Egg Viability Research Articles

Biodiversity and efficacy of fungal isolates associated with Kenyan populations of potato cyst nematode (Globodera spp.)

Potato Cyst Nematodes (PCN) (Globodera rostochiensis and G. pallida Woll.) are quarantine pests of potato (Solanum tuberosum L.) worldwide capable of causing significant yield loss and difficult to manage with conventional methods. The study explored the diversity of antagonistic fungi associated with PCN obtained from soil samples collected in Nyandarua and Nakuru Counties in Kenya and their effect on PCN egg viability and hatching was also evaluated. Twelve fungal isolates from five genera were isolated and characterized using morphological and molecular techniques. The twelve isolates were Trichoderma asperellum (4), T. hamatum, T. breve, T. atrobruneum, Amanita basiorubra, Setophoma terrestris (2), Penicillium chrysogenum and Clonostachys rosea. The most abundant isolate was Trichoderma spp. with 58 % occurrence. The effect of seven of the isolates on PCN eggs showed that T. breve and P. chrysogenum reduced egg viability by 41 % and 34 %, respectively while T. asperellum and T. breve reduced their hatching by 50 % on average. Trichoderma atrobrunneum, T. hamatum, and A. basiorubra also reduced the PCN egg viability by 27 % on average. These fungal isolates could provide a potential tool for PCN management in potato production systems for improved yields. However, further studies are warranted to validate these findings under greenhouse and field conditions. A more comprehensive bioprospecting survey for PCN associated antagonistic fungi needs to be extended to other potato growing regions to explore further cyst pathogens.

Worker Reproduction in the Highly Polygynous Ant Crematogaster pygmaea Forel, 1904 (Hymenoptera: Formicidae)

In most ant species, workers have retained functional ovaries, allowing them to potentially lay viable unfertilized eggs that develop into males. Mechanisms (ex.: queen and/or worker policing) have nevertheless evolved to control worker reproduction when the queen is present. In many species with a high degree of polygyny, especially in tramp species, complete sterility of workers has evolved, presumably to “trap” them within their “worker phenotype”. Our study showed for the first time that in the highly polygynous and polydomous ant Crematogaster pygmaea, workers retained the full capacity to produce reproductive eggs in queenless colonies, with at least some of them developing in adult males. We provide evidence that worker-produced males are reproductively functional. Although most queenless colonies produced eggs, few larvae developed into pupae and adult males. We conclude that workers strongly police the worker-produced offspring, even in the queen's absence. Probable high relatedness between queens of C. pygmaea colonies and strong genetic proximity between brood and workers could force the workers in their helper, non-reproductive function even if they keep the ability to reproduce. Our observations indicate that the production of adult males and gynes in C. pygmaea is controlled by seasonal factors related to the rainy season.

Yaikuula (wind-driven evaporative cooling) saves most guinea fowl eggs for hatching in the Sudano-Sahelian belt

Guinea fowl meat and eggs are highly prized by consumers in the Sudan-Sahelian belt countries such as Burkina Faso and Niger. However, compared to chicken, guinea fowl stocks in these countries are low. One of the reasons for the low stock holdings is that guinea fowl in captivity are poor at being broody hens. They do not sit on their eggs for the hatching of their keets. This problem has been addressed using synchronized surrogate chicken hens for brooding. Many chicken hens are provided with dummy eggs until they begin to brood, at which time the dummy eggs are switched to fertile guinea fowl eggs. The challenge with this solution is storing the guinea fowl eggs at room or ambient temperatures until the surrogate brooders are ready. The high room temperatures during storage initiates pre-embryo development that results in hatching unhealthy keets. Refrigerated storage is not an option, as most smallholder farmers in rural settings do not have access to electricity. The purpose of this study was to address the storage problem by introducing wind-driven evaporative cooling (YaiKuula); “Yai” is a Swahili word for “egg.” YaiKuula lowers the storage temperature ~15oC below ambient temperature during the day. Viable guinea fowl eggs were stored using YaiKuula for 0-3, 4-7, and 8-14 days. Ambient temperature and refrigerated (8oC) storage were done in parallel as negative and positive controls, respectively. Twenty-four surrogate brooders with six eggs each were used to hatch the stored eggs. Early and late embryo mortality, in addition to healthy hatching were monitored. The Student’s t-test was used to compare results. The highest rate (p<0.05) of early embryonic mortality (65%) was obtained with refrigerated storage for 8-14 days versus 37 and 12%, respectively, for ambient and YaiKuula storage for the same length of time. The hatching rates of eggs from 0-3 days of storage showed no significant difference between the three storage methods. However, YaiKuula storage yielded significantly (p<0.05) higher hatching rates of 80% versus 37 and 22% from ambient and refrigeration storage at 8-14 days, respectively, and 84% versus 65 and 61% for ambient and refrigeration storage at 4-7 days, respectively. YaiKuula has the potential to increase the number of guinea fowl among smallholder poultry farmers for increased incomes/resilience and better nutrition. Key words: Numida meleagris, evaporative cooling, wind energy, Rakai chicken model

THE EFFECTIVENESS OF COMPOSTING USING STABILIZING URBAN SEWAGE SLUDGE COMPOUNDS

The purpose of this investigation was to verify the effectiveness of composting in the sanitization of sludge from urban sewage (SS). The treatments (T) used consisted of SS mixed with sugarcane bagasse (SB), tree pruning residues (TP), poultry litter (PL) or grass clipping (GC) at a carbon/nitrogen ratio of approximately 30/1 and ratios of T1 (SS+SB), T2 (SS+SB+TP), T3 (SS+SB+GC), T4 (SS+SB+PL) or T5 (SS+SB+TP+GC). Temperature was measured daily for over 280 days of composting. Every two weeks, the compounds were analyzed for thermotolerant coliforms and viable helminth eggs using the multiple-tube and Yanko techniques; and once each month to identify Cryptosporidium spp. and Giardia spp. (oo)cysts using the sucrose and zinc sulfate centrifugal flotation technique and nested PCR followed by sequencing. The maximum temperatures measured in the thermophilic phase of the compounds ranged from 55°C to 64.8°C, and at day 280, weight reductions of 27% (T1), 48% (T2), 63% (T3), 66% (T4) and 64% (T5) were observed. The absence of fecal coliforms was observed from day 98 (T4), day 126 (T1), day 196 (T3 and T5) and day 210 (T2). All treatments resulted in helminth egg inviability and the absence of protozoan (oo)cysts. Only T4 and T5 were positive for G. duodenalis according to the sequencing analysis. In conclusion, high temperatures during the composting thermophilic phase made the use of pathogens required by legislation unfeasible; therefore, it is important to investigate the viability of protozoa in compounds to ensure a safe final product for human and animal health.

Activity of cumin essential oil to control fascioliasis: Efficacy and changes in the tegument of Fasciola hepatica

Fasciola hepatica, the liver trematode, infects ruminants and causes economic loss. Because parasites are developing resistance to commercial drugs, the negative effects of parasitism are increasing. In this study, we aimed to evaluate the efficacy of cumin (Cuminum cyminum) essential oil against F. hepatica eggs and adults. The eggs were incubated with eight concentrations of the essential oil (0.031125–4.15 mg/mL), and viable eggs were counted after 14 days and classified as embryonated or non-embryonated. Adult flukes were incubated in Roswell Park Memorial Institute medium to ensure their viability and then incubated in essential oil. They were observed for 24 h after treatment. The adults were assessed with the two lowest effective oil concentrations used in the ovicidal test. Three controls were used for both tests: nitroxynil, a negative control, and Tween®80. After incubation in oil, the adult specimens were processed for histological analysis and stained with hematoxylin-eosin. In addition, the oil was tested for cytotoxicity using Madin–Darby bovine kidney cells to assess any possible effect on them. The oil was effective in ovicidal and adulticidal inhibition of the trematode, with statistically significant results. All concentrations assessed in the ovicidal test were 100% effective. The adult test was effective within 15 h and inactivated all the specimens at the highest concentration evaluated (0.06225 mg/mL). Histological analysis showed that cumin essential oil resulted in marked areas of vacuolization. The spines showed no structural changes but were surrounded by microvesicles. These findings indicated that cumin oil could be a potential compound in the control of fasciolosis.

Effects of SmartStax® and SmartStax® PRO maize on western corn rootworm (Diabrotica virgifera virgifera LeConte) larval feeding injury and adult life history parameters.

Field-evolved resistance of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, to Bacillus thuringiensis Berliner (Bt) proteins Cry3Bb1 and Cry34/35Ab1 (now classified as Gpp34Ab1/Tpp35Ab1) expressed in the pyramid SmartStax® has been documented in areas of the United States (U.S.) Corn Belt. SmartStax® PRO is a recently registered rootworm-active pyramid containing the same Bt proteins expressed in SmartStax® plus DvSnf7 dsRNA. Little to no published data is available comparing efficacy of the technologies or potential effects of dietary exposure on adult WCR fitness. Therefore, experiments were conducted to compare effects of adult WCR dietary exposure to SmartStax® and SmartStax® PRO on life history parameters and efficacy of the technologies in the field with both Bt-susceptible and Bt-resistant WCR populations. WCR life history parameters evaluated included adult longevity, head capsule width, egg production, and egg viability. Results of small-plot field trials indicated that both technologies provided a high level of root protection when a Bt-susceptible WCR population was present. Root protection was reduced on SmartStax® but maintained on SmartStax® PRO when WCR Bt resistance occurred. Lifetime egg production was the key life history parameter that was significantly reduced when either Bt-susceptible or Bt-resistant adult WCR were fed SmartStax® or SmartStax® PRO diet. A potential fitness advantage was apparent as egg production was significantly higher in the Bt-resistant than Bt-susceptible population. The similar response by the Bt-susceptible WCR population to SmartStax® and SmartStax® PRO indicates that results were caused by sublethal dietary exposure to Bt proteins. Adult size (males < females) and egg viability (high: >95%) were not significantly different among treatments but longevity results were inconsistent between years. Collectively, the field efficacy and life history parameter data expand existing knowledge of SmartStax® and SmartStax® PRO technologies, which will inform practical WCR resistance management programs.

Comparative toxicity of coffee insecticides to the green lacewing Chrysoperla externa in laboratory and persistence trials

The green lacewing Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) is a generalist predator with a diet including major coffee pests. Aiming at a harmonious integration of biological and chemical control in coffee production systems, ecotoxicology studies are required to provide information on insecticide harmfulness toward natural enemies. We investigated the side effects of five coffee insecticides sprayed on eggs and third-instar larvae (L3) of C. externa. The assessed endpoints included C. externa viability (egg hatchability and L3 survival), developmental time, cycle completion, and body weight, sex ratio (female proportion) and accumulated oviposition of adults derived from the treated stages. Cyantraniliprole reduced viability of treated eggs, whereas abamectin prolonged the developmental time and reduced the oviposition of adults reared from the treated L3. In the F1 generation from treated L3, abamectin diminished egg viability and cycle completion and interfered with sex ratio and adult weight. Apart from these results, metaflumizone caused the most striking effects on C. externa by producing high L3 mortality (96%). The hazardousness of this compound, however, was dismissed in persistence bioassays (L3 exposure to aged residues in coffee leaves), indicating that metaflumizone requires direct spraying to kill C. externa. These findings allow us to conclude that while the other compounds (abamectin, abamectin + chlorantraniliprole, chlorantraniliprole and cyantraniliprole) are intrinsically safer for C. externa, metaflumizone applications should be performed in periods of low C. externa activity in plants to avoid direct predator exposure.

Effects of Long-Term Storage on Hatchability and Incubation Length of Game Farmed Quail Eggs.

The long-term storage of eggs before incubation is a common practice in some alternative poultry systems but needs to be performed under conditions that preserve egg viability. The effects of the long-term storage of game farmed quail (Coturnix coturnix) eggs on weight loss during the storage and incubation periods, chick weight at hatch, hatchability, and incubation length were investigated. The eggs were arranged in six treatments submitted to 0-, 7-, 14-, 21-, 28-, and 35-day storage periods at 15.8 °C and 80% relative humidity. The storage length reduced the hatchability of eggs (p < 0.05) when the storage was extended to 35 days, decreasing by more than half compared to eggs stored up to 28 days. Egg weight loss during storage progressively increased with the storage length (p < 0.05). Chick weight at hatching was reduced in eggs stored for more than 14 days (p < 0.05), and relative chick weight decreased significantly in eggs stored for 35 days (p < 0.05). Incubation length progressively increased with the storage length (p < 0.05), achieving less hatching synchrony in eggs stored for a longer time (p < 0.05). In conclusion, game quail eggs store well with little deterioration up to 28 days at 15.8 °C and 80% relative humidity, allowing for extended storage when shipping long-shelf-life eggs or assembling batches large enough to fully set an incubator in farms with small breeding flocks.

Reduced male fertility of an Antarctic mite following extreme heat stress could prompt localized population declines.

Climate change is leading to substantial global thermal changes, which are particularly pronounced in polar regions. Therefore, it is important to examine the impact of heat stress on the reproduction ofpolar terrestrial arthropods, specifically, how brief extreme events may alter survival. We observed that sublethal heat stress reduces male fecundity in an Antarctic mite, yielding females that produced fewer viable eggs. Females and males collected from microhabitats with high temperatures showed a similar reduction in fertility. This impact is temporary, as indicated by recovery of male fecundity following return to cooler, stable conditions. The diminished fecundity is likely due to a drastic reduction in the expression of male-associated factors that occur in tandem with a substantial increase in the expression of heat shock proteins. Cross-mating between mites from different sites confirmed that heat-exposed populations have impaired male fertility. However, the negative impacts are transient as the effect on fertility declines with recovery time under less stressful conditions. Modeling indicated that heat stress is likely to reduce population growth and that short bouts of non-lethal heat stress could have substantial reproductive effects on local populations of Antarctic arthropods.

The Effects of Environmental Contaminants on Animal Health and Reproduction

Purpose: The aim of the study is to investigate effects of environmental contaminants on animal health and reproduction&#x0D; Methodology: This study adopted a desktop methodology. This study used secondary data from which include review of existing literature from already published studies and reports that was easily accessed through online journals and libraries.&#x0D; Findings: The study found that Environmental contaminants can cause a range of health problems in animals. They can disrupt hormonal systems, compromise immune function, damage organs, and lead to various diseases. Environmental contaminants have profound effects on animal reproduction. They can interfere with fertility, reduce reproductive success, and disrupt normal reproductive behaviors. These contaminants can alter hormone levels, impair sperm quality, decrease egg viability, and increase the incidence of reproductive disorders and birth defects.&#x0D; Unique Contribution to Theory, Practice and Policy: The study was anchored on Immune Dysfunction Theory and Disruption of Microbiota Theory. The recommended that practical diagnostic tools and biomarkers to assess the impact of environmental contaminants on animal health and reproduction. These tools can aid in early detection of contamination-related issues, monitoring population trends, and guiding conservation efforts. They can also help identify specific contaminants and their sources, facilitating targeted mitigation strategies. Advocate for stricter regulations and enforcement of laws governing the release and disposal of environmental contaminants.

The effects of pre-hatch elevated corticosterone and post-hatch restrictive food availability on the HPA axis development of mallard ducks (Anas platyrhynchos)

Environmental changes can be stressors (altered habitat and food supply, climate change, etc.) to wild animals. Stressors trigger the hypothalamic pituitary adrenal (HPA) axis to release corticosterone (CORT) which modifies energy homeostasis. During nesting, stressed females can deposit increased concentrations of CORT into eggs, altering egg viability and offspring characteristics, constituting a significant mechanism regulating population productivity in subsequent generations. In this study, increased maternal disposition of CORT was mimicked through a 15 ng/g in ovo injection of CORT into mallard duck eggs. Growth and HPA axis function were measured during post-hatch development. For growth, changes in mass were compared at hatch, 7 weeks and 11 weeks. The HPA axis was assessed at seven weeks by measuring CORT at baseline, followed by restraint stress, dexamethasone (negative feedback) and ACTH (maximal adrenal capacity) challenges. At eleven weeks of age, ducks were subjected to a 6-day 25% feed reduction to simulate a poor quality environment to evaluate response to a chronic stressor by comparing CORT at baseline and after restraint stress. Growth and CORT concentration did not differ between treatments at seven weeks or after feed restriction (11 weeks). The CORT dosage administered did not appear to affect HPA axis development in ducklings. Mallards are a highly adaptable species and may have overcome any early alterations to their phenotype. Further research is needed to determine the effects of increased maternal CORT on growth and the development of the HPA axis in ducks. Summary statementThis study examines how maternal stress (simulated through elevated corticosterone in ovo) and post-hatch chronic stressors (food restriction) affect the development of the HPA axis in a precocial bird.

Variation in the susceptibility of blackberry varieties to Drosophila suzukii infestation

Drosophila suzukii Matsumura (Diptera: Drosophilidae) is an invasive polyphagous species, that is frequently found in blackberry culture, affecting the commercial value of fruits. Between 2020-2021, in the blackberry collection of the University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca (Romania), were carried out observations on susceptibility of five cultivated varieties (‘Thornless’, ‘Loch Ness’, ‘Thornfree’, ‘Thornless Evergreen’ and ‘Navaho’) to D. suzukii. In 2020, the attack frequency in the whole collection was 78.2%. ‘Thornfree’ had the highest attack frequency, 89% while ‘Loch Ness’ was the least susceptible with a frequency of attack of 71%. In 2021, the overall proportion of damaged fruits in the collection was 59.6%. The most susceptible was ‘Thornless’ with an attack frequency of 66% and ‘Thornless Evergreen’ with only 49%. The incidence of infestation by the spotted-wing Drosophila suzukii is influenced by the thermal characteristics of the year, with temperatures higher than 30 °C impacting the fertility of females and the viability of eggs. In the year 2020, the average number of larvae per fruit collected was 6.4, while the average number of larvae in the ‘Loch Ness’ cultivar was 9.4, with a maximum of 48 larvae per fruit. In 2021, an average of 3.4 larvae per fruit were observed, with variations ranging from 2.8 larvae in the ‘Thornfree’ cultivar to 4.2 larvae in the ‘Navaho’ cultivar.

Effectiveness Evaluation of Viti's vinifera Leaf Extract on the Viability of Echinococcus Eggs and Protoscolices In Vitro.

Echinococcosis is a zoonotic disease caused by the genus Echinococcus. Globally, it is one of the most central helminthic diseases. Surgery remains the method of choice to remove cystic Echinococcus. Various sporicidal agents have been used to invalidate the substances in hydatid cysts. Nevertheless, many sporicidal agents cause inflammation and can cause side complications, so their use should be limited. The study aims to evaluate the effectiveness of Vitis vinifera leaf methanolic extract as a sporicidal agent for Echinococcus eggs and protoscolices and determines the best concentration. The mortality and viability of protoscolices were measured in samples exposed to four concentrations of V. vinifera leaf extract (VVLE) (5, 10, 30, and 50 mg/mL) for 5, 10, 20, and 30 min and in eggs exposed to three concentrations (100, 200, and 300 mg/mL) for 24 and 48 h. An infrared spectroscopy chemical test was conducted to assess the presence of numerous expected active components in the extract. The viability of eggs and protoscolices was confirmed using 0.1% eosin staining. Vinifera leaf extract exhibited the decisive sporicidal effect at 100%, 91%, 60%, and 41% after 30 min at concentrations of 50, 30, 10, and 5 mg/mL, and in eggs at 11% and 19% after 24 and 48 h at a concentration of 200 mg/mL, respectively. Increased incubation times and higher dosages often increase mortality. The results exhibited that V. vinifera is effective. This study confirmed that grape leaf extract has high sporicidal activity in vitro. However, more studies are required to determine the exact active chemical and its action mechanism and perform in vivo utilization to confirm these results.

Effect of Insect Growth Regulator Insecticides Novaluron, Teflubenzuron and Lufenuron on the Morphology and Physiology of Euschistus heros

The Neotropical brown stink bug, Euschistus heros (F.) (Heteroptera: Pentatomidae), is an important pest that damages soybean, especially in the central-west region of Brazil. The effect of insect growth regulator insecticides on fourth-instar nymphs and adults of the neotropical brown stink bug was evaluated under laboratory and greenhouse conditions, respectively. In the laboratory, the insecticides (doses in g a.i. ha-1) novaluron (20.0 and 40.0), teflubenzuron (26.2 and 52.5), and lufenuron (20.0 and 40.0), in addition to the control (water), were tested on fourth-instar nymphs of E. heros and their development were followed to adulthood. Mortality, number of adults with and without deformities, and fecundity were determined. In a greenhouse, the effects of the same insecticides on the adult of the stink bug were evaluated by determining the fecundity and viability of the eggs laid. The fourth-instar nymphs of E. heros, when exposed to either dose of the tested insecticides presented mortality and insects with deformations, as well as reduced fecundity of females that reached adulthood. In the trial with adult E. heros, all tested insecticides reduced stink bug fecundity. In the same way, the viability of the produced eggs was reduced in all the chemical treatments, except for novaluron at the lowest dose tested, in which egg viability did not differ from the control treatment. Based on the obtained results, one can infer that the growth-regulator insecticides evaluated, although usually more suitable for the control of caterpillars, can interfere negatively in the development and reproduction of the neotropical brown stink bug, thus constituting a complementary alternative for the management of this pest.

Effects of Tebufenozide on Eggs, Larvae and Adults of Chrysoperla carnea (Neuroptera: Chrysopidae).

Quantifying compatibility among control agents is essential for development of integrated pest management (IPM). Chrysoperla carnea (Siemens) and insect growth regulator insecticides are widely used in IPM of Lepidoptera. C. carnea is a generalist predator naturally present in the Mediterranean agroecosystems and bred in insectariums for commercial purposes. Here, we evaluated lethal and sublethal effects of tebufenozide on C. carnea under laboratory conditions. The treatment of eggs with tebufenozide 24 or 48 h after they were laid did not affect the hatching rate or survival of the neonate larvae. Toxic effects of tebufenozide on topically treated larvae was low; development times of surviving larvae and pupae decreased significantly compared with controls. In choice bioassays, a high percentage of third-instar larvae chose prey (Spodoptera littoralis) treated with tebufenozide in preference to untreated prey. Moreover, second-instar larvae of C. carnea that had previously consumed tebufenozide-treated prey (0.75 mL/L) had significantly reduced larval development time compared with controls, while longevity of surviving adults, fecundity and egg viability were unaffected. Ingestion of tebufenozide by adults of C. carnea at the recommended field dose had no significant effect on female fecundity, egg viability or adult longevity. Tebufenozide exhibited low toxicity towards the developmental stages of C. carnea and is therefore a candidate for inclusion in IPM strategies.

Lack of fitness costs in dsRNA-resistant Leptinotarsa decemlineata ([Coleoptera]: [Chrysomelidae]).

The Colorado potato beetle, Leptinotarsa decemlineata (Say) ([Coleoptera]: [Chrysomelidae]), is the most important defoliator of solanaceous plants worldwide. This insect displays a notorious ability in adapting to biological and synthetic insecticides, although in some cases this adaptation carries relevant fitness costs. Insecticidal gene silencing by RNA interference is a novel mode of action pesticide against L. decemlineata that is activated by ingestion of a double stranded RNA (dsRNA) targeting a vital L. decemlineata gene. We previously reported laboratory selection of a > 11,000-fold resistant strain of L. decemlineata to a dsRNA delivered topically to potato leaves. In this work, we tested the existence of fitness costs in this dsRNA-resistant colony by comparing biological parameters to the parental strain and an additional susceptible reference strain. Biological parameters included length of egg incubation period, number of eggs per clutch, egg viability, larval viability, length of larval and pupal periods, adult emergence, number of eggs laid per day, sex ratio, and adult longevity. Comparisons between the 3 beetle strains detected no fitness costs associated with resistance to dsRNA. This information is important to guide effective insect resistance management plans for dsRNA insecticides against L. decemlineata applied topically to potato leaves.

Selectivity of Bacillus thuringiensis (Bacillales: Bacillaceae) to the polyphagous predator Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae)

AbstractBioinsecticides based on Bacillus thuringiensis (Bt) are widely used to control agricultural pests. However, there are concerns about their impact on non‐target organisms, with for example, the green lacewing Ceraeochrysa claveri, a polyphagous predator with important value in the biological control of insect pests in agroecosystems. This study aimed to analyse the effects of Agree® bioinsecticide (containing Bt serovar aizawai GC‐91) on the post‐embryonic development of C. claveri. For this, neonate larvae of C. claveri were fed with Diatraea saccharalis eggs contaminated with different concentrations of Agree® (0.62, 1.25, 2.50 and 5.00 g L−1) until their pupation. Samples of the midgut of larvae were collected for histological and ultrastructural analysis. The larval and pupal inviability data were collected at the end of the respective developmental stages. After the emergence of adult insects, were considered inviable those with morphological alterations. To evaluate the reproduction, adult insect couples were formed, and the oviposition was collected. No significant differences in the viability of eggs, larvae, pupae and adults of C. claveri contaminated with Agree® were reported. Midgut analyses did not reveal cellular damage in the epithelium, indicating a possible lack of insecticidal proteins receptors. The oviposition and their viability were similar between treated and control groups. Our results demonstrated that Agree® bioinsecticide did not affect the post‐embryonic development of C. claveri. This illustrates that the combined use of Bt and C. claveri for the biological control of arthropod pests can be a sustainable strategy for integrated pest management.

Effects of Fluctuating Thermal Regimes and Pesticides on Egg Hatching of a Natural Enemy Harmonia axyridis (Coleoptera Coccinellidae)

The harlequin ladybird, Harmonia axyridis, is a valuable asset in integrated pest management (IPM); however, issues related to low-temperature storage and transportation have resulted in low hatching rate, while the use of pesticides may lead to non-target effects against this natural enemy during field application. Fluctuating thermal regimes (FTR) have been shown to be beneficial during the low-temperature storage, and the type and concentration of insecticides used are crucial for field application of H. axyridis. Despite this, little research has been conducted on the effects of FTR on the hatching rate of ladybird eggs, and the impact of pesticides on their egg viability remains unclear. To address these gaps, we investigated the effects of different thermal temperatures, recovery frequencies (the number of changes in temperature conditions per unit time), and recovery durations (the duration of the treated temperature condition) on egg hatching under constant low-temperature conditions. We also examined the toxicity and safety of seven commonly used insecticides on egg hatching. Our results indicate that the temperature during FTR application did not significantly affect egg hatching, but the interaction between temperature and recovery frequency can significantly affect egg hatching. Moreover, the recovery frequency and recovery duration had a significant impact on hatching. Under specific conditions, the hatching rate of eggs subjected to FTR was similar to that of eggs stored at 25 °C. Furthermore, we found that matrine (a kind of alkaloid pesticide isolated from Sophora flavescens) had low toxicity to ladybird eggs and is a safe pesticide for use in conjunction with this natural enemy. The study provides valuable information on effectively managing H. axyridis by taking into account both storage temperature and pesticide exposure.

Toxic effects of synthetic and natural indigo dyes on Danio rerio reproduction

The textile industry releases significant amounts of toxic pollutants. In the aquatic environment, the presence of these compounds can impact fauna and flora. The aim of this study was to verify if synthetic (95% purity) and natural indigo blue dye obtained from Indigofera tinctoria plants pose a risk to the aquatic fauna. To investigate ecotoxicological effects of these dyes at concentration of 100 mg.L-1, adult females and males of Danio rerio were exposed in chronic tests. At the end of the twenty-first day, reproduction was performed to evaluate the endpoints: number of eggs, egg viability, larvae survival, and gonadal histology, and the same experiments were repeated after another 21 days in clean water to evaluate the potential of biological recovery. All of the analyzed reproductive parameters were significantly reduced in the organisms exposed to both synthetic and natural indigo blue dyes in relation to the control, and males exposed to the synthetic dye, and females exposed to both natural and synthetic dyes presented gonadal histological alterations, evidencing an important chronic effect of these substances to the reproduction of D. rerio. After the biological recovery period, organisms exposed to both types of dyes showed histological improvements and they recuperated offspring production, but those exposed to the natural dye showed better reproductive performance. Overall, our findings suggested that levels of natural and synthetic indigo dyes permitted by the current legislations must be reviewed, and the substitution of synthetic by natural indigo whenever possible is recommended.

Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders (Cryptobranchus alleganiensis).

AbstractIn species that provide parental care, parents will sometimes cannibalize their own young (i.e., filial cannibalism). Here, we quantified the frequency of whole-clutch filial cannibalism in a species of giant salamander (eastern hellbender; Cryptobranchus alleganiensis) that has experienced precipitous population declines with unknown causes. We used underwater artificial nesting shelters deployed across a gradient of upstream forest cover to assess the fates of 182 nests at 10 sites over 8 years. We found strong evidence that nest failure rates increased at sites with low riparian forest cover in the upstream catchment. At several sites, reproductive failure was 100%, mainly due to cannibalism by the caring male. The high incidence of filial cannibalism at degraded sites was not explained by evolutionary hypotheses for filial cannibalism based on poor adult body condition or low reproductive value of small clutches. Instead, larger clutches at degraded sites were most vulnerable to cannibalism. We hypothesize that high frequencies of filial cannibalism of large clutches in areas with low forest cover could be related to changes in water chemistry or siltation that influence parental physiology or that reduce the viability of eggs. Importantly, our results identify chronic nest failure as a possible mechanism contributing to population declines and observed geriatric age structure in this imperiled species.