and anal fins while chasing females. The female releases the eggs and is attached to the substrate, rapidly fertilized by the male fish. There is a phenomenon of females carrying eggs on the genital pore before being released to the substrate (non-pelvic brooder). Spawning only occurs during the day, and spawning is getting faster, which is at 09:00 AM on the fifth day. Oryzias woworae eggs have a diameter of 1.3 ± 0.2 mm, equipped with attaching and non-attaching filaments. Observations of O. woworae embryos showed that embryo hatching occurred at seven days 23 hours post-fertilization.

Influence of dietary protein levels and some cold pressed oil supplementations on productive and reproductive performance and egg quality of laying Japanese quail

The present study was carried out to examine the effect of dietary protein levels (18, 20, and 22%) and addition of cold-pressed oils (no addition, 1 g thyme, 1 g oregano, and 0.5 g thyme + 0.5 g oregano /kg diet) on the productive and reproductive performance and egg quality of Japanese quail at the laying period. 324 mature ten-week-old Japanese quails (216 females and 108 males) were used. Quails were randomly distributed to 12 treatment groups, 27 in each group, with 3 replicates of 9 quails (6 females and 3 males) per group. Feed conversion ratio (FCR) significantly improved in the layers fed with the diets containing 20 or 22% CP in all experimental periods, except in 3- to 4-month-old birds. The diets supplemented with thyme only or interaction with oregano improved FCR significantly compared to the control or oregano -administered group in all experimental periods, except in 2- to 3-month-old birds. Dietary supplementation with thyme oil caused the egg number and egg mass to increase significantly in all experimental periods compared to the other dietary groups. Fertility percentages were significantly higher in the groups which had oregano than in the control group. Dietary supplementation with thyme oil significantly increased the egg number (P<0.05) and egg mass (P<0.01) in all experimental periods compared to other dietary groups. Fertility and hatchability percentages were not significantly affected due to varying dietary protein levels throughout the experiment. In conclusion, the quails fed with a diet containing 20 to 22% CP or supplemented with oregano or thyme oil exhibited an improved productive and reproductive performance without any detrimental impacts on the other parameters studied.

Genetic effects on growth and egg production traits in two-way crosses of Egyptian and commercial layer chickens

A crossbreeding experiment was conducted between the Sinai (SI), an indigenous Egyptian strain, and the exotic Lohmann Brown (LB) breeds of chickens. A total of 790 chicks were produced in four genetic groups, namely SI x SI, LB x LB, SI x LB, and LB x SI. The objective was to estimate the direct additive effect (gi), individual heterosis (hi), and maternal additive effect (gm) for growth and reproduction traits. Direct additive effects were positive (P ≤0.01) for bodyweight (BW) at 4, 8, and 12 weeks old in favour of SI. For egg production traits, gi was positive for age at sexual maturity (ASM) and age at which the first 10 eggs were produced (P10), but negative for mean 10 egg production (MP10), egg number at 90 days (EN90),mean egg number at 90 days (MEN90), and egg mass (EM). The estimates of heterosis (%) were high for BW and daily gain except for BW0. Maternal effect estimates of BW and daily weight gain were significant (P <0.05) only for bodyweight at hatching (BW0), bodyweight at 4 weeks old (BW4) and daily weight gain from four to eight weeks old (DWG4-8). Thus, the Sinai and Lohmann Brown crossbreed produced favourable heterosis on the growth of the chicks. As an adapted indigenous strain, SI should be regarded as a dam line in crossing with LB, which has greater genetic potential for growth. Use of LB as a sire strain in conjunction with Sinai would increase egg production from the resulting hybrid chickens.

Identification of candidate genomic regions for chicken egg number traits based on genome-wide association study

Background Since the domestication of chicken, various breeds have been developed for food production, entertainment, and so on. Compared to indigenous chicken breeds which generally do not show elite production performance, commercial breeds or lines are selected intensely for meat or egg production. In the present study, in order to understand the molecular mechanisms underlying the dramatic differences of egg number between commercial egg-type chickens and indigenous chickens, we performed a genome-wide association study (GWAS) in a mixed linear model. Results We obtained 148 single nucleotide polymorphisms (SNPs) associated with egg number traits (57 significantly, 91 suggestively). Among them, 4 SNPs overlapped with previously reported quantitative trait loci (QTL), including 2 for egg production and 2 for reproductive traits. Furthermore, we identified 32 candidate genes based on the function of the screened genes. These genes were found to be mainly involved in regulating hormones, playing a role in the formation, growth, and development of follicles, and in the development of the reproductive system. Some genes such as NELL2 (neural EGFL like 2), KITLG (KIT ligand), GHRHR (Growth hormone releasing hormone receptor), NCOA1 (Nuclear receptor coactivator 1), ITPR1 (inositol 1, 4, 5-trisphosphate receptor type 1), GAMT (guanidinoacetate N-methyltransferase), and CAMK4 (calcium/calmodulin-dependent protein kinase IV) deserve our attention and further study since they have been reported to be closely related to egg production, egg number and reproductive traits. In addition, the most significant genomic region obtained in this study was located at 48.61–48.84 Mb on GGA5. In this region, we have repeatedly identified four genes, in which YY1 (YY1 transcription factor) and WDR25 (WD repeat domain 25) have been shown to be related to oocytes and reproductive tissues, respectively, which implies that this region may be a candidate region underlying egg number traits. Conclusion Our study utilized the genomic information from various chicken breeds or populations differed in the average annual egg number to understand the molecular genetic mechanisms involved in egg number traits. We identified a series of SNPs, candidate genes, or genomic regions that associated with egg number, which could help us in developing the egg production trait in chickens.

Facultative and obligate diapause phenotypes in populations of the European spruce bark beetle Ips typographus

The bark beetle Ips typographus is the most destructive insect pest in Norway spruce-dominated forests. Its potential to establish multiple generations per year (multivoltinism) is one major trait that makes this beetle a severe pest. Ips typographus enters diapause to adjust its life cycle to seasonally changing environments. Diapause is characterized by developmental and reproductive arrest; it prolongs generation time and thus affects voltinism. In I. typographus a facultative, photoperiod-regulated diapause in the adult stage has been described. In addition, the presence of an obligate, photoperiod-independent, diapause has been hypothesized. The diapause phenotype has important implications for I. typographus voltinism, as populations with obligate diapausing individuals would be univoltine. To test for the presence of different I. typographus diapause phenotypes, we exposed Central and Northern European individuals to a set of photoperiodic treatments. We used two ovarian traits (egg number and vitellarium size) that are associated with gonad development, to infer reproductive arrest and thus diapause. We found a distinct effect of photoperiod on ovarian development, with variable responses in Central and Northern European beetles. We observed obligate diapausing (independent of photoperiod) individuals in Northern Europe, and both facultative (photoperiod-regulated) as well as obligate diapausing individuals in Central Europe. Our results show within-species variation for diapause induction, an adaptation to match life cycles with seasonally fluctuating environmental conditions. As the diapause phenotype affects the potential number of generations per season, our data are the basis for assessing the risk of outbreaks of this destructive bark beetle.

Commission test of the efficacy of the supramolecular complex of ivermectin against gastrointestinal strongylatoses of horses

The purpose of the research is a commission test of the efficacy of the supramolecular complex of ivermectin at gastrointestinal strongylatoses of horses.Materials and methods. The commission experiment was performed in June 2019 in the North Caucasian Federal District of the Chechen Republic. The efficacy of the supramolecular complex of ivermectin was evaluated on 20 horses of different breeds in the Seradin Equestrian Center. To determine the rate of gastrointestinal nematode infection in horses, we collected fresh feces in the morning, made tissue imprints from perianal folds and examined them by the Fülleborn's method using a saturated solution of sodium chloride.Results and discussion. The coproovoscopic examination determined a 100% infection of horses with Strongylates and 40.0% infection with Oxyuris sp., with 488.7±24.4 strongylates eggs and 16.9±0.84 Oxyuris sp. eggs found in 1 g of feces, respectively. Seven and 15 days after the supramolecular complex of ivermectin administered to the horses from the first test group at a dose of 0.15 mg/kg for the active substance (7.5 mg/kg for the drug) in a mixture with mixed feed, we did not find any Strongylata eggs or Oxyuris sp. eggs in feces or on tissue imprints. Insufficient efficacy was obtained in the horses from the second test group after being treated with the active substance of ivermectin at a dose of 0.15 mg/kg. The strongylate egg number decreased on average by 244.3±12.21, namely, by 50.1%, and no Oxyuris sp. eggs were found. The efficacy against Oxyuris sp. was 100%. The horses consumed the mixture of drugs with feed readily. There were no side effects after the drugs applied. Thus, we established the high efficacy of the supramolecular complex of ivermectin against gastrointestinal strongylatoses, and the convenience of its use in a mixture with feed to untamed herd horses individually and by group feeding.

Larval morphology of three syntopic species of Kaloula Gray (Anura: Microhylidae) from Vietnam

The external larval morphology of three species of the microhylid genus Kaloula (K. indochinensis, K. mediolineata, and K. pulchra) inhabiting the southern and central regions of Vietnam is studied. The similarities and the distinctive features of their morphometric characters, the structure of their mouthparts and spiracle, and their coloration are analysed with consideration of the geographic variability. A description of the tadpole of K. indochinensis is provided for the first time. The interspecific comparison revealed the shape of the mouthparts and the spiracle as the most reliable diagnostic characters for the field identification of the coexistent Kaloula tadpoles. The first description of the larval chondrocranium and hyobranchial apparatus of K. indochinensis demonstrates a set of morphological traits characteristic of suspension-feeding microhylids. Some developmental parameters (egg number and size, duration of embryonic and larval development, larvae size and stage at hatching) are provided for K. indochinensis and K. pulchra.

Detection of loci exhibiting pleiotropic effects on body weight and egg number in female broilers

The objective of the present study was to discover the genetic variants, functional candidate genes, biological processes and molecular functions underlying the negative genetic correlation observed between body weight (BW) and egg number (EN) traits in female broilers. To this end, first a bivariate genome-wide association and second stepwise conditional-joint analyses were performed using 2586 female broilers and 240 k autosomal SNPs. The aforementioned analyses resulted in a total number of 49 independent cross-phenotype (CP) significant SNPs with 35 independent markers showing antagonistic action i.e., positive effects on one trait and negative effects on the other trait. A number of 33 independent CP SNPs were located within 26 and 14 protein coding and long non-coding RNA genes, respectively. Furthermore, 26 independent markers were situated within 44 reported QTLs, most of them related to growth traits. Investigation of the functional role of protein coding genes via pathway and gene ontology analyses highlighted four candidates (CPEB3, ACVR1, MAST2 and CACNA1H) as most plausible pleiotropic genes for the traits under study. Three candidates (CPEB3, MAST2 and CACNA1H) were associated with antagonistic pleiotropy, while ACVR1 with synergistic pleiotropic action. Current results provide a novel insight into the biological mechanism of the genetic trade-off between growth and reproduction, in broilers.