Highest Number Of Eggs Research Articles

CARP HATCHERY MANAGEMENT (Cyprinus carpio L.) NATURALLY AT THE PUNTEN AQUACULTURE INSTALLATION (IPB), BATU CITY, EAST JAVA

The large market demand for consumption fish makes some farming communities interested in farming, especially consumption fish farming. Fish hatchery business is the first step to the success of fish farming, because for each growing season the aquaculture business requires a supply of seeds from the hatchery business. Goldfish hatcheries are relatively easy because carp can spawn naturally or artificially. Goldfish have a relatively high fecundity or number of eggs, which ranges from 84,000-110,000 eggs per kilogram of brood. The implementation of carp hatchery techniques includes several processes, namely pond preparation, brood selection, kakaban installation, brood release, spawning, hatching eggs, larval care, checking water quality, seeding, pest and disease control. calculation of fecundity, fertilization rate (FR), hatching rate (HR), and survival rate (SR). The data collection method used in this street vendor is primary data. Primary data include active participation, observation, interviews, and documentation. The carp hatchery technique (Cyprinus carpio L.) at IPB Punten, Batu City is carried out naturally, the carp mother used comes from Punten using a ratio of male to female parents of 1: 3. The feeding method, namely Blind Feeding, obtained an F value of 40,000 eggs, FR 84%, HR 84.5% and SR 90.2%.

Effectiveness of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) on Parthenium weed (Parthenium hysterophorus) under greenhouse condition in Ethiopia

Background Parthenium is an invasive annual weed that affects crop production, rangelands, grasslands, animals, the environment, and human health. Since its introduction into Ethiopia, different management options such as uprooting, slashing, burning, plowing, and applying synthetic herbicides have been practiced. However, these options are not sustainable in weed management. However, Zygogramma bicolorata is known to be used in different countries. Although many countries use it under field conditions, its population-based efficacy has not been well studied in Ethiopia. This study aimed to determine the effectiveness of Z. bicolorata populations on parthenium plants under greenhouse conditions. Methods This experiment was conducted at the Ambo Agricultural Research Center. Different numbers of Z. bicolorata per plant were used as treatments and were laid out in a completely randomized design with three replications. The numbers of damaged leaves, eggs, and larvae were recorded daily until the leaves were completely defoliated. The collected data and the correlation between beetle population and leaf defoliation were analyzed using SAS. Results The result revealed that all beetle populations caused damage to weed plants. A higher population of beetles completely defoliated the leaves within 12 days. However, lower numbers required 21 days to completely defoliate the weed. In contrast, a higher number of eggs (328.67) and larvae (272.33) were obtained from plants that received 20 pairs of beetles. The beetle population and exposure time were positively correlated, and the effectiveness of the bioagent was greater following the emergence of larvae. Conclusions Z. bicolorata can manage parthenium weeds, even with a lower population. However, more than 15 pairs of beetles could be suggested to manage weeds in a shorter time, and further study is needed under field conditions by considering the different agroecologies of the country.

Photoaged polystyrene nanoplastics exposure results in reproductive toxicity due to oxidative damage in Caenorhabditis elegans

The increase of plastic production together with the incipient reuse/recycling system has resulted in massive discards into the environment. This has facilitated the formation of micro- and nanoplastics (MNPs) which poses major risk for environmental health. Although some studies have investigated the effects of pristine MNPs on reproductive health, the effects of weathered MNPs have been poorly investigated. Here we show in Caenorhabditis elegans that exposure to photoaged polystyrene nanoplastics (PSNP-UV) results in worse reproductive performance than pristine PSNP (i.e., embryonic/larval lethality plus a decrease in the brood size, accompanied by a high number of unfertilized eggs), besides it affects size and locomotion behavior. Those effects were potentially generated by reactive products formed during UV-irradiation, since we found higher levels of reactive oxygen species and increased expression of GST-4 in worms exposed to PSNP-UV. Those results are supported by physical-chemical characterization analyses which indicate significant formation of oxidative degradation products from PSNP under UV-C irradiation. Our study also demonstrates that PSNP accumulate predominantly in the gastrointestinal tract of C. elegans (with no accumulation in the gonads), being completely eliminated at 96 h post-exposure. We complemented the toxicological analysis of PSNP/PSNP-UV by showing that the activation of the stress response via DAF-16 is dependent of the nanoplastics accumulation. Our data suggest that exposure to the wild PSNP, i.e., polystyrene nanoplastics more similar to those actually found in the environment, results in more important reprotoxic effects. This is associated with the presence of degradation products formed during UV-C irradiation and their interaction with biological targets.

Additive intercropping system or acaricides: which one is more efficient to prevent population buildup of two-spotted spider mite?

Habitat manipulation such as intercropping can be used as a simple and common cultural practice in pest management. This method is based on the principle of reducing pest populations by increasing the diversity of an ecosystem. This study has been carried out to evaluate the influence of additive series intercropping common bean with some aromatic plants (AP), and 2 acaricides on the different life stages (egg, immature mobile stages, and adult) of Tetranychus urticae Koch (Trombidiformes: Tetranychidae), over 2 yr of experimentation (2020 and 2021). This experiment was conducted following a randomized complete block design with 7 treatments including common bean monoculture, common bean sprayed by spiromesifen or Dayabon, and common bean + companion plants (coriander, ajwain, basil, or dill). Each treatment was replicated 3 replicates. The lowest and highest number of eggs, immature mobile stages, and adults were observed in common bean + spiromesifen and the common bean monoculture, respectively. Additionally, the common bean + Dayabon supported significantly different T. urticae life stage densities compared to common bean monoculture. Also, among intercropped treatments, common bean + basil showed the lowest number of T. urticae (eggs, immature mobile stages, and adults). The highest yield and land equivalent ratio were recorded in common bean + basil and common bean + spiromesifen, respectively. Finally, it can be concluded that additive intercropping with these AP can effectively decrease the T. urticae population density, which is useful for the safe production of common bean.

Functional response of larval and adult Coccinella septempunctata to eggs and larvae of Plutella xylostella on canola

AbstractUnderstanding of functional responses (i.e., changes in predator feeding rates with prey density) of key predators to different crop pest stages is critical to strengthening biological control, particularly in view of climate change and temperature variation. We investigated prey preferences of Coccinella septempunctata L. (Coleoptera: Coccinelidae) to egg and larval stages of a key brassicaceous pest of canola (Brassica napus L., Brassicaceae), the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae). First, laboratory choice and no‐choice bioassays tested the hypotheses that C. septempunctata accepts and differentially prefers two prey developmental stages (eggs and larvae). Then, C. septempunctata larvae and adults were exposed to six densities of P. xylostella eggs over 24 h in functional response bioassays that determined the number of eggs consumed. Finally, the functional response bioassays were repeated with larval prey and extended with three temperature regimes: 10, 22 and 32 °C. In both choice and no‐choice assays, C. septempunctata adults and larvae consumed more P. xylostella larvae than eggs. The functional response of C. septempunctata depended on predator developmental stage and temperature, with reduced handling time and increased attack rates and consumption under warmer conditions. At 10 and 22 °C, the functional responses of both C. septempunctata larvae and adults were of Type II, i.e., rates of prey consumption increase at decelerating rates and then plateau with increasing prey density. Our study demonstrates that both larvae and adults of C. septempunctata can consume high numbers of eggs and early instar P. xylostella larvae; these responses are temperature‐dependent with increased consumption rates at higher temperatures. This may lead to improvements in management of P. xylostella in canola.

Polyandry contributes to Gonipterus platensis (Coleoptera: Curculionidae) rearing.

Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations. Biological control with egg parasitoids is one of the main control strategies for this pest and a constant supply of fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus oviposition by increasing female fecundity and fertility; however, the high density of individuals in laboratory colonies can lead to male harassment, resulting in lower reproduction rate. The aim of this study was to measure the effects of monoandry and polyandry on the reproduction of G. platensis and the effects of male harassment on laboratory rearing conditions. Reproductive parameters were compared between three treatments: monoandry, where the female was allowed to mate daily with the same male; no choice polyandry, where the female was allowed to mate daily with a different male; and polyandry with choice, where the female was allowed to mate daily, but with a choice between five different males. Another experiment varying the density of males was conducted to evaluate the effect of male harassment. Polyandry with choice resulted in the longest period of oviposition, highest fecundity and highest number of eggs per egg capsules when compared to monoandrous females. No negative effect related to male harassment in the laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule, was detected. Polyandry contributes to mass rearing as it increases fecundity and oviposition period on females and there is no evidence of male harassment on G. platensis.

Influence of Tempetature on Viability and Deveplopment of Heterakis gallinarum (Nematoda, Heterakidae) Eggs

Pinworms of the genus Heterakis Dujardin, 1845 parasitize a wide range of hosts, including a number of species of domestic and wild birds. These nematodes are ecologically adapted to the climatic conditions of many geographical zones, which contributes to their widespread distribution. The aim of the work was to investigate the influence of different temperature regimes at laboratory conditions on the growth, development and viability of eggs isolated from the gonads of female nematodes Heterakis gallinarum Schrank, 1788. The conducted studies established that, depending on the cultivation temperature, nematode eggs developed from 6 to 56 days, and their survival rate was from 67.7 to 83.7 %. The temperature of 25 °С was the most favourable for the development of H. gallinarum eggs, the development lasted 12 days and the highest number of eggs with motile infective larvae was formed (83.7 %). It was found that the period of egg development in cultures gradually decreased with increasing temperature: it was 56 days at 15 °C, 18 days at 20 °C, 12 days at 25 °C and 6 days at 30 °C. The survival rate of H. gallinarum eggs gradually increased with increasing temperature in regimes of 15 °С, 20 °С and 25 °С to 67.7 %, 80.7 % and 83.7 %, respectively. At a temperature of 30 °C, egg survival decreased slightly to 78.7 %. It was found that the development of H. gallinarum eggs from the zygote stage to the formation of motile infective larvae, depending on the temperature regime of cultivation, is accompanied by a decrease in egg length by 4.9–5.4 %, an increase in egg width by 4.1–7.6 % and a thinning of the shell by 9.5–28.6 %. Under different temperature regimes, the morphometric parameters of eggs during their development differ in terms of their length, width and shell thickness.

Variability of biological traits of Bulinus truncatus and Biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, from three climatic zones of Côte d’Ivoire

Background: Schistosomiasis is endemic throughout all regions of Côte d’Ivoire, however, species of the intermediate snail host vary across bioclimatic zones. Hence, a deeper knowledge of the influence of climatic on the life history traits of the intermediate snail host is crucial to understand the environmental determinants of schistosomiasis in a rapidly changing climate. The aim of this study was to run a common garden experiment to assess differences in survival, somatic growth and fecundity of both Bulinus truncatus and Biomphalaria pfeifferi snails collected in three different bioclimatic areas.Methods: A cross-sectional malacological survey was conducted in February 2021 in the south, center and north of Côte d’Ivoire. We sampled two populations of B. truncatus, the intermediate host snail of Schistosoma haematobium, from northern and central Côte d’Ivoire, and two populations of Bi. pfeifferi, the intermediate host snail for Schistosoma mansoni, from the southern and central regions. Snails collected at the human-water contact sites were brought in the laboratory where they reproduced. The first generation snails (G1) for each population were reared under the same laboratory conditions, i.e., at 24°C–26°C, during 63 days (9 weeks), to estimate survival, growth, and fecundity.Results: We found that G1Bulinus snails from the north population showed higher survival and growth rates during our study and higher number of eggs at first reproduction, compared to the ones from the central region. For Bi. pfeifferi, no significant difference in survival rate was observed between G1 snails from the southern and central populations, whereas those from the south exhibited higher growth rates and higher number of eggs per individual at first reproduction than G1 snails from the central population.Conclusion: Our study provides evidence for heterogeneity in snails’ life-history traits in response to temperature among the populations from the three climatic regions. Further experiments from multiple populations are needed to confirm that snails express traits under optimal conditions, can lead to expansion of their geographical range and hence an increase in the risk of schistosomiasis transmission. Transplantation experiments will be required to assess implications of the changing climate on snails persistence, distribution and abundance.

Cross-breeding of Tenebrio molitor strains from a large-scale perspective

Abstract To meet the increased future needs in insect Processed Animal Proteins PAPs, insect sector has to optimize the mass rearing of insects. That being the case, a means to tackle this growing demand for insects is to invest in breeding strategies aiming for the production of hybrids with improved economically and biologically valuable traits. In this framework, the objective of the present study was to evaluate the mating compatibility among four strains of the yellow mealworm, Tenebrio molitor, from different geographical areas (Greece, Belgium, Italy and USA) and to assess and compare the performance of the produced inbred and partially outbred lines. All trials were performed in crates of the size (40 × 60 cm) typically used in industrial rearing of mealworm. Adults of T. molitor were placed in the crates and were left to mate and oviposit. To assess mating compatibility, the amount of oviposited eggs (g) as well as the larval hatching rate were recorded. For the assessment of larval performance of inbred and partially outbred lines, two to three weeks old larvae were placed in crates together with Insectus as feeding substrate. The results showed that all crossed lines demonstrated compatibility, and certain combinations outperformed others as suggested by the high cumulative number of eggs and the larval hatch rates for both inbred and partially outbred lines produced. For hatched larvae, there were significant differences among the inbred and partially outbred lines. The highest hatch rates recorded for the Italian-Italian, Belgian-Italian, and Belgian-USA lines. Concerning offspring performance, all crosses followed a similar pattern in terms of final larval weight. The present study aims to draw the attention of the scientific community and insect producing companies to cross-breeding practices to start unfolding its potential for the genetical improvement of commercially farmed insects.

Secretory oviducts contribute to the high egg-laying rate of physogastric termite queens (Isoptera: Termitidae)

Physogastric termite queens are characterized by a notorious enlargement of the abdomen triggered by an equal development of the ovaries. Other physogastry-related modifications have been reported on the fat body, cuticle, midgut, tracheal system, and hemolymph. Surprisingly, modifications on the lateral oviducts of these females, important sites for ovulation and egg transport, have received little attention. Here we took advantage of the high fecundity of physogastric queens in three termitid species to evaluate ovary development and also to compare the morphophysiological features of the lateral oviducts between early-mated and physogastric queens of Cornitermes cumulans. Older queens show well-developed ovaries, with numerous ovarioles connected to the lateral oviducts through pedicels. At these sites, several corpora lutea were observed, residual follicle cells from previous ovulation events. Such features were absent among early-mated queens and reflect then the maturity and ageing of the queens. Histological and histochemical analyses indicated that secretory activity of the lateral oviducts was also restricted to physogastric queens, in which proteins, but not polysaccharides, are secreted into the oviduct lumen. The likely function of these proteins, based on previous studies, is to lubricate the lateral oviducts and stimulate muscular contractions to the egg transport. The physogastry of termite queens is a notorious feature, characterized by several body modifications, especially concerning the ovaries. Our results shed light on the physogastry-related changes in the lateral oviducts of termite queens, as their increasing secretory activity is in agreement with the high number of eggs produced and transporting through these structures. Thus, such changes correspond to an important step allowing the high egg-laying rate shown by physogastric termite queens.

Oviposition-Site Selection and Egg-Hatching of <em>Aedes aegypti</em> and <em>Aedes albopictus </em>(Diptera: Culicidae) in Leaf Infusions of Three Invasive Plants Found in Sri Lanka

Aedes aegypti and Aedes albopictus (Diptera: Culicidae) are the main human arboviral vectors in Sri Lanka. The oviposition behaviour of Aedes mosquitoes determines their survival and population dispersion. Using varying concentrations of plant leaf infusions is a vital technique in determining mosquito oviposition behaviour. The objective of this study was to evaluate the oviposition behavior and egg-hatching rate of Ae. aegypti and Ae. albopictus to three leaf infusions of three invasive plants found in Sri Lanka. The oviposition media were prepared using guinea grass (Megathyrsus maximus), alligator weed (Alternanthera philoxeroides) and Austroeupatorium (Austroeupatorium inulifolium). Each oviposition medium was prepared in four different concentrations: 25%, 50%, 75%, and 100%. The ovitraps were placed in a rubber plantation in Rathnapura district, Palmadulla, Sri Lanka in order to determine the oviposition site selection towards those leaf infusions. Different plant infusions have a significant effect on the oviposition and egg hatch rate of Ae. aegypti and Ae. albopictus. Accordingly, the highest number of eggs has been laid in ovitraps with a 25% concentration of M. maximus infusion. The ovitrap positivity index values were highest in A. philoxeroides at 25%, 50% and 75% concentrations; M. maximus at 25%, 50% and 100% concentrations; and A. inulifolium at 25% and 75% concentrations. Despite the type of infusion and concentration, the egg-hatching rate was highest on the second day of rearing. Ae. aegypti and Ae. albopictus responded differently to different plant infusions based on the plant species and biomass employed. The study shows that organic matter infusions composed of guinea grass improve trap effectiveness and attract females more effectively than ovitraps using aerated tap water. The use of leaf infusions of guinea grass at 25% concentration as an attractant in combination with lethal substances to control container-breeding mosquito species is suggested as a strategy in integrated pest management.

Comparison of Mini-FLOTAC, Flukefinder® and sedimentation techniques for detection and quantification of Fasciola hepatica and Calicophoron daubneyi eggs using spiked and naturally infected bovine faecal samples

BackgroundFasciolosis (Fasciola hepatica) and paramphistomosis (Calicophoron daubneyi) are two important infections of livestock. Calicophoron daubneyi is the predominant Paramphistomidae species in Europe, and its prevalence has increased in the last 10–15 years. In Italy, evidence suggests that the prevalence of F. hepatica in ruminants is low in the southern part, but C. daubneyi has been recently reported at high prevalence in the same area. Given the importance of reliable tools for liver and rumen fluke diagnosis in ruminants, this study evaluated the diagnostic performance of the Mini-FLOTAC (MF), Flukefinder® (FF) and sedimentation (SED) techniques to detect and quantify F. hepatica and C. daubneyi eggs using spiked and naturally infected cattle faecal samples.MethodsBriefly, negative bovine faecal samples were artificially spiked with either F. hepatica or C. daubneyi eggs to achieve different egg count levels: 10, 50 and 100 eggs per gram (EPG) of faeces. Moreover, ten naturally infected cattle farms from southern Italy with either F. hepatica and/or C. daubneyi were selected. For each farm, the samples were analysed individually only with MF technique and as pools using MF, FF and SED techniques. Bayesian latent class analysis (LCA) was used to estimate sensitivity and accuracy of the predicted intensity of infection as well as the infection rate in the naturally infected farms.ResultsThe outcome of this study showed that the highest number of eggs (F. hepatica and C. daubneyi) recovered was obtained with MF, followed by FF and SED in spiked infected samples at 50 and 100 EPG, while at lower infection levels of 10 EPG, FF gave the best results. Moreover, the sensitivity for all the techniques included in the study was estimated at > 90% at infection levels > 20 EPG for both F. hepatica and C. daubneyi eggs. However, MF was the most accurate of the three techniques evaluated to estimate fluke infection intensity. Nevertheless, all three techniques can potentially estimate infection rate at farm level accurately.ConclusionsOptimization and standardization of techniques are needed to improve the FEC of fluke eggs.Graphical

Host selection behavior of tasar silkworm, Antheraea mylitta (Drury) for oviposition

Aim: Seed production is the backbone of sericulture in India. In order to cater for the increased demand for seed (egg), the already prevailing seed production techniques need to replace with new and robust techniques. Therefore, the present study was designed to understand the oviposition preference of Antheraea mylitta and selected suitable host plants for future improvement of seed production. Methodology: Choice (nylon net cage) and no-choice (earthen cup) experiments were conducted to study the oviposition preference of A. mylitta on Shorea robusta, Terminalia tomentosa, T. arjuna, Ziziphus mauritiana, Careya arborea, Syzygium cumini and Buchanania lanzan. Mated female moths were released freely into the nylon cage to observe their oviposition preference in the choice test. Whereas, half of both fore wings and hind wings of mated female moths were excised and individually placed in an earthen cup for oviposition. The total number of eggs laid on the host plants in both experiments was recorded and analysed. Results: Mated females released freely within the cage have laid the majority of their eggs on the floor and net instead of their host plants. Among the host plants, the highest number of oviposition was recorded on the S. robusta, T. tomentosa and T. arjuna compared to other host plants. The highest number of eggs per moth was observed on T. tomentosa and followed by S. robusta, T. arjuna and Z. mauritiana, and exceeded the numbers of eggs in the control in the no-choice experiment. Interpretation: The study revealed that both S. robusta and T. tomentosa were highly preferred host plants of A. mylitta for oviposition. Therefore, the volatiles or feeding supplements of S. robusta and T. tomentosa may be identified and applied to A. mylitta during rearing and grainage to enhance seed production. Key words: Host plants, Oviposition preference, Sericulture, Tasar silkworm, Terminalia tomentosa

Effects of Different Diets on Biological Characteristics of Predatory Mite Amblyseius Eharai (Acari: Phytoseiidae)

In this study, we investigated the effects of different diets on the development and reproduction of the predatory mite Amblyseius eharai. The results show that feeding on citrus red mite (Panonychus citri) led to the fastest life cycle completion (6.9 ± 0.22 days), the longest oviposition period (26.19 ± 0.46 days), the greatest female longevity (42.03 ± 0.43 days), and the highest total number of eggs per female (45.63 ± 0.94 eggs). Feeding on Artemia fanciscana cysts resulted in the highest oviposition rate (1.98 ± 0.04 eggs), a high total number of eggs per female (33.93 ± 0.36 eggs), and the highest intrinsic rate of increase (rm = 0.242). The hatching rate did not differ significantly among the five types of food, and the proportion of females ranged from 60% to 65% across all diets.

Hay Infusion is More Effective than The Yeast and Palm Sugar Combination as an Ovitrap Attractant of Aedes Aegypti Mosquitoes

The Aedes aegypti mosquito is widely known as a vector for Dengue Hemorrhagic Fever (DHF). Mosquito population can be controlled by using oviposition traps (ovitrap). Attractants can be used to attract mosquitoes to lay their eggs. This study aims to compare the effectiveness of Ae. aegypti mosquitoes ovitrap attractant between hay infusion, the yeast-palm sugar combination and ovitrap standard without attractant. The research method was an experimental research posttest only control group design. The results showed that the highest number of eggs during the 4 days of observation was in the hay infusion with an average number of eggs 253,44±58,445 followed by ovitrap without attractant and palm sugar with the number of eggs 31,89±25,300 and 89,78±39,499 respectively sequentially. There was a significant difference in the mean number of eggs between 10% hay infusion and 10% yeast and palm sugar combination and water with p=0.000. The conclusion of this study is that hay infusion attractant is more effective than yeast and palm sugar combination. Keywords: Aedes aegypti, Yeast, Hay Infusion, Ovitrap, Palm Sugar.

Oviposition Preference and Age-Stage, Two-Sex Life Table Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Different Maize Varieties

Host plants play an important role in the growth, development, and reproduction of insects. However, only a few studies have reported the effects of maize varieties on the growth and reproduction of S. frugiperda. In this study, a free-choice test was used to evaluate the oviposition preferences of female adults on ten common maize varieties and ten special maize varieties. The population fitness of S. frugiperda on six different maize varieties was also examined using the age-stage, two-sex life table method. The results showed that S. frugiperda oviposited and completed its life cycle across all maize cultivars. Moreover, the S. frugiperda females exhibited a significantly higher oviposition preference on the special maize varieties than on the common maize varieties. The highest number of eggs and egg masses occurred on Baitiannuo and the lowest on Zhengdan 958. The egg + larval stage, preadult, pupal stage, adult, APOP, TPOP, and total longevity of S. frugiperda were significantly shorter on the special maize varieties than on the common maize varieties. The fecundity, oviposition days, pupal weight, and hatching rate of S. frugiperda were significantly higher on the special maize varieties than on the common maize varieties. Specifically, S. frugiperda had the highest fecundity, female, and male pupal weight on Baitiannuo. Moreover, the net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of S. frugiperda were the greatest on Baitiannuo, whereas the shortest mean generation time (T) occurred on Zaocuiwang. The lowest R0, r, and λ, and longest T occurred on Zhengdan 958, suggesting that Zhengdan 958 is a non-preferred host plant compared to the other tested maize varieties. The findings of this study can provide a reference for the rational planting of maize and provide basic scientific information for the management of S. frugiperda.

Comparative studies of ovipositional preference, larval feeding selectivity, and nutritional indices of Spodoptera frugiperda (Lepidoptera: Noctuidae) on 6 crops.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a significant invasive pest identified as a serious threat to global agricultural production and food security. However, its ovipositional preference, larval feeding selectivity, and nutritional indices are less studied. Here, we investigated these traits of FAW when fed on maize, wheat, soybean, tomato, cotton, and Chinese cabbage, and analyzed the correlation between its nutritional indices and the nutritional contents of crops. The results showed that the highest number of eggs were laid on maize and the lowest number were laid on tomato. The highest feeding choice rate of third instar larvae was on maize, and the lowest was on Chinese cabbage. The fifth instar larvae showed the highest feeding choice rate on maize, but no significant differences were found among other crop species. The food consumption (FC), the relative growth rate (RGR), and the approximate digestibility (AD) were significantly higher on maize and wheat, while the efficiency of conversion of ingested food (ECI) and the efficiency of conversion of digested food (ECD) were significantly higher when fed on cotton and Chinese cabbage. The FC, the relative consumption rate (RCR), RGR, and AD were significantly and positively correlated with soluble sugar and protein contents of host plants, while the ECI and ECD were significantly and negatively correlated with the soluble sugar content. The present study indicates that FAW may cause potential economic losses to these crops besides maize, and these findings are valuable in managing and controlling this pest.

Effects of chilled storage and cryopreservation of sperm, and sperm to egg ratio on fertilization success in lumpfish (Cyclopterus lumpus)

Lumpfish males usually release small amounts of milt and are therefore often sacrificed for surgical harvesting of gonads. To optimize the utilization of sperm obtained by dissection of the gonads, a series of small-scale fertilization experiments was carried out in petri dishes. Sperm extracted from homogenized gonads were diluted 1:1 with a commercial extender solution before use (AquaBoost®SpermCoat). Fertilization success was evaluated as percentage eyed eggs ∼120 day-degrees post fertilization. Firstly, the effect of chilled storage (3 °C) of diluted milt were evaluated by fertilizing eggs (2.27 × 105 sperm/egg) from two freshly stripped females every 2nd or 3rd day over a 14-day period. Storage time did not affect the fertilization rates which were high throughout the 14-days trial period (89.1–99.8%). Secondly, the effect of sperm to egg ratio of cryopreserved and chilled stored sperm (3 °C for 3 days) on fertilization rate was investigated and compared by fertilizing eggs from three separate females with six different sperm to egg ratios (1.25 × 105 to 2 × 109). For both storage methods, only the lowest sperm to egg ratio (1.25 × 105) resulted in a significant lower but still high fertilization rate (80.7%). Using freshly extracted sperm at lower sperm to egg ratios (1.25 × 105 to 3.1 × 104) to fertilize eggs from three females revealed, however, no relationship between sperm to egg ratio and fertilization rates as they were high for all ratios (91.2–93.4%). Two additional experiments were undertaken at a real scale to validate the petri dish results at higher egg numbers and volumes. A fixed volume of 40 ml eggs (∼4800 eggs) was fertilized with four sperm to egg ratios ranging from 3.1 × 104 to 5 × 105. All sperm to egg ratios resulted in high fertilization rates ranging from 93.7 to 99%. In the second real scale experiment increasing volumes of eggs (1 up to 160 ml) were fertilized with a fixed sperm to egg ratio (2.5 × 105). The fertilization success (95.9–97.5%) was not affected by egg volume. In conclusion, the current study showed that lumpfish sperm can be chilled stored at 3–4 °C for 14 days and can be cryopreserved and thawed without any significant reduction in fertilization success under the conditions used in this study. Compared to other marine teleosts, lumpfish require a low sperm to egg ratio for successful fertilization, but the critical low ratio to obtain high fertilization was not revealed in this study.

Parámetros Biológicos de Spodoptera frugiperda1 Alimentado con Tres Hospederos

Spodoptera frugiperda (J.E. Smith) is the most important pest of maize and constitutes an ideal host for mass rearing of some natural enemies. Three substrates were tested: Zea mays, Cucurbita pepo, and Racinus communis to produce a more efficient and cheaper diet for mass production of S. frugiperda to be used as host. The life cycle of S. frugiperda did not differ in the duration of adult emergence between Z. mays (32.3 ± 0.4) and R. communis (32.8 ± 1.4), while C. pepo had the longest duration (37.0 ± 0.5). The difference in its biological cycle was observed when feeding larvae with R. communis leaves, which presented the best biological attributes such as higher percentage of egg hatching (95%), higher percentage of pupae (93%), higher percentage of adult emergence (78%), and higher number of eggs in the next generation (1,569 ± 32). Life tables showed low mortality rate (qx) and high life expectancy when fall armyworm larvae were fed R. communis. The logrank test indicated a difference between the different life tables between C. pepo and Z. mayz; C. pepo and R. communis; and R. communis and Z. mayz, with R. communis a better substrate for rearing S. frugiperda.

Two Candidate Meloidogyne javanica Effector Genes, MjShKT and MjPUT3: A Functional Investigation of Their Roles in Regulating Nematode Parasitism.

During parasitism, root-knot nematode Meloidogyne spp. inject molecules termed effectors that have multifunctional roles in construction and maintenance of nematode feeding sites. As an outcome of transcriptomic analysis of Meloidogyne javanica, we identified and characterized two differentially expressed genes encoding the predicted proteins MjShKT, carrying a Stichodactyla toxin (ShKT) domain, and MjPUT3, carrying a ground-like domain, both expressed during nematode parasitism of the tomato plant. Fluorescence in-situ hybridization revealed expression of MjShKT and MjPUT3 in the dorsal esophageal glands, suggesting their injection into host cells. MjShKT expression was upregulated during the parasitic life stages, to a maximum at the mature female stage, whereas MjPUT3 expression increased in third- to fourth-stage juveniles. Subcellular in-planta localization of MjShKT and MjPUT3 using a fused fluorescence marker indicated MjShKT co-occurrence with the endoplasmic reticulum, the perinuclear endoplasmatic reticulum, and the Golgi organelle markers, while MjPUT3 localized, to some extent, within the endoplasmatic reticulum and was clearly observed within the nucleoplasm. MjShKT inhibited programmed cell death induced by overexpression of MAPKKKα and Gpa2/RBP-1. Overexpression of MjShKT in tomato hairy roots allowed an increase in nematode reproduction, as indicated by the high number of eggs produced on roots overexpressing MjShKT. Roots overexpressing MjPUT3 were characterized by enhanced root growth, with no effect on nematode development on those roots. Investigation of the two candidate effectors suggested that MjShKT is mainly involved in manipulating the plant effector-triggered immune response toward establishment and maintenance of active feeding sites, whereas MjPUT3 might modulate roots morphology in favor of nematode fitness in the host roots. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.