Generation Larvae Research Articles

Multigenerational expression of antimicrobial peptides in Aedes aegypti exposed to Metarhizium anisopliae: Is trans-generational immune priming involved?

We assessed, for the first time, a multigenerational expression of antimicrobial peptides (AMPs) in Aedes aegypti larvae exposed to the entomopathogenic fungus, Metarhizium anisopliae, and correlated it with a possible involvement in trans-generational immune priming (TGIP). Aedes aegypti larvae were first exposed to blastospores or conidia of M. anisopliae CG 489 for 24 and 48 h, and the relative expression of AMPs were measured using quantitative Real-Time PCR. A suspension of conidia was prepared, and two different survival tests were conducted with different larval generations (F0, F1, and F2). In the first bioassay, the survival curves of the three generations were conducted separately and compared with their respective control groups. In the other bioassay, the survival curves of the F0, F1, and F2 generations were compared simultaneously against a naïve group exposed to Tween 80. In both survival tests, the F0 generation was more susceptible to M. anisopliae than subsequent generations. For molecular analyses related to TGIP, F0, F1, and F2 larvae were exposed to conidia, and their expression of AMPs was compared with their control groups and a naïve group. There was no differential expression of cecropin, defensin A or cathepsin B between generations. Lysozyme C, however, showed an increase in expression across generations, suggesting a role in TGIP. These discoveries may help us develop biological insecticides against mosquito larvae based on entomopathogenic fungi.

Implications of cypermethrin exposure on population dynamics and fitness traits of laboratory-selected resistant and susceptible populations of Spodoptera litura (Fabricius)

The tobacco cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is an economically important agricultural polyphagous pest worldwide. It has shown high resistance to several insecticides, including cypermethrin, a synthetic pyrethroid that is used in large-scale commercial agricultural applications. The present study investigated the development of selection-induced resistance to cypermethrin and associated fitness costs in S. litura. After continuous exposure to cypermethrin for consecutive fifteen generations, the cypermethrin-selected population (CYP-Sel) of S. litura developed a 21.2-fold resistance. The CYP-Sel strain had a relative fitness of 0.16 when treated with LC50, prolonged larval duration, and development time. Meanwhile, the strain also showed shorter adult duration, lower fecundity, and hatchability compared with the Unsel-Lab population. CYP-Sel population showed a significant disadvantage in intrinsic rate of natural increase (rm), net reproductive rate (Ro), and finite rate of increase (λ) when compared to the Unsel-Lab population. This knowledge could help to design resistance management strategies against this particular pest, along with potential management strategies to overcome the development of resistance.

Rhodamine B, an organic environmental pollutant induces reproductive toxicity in parental and teratogenicity in F1 generation in vivo

This study investigated the reproductive toxicity of rhodamine B in zebrafish and its transgenerational effects on the F1 generation. In silico toxicity predictions revealed high toxicity of rhodamine B, mainly targeting pathways associated with the reproductive and endocrine systems. In vivo experiments on zebrafish demonstrated that rhodamine B exposure at a concentration of 1.5 mg/L led to significant impairments in fecundity parameters, particularly affecting females. Histopathological analysis revealed distinct changes in reproductive organs, further confirming the reproductive toxicity of rhodamine B, with females being more susceptible than males. Gene expression studies indicated significant suppression of genes crucial for ovulation in rhodamine B-treated female fish, highlighting hormonal imbalance as a potential mechanism of reproductive toxicity. Furthermore, bioaccumulation studies showed the presence of rhodamine B in both adult fish gonads and F1 generation samples, suggesting transgenerational transfer of the dye. Embryotoxicity studies on F1 generation larvae demonstrated reduced survival rates, lower hatching rates, and increased malformations in groups exposed to rhodamine B. Moreover, rhodamine B induced oxidative stress in F1 generation larvae, as evidenced by elevated levels of reactive oxygen species and altered antioxidant enzyme activity. Neurotoxicity assessments revealed reduced acetylcholinesterase activity, indicating potential neurological impairments in F1 generation larvae. Additionally, locomotory defects and skeletal abnormalities were observed in F1 generation larvae exposed to rhodamine B. This study provides comprehensive evidence of the reproductive toxicity of rhodamine B in adult zebrafish and its transgenerational effects on the F1 generation.

Comparison of prediction results of Dendrolimus punctatus larvae peak occurrence based on eight prediction models

AbstractIn order to clarify the prediction accuracy of eight models for predicting the peak occurrence of the first generation larvae of Dendrolimus punctatus and provide basis for the pest control, a catastrophe prediction model was established based on the peak occurrence of the first generation larvae of Dendrolimus punctatus in Qianshan City, Anhui Province from 1983 to 2016, and compared with other seven prediction models. Comparing the forecasting results in 2015 and 2016 with actual value and taking 1 head/plant as the error standard, the errors of multiple regression models with six factors as independent variables, namely, peak occurrence of pupae in overwintering generation, peak occurrence of eggs in the first generation, cumulative population in overwintering generation, peak occurrence of adults in overwintering generation, rainfall in early April and parasitic rate of Trichogrammatid in the first generation eggs of Dendrolimus punctatus, were 0.21 heads/plant and 0.23 heads/plant with accuracy rate of 100%. The errors of stepwise regression model with the same six factors were 0.23 head/plant and 0.29 head/plant. The prediction accuracy of artificial BP neural network model, Markov chain model, contingency table model, stationary time series model, and fuzzy comprehensive evaluation model was 100%, but variance period extrapolation model had an accuracy rate of 88%. The accuracy of catastrophe prediction model was related to the selection of catastrophe threshold. Comprehensive comparison of the above eight models, multiple regression, stepwise regression, artificial BP neural network, Markov chain model, stationary time series model, and catastrophe prediction model were more accurate.

SeBLOS2 knockout via CRISPR/Cas9 leads to the loss of larval integument coloration in Spodoptera exigua (Lepidoptera: Noctuidae).

CRISPR/Cas9 technology is a precise and powerful tool for functionally exploring insect genes. The present study tested CRISPR/Cas9 as a way of undertaking effective gene mutagenesis in an important agricultural pest, the beet armyworm Spodoptera exigua. Based on a S. exigua transcriptome database, the entire complementary DNA sequence of SeBLOS2 encoding 140 amino acid residues was cloned. The gene was highly expressed in late larval stages (L3-L5). Using the CRISPR/Cas9 method, SeBLOS2 was knocked out by altering two sites in the coding region. This resulted in 70%-74% of the G0 generation (L4-L5) larvae displaying mosaic translucent integument. Four different mutations occurred at SeBLOS2-specific target sites, as demonstrated by further polymerase chain reaction-based genotypic analysis. Homozygote mutant L3 larvae were obtained in the G1 generation, with complete loss of white stripes and spots on their larval integument. These results demonstrate a crucial role of SeBLOS2 in integument pigmentation and suggest that the gene can act as a suitable nonlethal marker for functional research on genes in S. exigua and other Lepidopteran pests.

Ecotoxicity and Accumulation of Perfluorononanoic Acid in the Fathead Minnow (Pimephales promelas) and an Approach to Developing Protective Thresholds in the Aquatic Environment Through Species Sensitivity Distribution.

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment. Locations where PFAS-containing aqueous film-forming foam (AFFF) has been used or accidentally released have resulted in persistently high concentrations of PFAS, including in surface water that may be adjacent to release sites. Perfluorooctane sulfonic acid (PFOS) is most frequently measured near AFFF release sites; however, other PFAS are being quantified more frequently and, of those, perfluorononanoic acid (PFNA) is common. The goal of our study was to fill data gaps on PFNA toxicity to freshwater fish using the fathead minnow (Pimephales promelas). We aimed to understand how PFNA may impact apical endpoints following a 42-day exposure to mature fish and a 21-day exposure to second-generation larval fish. Exposure concentrations were 0, 124, 250, 500, and 1000 µg/L for both adult (F0) and larval (F1) generations. The most sensitive endpoint measured was development in the F1 generation at concentrations of ≥250 µg/L. The 10% and 20% effective concentration of the tested population for the F1 biomass endpoint was 100.3 and 129.5 µg/L, respectively. These data were collated with toxicity values from the primary literature on aquatic organisms exposed to PFNA for subchronic or chronic durations. A species sensitivity distribution was developed to estimate a screening-level threshold for PFNA. The resulting hazard concentration protective of 95% of the freshwater aquatic species was 55 µg PFNA/L. Although this value is likely protective of aquatic organisms exposed to PFNA, it is prudent to consider that organisms experience multiple stressors (including many PFAS) simultaneously; an approach to understand screening-level thresholds for PFAS mixtures remains an uncertainty within the field of ecological risk assessment. Environ Toxicol Chem 2023;42:2229-2236. © 2023 SETAC.

How competition between overlapping generations can influence optimal egg-laying strategies in annual social insects.

Annual social insects are an integral functional group of organisms, particularly in temperate environments. An emblematic part of their annual cycle is the social phase, during which the colony-founding queen rears workers that later assist her in rearing sexual progeny (gynes and drones). In many annual social insects, such as species of bees, wasps, and other groups, developing larvae are provisioned gradually as they develop (progressive provisioning) leading to multiple larval generations being reared simultaneously. We present a model for how the queen in such cases should optimize her egg-laying rate throughout the social phase depending on number-size trade-offs, colony age-structure, and energy balance. Complementing previous theory on optimal allocation between workers vs. sexuals in annual social insects and on temporal egg-laying patterns in solitary insects, we elucidate how resource competition among overlapping larval generations can influence optimal egg-laying strategies. With model parameters informed by knowledge of a common bumblebee species, the optimal egg-laying schedule consists of two temporally separated early broods followed by a more continuous rearing phase, matching empirical observations. However, eggs should initiallybe laid continuously at a gradually increasing rate when resources are scarce or mortality risks high and in cases where larvae are fully supplied with resources at the egg-laying stage (mass-provisioning). These factors, alongside sexual:worker body size ratios, further determine the overall trend in egg-laying rates over the colony cycle. Our analysis provides an inroad to study and mechanistically understand variation in colony development strategies within andacross species of annual social insects.

Sublethal effects of acetamiprid and afidopyropen on Harmonia axyridis: insights from transcriptomics analysis

Evaluating the sublethal effects of insecticide is crucial for protecting and utilizing natural enemies. In this study, we determined the sublethal effects of acetamiprid and afidopyropen on Harmonia axyridis (Pallas) and explored the potential molecular mechanisms underlying these effects through transcriptomics analysis. The results showed that sublethal concentrations of acetamiprid significantly reduced the adult fecundity and longevity of F0H. axyridis and decreased the survival time and survival rate of the F1 generation. Sublethal concentrations of afidopyropen prolonged the developmental time of 4th instar larvae in the F0 generation. Additionally, acetamiprid and afidopyropen treatments significantly decreased the predation of H. axyridis. Furthermore, transcriptome sequencing analysis revealed that several P450 and UGT genes expressed differently when H. axyridis were exposed to sublethal concentrations of acetamiprid and afidopyropen, suggesting that the differential expression of detoxifying genes might be involved in the response and detoxification metabolism of acetamiprid and afidopyropen in H. axyridis. Our findings demonstrate that sublethal concentrations of acetamiprid adversely influences the development and predation of H. axyridis, while afidopyropen has limited effects on H. axyridis. These results are helpful for protecting and utilizing natural enemies and guiding the scientific use of pesticides in the field.

Unstable fipronil resistance associated with fitness costs in fipronil-selected Aedes aegypti L.

Mosquitoes are very serious household and medically important pests transmitting many diseases of humans and animals. Among mosquitoes, Aedes aegypti L., is an active transmitter of dengue and lumpy skin disease virus, horrible and terrifying diseases, causing human and animal death throughout the world. Fipronil is a new chemistry insecticide used to control agriculture and medically important insect pests. It affects the GABA receptors in the nervous system and consequently causes the death of the pests. A laboratory experiment was conducted to investigate the onset of fipronil resistance and associated fitness costs in Ae. Aegypti. Moreover, the stability of fipronil resistance was evaluated after five generations of rearing without selection pressure. The population of Ae. Aegypti was exposed continuously for 12 generations to fipronil under controlled conditions. The fipronil selected population (Fipro-Sel Pop) had a 317 and 115.7-fold level of resistance compared to a susceptible and field population, respectively. Relative fitness for Fipro-Sel Pop was 0.57, with a significant disadvantage in larval duration, developmental time, percent hatchability, intrinsic rate of natural increase (rm), net reproductive rate (Ro), number of larvae in the next generation, and mean relative growth rate (MRGR) when compared to the Unselected population (Un-Sel Pop). However, the relative fitness value of Cross1 (Un-Sel Pop ♂ × Fipro-Sel Pop ♀) and Cross2 (Fipro-Sel Pop ♂ × Un-Sel Pop ♀) was 1.69 and 1.12, respectively. It is evident from the results that fipronil resistance comes with a fitness disadvantage, and it is unstable in the Fipro-Sel Pop of Ae. Aegypti. Therefore, the alternation of fipronil with other chemicals or suspension of fipronil usage for some time could improve its efficacy by delaying resistance development in Ae. Aegypti. Further research should be performed to investigate the field applicability of our findings.

Path analysis of desirable traits and evaluation of reproductive performance of Crassostrea sikamea in different ages

Kumamoto oysters (Crassostrea sikamea) are important marine aquaculture shellfish because of their taste and round shell shape. Due to its small size, selective breeding is required to improve its market size, but there are no reports on traits suitable for direction selection and reproductive productivity of Kumamoto oysters of different ages. In this study, path analysis and one-way ANOVA were used to explore the influential indices of oyster body weight and fecundity. The results showed that shell height was the main factor affecting the body weight of Kumamoto oysters at one-year-old and two-year-old, followed by shell length. Body weight was the main factor influencing fecundity, and shell height showed a significant correlation with fecundity. Therefore, shell height should be considered the first parameter for selection when selecting Kumamoto oysters for body weight as the direct selection target. When one-year-old and two-year-old Kumamoto oysters were selected as parents from Xiangshan Bay, hatching parameters and growth parameters of F1 generation larvae were measured. The fecundity and egg diameters were 1.72 × 106 and 46.60 ± 3.62 μm, respectively, which were significantly greater than one-aged oysters (5.86 × 105, 40.26 ± 3.52 μm). The hatching parameters (fertilized egg size, fertilization rate, and hatching rate) and larval growth performance (D-stage veliger and veliger) were similar and did not differ significantly (P > 0.05), and after metamorphosis, there was also no significant difference in shell height size at 40 days of age (P > 0.05). Therefore, there was no significant effect of age on reproduction, larval development, and the early growth of Kumamoto oysters. These results could provide a basis for parental sources and proper traits for Kumamoto oyster selection, which is beneficial to developing and utilizing this excellent germplasm resource.

Impact Fed Larvae on Residues (Tramadol, Sildenafil Citrate and Diazepam) Chrysomya albiceps on Enzymes.

<b>Background and Objective:</b> <i>Chrysomya albiceps</i> are the insects most commonly associated with corpses, they are of medical and forensic value and thus their immature stages are used to estimate the post mortem interval (PMI) and may provide medicolegal experts essential information regardless of the time, place and cause of death. The current study's goal was to determine the impacts of these pharmaceuticals compounds in some of the biochemical parameters enzymes of the <i>C. albiceps</i> third instar larvae. <b>Materials and Methods:</b> The experiment was performed from April to June, 2018. <i>C. albiceps</i> was fed rabbit tissues during its development for three generations tramadol is administered an overdose of (30.8 mg kg<sup></sup><sup>1</sup>), sildenafil citrate an overdose of (10.26 mg kg<sup></sup><sup>1</sup>) and diazepam an overdose of dissolved in distilled water (4.06 mg kg<sup></sup><sup>1</sup>), by intra-injection into the abdominal cavity twice daily for one week and rabbits injected with distilled water were also used to raise the control group. <i>Chrysomya albiceps</i> larvae in their third instars measured enzymes by using a spectrophotometer. <b>Results:</b> The results indicated to significantly increase of antioxidant enzymes activity of control group of TP, TAC, SOD, GST and CAT and decrease of MDA and significantly decreased of TP, TAC, SOD, GST and CAT and increase of MDA for the tramadol, sildenafil and diazepam groups for the three generations of larvae, respectively. <b>Conclusion:</b> In conclusion, the evidence suggested that decreased antioxidant enzyme activity and increase of MDA might be involved in the production of free radicals in <i>C. albiceps</i> oxidative stress is caused by these pharmaceuticals compounds.

Nano-sized polystyrene plastic particles affect many cancer-related biological processes even in the next generations; zebrafish modeling

With the ever-increasing plastic pollution, the nano-sized plastic particles that are constantly released from the main materials have a greater potential threat. Studies continue on how to eliminate plastic waste, which has become a global problem, from nature. We are aware that complete elimination is not easy at all, but it is not known clearly that even if it is successful, its effects on organisms will also disappear completely. In this study, zebrafish injected with 20 nm-sized polystyrene particles (PS) only during the embryonic period were grown in an environment without plastic exposure. The effects of PS on their offspring embryo/larvae were examined at morphological, molecular and metabolomic levels. Results showed that parental PNP exposure caused significant malformations, decreased survival rate, increased heart rate and blood flow rate, as well as decreased eye size, height and locomotor activity, which were attributed to growth retardation in the offspring. According to the results of whole-mount immunofluorescence larval staining, cell death and reactive oxygen species were significantly increased, while lipid accumulation was decreased in new generation larvae from zebrafish injected with PNP. In order to elucidate the mechanisms underlying these morphological, physiological and molecular damages, the metabolome analyses were performed by evaluating the Q-TOF MS/MS spectra with chemometric analyses in the offspring larvae. According to the metabolomics results, 28 annotated metabolomes suggested by the OPLS-DA analysis that may vary significantly through a variable in projection scores were detected. In addition, it was detected that the significantly increased histopathological findings and immunopositivity of JNK, H2A.X, PI3 and NOP10 in new generation larvae. In conclusion, it has been shown that exposure to PS, even only during the embryonic period, may affect many cancer-related biological processes in the next generation.

Status Kerentanan Larva Aedes aegypti Terhadap Temephos Di Wilayah Kerja Pelabuhan KKP Kelas II Tarakan

Various methods of vector eradication have been used to overcome the problem of Indonesian dengue fever with the aim of breaking the chain of dengue transmission, one of which is the use of larvicides to eradicate mosquito larvae. The commonly used larvicide is Abate 1G which contains 1% active substance in the form of temephos, but the use of insecticides continuously and in the long term can reduce the killing power of larvicides and resistance can occur more quickly. The aim of this study was to determine the susceptibility status of Aedes aegypti larvae to temephos. This type of research is experimental with post test only control group design. The population in this study were all larvae survey results of larvae in the buffer area of Tarakan City Harbor which will be used as research objects. The samples of this study were initial III and IV instar Aedes aegypti larvae which were the results of raising the first generation (F1) larvae of the survey results. The results showed 80-98% larval mortality at a concentration of 0.02 mg / l at a concentration of 0.02 mg / l with The 24-hour LC50 value was 0.012 mg / l, while the 24-hour LC99 value ranged from 0.035 mg/l. Larvae in the buffer area of the health port office Tarakan were tolerant of temephos and periodic testing should be carried out and if necessary larvicide rotation to avoid resistance

Ocean acidification impacts fish larvae but warming could compensate juveniles

As we pump more CO2 into the atmosphere, the pH of the oceans is decreasing and although a reduction of 0.1 pH units may not sound much, the reality is that the acidity of the seas has increased by 30% since the start of the Industrial Revolution in the 18th century. But no one knew how much of an impact decreasing pH might have on long-lived fish species. ‘Fish had been thought to be less vulnerable to ocean acidification due to well-developed acid–base regulation systems’, says Sarah Howald from the Alfred Wegener Institute for Polar and Marine Research (AWI), Germany. However, scientists have recently discovered that fish larvae may be more vulnerable than thought. Some grew faster in more acidic waters, while others suffered tissue and hearing damage in addition to growing more slowly. Yet, no one knew how ocean acidification might impact subsequent generations. Felix Mark from AWI, with colleagues from Germany and France, embarked on an ambitious 5.5 year investigation to find out how European sea bass (Dicentrarchus labrax) larvae and their eventual offspring deal with acidic conditions.In October 2013, at the Ifremer-Centre de Bretagne, France, Guy Claireaux (University of Brest, France), José Zambonino and David Mazurais (both from Ifremer), Myron Peck (University of Hamburg, Germany) and Mark allocated recently hatched sea bass larvae to small tanks of seawater pumped in from the Bay of Brest at summer temperatures (19°C) while other larvae lived in tanks of seawater where the acidity had been raised to 1700 μatm CO2, the IPCC's prediction for seawater CO2 concentrations 120 years in the future. Once the larvae had developed into juveniles (∼2.5 months old), the team relocated the youngsters to larger cool (15°C) tanks, maintaining the two different pH levels until the fish were adult (spring 2017), when the researchers selected ∼30 adult fish each from the two water conditions to rehome in palatial 3000 l tanks. Then, in March 2018, the 5 year old adults spawned to produce the next generation of larvae. But this time the scientists added a twist, dividing the offspring of the parents from the modern day (current CO2) seawater conditions and those of the parents raised in the acidic future water conditions (1700 μatm CO2) into cool and warm tanks, to simulate climate change. Meanwhile, the team kept track of the first and the second generations as they grew and developed.Initially, the first generation of sea bass youngsters didn't seem to be affected by their acidic start in life and neither did their offspring. However, when the team altered the water temperature as the second generation developed in the acidic future water, they found the larvae from the warmer (20°C) tank were much smaller when they metamorphosed into juveniles than those in cool acidic seawater and those that developed in modern warm water. Mark suspects that the warmer high-CO2 conditions in the future could impair energy production by the youngsters’ mitochondria, limiting their growth. However, once the larvae developed into juvenile fish, they seemed to benefit, growing faster, although the team isn't sure whether the warmth was accelerating the fish's growth or whether the acidity failed to impair the growing juveniles.The team warns that the faster growth of larvae in a warmer more acidic world could place them at risk if there is insufficient food for the rapidly growing youngsters. But it seems that if the youngsters develop successfully into juvenile fish, their chances may improve.

Several local food plants with the potential as hosts for Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract. Nelly N, Hamid H, Lina EC, Yunisman, Hidrayani, Widyasari DM. 2022. Several local food plants with the potential as hosts for Spodoptera frugiperda (Lepidoptera: Noctuidae). Biodiversitas 23: 1693-1699. Fall armyworm (Spodoptera frugiperda) or abbreviated as FAW is a major invasive pest of corn crops in America, its native country. Therefore, this study aims to examine the effect of several plant types as hosts on FAW biology and reproduction. It was conducted at the Insect Bioecology Laboratory, Department of Plant Protection, Andalas University using a completely randomized design (CRD) with 3 treatments and 4 replications. The FAW larvae from the field were fed with different plant leaves, namely corn (Zea mays), rice (Oryza sativa), soybeans (Glycine max), and reared until the second generation. Meanwhile, the larvae in the second generation were used as test insects with different feed treatments. Observations were made on the morphology and life parameters of FAW, including the length of the stadia, egg, larvae, pupae, and adult, as well as the laying time and pattern, with the number of eggs produced. The results showed that there were no morphological differences in S. frugiperda, except for the size. Moreover, the body size of the adult-derived from larvae fed with soybean leaves, namely 25.95 mm, was the smallest compared to corn and rice, while the shortest time for larvae development from instar I to VI was obtained with corn leaf feed for 13.55 days. The life span of females derived from larvae fed on soybean leaves was shorter than the others. Larvae fed on soybeans, female life span was 26.00, rice was 34.00 and corn was 31.44 days. Adult females of larvae given soybean leaves produced the highest number of eggs (879.44 eggs) compared to rice (505.00 eggs) and maize (546.33 eggs). Local food crops other than corn, namely rice and soybeans, can be potential hosts for S. frugiperda.

Host-mediated, cross-generational intraspecific competition in a herbivore species

Conspecific insect herbivores co-occurring on the same host plant interact both directly through interference competition and indirectly through exploitative competition, plant-mediated interactions and enemy-mediated interactions. However, the situation is less clear when the interactions between conspecific insect herbivores are separated in time within the same growing season, as it is the case for multivoltine species. We hypothesized that early season herbivory would result in reduced egg laying and reduced performance of the next generation of herbivores on previously attacked plants. We tested this hypothesis in a choice experiment with box tree moth females (Cydalima perspectalis Walker, Lepidoptera: Crambidae). These females were exposed to box trees (Buxus sempervirens L., Buxaceae) that were either undamaged or attacked by conspecific larvae earlier in the season. We then compared the performance of the next generation larvae on previously damaged vs undamaged plants. Previous herbivory had no effect on oviposition behaviour, but the weight of next generation larvae was significantly lower in previously damaged plants. There was a negative correlation between the number of egg clutches laid on plants by the first generation and the performance of the next generation larvae. Overall, our findings reveal that early season herbivory reduces the performance of conspecific individuals on the same host plant later in the growing season, and that this time-lagged intraspecific competition results from a mismatch between the oviposition preference of females and the performance of its offspring.

Воздействие регуляторов развития насекомых на рыжих тараканов двух рас и рыжих домовых муравьёв

When eating poisoned baits based on 0.1–1.0 % pyriproxyfen, within 6 weeks killed up to 50 % of German cockroaches of the S-NIID strain, and 12 % of cockroaches of the OBN strain. The resulting oothecae turned out to be defective and the second generation of cockroaches did not hatch. Morphological changes consisted were in the deformation of the wings (rudimentary, curved, twisted) and in the inability of the larvae to transform into adults. In experiments with an alternative food, similar results were obtained, females formed more oothecae, but the emergence of new generation larvae was not recorded. The consumption of pyriproxyfen-based baits by Pharaoh ant led to the elimination of colonies. A significant decrease in brood number was recorded at 3–6 weeks, and complete death of brood was observed at 6–8 weeks in all treated colonies. The absence of brood can be explained by both mortality as a result of developmental disorders and the cessation of egg laying by queens. Keywords: insect growth regulators, German cockroach, Pharaoh ant, pyriproxifen, hydroprene.

BIOLOGICAL PARAMETERS AND ENZYME ACTIVITIES IN MUSCA DOMESTICA UNDER SELECTION WITH FIPRONIL

Insect resistance to insecticides is one of the main issues of veterinary, medicine, and horticulture around the world. Knowledge of insecticidal resistance mechanisms is crucial for the development of insect control programs. The aim of the present study was to assess some biological parameters and enzyme activities in the house fly Musca domestica L. under selection with fipronil. The selection of M. domestica with fipronil was conducted by non-choice feeding when adults in each generation were fed with sugar that was pre-treated with insecticide solution. In even-numbered year generation, we evaluated the duration of individual development stages, the weight of individuals, fertility, and activity of the main detoxification enzymes (monooxygenases, esterases, and glutathione-S-transferases) in larvae and adults. The assessment of insect susceptibility to fipronil showed that larvae in the tenth generation of the fipronil-selected strain were more susceptible to fipronil than the individuals in the laboratory strain, and adults did not differ from the control as per this indicator. In the tenth generation of the fipronil-selected strain, we found that the duration of the development period from the egg stage to the emergence of adults lasted longer (by 18%) compared to the laboratory line. We noted that the activity of monooxygenases and glutathione-S-transferase in larvae and adults varied in certain generations of the fipronil-selected strain.

Amino-nanopolystyrene exposures of oyster (Crassostrea gigas) embryos induced no apparent intergenerational effects

Early life stages (ELS) of numerous marine invertebrates mustcope with man-made contaminants, including plastic debris, during their pelagic phase. Among the diversity of plastic particles, nano-sized debris, known as nanoplastics, can induce effects with severe outcomes in ELS of various biological models, including the Pacific oyster Crassostrea gigas. Here, we investigated the effects of a sub-lethal dose (0.1 µg mL−1) of 50 nm polystyrene nanobeads (nano-PS) with amine functions on oyster embryos (24 h exposure) and we assessed consequences on larval and adult performances over two generations of oysters. Only a few effects were observed. Lipid analyses revealed that first-generation (G1) embryos exposed to nano-PS displayed a relative increase in cardiolipin content (+9.7%), suggesting a potential modification of mitochondrial functioning. G1-larvae issued from exposed embryos showed decreases in larval growth (−9%) and lipid storage (−20%). No effect was observed at the G1 adult stage in terms of growth, ecophysiological parameters (clearance and respiration rates, absorption efficiency), or reproductive outputs (gonadic development, gamete quality). Second generation (G2) larvae issued from control G1 displayed a significant growth reduction after G2 embryonic exposure to nano-PS (−24%) compared to control (as observed at the first generation), while no intergenerational effect was detected on G2 larvae issued from G1 exposed embryos. Overall, the present experimental study suggests a low incidence of a short embryonic exposure to nano-PS on oyster phenotypes along the entire life cycle until the next larval generation.

Multigenerational Impacts of Benzo[a]pyrene on Bone Modeling and Remodeling in Medaka (Oryzias latipes).

Ancestral benzo[a]pyrene (BaP) (1 μg/L, 21 days) exposure has previously been shown to cause skeletal deformities in medaka (Oryzias latipes) larvae in the F1-F3 generation. However, when and how this deformity is induced during bone development remain to be elucidated. The col10a1:nlGFP/osx:mCherry double transgenic medaka model was employed to determine the temporal and spatial changes of col10a1:nlGFP- positive osteochondral progenitor cells (OPCs) and osx:mCherry-positive premature osteoblasts (POBs) [8 days postfertilization (dpf)-31 dpf] in combination with changes in bone mineralization at the tissue level. Ancestral BaP exposure delayed the development of col10a1:nlGFP- and osx:mCherry-positive osteoblasts and reduced the abundance of col10a1:nlGFP-positive osteoblast progenitors and col10a1:nlGFP/osx:mCherry double-positive premature osteoblasts during critical windows of early vertebral bone formation, associated with reduced bone mineralization in embryos (14 dpf) and larvae (31 dpf), compressed vertebral segments in larvae (31 dpf), and reduced bone thickness in adult male medaka (6 months old) of the F1-F3 generations. Both Col10a1:nlGFP and osx:mCherry were identified as potential targets of epigenetic modifications underlying the transgenerational inheritance of BaP bone toxicity. The present study provides novel knowledge of the underlying mechanisms of transgenerational toxicity of BaP at the cellular level.