Survival Rate Of Eggs Research Articles

High voltage pulsed electric field: A novel method for killing parasitic eggs on the surface of raisins

Aiming to address the issue of stored grain pests easily breeding during the process of dried fruits in Xinjiang, this study proposes a method and a device for killing raisin parasitic eggs based on a high-voltage pulsed electric field. A one-way test and a Box-Behnken central combination test were conducted to investigate the effects of high-voltage pulsed electric field strength and frequency on the unhatched rate and larval survival rate of Plodia interpunctella eggs on raisin surfaces. The experimental results were qualitatively and quantitatively analyzed using biooptical microscope observation and incubation at constant temperature and humidity post-treatment. The findings revealed that with an output voltage of 22.8 kV, the delivery speed of 0.024 m/s, and the electric field frequency of 3.8 Hz, the unhatched rate of the eggs was 68.14 % while the survival rate of the larvae was 20.36 %. These results can provide new insights for both theoretical development and system implementation regarding the use of high voltage pulsed electric fields for eliminating raisin surface eggs, as well as providing valuable academic references for field crop diseases and pests control strategies.

Ecological inferences on invasive carp survival using hydrodynamics and egg drift models

Bighead carp (Hypophthalmichthys nobilis), silver carp (H. molitrix), black carp (Mylopharyngodon piceus), and grass carp (Ctenopharyngodon idella), are invasive species in North America. However, they hold significant economic importance as food sources in China. The drifting stage of carp eggs has received great attention because egg survival rate is strongly affected by river hydrodynamics. In this study, we explored egg-drift dynamics using computational fluid dynamics (CFD) models to infer potential egg settling zones based on mechanistic criteria from simulated turbulence in the Lower Missouri River. Using an 8-km reach, we simulated flow characteristics with four different discharges, representing 45–3% daily flow exceedance. The CFD results elucidate the highly heterogeneous spatial distribution of flow velocity, flow depth, turbulence kinetic energy (TKE), and the dissipation rate of TKE. The river hydrodynamics were used to determine potential egg settling zones using criteria based on shear velocity, vertical turbulence intensity, and Rouse number. Importantly, we examined the difference between hydrodynamic-inferred settling zones and settling zones predicted using an egg-drift transport model. The results indicate that hydrodynamic inference is useful in determining the ‘potential’ of egg settling, however, egg drifting paths should be taken into account to improve prediction. Our simulation results also indicate that the river turbulence does not surpass the laboratory-identified threshold to pose a threat to carp eggs.

The effect of an organomineral chelate complex on the reproductive function of females and the survival of <i>DANIO RERIO</i> eggs

Danio rerio is a popular model organism used in various fields of scientific research, including aquaculture. The use of Danio rerio in toxicological studies of drugs promising for use in aquaculture allows reducing the cost of livestock of commercial fish for the needs of experiments. The aim of the study was to evaluate the effect of an organomineral chelate complex on the reproductive function of females and the survival of Danio rerio eggs. An organomineral chelate complex was studied (JUPITER, Russia). The active basis of a biologically active additive (hereinafter dietary supplements): a complex of ethylenediaminediantaric acid and lysine with trace elements (Fe, Mn, Cu, Zn, Co, Se, I). The fish of the experimental groups were given an additive for 30 days, the data were compared with the control. The drug was given together with the feed once a day, in 3 different concentrations (0.25 g / l, 0.125 g / l, 0.0625 g / l). The weight of females at the beginning and end of the experiment, the total number of eggs (from each female for spawning), the number of eggs per 1 g, the survival rate of eggs, the diameter of eggs and the length of larvae 5 dfp (five days after fertilization) were estimated. To obtain caviar, the parent pairs were planted in spawning jigs and left for 12 hours. The effectiveness of the organomineral chelate complex was observed when using it at a dosage of 0.25 g/l. The use of the complex for 30 days led to an increase in the weight of females and the weight of eggs, as well as the number of eggs per spawning. It is also important to note that the use of the drug did not have a significant effect on the survival of the eggs, the diameter of the eggs and the length of the larva. The enhancement of reproductive function and the increase in the size of Danio rerio females can be explained by the influence of the components of the organomineral chelate complex on the course of biochemical reactions in the body of fish.

Maternal Care Behavior and Its Consequences in Competition.

Parental care behavior has evolved as a life history strategy to improve reproductive success, particularly in organisms facing challenging environments. However, the variation in maternal care, such as egg-guarding behavior in response to the social environment and the associated ecological consequence of competition, remains largely unknown. This study addresses a gap in current knowledge by examining the plasticity of maternal care behavior in the predatory mite C. eruditus and its impact on offspring survival and intra- and interspecific competition. Our results demonstrated that the reproductive females frequently exhibit egg-guarding behaviors, with enhanced maternal care efforts when the interspecific competitor is present. Egg masses are significantly more vulnerable to predation in the absence of maternal care. Guarding females increased egg survival rates and adversely influenced the survival of both con- and heterospecific competitors, with higher mortality rates being detected. Our findings highlight the ecological significance of maternal care behaviors and suggest that releasing C. eruditus and Neoseiulus cucumeris (Oudemans) together is not recommended for pest management in storage products.

The Effect Dose and Soaking Time of Camellia sinensis Solution to the Egg Adhesion and Hatching of Pangasionodon hypophthalmus

Cultivation of Pangasianodon hypophthalmus is growing rapidly, but there was a problem with the egg’s adhesiveness. Overcome this problem given a tea solution that serves as a remove of Pangasianodon hypophthalmus egg adhesion. This study conducted on June 2022 at Fish Hatchery and Breeding Laboratory, Faculty of Fisheries and Marine, University of Riau. The purpose of this study was determining the effect of immersion eggs with different doses and immersion duration of the black tea (Camellia sinensis) solution on adhesion of Pangasianodon hypophthalmus eggs. This study used a Completely Randomized Design Factorial with 2 factors. The first factor was the dose (g/L) of the black tea with 4 levels; 0 (D0), 8 (D8), 10 (D10), and 12 (D12). The second factor was the immersion duration (minutes) with three levels of 3 (W3), 4 (W4), and 5 (W5). Pangasianodon hypophthalmus larvae reared for 7 days. Parameters measured were egg adhesion, fertilization rate, hatching rate, survival rate, and water quality. The result showed that the doses of C. sinensis solution had a significant effect (P<0.05) on the degree of fertilization and hatching of Pangasianodon hypophthalmus eggs. The optimum treatment with a dose of 10 g/L and 4 minutes (D10W4) give increased eggs adhesion 5.99%, fertilization rate 94.13%, hatching rate 92.88%, and survival rate 96.99%. The water quality during the study were temperature 26.7-27.9OC, pH of larvae maintenance water 6.5-7.1 and DO 4.0-5.2 mg/L. There is an interaction between dose and immersion duration of C. sinensis solution to the egg adhesion and hatching eggs of Pangasianodon hypophthalmus.

Arboreal or terrestrial: Oviposition site of Zhangixalus frogs affects the thermal function of foam nests.

Temperature is essential for the survival and development of eggs. Some anurans have evolved and developed foam nesting traits, with thermal insulation considered to be among their functions. Foam-nesting frogs tend to exhibit reproductive plasticity. For example, they oviposit on both trees and the ground. How such plasticity affects foam nest function is of major relevance and is likely related to the adaptation of foam nesting frogs. However, this has not been well studied. In this study, we examined the interaction between foam nest site, foam nest function, and egg fate using the Japanese green tree frog, Zhangixalus arboreus, and analysed how nest site differences (arboreal or terrestrial) affect the thermal function of foam nests. We compared the thermal functions of foam nests between arboreal and terrestrial oviposition sites of Z. arboreus. We artificially replaced half of the arboreal nests with terrestrial environments and recorded temperature in and outside of the experimental terrestrial nest and original arboreal nests. We also examined egg survival and hatching rates for all the nests. The results indicated superior heat insulation in terrestrial nests, with warmer temperatures inside than outside the nests, especially at night, which led to a high egg survival rate. Therefore, terrestrial ovipositing should be valid under cold weather conditions. This may be related to the evolutionary history of oviposition site plasticity of this genus, which originally had an arboreal oviposition trait but evolved into terrestrial site use owing to global cooling. Our novel insights into the evolution and adaptivity of foam nesting and oviposition site use in Z. arboreus make an important contribution to animal ecology.

Enhancing Reproductive Performance of Nilem Fish (Osteochilus hasselti) through Artificial Spawning

This study aims to evaluate the reproductive performance of Nilem fish (Osteochilus hasselti) through artificial spawning methods. Spawning was conducted in glass aquaria using the sGnRH-a hormone on both male and female broodstocks. Egg production, fertilization rate (FR), hatching rate (HR), and survival rate (SR) were the main observed parameters. The research results revealed that the average egg production per female broodstock reached 25,350, indicating a high level of fecundity. The fertilization rate reached 97.70%, indicating an effective egg fertilization process. The hatching rate (HR) value of 92.20% indicates success in the egg-hatching process. Larval survival rate (SR) during the 4-day rearing period reached 84.70%. Maintaining optimal water quality also contributed to the success of artificial spawning. In conclusion, artificial spawning in Nilem fish could achieve high levels of success by optimizing reproductive parameters and considering environmental factors. This study provides valuable insights into the sustainable development of Nilem fish cultivation.

Comparative study of the growth, survival and morphology of the whitefish hybrids and parent species in the first year of rearing in cage aquaculture

The purpose of the work: to estimate fish breeding indicators of three hybrid forms of whitefish in comparison with parental species when grown in cage aquaculture.Methods used: the production and cultivation of hybrids and parental species were carried out using standard technology for whitefish from November 2021 to May 2022. We have studied the survival and growth rate of fingerlings, and we also conducted a comparative assessment of the exterior of yearlings using factor and cluster analyses.Novelty: for the first time, three hybrid forms of peled and parent species (peled, muksun, broad whitefish, nelma) were grown in cages, and a comparative analysis of survival, growth and morphology of hybrids and parent species was performed.Results: all hybrid forms occupy an intermediate position in terms of growth rate, surpassing the maternal species (peled), yielding to the paternal ones. The best results in terms of weight and linear growth among hybrids were noted in pelchir. In terms of survival, oneyearlings of all hybrids show the effect of heterosis, although at the stage of larvae and early juveniles, the superiority in survival of hybrid forms over the parental pair was noted only in pelnelm. The survival rate of hybrid eggs, as well as the survival rate of pelchir and pelmuk at the early stages of cultivation, had intermediate values — lower than that of peled, but significantly higher than that of paternal species. The lowest survival rate of eggs among hybrids is shown in pelchir. The peled has the most significant morphological differences from other pure species and hybrid forms used in the experiment, all hybrid forms show more similarity with the paternal species.Practical significance: results provide a potential assessment of whitefish hybrids for the prospect of their use in commercial aquaculture.

Effect ofcarica papayaleaf extract toward hatching and survival rate of nilem fish (Osteochilus hasselti) larvae

One of the problems in nilem fish (Osteochilus hasselti) harvesting is the unfulfilled availability of seed that is caused by low hatchability of eggs and larvae survival as well as high larvae abnormalities due to attacks by microorganisms such as fungi and bacteria. Papaya leaf was known as one alternative to increase the egg’s hatching rate because it has antifungal and antibacterial bioactive compounds. This study aimed to determine the effect of papaya leaf extract on egg hatchability, larvae abnormalities, and larvae survival. This study used an experimental method using Completely Randomized Design (CRD) with 4 treatments and 4 repetitions. The treatment doses of the papaya leaf extract that were tested were control (A), 0.75 mg/L (B), 1 mg/L (C), and 1.25 mg/L (D). The results showed that the addition of papaya leaf extract had a significant effect (P<0.05) on egg hatchability, larvae abnormalities, and survival rate ofOsteochilus hasseltilarvae. The hatching rate results for each treatment were 76.50% (A), 79.50% (B), 83.50% (C), and 87.25% (D). The results of larvae abnormalities showed 9.16% (A), 7.24% (B), 5.09% (C), and 4.30% (D). Meanwhile, the results of larvae survival showed 73.87% (A), 76.13% (B), 77.25% (C), and 80.55% (D). Treatment D (1.25 mg/L) was the best treatment in this study, resulting in egg hatchability of 87.25%, larvae abnormality of 4.30%, and larvae survival of 80.55%.

A predator–prey population dynamics simulation for biological control of Frankliniella occidentalis (Western Flower Thrips) by Orius laevigatus in strawberry plants

The use of predatory insect species to control agricultural pests is a key aspect of Integrated Pest Management (IPM) that can help to reduce the use of chemical pesticides. A simulation model that captures the population dynamics and interactions of this predator–prey system can serve as a valuable IPM decision-support tool. However, such a simulation is challenging to construct due to the interactions between life stages of insect predators, prey and the crop plants. Frankliniella occidentalis (Western Flower Thrips, WFT) is an economically devastating global pest that damages diverse crops. Orius laevigatus is an effective and commercially available predator that controls WFT. We, therefore, developed a population dynamics simulation that models their interactions to better understand these insects’ predator–prey dynamics in a strawberry crop. The model considers critical multi-stage predator–prey interaction, prey consumption reduction due to intraspecific competition, and the relationship between predation and oviposition rates of Orius. The simulation was structured using the boxcar train method, a stage-structured approach allowing insect populations to flow from one stage to the next over time. It was parameterised using data from existing literature. The results indicate the potential of the model to forecast the predator and prey species’ population dynamics for different initial populations. A global sensitivity analysis identified that the daily oviposition rate of WFT and egg survival rate of Orius were the most significant parameters. The prey handling time of Orius on WFT did not significantly impact population variation. This model provides a useful tool for scenario exploration and assessment of the effects of Orius on WFT that can aid decision-making in IPM prior to implementation.

Effects of water temperature and light/dark cycles on in vitro egg laying and hatching of the monogenean Microcotyle sebastis on Korean rockfish (Sebastes schlegelii)

Aquaculture faces increasing challenges from parasitic infections, notably impacting the marine cage farming of Korean rockfish (Sebastes schlegelii). A primary contributor to these challenges is the monogenean parasite Microcotyle sebastis, which incurs significant economic losses. To formulate effective management strategies, it is essential to understand how environmental variables influence the reproductive behavior and survival of M. sebastis. In this study, we conducted controlled in vitro experiments to assess the fecundity, hatching success, and viability of M. sebastis across a temperature range from 25 °C to 4 °C, as well as under varying light/dark conditions. We found that the parasite's fecundity was optimal at 15 °C and minimal at 4 °C. Survival rates exhibited an inverse correlation with increasing temperatures. The hatching process was most rapid at 25 °C, with no hatching observed at 4 °C. Upon hatching, the maturation and lifespan of oncomiracidia varied depending on temperature: cilia degenerated within 36 h at temperatures ranging from 25 °C to 15 °C, whereas at 10 °C, cilia began to degenerate on the fourth day post-hatching, surviving for up to nine days. Interestingly, conditions of perpetual darkness led to increased egg production and survival rates compared to light exposure. Our findings provide critical insights into the adaptive responses of parasites to environmental changes and suggest that current deworming strategies may not adequately address the rapid hatching and increased egg production of M. sebastis. We emphasize the need for ongoing research to adapt aquaculture management strategies to the evolving challenges posed by parasites and recommend that future research focus on field studies examining the impact of environmental variables and multiple parasite species.

Effects of rapid cold-hardening and cold acclimation on egg survival and cryoprotectant contents in Ceracris kiangsu (Orthoptera: Arcypteridae)

Abstract The bamboo grasshopper, Ceracris kiangsu Tsai, is a serious pest of bamboo in China and Southeast Asia, and it overwinters as eggs for a period of up to 9 mo. Despite its importance, cold tolerance has not been thoroughly examined in this species. Thus, the present study investigated the low-temperature tolerance of overwintering eggs collected in the field, particularly the effects of rapid cold-hardening (RCH) and cold acclimation (ACC) on egg survival, and changes in the cryoprotectant contents. The supercooling point of overwintering eggs collected from the field was −23.9 °C, and their survival rate after exposure to −22 °C for 6 h was 26.6%, thereby suggesting that the cold tolerance strategy employed by C. kiangsu is freeze avoidance. After exposure to 0 and 4 °C for 12 and 24 h, or 0, 4, and 8 °C for 5 days, the survival rate of eggs subjected to −22 °C increased to approximately 50%, with significant effects of RCH and ACC. The glycerol levels in RCH and ACC treated eggs were also significantly higher than those in the control group, but the protein and trehalose contents were either reduced or not significantly altered. These results indicate that glycerol functions as a low molecular weight cryoprotectant in C. kiangsu eggs, and that RCH and ACC treatment facilitate its accumulation, thereby enhancing cold tolerance. Furthermore, the correlation between RCH and ACC was investigated.

Identification of Potential Gene Targets for Suppressing Oviposition in Holotrichia parallela Using Comparative Transcriptome Analysis.

Holotrichia parallela is an important plant pest. Comparative feeding experiments showed that the egg production, oviposition duration and survival rate of H. parallela beetles were significantly higher when they fed on elm leaves than when they fed on willow or purpus privet leaves. RNA sequencing was used to determine transcriptomic changes associated with oviposition. Comparative transcriptome analysis revealed that the beetles that fed on elm and willow had a total of 171 genes with differential expression. When the beetles fed on elm and purpus privet, 3568 genes had differential expression. The vitellogenesis, ovarian serine protease, odorant-binding proteins, acyl-CoA synthetase and follicle cell proteins were commonly upregulated genes in elm-fed beetles compared with those fed on willow/purpus privet leaves. The involvement of the follicle cell protein 3C gene in the regulation of oviposition was confirmed using RNA interference. The results provide insights into the molecular mechanisms underlying oviposition in H. parallela feeding on different host plants. This study also describes a method for identifying potentially effective genes for pest control.

Protective function of maternal care against egg predators in the shield bug Sastragala esakii (Hemiptera: Acanthosomatidae)

AbstractFemales of many acanthosomatid shield bugs attend eggs and young nymphs by covering them with their bodies. Although such form of maternal care has been suggested to have evolved independently in four genera, Elasmucha, Sastragala, Acanthosoma and Sinopla, previous studies exploring its adaptive function have solely focused on species of Elasmucha. This study pioneered an experimental examination of maternal care in the Japanese species Sastragala esakii. Field experiments demonstrated that unattended egg masses suffered intense predation, whereas egg masses attended by their mothers were rarely preyed upon. The ant Crematogaster sp. was the most common egg predator, while two other insect species were also observed to prey on eggs. The exclusion of ant workers and other walking predators from accessing egg masses through the utilization of a sticky trap resulted in a remarkably improved egg survival rate in orphaned egg masses, suggesting that, at least in our study site, maternal care of S. esakii primarily functions to protect eggs from walking predators. Laboratory observations revealed that egg protection against predators was achieved through at least two distinctive defensive behaviors shown by egg‐tending females: (i) tilting their bodies when approached by predators; and (ii) fanning their wings when in contact with predators. However, females displayed a limited response to predators approaching from the posterior direction, suggesting that visual cues play a significant role in predator recognition. These results indicate a similarity in the maternal care functions between Elasmucha and Sastragala, and suggest the parallel evolution of female defensive behaviors.

Egg Hatching and Larval Survival of Common Carp (Cyprinus carpio Linnaeus, 1758) Againts Exposure to Carbamate Insecticides with Different Concentrations

The purpose of this study was to determine the value of Hours from the use of carbamate insecticides on hatchability of Common carp (Cyprinus carpio) eggs, to compare hatchability of carp (Cyprinus carpio) eggs exposed to carbamate insecticides at different concentration levels, to compare survival rates. goldfish exposed to carbamate insecticides at different concentration levels. This study used a completely randomized design (RAL) where there were 3 treatments and 1 control. In each treatment there were 3 replications. Data analysis used ANOVA and DNMRT tests. The results showed that the average percentage of goldfish egg hatchability was at a concentration of 0.4 ppm with 58% hatchability. While the percentage of survival is at a concentration of 0.4 ppm with hatchability of eggs is 56%. The results of acute toxicity test Hours of carp eggs are at a concentration of 0.8 ppm. The conclusion obtained is that the acute concentration of hours of carbamate pesticides with the active ingredient karbosulfan in Common carp eggs (Cyprinus carpio) is a concentration of 0.8 ppm. There are differences in egg hatchability and survival rate of carbamate (Cyprinus carpio) larvae on exposure to carbamate insecticides with different concentrations, and there is a tendency that the higher the concentration of carbamate insecticides used, the lower the hatchability of eggs and carbamate (Cyprinus carpio) larvae survival.

Respon Intensitas Cahaya Terhadap Daya Tetas Telur dan Perkembangan Larva Ikan Patin Siam (Pangasianodon Hypopthalmus. F)

This study aims to see the effect of light intensity on the hatchability of catfish (P. hypopthalmus. F) eggs. This research was conducted in December 2021, for 30 days at the Inti Karya Perdana Sijenjang Farmers Group, Jambi province. The design in this study was a completely randomized design (CRD) with 4 levels and 3 replications, the treatments included: without light (A), 20 watt light (B), 30 watt light (C) and 40 watt light (D). Parameters observed included egg hatchability, hatching time, survival rate and water quality. The results showed that the average hatchability of eggs was 83.00 ± 5.46 % and ranged from 78.00 ± 2.65 to 90.67 ± 2.08 %. The average value of hatching time was 19.71 ± 2.31 hours, minutes. The average survival rate was 85.75 ± 4.03% and ranged from 80.67 ± 3.51 to 90.00 ± 3.61%. The temperature of the media for hatching catfish eggs ranged from 26.82-30.500C in the morning and 29.50-31.830C in the afternoon, the pH ranged from 6.65-7.76 in the morning and 6.23-6.78 in the afternoon. afternoon. Dissolved oxygen ranged from 4.3-4.5 mg/L, CO2 ranged from 13-15 mg/L and ammonia for all treatments was 0.001 mg/L. The temperature of the larval rearing medium during the study ranged from 26.93ºC-31.11 ºC in the morning and 27.47ºC-31.45ºC in the afternoon, the pH ranged from 6.32-7.34 in the morning and 6.10-7. .81 in the afternoon, dissolved oxygen ranged from 4.0-4.3 mg/L, CO2 ranged from 12-13 mg/L and ammonia was 0.001 mg/L. Differences in light intensity in the form of different lamp watts affect egg hatchability and hatching time for Siamese catfish (P. hypopthalmus. F.) eggs.

Estimation of repeatability and phenotypic correlation of reproductive traits in zebrafish Danio rerio

This study was conducted to estimate the repeatability and phenotypic correlation of reproductive traits of zebrafish Danio rerio, in captive condition. Breeding trials were conducted on 10 breeding pairs (2 male:1 female). The data on fecundity, fertility, hatchability and survival rate were recorded. The repeatability values were computed as a measure of consistency using the intra-class correlation coefficient. The repeatability estimates for fecundity, fertility, hatchability of total eggs, hatchability of fertilised eggs, survival rate of total eggs and survival rate of larvae were 0.701, 0.406, 0.336, 0.049, 0.295 and 0.314, respectively. Most of the reproductive traits analysed had moderate repeatability values barring the hatchability of fertilised eggs. The phenotypic correlation was calculated using the Pearson correlation method. The phenotypic correlations of fertility with hatchability of fertilised eggs; hatchability of total eggs; survival rate of total eggs and survival rate of larvae were highly significant (p≤0.01). This study provided valuable information on the consistency of reproductive parameters which would serve as model for conducting research in other fish species. Keywords: Genetic parameters, Phenotypic correlation, Repeatability, Reproductive traits, Zebrafish

CRISPR/Cas9-mediated knockout of NlCYP6CS1 gene reveals its role in detoxification of insecticides in Nilaparvata lugens (Hemiptera: Delphacidae).

The brown planthopper (Nilaparvata lugens) is one of the major rice insect pests in Asia. Recently, high levels of insecticide resistance have been frequently reported and cytochrome P450 monooxygenase (P450)-mediated metabolic detoxification is a common resistance mechanism in N. lugens. However, there has been no persuasive genetic method to prove the role of P450s in insecticide resistance in N. lugens. Here, CRISPR/Cas9 system was used to disrupt the P450 gene NlCYP6CS1 to elucidate its role in insecticide resistance in field populations of N. lugens. We successfully constructed a homozygous strain (Nl6CS1-KO) with a 5-bp deletion and 1-bp insertion mutation of NlCYP6CS1. Compared with a background resistant strain (Nl-R), the susceptibility of knockout strain Nl6CS1-KO to imidacloprid, nitenpyram, thiamethoxam, dinotefuran, and pymetrozine was increased by 2.3-, 3.4-, 7.0-, 4.2- and 3.9-fold, respectively, but not significantly changed to triflumezopyrim, chlorpyrifos and buprofezin. Life table analysis demonstrated that the Nl6CS1-KO strain resembled the Nl-R strain in terms of egg and nymph developmental duration and adult lifespan, but differed from the Nl-R strain in the survival rate of eggs and nymphs, reproduction, and body weight. Our study demonstrates the effect of functional deletion of NlCYP6CS1 on multiple insecticide resistance in N. lugens. For the first time, we applied CRISPR/Cas9 system to reveal the mechanism of insecticide resistance in N. lugens, which may shed light on similar studies in other hemipteran insects. © 2023 Society of Chemical Industry.

European Pond Turtle (Emys orbicularis) Nest Predation: A Study with Artificial Nests

Nest predation significantly impacts the population decline of the long-living European pond turtle (Emys orbicularis). Kis-Balaton is one of the most important habitats of this species in Hungary, and in May 2017 more than 400 damaged nests were counted. To reveal predation pressure, we conducted a study with artificial nests on three sites in this area. On each site, we used 11 depredated real nests, and near each of them, we created new artificial nests; then in every nest we put one quail egg, one plasticine egg and several turtle egg shells. After that, we sprayed the smoothed surface of the covered holes with water-diluted turtle urine, imitating the turtle's behaviour. Already in the first three nights, 94% of all nests were depredated by the red fox (Vulpes vulpes) and in one case by the European badger (Meles meles), which was confirmed by the bite marks preserved on the plasticine eggs, by the footprints and excrements found near the nests, as well as by camera recordings. Only 6% of the nests survived during the three weeks of our study. Daily survival rates of quail eggs in artificial nests established in both real (damaged) and in new nests were similar, suggesting that estimates obtained with artificial nests reflect the degree of predation pressure on real nests. On the site where the nests were scattered, their daily survival rate (33%) was significantly lower than on the sites where their arrangement was partly scattered, partly linear (83%), or only linear (76%). On two additional sites, by using simulated turtle nests we showed that spraying the nests with diluted turtle urine and marking them with a flag did not affect their survival, although further methodological testing is needed. The information obtained with artificial nests enables the organization of the protection of the nests of the European pond turtle and selective predator control.

Cut to Disarm Plant Defence: A Unique Oviposition Behaviour in Rhynchites foveipennis (Coleoptera: Attelabidae)

Female weevils of the family Attelabidae (Coleoptera: Curculionoidea) possess a unique behaviour of partially cutting the branches connecting egg-bearing organs of their host plants during oviposition. However, the consequence of such behaviour remains unclear. Using Rhynchites foveipennis and its host pear (Pyrus pyrifolia), the present study tested the hypothesis that the oviposition behaviour could disarm the host plants' defence. We compared the survival rates, growth rates, and performance of eggs and larvae under two conditions: (1) the fruit stems were naturally damaged by the females before and after oviposition, and (2) the fruit stems were artificially protected from the females. When fruit stems were protected from female damage, the survival rates of eggs and larvae were only 21.3-32.6%, respectively; and the larval weight was 3.2-4.1 mg 30 days after laying eggs. When the fruit stems were damaged, the survival rates of eggs and larvae reached 86.1-94.0%, respectively; and the larval weight reached 73.0-74.9 mg 30 days after laying eggs. The contents of tannin and flavonoids in the pears did not change significantly along with the oviposition and larval feeding, but weevil eggs were crushed and killed by the callus in the pears. Once the stunted larvae in branch-growing pears were moved into the picked-off ones, the growth and development recovered. The findings indicate that the oviposition behaviour can significantly increase the survival of the offspring. Our study suggested that the oviposition behaviour of attelabid weevils is a strategy to overcome plant defence.