Number of Blastodisc Cells During the Laying Period for Two Successive Generations of Layer and Broiler Breeder.

In the poultry industry, genetic selection for growth performance is associated with poor reproductive efficiency and an increase in embryo mortality. The identification of new biomarkers is essential to improve these parameters. The blastodisc, composed of blastodermal cells, undergoes cellular events to achieve embryo development. Factors such as hen's age, temperature and time of egg storage could influence the number of blastodermal cells and impair embryo development. In this study, we investigated the variability of the number of viable cells of blastodisc (NVCB) that could be dependent on the stage of laying and on the breed and potentially associated with reproductive parameters. In experimental breeds, eggs were collected during the whole cycle of laying. Then, the protocol was repeated on industrial breeds (breeder hens) during five successive days at three stages of laying (before, after laying peak and at the end of laying period) for two generations (mothers and offsprings). For each egg, the blastodisc was dissected in order to count viable cells. For both experiments, the NVCB increased during the laying cycle. The NVCB was higher in broiler blastodisc compared to layer blastodisc for both generations. For layer breed, the NVCB were negatively correlated with laying rate for the first generation while positively associated for offsprings. However, the NVCB was positively correlated with laying rates in both generations for broiler hens and with fertility and hatchability rates. The NVCB from fresh oviposited fertilised eggs could be a potential tool in predicting on reproductive performances in poultry.

Integrating Genomics and Transcriptomics to Identify Candidate Genes for Egg Production in Taihe Black-Bone Silky Fowls (Gallus gallus domesticus Brisson).

The Taihe Black-Bone Silky Fowl (Gallus gallus domesticus Brisson) possesses significant value in terms of consumption, medicinal applications, and ornamental appeal, representing a precious genetic resource and traditional Chinese medicinal material. However, considerable variation exists within populations regarding egg-laying performance. This study integrates a whole-genome selection signal analysis (SSA) with a transcriptome analysis to identify genes associated with egg-laying traits in Taihe Black-Bone Silky Fowls. We identified 31 candidate genes under selection from the high-yield chicken (HC) and low-yield chicken (LC) groups. Additionally, through RNA-seq analysis, 257 common differentially expressed genes (DEGs) were identified from four comparative groups. Two overlapping genes-LPL and SETBP1-were found in both the selected gene and DEG lists. These selected genes and DEGs were enriched in pathways related to ovarian development, including the lysosome pathway, the ECM-receptor interaction pathway, the TGF-beta signaling pathway, the Wnt signaling pathway, the PPAR signaling pathway, and the glycerolipid metabolism pathway. These research findings contribute to the breeding of Taihe Black-Bone Silky Fowls with high egg production traits and provide a theoretical foundation for exploring the regulatory mechanisms of avian reproduction.

Interactions at the Oviposition Scar: Molecular and Metabolic Insights into Elaeagnus angustifolia's Resistance Response to Anoplophora glabripennis.

The Russian olive (Elaeagnus angustifolia), which functions as a "dead-end trap tree" for the Asian long-horned beetle (Anoplophora glabripennis) in mixed plantations, can successfully attract Asian long-horned beetles for oviposition and subsequently kill the eggs by gum. This study aimed to investigate gum secretion differences by comparing molecular and metabolic features across three conditions-an oviposition scar, a mechanical scar, and a healthy branch-using high-performance liquid chromatography and high-throughput RNA sequencing methods. Our findings indicated that the gum mass secreted by an oviposition scar was 1.65 times greater than that secreted by a mechanical scar. Significant differences in gene expression and metabolism were observed among the three comparison groups. A Kyoto Encyclopedia of Genes and Genomes annotation and enrichment analysis showed that an oviposition scar significantly affected starch and sucrose metabolism, leading to the discovery of 52 differentially expressed genes and 7 differentially accumulated metabolites. A network interaction analysis of differentially expressed metabolites and genes showed that EaSUS1, EaYfcE1, and EaPGM1 regulate sucrose, uridine diphosphate glucose, α-D-glucose-1P, and D-glucose-6P. Although the polysaccharide content in the OSs was 2.22 times higher than that in the MSs, the sucrose content was lower. The results indicated that the Asian long-horned beetle causes Russian olive sucrose degradation and D-glucose-6P formation. Therefore, we hypothesized that damage caused by the Asian long-horned beetle could enhance tree gum secretions through hydrolyzed sucrose and stimulate the Russian olive's specific immune response. Our study focused on the first pair of a dead-end trap tree and an invasive borer pest in forestry, potentially offering valuable insights into the ecological self-regulation of Asian long-horned beetle outbreaks.

Invasive brown algae (Sargassum spp.) as a potential source of biocontrol against Aedes aegypti.

Influxes of sargassos are responsible for economic and environmental disasters in areas where they bloom, especially in regions whose main income relies on tourism and with limited capacity for sanitation and public health response. A promising way of valorization would be to convert this incredible biomass into tools to fight the deadly vector mosquito Aedes aegypti. In the present study, we generated hydrolates and aqueous extracts from three main Sargassum morphotypes identified in Guadeloupe (French West Indies): Sargassum natans VIII, Sargassum natans I and Sargassum fluitans. We conducted a chemical characterization and a holistic evaluation of their potential to induce toxic and behavioral effects in Ae. aegypti. Despite the low insecticidal potential observed for all the extracts, we found that S. natans VIII and S. fluitans hydrolates deterred oviposition, induced contact irritancy and stimulated blood feeding behavior in host seeking Ae. aegypti females, while aqueous extracts from S. natans I and S. fluitans deterred both blood feeding behavior and oviposition. Chemical characterization evidenced the presence of phenylpropanoid, polyphenols, amino acids and esters. Thus, Sargassum spp. aqueous extracts and hydrolates could be used to manipulate Ae. aegypti behavior and be valorized as control tools against this mosquito.

Evaluation of the temperature adaptation of three rubber tree pest mites based on their two-sex life table.

To determine the optimal temperature range for the development and reproduction of three spider mites (Eotetranychus sexmaculatus, Eotetranychus orientalis, and Oligonychus biharensis), this study investigated their developmental period, survival rate, lifespan, and reproduction under five temperatures, 21, 24, 27, 30, and 33°C, to predict and control in the field. With the gathered data, a two-sex life table was constructed for each of them. The results revealed that as the temperature increased, both O. biharensis and E. orientalis displayed a gradual reduction in their generation period. Furthermore, an inverse relationship was observed between lifespan and temperature for all three spider mite species. When examining the survival rates at varying temperatures, E. sexmaculatus exhibited the highest rate (98%) at 33°C, while E. orientalis and O. biharensis demonstrated their highest survival rates at 24°C, reaching 90% and 100% respectively. Regarding reproduction, O. biharensis displayed the highest oviposition rates at 30°C with an average of 17.45 eggs per individual. Conversely, E. sexmaculatus and E. orientalis exhibited the highest oviposition rates at 33°C, averaging at 15.22 and 21.38 eggs per individual respectively. Significantly higher intrinsic growth rates were observed for O. biharensis and E. orientalis at 33°C, with rates of 0.22 and 0.26 respectively. In contrast, E. sexmaculatus demonstrated the highest intrinsic growth rate at 27°C. The temperature of 27°C was more suitable for the growth of the E. sexmaculatus, while 33°C was the optimal temperature for the E. orientalis and O. biharensis. The current findings provide valuable guidance for the control and prevention of these three spider mites.

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

Background: 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. Methods: 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. Results: 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. Conclusion: 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.

Mating of unfed, engorged, and partially to fully gravid Aedes aegypti (Diptera: Culicidae) female mosquitoes in producing viable eggs.

BACKGROUND: Understanding the relationship between blood-feeding and mating is important in effectively managing the most well-adapted vector insect, Aedes aegypti (Linnaeus). Although extensive studies have investigated the behavioural aspects of Aedes such as blood-feeding, mating, and their relationship, several knowledge gaps still exist. Therefore, the present study was undertaken to determine the possibility of successful mating by unfed, engorged, and partially to fully gravid (up to 5 days after blood-feeding with fully developed eggs) female Ae. aegypti mosquitoes and production of viable eggs. METHODS: Mating of sexually mature adult Aedes aegypti was allowed in three different ways. In control 1, the females were allowed to mate before taking blood meal, and in control 2, the females were not at all allowed to mate. In the experiment, the females were separated into six categories, viz. D-0 to D-5. In D-0, the females were allowed to mate immediately after the bloodmeal and, in D-1, the females were allowed to mate on the first day of blood feeding, likewise, the females of D-2, D-3, D-4 and D-5 were allowed to mate on 2nd, 3rd, 4th and 5th day of blood feeding. Ovitrap was uniformly kept on the 4th day of blood feeding for the cages D-0 to D-3 for 1 h and then removed and for the cages D-4, and D-5, the ovitrap was kept on 4th and 5th day of blood feeding for 1h immediately after mating. The total number of eggs and the total number of hatching were counted. In the subsequent days, the entire experiment was replicated two times with different cohorts of mosquitoes, and the mean value of three experiments was used to draw Excel bars with 5% error bars and also for the statistical analysis. RESULTS: It was found that mating just before oviposition was sufficient to produce 1581 eggs (70% compared with control) and fertilize 1369 eggs (85% compared with total eggs laid), which is far higher than the 676 non-hatching (unfertilized) eggs (30%) laid by unmated females. Although mating is not essential for producing eggs, our study shows that even brief exposure to the semen and seminal fluids greatly enhances the oviposition and hatching efficiency, even if the mating occurs just before oviposition. However, those females mating before blood-feeding and those mating after blood-feeding produced 2266 and 2128 eggs, with hatching rates of 96.78% and 95.54%, respectively. Hence, the retention time of seminal fluid in the female seems to influence the number of eggs laid and the number of eggs hatched. CONCLUSIONS: In general, mating is possible in Ae. aegypti even minutes before oviposition and is sufficient to produce a greater number of viable eggs.

Obstacle negotiation in female desert locust oviposition digging.

The female locust lays its eggs deep within soft substrate to protect them from predators and provide optimal conditions for successful development and hatching. During oviposition digging, the female's abdomen is pooled and extends into the ground, guided by a dedicated excavation mechanism at its tip, comprising two pairs of specialized digging valves. Little is known about how these active valves negotiate the various obstacles encountered on their path. In this study, female locusts oviposited their eggs in specialized sand-filled tubes with pre-inserted 3D-printed plastic obstacles. The subterranean route taken by the abdomen and digging valves upon encountering the obstacles was investigated, characterized, and compared to that in control tubes without obstacles. Data were obtained by way of visual inspection, by utilizing cone beam computed tomography scans in high-definition mode, and by making paraffin casts of the oviposition burrows (after egg hatching). We demonstrate, for the first time, the subterranean navigation ability of the female locust's excavation mechanism and its ability to circumvent obstacles during oviposition. Finally, we discuss the role of active sensory-motor mechanisms versus the passive embodied function of the valves, central control, and decision-making.

Genome-wide variation study and inter-tissue communication analysis unveil regulatory mechanisms of egg-laying performance in chickens.

Egg-laying performance is of great economic importance in poultry, but the underlying genetic mechanisms are still elusive. In this work, we conduct a multi-omics and multi-tissue integrative study in hens with distinct egg production, to detect the hub candidate genes and construct hub molecular networks contributing to egg-laying phenotypic differences. We identifiy three hub candidate genes as egg-laying facilitators: TFPI2, which promotes the GnRH secretion in hypothalamic neuron cells; CAMK2D, which promotes the FSHß and LHß secretion in pituitary cells; and OSTN, which promotes granulosa cell proliferation and the synthesis of sex steroid hormones. We reveal key endocrine factors involving egg production by inter-tissue crosstalk analysis, and demonstrate that both a hepatokine, APOA4, and an adipokine, ANGPTL2, could increase egg production by inter-tissue communication with hypothalamic-pituitary-ovarian axis. Together, These results reveal the molecular mechanisms of multi-tissue coordinative regulation of chicken egg-laying performance and provide key insights to avian reproductive regulation.

A preliminary note on attraction and oviposition preferences of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae).

Chrysomya rufifacies (Diptera: Calliphoridae) is a blow fly species of forensic importance, documented to have a strong preference for colonisation of substrate already inhabited by heterospecific blow fly larvae, thus exhibiting secondary colonisation behaviour. Larvae exhibit predatory behaviour that may be useful to support development where food substrate is limited or high competition exists, but they may alternately be drawn to pre-colonised substrate to capitalise on the advantages of collective exodigestion by previous/current colonisers. Previous authors have suggested female Ch. rufifacies may use visual orientation to detect substrate currently colonised by heterospecific larvae, rather than chemoreception of volatile organic compounds (VOCs), that signify condition of substrate, which would infer that active colonisation is likely a more important oviposition cue for Ch. rufifacies than substrate condition. This study addressed attraction as well as oviposition, examining whether the condition of substrate (either previously colonised or never colonised) or the presence of heterospecific larvae was more important in the initial choice of food source by female Ch. rufifacies where conspecifics were not present, and whether the condition of substrate and presence of heterospecific larvae affects the number of offspring deposited by a female. Attraction was studied using a Y-olfactometer system, and oviposition using a binary-choice assay, with females responding to pairwise choice between an array of meat conditions (fresh, larval aged or aged) and presence/absence of Lucilia sericata larvae. Females displayed a hierarchy of choice of larval aged substrate > aged substrate > fresh substrate, with the active presence of heterospecific larvae a secondary factor in choice. Females produced higher offspring numbers on meat that was either currently or previously colonised by heterospecific larvae, demonstrating the importance of heterospecific indicators of previous or current colonisation as an oviposition cue. This serves as an important consideration for entomologists working with Ch. rufifacies in any capacity where other blow fly species may be present, and most importantly for forensic entomologists where time of colonisation is utilised to estimate PMI.

Influence of plant community on Aedes albopictus (Diptera, Culicidae) oviposition behaviour: Insights from a Spanish botanical garden.

Mosquitoes are capable of transmitting pathogens of both medical and veterinary significance. Addressing the nuisance and vector roles of Aedes albopictus through surveillance and control programs is a primary concern for European countries. Botanical gardens provide suitable habitats for the development of Ae. albopictus and represent typical points of entry of invasive species. To assess the oviposition preferences alongside various biotic parameters (plant species community, shade index, and flowering), we conducted a study in a botanical garden of Sóller (Mallorca, Balearic Islands, Spain). A total of 6,368 Ae. albopictus eggs were recorded in 36 ovitraps positioned and revised every 15 days in seven different habitats over six months in 2016. Zero-inflated and generalized linear mixed-effects models were used to analyse Ae. albopictus habitat preferences. The number of eggs increased throughout the sampling period, peaking in September. The oviposition rates showed a patchy distribution, with Ae. albopictus showing preference for oviposition in laurel forest and cropland habitats. A positive effect of large leaves and presence of flowers on the oviposition of Ae. albopictus were also recorded. This study provides valuable information into the behaviour of Ae. albopictus in botanical gardens, which is essential data for informing surveillance and control programs.

Effect of active immunization with OPN5 on follicular development and egg production in quail under different photoperiods.

OPN5 is one of the main deep brain photoreceptors (DBPs), converting photoperiodic information into neuroendocrine signals to regulate reproduction in birds. This study investigated the mechanism of OPN5-mediated photoperiodic regulation of reproduction by active immunization against OPN5. 96 female quail were divided into OPN5-immunized and control group under the same photoperiod: 16 L:8 D (d 1 to d 35), 8 L:16 D (d 36 to d 70) and 12 L:12 D (d 71 to d 126). OPN5-immunized group was conducted with OPN5 protein vaccination and control group was given a blank vaccine. Samples were collected on d 1, d 30, d 60, and d 126. Results showed switching photoperiod to 8 L:16 D decreased the laying rate, GSI%, numbers of YFs and WFs, serum levels of PRL, P4 and E2, and pituitary PRL and TSHß protein expressions in both groups (P < 0.05). Whereas the OPN5-immunized group exhibited higher laying rates than the control group (P < 0.05). The control group showed reduced GnRHR and TSHß gene expressions in the pituitary and increased GnIH and DIO3 transcript and/or protein abundance in the hypothalamus. (P < 0.05). The OPN5-immunized group had lower DIO3 expression at both mRNA and protein levels. (P < 0.05). Switching photoperiod from 8 L:16 D to 12 L:12 D increased the laying rates, GSI%, numbers of YFs and WFs, serum levels of PRL, and PRL protein expression in both groups (P < 0.05), and the responses were more pronounced in OPN5-immunized group (P < 0.05). In contrast to the control group, quail with OPN5-immunization had higher OPN5 and DIO2 transcript and/or protein levels but lower DIO3 expressions in the hypothalamus along the transition photoperiods (P < 0.05). The results revealed that OPN5 responds to photoperiod transition, and its activation mediates related signaling to up-regulate TSH-DIO2/DIO3 pathway and VIP-PRL secretion to prime quail reproductive functions.

EVALUATION OF THE EFFICIENCY OF BEETROOT PEEL (BETA VULGARIS) IN OVITRAPS AS AN ATTRACTANT FOR SURVEILLANCE OF ARBOVIRUS VECTORS IN THE MUNICIPALITY OF AGRESTINA, STATE OF PERNAMBUCO, BRAZIL.

It is estimated that there are over 500 species of arboviruses worldwide, with more than 150 of them directly associated with human diseases, the majority of which are zoonotic. Among the main arboviruses circulating in Brazil, dengue, Zika, and chikungunya stand out, all transmitted through a common vector, Aedes aegypti. Given this scenario, the development and implementation of more efficient surveillance strategies become urgent. This study aims to compare and evaluate the efficiency of beetroot peel, Beta vulgaris, as an attractant for Ae. aegypti oviposition under field conditions in the municipality of Agrestina, State of Pernambuco, Brazil. Beetroot peel extract is a cheap and accessible source of geosmin, which holds significant potential as an attractant for mosquitoes due to its resemblance to microbial volatiles found in water bodies rich in organic material. During the study period (November 2023 to April 2024), 40 traps were set in each neighborhood, with 20 of each attractant. Two traps were used per property, one following the traditionally used model (beer yeast infusion) and another containing beetroot peel. Overall, in both analyzed neighborhoods (Campo Novo and Cohab), beetroot peel appeared to be a more efficient attractant for the oviposition of culicids. Beetroot peel showed the highest values in egg abundance and in the analyzed indices.

Histological changes of oocytes of the cattle tick Rhipicephalus microplus (Canestrini, 1888) treated with copper solutions.

Infections caused by the ectoparasite Rhipicephalus microplus can cause major health problems in cattle, including death. Tick control is regularly made using a range of acaricide products. As a consequence, tick populations have been heavily selected for drug resistance. The objective of this work was to determine the in vitro efficacy of copper chloride and sulfate (CuCl2 and CuSO4) solutions against R. microplus. The adult immersion test (AIT), which measures the egg-laying and egg-hatch effects, was used for the Cu-II solutions at 30, 60, 120, 240, 480, and 1000 mM, in triplicates. Distilled water and the combination of cypermethrin 20% and chlorpyrifos 50% were used as controls. Histological sections were performed from the ovaries of adult engorged female ticks treated with 240, 480, and 1000 mM of CuCl2 and CuSO4. We have established a histological index of the damage caused by the solutions to the tick oocytes. The overall efficacy (egg laying & egg hatch) for CuCl2 and CuSO4 was 81.3, 82.5, 89.8, 84.5, 100.0, and 100%, and 61.7, 43.4, 62.5, 93.1, 100.0, and 98.5% respectively. Smaller oocytes were found in the Cu-II groups compared to the negative control. The histological data showed a concentration-dependent degenerative lesion of oocytes, described as cytoplasmic vacuolation and nuclear disorganization. The combination of cypermethrin and chlorpyriphos showed 100% efficacy. Cu-II solutions showed in vitro efficacy against adult engorged ticks being particularly harmful to oocytes. Thus, bioactive metals could be a complementary biofriendly treatment to control R. microplus and these injuries could be responsible for preventing egg hatch, and reducing pasture contamination. Safety studies are underway demonstrating the Cu-II potential in naturally infected cattle and their persistence in the environment.

Olfactory learning in Pieris brassicae butterflies is dependent on the intensity of a plant-derived oviposition cue.

Butterflies, like many insects, use gustatory and olfactory cues innately to assess the suitability of an oviposition site and are able to associate colours and leaf shapes with an oviposition reward. Studies on other insects have demonstrated that the quality of the reward is a crucial factor in forming associative memory. We set out to investigate whether the large cabbage white Pieris brassicae (Linnaeus) has the ability to associate an oviposition experience with a neutral olfactory cue. In addition, we tested whether the strength of this association is dependent on the gustatory response to the glucosinolate sinigrin, which is a known oviposition stimulus for P. brassicae. Female butterflies were able to associate a neutral odour with an oviposition experience after a single oviposition experience, both in a greenhouse and in a semi-natural outdoor setting. Moreover, butterflies performed best when trained with concentrations of sinigrin that showed the strongest response by specific gustatory neurons on the forelegs. Our study provides novel insight into the role of both gustatory and olfactory cues during oviposition learning in lepidopterans and contributes to a better understanding of how these insects might be able to adapt to a rapidly changing environment.

Short-term responses of spider mites inform mechanisms of maize resistance to a generalist herbivore.

Plants are attacked by diverse herbivorous pests with different host specializations. While host plant resistance influences pest pressure, how resistance impacts the behaviors of generalist and specialist herbivores, and the relationship to resistance, is less well known. Here, we investigated the short-term (< 1 h) behavioral changes of a generalist herbivore, the two-spotted spider mite (TSM), and a specialist herbivore, the Banks grass mite (BGM), after introduction to no-choice Tanglefoot leaf-arenas (2 × 2 cm) of three maize inbred lines (B73, B75, and B96). The widely-used inbred line B73 is susceptible to spider mites, while B75 and B96 are known to be mite resistant, especially to TSM. Video tracking was used to record TSM and BGM walking, probing, feeding, resting, web-building and travel distance on arenas of each line. Mite oviposition was also recorded after 72 h. B75, a resistant line, decreased the feeding behavior (i.e., time) of both mite species compared to B73 (susceptible control) and B96. Moreover, TSM appeared to be sensitive to both resistant lines (B75 and B96) with reduced oviposition, and increased resting and web-building times compared to susceptible B73. In contrast, the specialist BGM showed no difference in oviposition, resting and web-building time across all maize inbred lines. Our findings of quite broad and short-term responses of TSM to B75 and B96 are consistent with a role for constitutive or rapidly induced plant defenses in maize in conferring TSM resistance. Other mechanisms of plant resistance may be needed, however, for defense against specialists like BGM.

Functional dissection of mosquito humidity sensing reveals distinct Dry and Moist Cell contributions to blood feeding and oviposition.

Aedes aegypti mosquitoes are major vectors of dengue, chikungunya, and other arboviral diseases. Ae. aegypti's capacity to reproduce and to spread disease depends on the female mosquitoes' ability to obtain blood meals and find water-filled containers in which to lay eggs (oviposit). While humidity sensation (hygrosensation) has been implicated in these behaviors, the specific hygrosensory pathways involved have been unclear. Here, we establish the distinct molecular requirements and anatomical locations of Ae. aegypti Dry Cells and Moist Cells and examine their contributions to behavior. We show that Dry Cell and Moist Cell responses to humidity involve different ionotropic receptor (IR) family sensory receptors, with dry air-activated Dry Cells reliant upon the IR Ir40a, and humid air-activated Moist Cells upon Ir68a. Both classes of hygrosensors innervate multiple antennal sensilla, including sensilla ampullacea near the antennal base as well as two classes of coeloconic sensilla near the tip. Dry Cells and Moist Cells each support behaviors linked to mosquito reproduction but contribute differently: Ir40a-dependent Dry Cells act in parallel with Ir68a-dependent Moist Cells to promote blood feeding, while oviposition site seeking is driven specifically by Ir68a-dependent Moist Cells. Together these findings reveal the importance of distinct hygrosensory pathways in blood feeding and oviposition site seeking and suggest Ir40a-dependent Dry Cells and Ir68a-dependent Moist Cells as potential targets for vector control strategies.

Gustatory receptor 11 is involved in detecting the oviposition water of Asian tiger mosquito, Aedes albopictus.

BACKGROUND: Aedes albopictus is a major arbovirus vector with small stagnant water containers being its oviposition sites. Mosquitoes search for these sites based on their olfactory cues (odor and moisture emanating from the water at the oviposition site), visual cues (size and color of the site), and gustatory cues (ion and nutrient concentration in that water). The gustatory mechanism through which mosquitoes search for oviposition sites remains unknown. METHODS: To investigate the role of taste receptors in Ae. albopictus oviposition site selection, we developed a laboratory model. This model assessed mosquito behavior in locating and detecting oviposition sites, using a location index to quantify site preference and detection time to measure response to water presence. We compared oviposition site-searching efficiency between mosquitoes with blocked and unblocked appendages, targeting the taste organs. Transcriptome sequencing was conducted to identify differentially expressed genes between water-exposed and unexposed mosquitoes. CRISPR/Cas9 technology was then employed to generate a mutant strain with a targeted gene knockout. RESULTS: There was no significant difference between the blocked and unblocked groups in the location index. In contrast, the detection time of the unblocked group differed significantly from all other groups, including those with blocked foreleg tarsus, midleg tarsus, hindleg tarsus, all tibia, and all tarsus. Transcriptome sequencing analyses of water-exposed and unexposed mosquitoes revealed that the taste-related gene gustatory receptor 11(gr11) was differentially expressed. This gene was knocked out with CRISPR/Cas9 technology to generate a pure mutant strain with 2- and 4-bp deletions, which exhibited a significantly longer detection time than the wild-type strain. CONCLUSIONS: This study reveals the role of Ae. albopictus gr11 in water detection at oviposition sites, thereby providing a theoretical basis and scientific guidelines for managing the breeding sites of these mosquitoes.

Male condition and seminal fluid affect female host-marking behavior in the Mexican fruit fly.

Mating and the transfer of seminal fluid components including male accessory glands (MAGs) proteins can affect oviposition behavior in insects. After oviposition, some species of fruit flies deposit a host-marking pheromone (HMP) on the fruit that discourages oviposition by other females of the same or different species or genus and reduces competition between larvae. However, we know very little about how mating, receiving seminal fluid, or male condition can affect female host marking behavior. Here, we tested how the physiological state of females (mated or unmated), the receipt of seminal fluid, and the condition of the male (wild or sterile) affect oviposition and host-marking behavior (HMB) in Anastrepha ludens (Diptera: Tephritidae). We also determined the efficiency of the host-marking pheromone from mated or unmated females in deterring oviposition. In a further examination of how seminal fluid may be affecting HMB we assessed if there were differences in the size of wild or sterile MAGs and the protein quantity transferred during mating. Our results indicate that receiving seminal fluid increased egg laying and increased time invested in host-marking (HM). Unmated females laid fewer eggs than mated females but invested the same amount of time in depositing host-marking pheromone, which had similar effectiveness in deterring oviposition as that of mated females. Females that mated with sterile males laid the same number of eggs as females that mated with wild males but spent less time depositing host-marking pheromone, which suggests that females detect the condition of the male and invest less in marking hosts. Finally, sterile males had larger accessory glands and transferred more MAGs proteins during mating compared to wild males. Seminal proteins could be manipulating HM behavior and female investment into their current reproductive effort. We are only beginning to understand how male condition and seminal fluid can affect female physiology and maternal investment in HMP.

Oxidative Stress, Oxidative Damage, and Cell Apoptosis: Toxicity Induced by Arecoline in Caenorhabditis elegans and Screening of Mitigating Agents.

As the areca nut market is expanding, there is a growing concern regarding areca nut toxicity. Areca nut alkaloids are the major risky components in betel nuts, and their toxic effects are not fully understood. Here, we investigated the parental and transgenerational toxicity of varied doses of areca nut alkaloids in Caenorhabditis elegans. The results showed that the minimal effective concentration of arecoline is 0.2-0.4 mM. First, arecoline exhibited transgenerational toxicity on the worms' longevity, oviposition, and reproduction. Second, the redox homeostasis of C. elegans was markedly altered under exposure to 0.2-0.4 mM arecoline. The mitochondrial membrane potential was thereafter impaired, which was also associated with the induction of apoptosis. Moreover, antioxidant treatments such as lycopene could significantly ameliorate the toxic effects caused by arecoline. In conclusion, arecoline enhances the ROS levels, inducing neurotoxicity, developmental toxicity, and reproductive toxicity in C. elegans through dysregulated oxidative stress, cell apoptosis, and DNA damage-related gene expression. Therefore, the drug-induced production of reactive oxygen species (ROS) may be crucial for its toxic effects, which could be mitigated by antioxidants.