Male Density Research Articles

Natural History Observations on a Population of Vesperus luridus (Coleoptera: Cerambycidae) in Central Italy

Natural history observations were made, during August–September 2021, on a population of the ecologically poorly known Vesperus luridus (Cerambycidae) at a hilly locality of Latium, Central Italy. These beetles were searched for by night along a 170 m long transect, with the help of hand torches. During the field surveys, we recorded a total of 130 individuals, of which 128 were males and 2 females. All individuals were observed between 21 h 45 and 01 h 15, with above-ground activity peaking from 22 h 45 to 23 h 45. The minimum observed density per day showed a rapid increase to a peak at the end of August, followed by a slower decrease in the following two weeks. Mean male density was 0.32 individuals per transect m2, whereas only two females were observed (mean density = 0.006 individuals per transect m2). Most individuals were found on trees, and they appeared to be highly attracted to artificial lights. One female, situated on a tree at a height of 170 cm, was surrounded by five courting males.

Post-weaning social isolation causes sex-specific alterations to dendritic spine density in subregions of the prefrontal cortex and nucleus accumbens of adult mice

Post-weaning social isolation stress has been shown to increase addiction-like behavior in adulthood. These long-term behavioral alterations may be due to long lasting isolation-induced structural changes to neurons in brain regions involved in reward processing. Previous studies have shown that various stressors alter dendritic spine density in the prefrontal cortex (PFC) and the nucleus accumbens, though many of these studies examine the short-term effects of stress, and are primarily conducted in males. There is mounting evidence that males and females exhibit differences in their stress responses, with some studies showing sex differences in stress-induced plasticity. To determine the long-lasting, sex-specific alterations in spine density following post-weaning social isolation, male and female mice were either isolated or group housed at weaning and spine density was measured once they reached adulthood. Post-weaning isolation increased spine density in the PFC of both the males and females, although the effects in the infralimbic cortex were more pronounced in the females. In the nucleus accumbens, adolescent isolation increased spine density in males only in the core and shell. Females also had higher baseline spine density than males in the nucleus accumbens core. Together these data suggest that adolescent social isolation causes long-term, sex-specific alterations to the prefrontal cortex and the nucleus accumbens.

The effects of conspecific male density on the reproductive behavior of male Schizocosa retrorsa (Banks, 1911) wolf spiders (Araneae: Lycosidae)

In the context of competitive mate searching, males may use cues from conspecifics, such as movement cues and/or courtship signals, to locate mates. For ground-dwelling wolf spiders, substrate-borne vibratory cues may be particularly important sources of information, given the potential presence of many visual obstacles. This study explores the possible use of conspecific male cues in wolf spiders by asking: (i) Do male Schizocosa retrorsa (Banks, 1911) wolf spiders use vibratory cues from conspecific males to alter their searching or signaling behavior? (ii) Can males assess the density of conspecific males using conspecific male cues? (iii) Does the variation in conspecific male density affect the behavioral response of focal males to the conspecific cues? To answer these questions, we tested the effects of (i) the number of conspecific males and (ii) the activity of conspecific males (e.g., courtship yes/no) on a focal male's behavior. We recorded the following focal male behavior: (a) the presence/absence of courtship behavior, (b) temporal/structural signal characteristics of the multimodal courtship signaling, and (c) locomotory patterns. Our results suggest that, (i) S. retrorsa males assess their competitive environment through substrate-borne vibratory cues generated by courting or non-courting behavior of conspecific neighbors, (ii) S. retrorsa males may alter their reproductive behavior between mate searching and courtship signaling by the assessment of cues associated with conspecific male density, and (iii) the assessment and perception of density-dependent conspecific courtship signaling can be used as social information to adjust the reproductive behavior.

Sex difference in tDCS current mediated by changes in cortical anatomy: A study across young, middle and older adults

IntroductionThe observed variability in the effects of transcranial direct current stimulation (tDCS) is influenced by the amount of current reaching the targeted region-of-interest (ROI). Age and sex might affect current density at target ROI due to their impact on cortical anatomy. The present tDCS simulation study investigates the effects of cortical anatomical parameters (volumes, dimension, and torque) on simulated tDCS current density in healthy young, middle-aged, and older males and females. MethodologyIndividualized head models from 240 subjects (120 males, 18–87 years of age) were used to identify the estimated current density (2 mA current intensity, 25 cm2 electrode) from two simulated tDCS montages (CP5_CZ and F3_FP2) targeting the inferior parietal lobule (IPL) and middle frontal gyrus (MFG), respectively. Cortical parameters including segmented brain volumes (cerebrospinal fluid [CSF], grey and white matter), cerebral-dimensions (length/width &length/height) and brain-torque (front and back shift, petalia, and bending) were measured using the magnetic resonance images (MRIs) from each subject. The present study estimated sex differences in current density at these target ROIs mediated by these cortical parameters within each age group. ResultsFor both tDCS montages, females in the older age group received higher current density than their male counterparts at the target ROIs. No sex differences were observed in the middle-aged group. Males in the younger age group had a higher current density than females, only for the parietal montage. Across all age groups, CSF, and grey matter volumes significantly predicted the current intensity estimated at the target sites. In the older age group only, brain-torque was a significant mediator of the sex difference. ConclusionsOur findings demonstrate the presence of sex differences in the simulated tDCS current density, however this pattern differed across age groups and stimulation locations. Future studies should consider influence of age and sex on individual cortical anatomy and tailor tDCS stimulation parameters accordingly.

Milk fat globule membrane attenuates high fat diet-induced neuropathological changes in obese Ldlr-/-.Leiden mice.

Milk-fat globule membrane (MFGM) is a complex structure secreted by the mammary gland and present in mammalian milk. MFGM contains lipids and glycoproteins as well as gangliosides, which may be involved in myelination processes. Notably, myelination and thereby white matter integrity are often altered in obesity. Furthermore, MFGM interventions showed beneficial effects in obesity by affecting inflammatory processes and the microbiome. In this study, we investigated the impact of a dietary MFGM intervention on fat storage, neuroinflammatory processes and myelination in a rodent model of high fat diet (HFD)-induced obesity. 12-week-old male low density lipoprotein receptor-deficient Leiden mice were exposed to a HFD, a HFD enriched with 3% whey protein lipid concentrate (WPC) high in MFGM components, or a low fat diet. The impact of MFGM supplementation during 24-weeks of HFD-feeding was examined over time by analyzing body weight and fat storage, assessing cognitive tasks and MRI scanning, analyzing myelinization with polarized light imaging and examining neuroinflammation using immunohistochemistry. We found in this study that 24 weeks of HFD-feeding induced excessive fat storage, increased systolic blood pressure, altered white matter integrity, decreased functional connectivity, induced neuroinflammation and impaired spatial memory. Notably, supplementation with 3% WPC high in MFGM components restored HFD-induced neuroinflammation and attenuated the reduction in hippocampal-dependent spatial memory and hippocampal functional connectivity. We showed that supplementation with WPC high in MFGM components beneficially contributed to hippocampal-dependent spatial memory, functional connectivity in the hippocampus and anti-inflammatory processes in HFD-induced obesity in rodents. Current knowledge regarding exact biological mechanisms underlying these effects should be addressed in future studies.

A study on sexual dimorphism in fingerprint ridge density among medical students of Nellore south coastal district of Andhra Pradesh

Fingerprints are unique, and each fingerprint of an individual differs from another. Studies were conducted to know how various factors like Race, Sex, and certain disorders influence fingerprint patterns. Similary, the number of ridges present in an area of palms and fingers and their variations were also studied. To study the sexual variations in fingerprint ridge density among medical students studying in Narayana Medical college from Andhra Pradesh. Fingerprints of one hundred and twenty medical students (sixty male and sixty female) were analyzed for this study. The mean ridge density in males is 128.5 (Range 124 -134) for ten digits, and in females, the mean ridge density for ten fingers is 148. 67 and (Range 145 -153). Average ridge density for 0.25sq.cm. in Male:Female is 12.85:14.86. The females exhibit higher ridge density than males; ridge density of more than 14 ridges of a finger in a 0.25 sq. mm area indicates that the finger likely belongs to a female.

Nongenetic inheritance of behavioural variability is context specific and sex specific

Abstract Environmentally mediated nongenetic inheritance extends the concept of phenotypic plasticity across generations, allowing for the experience of parents to influence the physiology, life history and behaviour of their offspring. We assess whether the perceived social environment of mothers and fathers impacts offspring behaviour in the Australian field cricket Teleogryllus oceanicus. We varied parents' perception of the density of conspecific males by exposing parents to either the presence or absence of male song throughout rearing. Following mating in a factorial design, the offspring of the parental pairs were also reared across the two acoustic environments and their behaviour assessed as adults. When reared in a no‐song environment, offspring of both sexes were more active, emerging from a shelter sooner and displaying greater mobility in search of male song. Offspring behaviour was not directly impacted by either the maternal or paternal social environments independently, but there was a significant interaction effect between the parental environments on the behaviour of daughters. When both parents were reared in song (‘paternal song × maternal song’), their no‐song‐reared daughters exhibited lower levels of mobility than the no‐song‐reared daughters of ‘paternal song × maternal no‐song’ and ‘paternal no‐song × maternal song’ pairs. Although our data suggest that nongenetic parental effects may have the potential to drive behavioural variability in offspring, such effects are highly complex, only arising as sex‐ and context‐specific traits. A free Plain Language Summary can be found within the Supporting Information of this article.

Reproductive changes in Foveaux Strait Ostrea chilensis, Southern New Zealand, after Bonamia exitiosa epidemics

ABSTRACT The commercially significant Foveaux Strait Ostrea chilensis fishery has been typified by consistently low brooding rates and recruitment failures since recurrent mass mortalities from Bonamia exitiosa infection. The present study examined the gametogenic cycle of Foveaux Strait O. chilensis monthly, from July 2017 to September 2018, using histological examination of the gonad and condition indices to determine resulting changes to gametogenesis, spawning, brooding, and spatial variation, compared to an initial study of reproduction before B. exitiosa epidemics. The seasonal gametogenic cycle and brooding period were similar to previous descriptions. However, there was evidence for a more female skewed sex ratio, and the development and release of ova into the mantle cavity at smaller sizes. Despite similarities in gametogenesis, sex ratios, temperature, and chlorophyll-a concentrations between five sites across Foveaux Strait, the western-most site had no brooders and consistently lower condition indices, compared to the eastern-most site. Oysters may need to be in sufficient condition to initiate brooding, and reduced male densities may contribute to sperm limitation, which, along with a disconnect between the peak release of gametes and brooding, may have contributed to lower brooding rates.

Perinatal Exposure of Bisphenol A Differently Affects Dendritic Spines of Male and Female Grown-Up Adult Hippocampal Neurons.

Perinatal exposure to Bisphenol A (BPA) at a very low dose may modulate the development of synapses of the hippocampus during growth to adulthood. Here, we demonstrate that perinatal exposure to 30 μg BPA/kg per mother’s body weight/day significantly altered the dendritic spines of the grownup rat hippocampus. The density of the spine was analyzed by imaging of Lucifer Yellow-injected CA1 glutamatergic neurons in adult hippocampal slices. In offspring 3-month male hippocampus, the total spine density was significantly decreased by BPA exposure from 2.26 spines/μm (control, no BPA exposure) to 1.96 spines/μm (BPA exposure). BPA exposure considerably changed the normal 4-day estrous cycle of offspring 3-month females, resulting in a 4∼5 day estrous cycle with 2-day estrus stages in most of the subjects. In the offspring 3-month female hippocampus, the total spine density was significantly increased by BPA exposure at estrus stage from 2.04 spines/μm (control) to 2.25 spines/μm (BPA exposure). On the other hand, the total spine density at the proestrus stage was moderately decreased from 2.33 spines/μm (control) to 2.19 spines/μm (BPA exposure). Thus, after the perinatal exposure to BPA, the total spine density in males became lower than that in females. Concerning the BPA effect on the morphology of spines, the large-head spine was significantly changed with its significant decrease in males and moderate change in females.

Juvenile Experience with Male Cues Triggers Cryptic Choice Mechanisms in Adult Female Redback Spiders.

Simple SummaryFemales of many species vary in their receptivity to male mating attempts. When many males are present in the habitat, the theory predicts that females should be choosy and discriminate among potential mates. When few males are available, females should mate readily with the first male who courts, and thus avoid the risk of remaining unmated. We predicted that cues perceived as juveniles that indicate male availability would affect the mating behaviour of adult females. In our first experiment, juvenile females were exposed to airborne chemicals produced by males at high or low densities. In our second experiment, we mimicked a natural situation where males or other juveniles live on the webs of females shortly before they become sexually mature, and compared this to females developing in isolation. As was consistent with our predictions, we found that the adult females changed their behaviour after exposure to cues of high male availability during development. When the females perceived many males nearby (high density airborne cues or living with males) they more often interrupted copulation, or cannibalized the males before the mating was complete as adults. In comparison, when the cues indicated low male availability, the adult females were more likely to allow the males to complete mating, and cannibalism was less common.Female choice may be linked to population density if the expected encounter rates with potential mates affects choosiness (the energy and risk engaged to express mate preferences). Choosiness should covary with male availability, which could be assessed using the social cues available during development. We tested whether the exposure of juvenile females to cues of male density affected the mechanisms of choosiness of adult Latrodectus hasselti spiders in two experiments simulating natural contexts. The juvenile females were exposed to (1) volatile chemicals from two densities of adult males (airborne cues), and (2) tactile, vibrational and chemical cues from adult males or other females (cohabitation cues). As adults, the females mated readily, regardless of the treatment, but there was strong evidence for post-copulatory mechanisms of choosiness in females exposed to cues of high male availability. These included abbreviated matings (in both experiments), cannibalism of the males before the mating was complete (cohabitation), and, remarkably, a reduction in the successful placement of internal sperm plugs (cohabitation). These shifts decrease the likelihood that the first mate would monopolize paternity if the female chose to mate again. We conclude that female choosiness may impose a strong selection on males despite the high mating rates, and these effects can hinge on the cues of male availability detected by juveniles.

Sperm production and quality in European eel (Anguilla anguilla) in relation to hormonal treatment.

Aquaculture production relies on controlled management of gametogenesis, especially in species where assisted reproduction is needed for obtaining gametes in captivity. The present study used human chorionic gonadotropin (hCG) treatments to induce and sustain spermatogenesis in European eel (Anguilla anguilla). The aim was to evaluate effects of strip-spawning timing (12 vs. 24hr) after weekly administration of hCG and the necessity of a primer dose (in addition to weekly hormonal treatment) prior to strip spawning (primer vs. no-primer) on sperm quality parameters. Sperm parameters included milt production (weight), density and sperm kinematics at Week 9, 11 and 13 after onset of treatment. Spermiation commenced in 11.5% of males in Week 5 and by Week 9, and all males produced milt. Male weight, milt production, sperm density and spermatocrit did not differ among hormonal treatments during the experimental period. Overall, male weight decreased from 106.3 to 93.0g, milt weight increased from 3.5 to 5.4g, sperm density counts decreased from 11.7×109 to 10.5×109 cells/ml, and spermatocrit decreased from 46.5% to 40.5%. Furthermore, spermatocrit was positively related to haemocytometer counts (R2 =.86, p<.001), providing a reliable indicator of sperm density. Differences in sperm kinematics were observed depending on strip-spawning timing after hormonal injection (12 vs. 24hr) but with no consistent pattern. These sperm quality parameters also did not consistently differ between the no-primer and primer treatments. Considering that each male may be stripped 4-5 times over the 2-3months spawning season, omitting the primer would reduce animal handling, material costs and labour intensity, while sustaining high-quality sperm production.

No association between serum uric acid and lumbar spine bone mineral density in US adult males: a cross sectional study

Available evidence linking serum uric acid (SUA) and bone mineral density (BMD) remains controversial, and data on this association are limited among adult men in the general population. Thus, the aim of this study was to evaluate the association of SUA with lumbar spine BMD in US adult males. A cross-sectional study was conducted based on the National Health and Nutrition Examination Survey (NHANES, 1999–2006) database. Multivariate linear regression analyses were employed to assess the association of SUA with lumbar spine BMD, considering complex survey design and sampling weights. Through rigorous eligibility criteria, a total of 6704 individuals were yielded for final data analysis (average age, 40.5 years; 70.6% white). After fully adjusting potential confounders, no associations were detected between SUA and lumbar spine BMD [β (95% confidence interval, CI), − 0.003 (− 0.007, 0.002)]. Additionally, similar results were observed in all stratification analyses, and no interactions were found based on all priori specifications. In brief, our findings did not provide an inspiring clue for the hypothesis that SUA may be beneficial to lumbar spine BMD. Future more prospective studies are needed to further explore the causal relationship of SUA with lumbar spine BMD.

Salmon subsidies predict territory size and habitat selection of an avian insectivore.

The annual migration and spawning event of Pacific salmon (Oncorhynchus spp.) can lead to cross-boundary delivery of marine-derived nutrients from their carcasses into adjacent terrestrial ecosystems. The densities of some passerine species, including Pacific wrens (Troglodytes pacificus), have been shown to be positively correlated with salmon abundance along streams in Alaska and British Columbia, but mechanisms maintaining these densities remain poorly understood. Riparian areas near salmon streams could provide higher quality habitat for birds through greater food availability and more suitable vegetation structure for foraging and breeding, resulting in wrens maintaining smaller territories. We examined relationships between salmon biomass and Pacific wren territory size, competition, and habitat selection along 11 streams on the coast of British Columbia, Canada. We show that male wren densities increase and territory sizes decrease as salmon-spawning biomass increases. Higher densities result in higher rates of competition as male wrens countersing more frequently to defend their territories along streams with more salmon. Wrens were also more selective of the habitats they defended along streams with higher salmon biomass; they were 68% less likely to select low-quality habitat on streams with salmon compared with 46% less likely at streams without salmon. This suggests a potential trade-off between available high-quality habitat and the cost of competition that structures habitat selection. Thus, the marine-nutrient subsidies provided by salmon carcasses to forests lead to higher densities of wrens while shifting the economics of territorial defence toward smaller territories being defended more vigorously in higher quality habitats.

Comparative response to post‐production process of two Anastrepha ludens strains: Application in the sterile insect technique

AbstractThe new desiccation‐resistant (DR) strain of Anastrepha ludens Loew differs in its life‐history traits from the non‐selected strain (NS). Given the innate resistance of DR flies to stressors, it is necessary to determine the packing and shipment conditions for their use in the sterile insect technique (SIT). First, we used pupae to evaluate the interaction of hypoxia period (12, 24 and 36 hr) and temperature (15.3 (±0.9), 19.5 (±1.0), 25.5 (±0.6) and 30.1 (±0.5) oC). Second, adults were exposed to densities of 1.0, 1.3 and 1.5 flies/cm2 and chilling periods of 0, 3 and 5 hr. We observed a negative relationship of emergence and flight ability with hypoxia period and temperature in both strains especially when flies were exposed to 36 hr of hypoxia and 30℃. Interestingly, knock‐down time decreased as male density increased, but when chilling time increased, recovery time also increased. Both chilling time and male density had negative effects on male weight. Chilling time reduced male survival when exposed to desiccation, while both chilling time and male density decreased male survival under starvation conditions. Negative effects on number of matings were observed only on the first day after chilling but not on the following days. We found that DR flies survive approximately twice as long as flies from the NS strain when exposed to starvation or desiccation stressors. We discuss our results on the basis of the potential use of DR flies in SIT programmes.

Sex differences in morphology across an expanding range edge in the flightless ground beetle, Carabus hortensis.

Species’ ranges are dynamic, changing through range shifts, contractions, and expansions. Individuals at the edge of a species’ shifting range often possess morphological traits that increase movement capacity, that are not observed in individuals farther back within the species’ range. Although morphological traits that increase in proportion toward the range edge may differ between the sexes, such sex differences are rarely studied.Here, we test the hypotheses that body size and condition increase with proximity to an expanding range edge in the flightless ground beetle, Carabus hortensis, and that these trait changes differ between the sexes.Male, but not female, body size increased with proximity to the range edge. Body size was positively correlated with male front and mid tibia length and to female hind tibia length, indicating that body size is indicative of movement capacity in both sexes. Body condition (relative to body size) decreased with increasing population density in males but not females. Population density was lowest at the range edge.Our results indicate that sex is an important factor influencing patterns in trait distribution across species’ ranges, and future studies should investigate changes in morphological traits across expanding range margins separately for males and females. We discuss the implications for sex differences in resource allocation and reproductive rates for trait differentiation across species’ shifting ranges.

A METHOD FOR DETECTING BONE DENSITY AT DIFFERENT SIDES AND FIVE SITES OF MANDIBULAR BONE BY NEW COMPUTERIZED MEASUREMENTS

Introduction: The bone quality also affects the stress distribution under buccolingual load. Low density bone presents reduced stiffness and increases implant displacement. Under highest displacement, the bone is deformed, consequently higher stresses in the cortical and cancellous bone are predicted. The mental foramen is a principle factor for placing implants in the foraminal rang of the mandibular arch. Objectives: To provide available clinical techniques to detect and identification of mandibular bone density around the tooth and alveolar ridges at the different five sites for both male and female groups and comparing them for accurate plane and not interfere with the mental foramen and canal during surgical treatment. Material and Methods: Twelve patients ranged from 45-60 year old (6 males and 6 female) came to the Department of Prosthodontics, Alexandria University with past medical history. The evaluation of alveolar mandibular bone density using a new computerized method (Image J program) which was not used in the previous studies for prober assessment of bone height measurements. Results: There was insignificant change of bone density around the 5 sites at both groups. In the midline, there was gradual increase in the bone density from midline region to molar region and in males more than females Conclusions: There was no statistical significant difference between the right side for female and male density at different sites, indicating more favorable stable supported overdenture with the use of accurate surgical position.

Compositional variation in early-life parenting structures alters oxytocin and vasopressin 1a receptor development in prairie voles (Microtus ochrogaster).

Paternal absence can significantly alter bio-behavioural development in many biparental species. This effect has generally been demonstrated by comparing the development of offspring reared under biparental care with those reared by a single mother. However, studies employing this design conflate two significant modifications to early-life experience: removal of father-specific qualities and the general reduction of offspring-directed care. In the socially monogamous prairie vole (Microtus ochrogaster), the experience of paternal absence without substitution during development inhibits partner preference formation in adulthood, a hallmark of social monogamy, in females and males. Employing alloparents as substitutes for fathers, our previous work demonstrated that paternal absence affects pair-bond formation in female offspring via reduced quantity of care, although it affects pair-bond formation in male offspring by means of a missing paternal quality (or qualities). Here, we present evidence that paternal absence (with and without alloparental substitution) may alter the ontogeny of neural oxytocin receptor (OXTR) and/or vasopressin 1a receptor (AVPR1a) distribution in male and female prairie voles. Compared to biparentally reared controls (BPC), male offspring reared in mother only (MON) and maternal-plus-alloparental (MPA) conditions show lower densities of OXTR in the central amygdala; and MPA males show lower densities of OXTR in the caudate putamen and nucleus accumbens. Early-life experience was not associated with differences in AVPR1a density in males. However, MON and MPA females show greater densities of AVPR1a in the medial amygdala than BPC; and MPA females show greater densities of AVPR1a in the ventromedial nucleus of the hypothalamus. We also demonstrate with corticosterone concentrations that MON and MPA offspring are not differentially susceptible to a stressor (ie, social isolation) than BPC offspring. These findings suggest that paternal absence, although likely not a salient early-life stressor, has neuroendocrine consequences for offspring, some of which may affect partner preference formation.

Pencegahan Penyakit Kusta di Lingkungan Hutan Tropis Lembab Kalimantan Melalui Pemodelan Geographically Weighted Poisson Regression

Geographically Weighted Poisson Regression (GWPR) model is a regression model developed from Poisson regression which is applied to spatial data. Parameter estimation of the GWPR model is done at each observation location using spatial weighting. This study goal is to obtain the GWPR model and the factors influencing the number of leprosy cases in each regency(municipality) on Kalimantan Island in 2018. Spatial weighting was obtained by using the adaptive bisquare kernel function and optimal bandwidth was determined by using Generalized Cross-Validation (GCV) criteria. The data of this study was secondary data namely the number of leprosy cases in 56 regency on Kalimantan Island in 2018. The parameter estimation method of GWPR model is Maximum Likelihood Estimation (MLE). The results of analysis showed that maximum likelihood estimator is obtained by using the Newton-Raphson iterative method and the factors affecting the number of leprosy cases in each regency were different and locally. The factors influencing locally were the number of health facilities, the number of health workers, the number of male population and population density.

Plasticity in Oviposition Site Selection Behavior in Drosophila suzukii (Diptera: Drosophilidae) in Relation to Adult Density and Host Distribution and Quality.

Flexibility in oviposition site selection under temporally shifting environmental conditions is an important trait that allows many polyphagous insects to flourish. Population density has been shown to affect egg-laying and offspring fitness throughout the animal kingdom. The effects of population density in insects have been suggested to be mutualistic at low densities, whereas intraspecific competition is exhibited at high densities. Here, we explore the effects of adult crowding and spatial resource variation on oviposition rate in the invasive pest Drosophila suzukii (Matsumura). In a series of laboratory experiments, we varied the density of adult males and females while holding oviposition substrate availability constant and measured per female oviposition rate using high and low-quality substrates. We found that oviposition behavior was affected more by substrate than adult density, though both variables had significant effects. When we varied the spatial arrangement of whole raspberries, we observed differences in oviposition rate and egg distribution between the grouped and solitary female treatments. Our results suggest that social interactions encourage oviposition, especially when exposed to unfamiliar or unnatural substrates. These results highlight the compensating effect of increased oviposition rate per female as adult populations decline. They will help researchers and crop managers better understand in-field population dynamics throughout the season as population densities change.

Association between social network structure and physical activity in middle-aged Korean adults

PurposeEvidence suggests that physical activity participation is shaped through a myriad of structural aspects of social relationships. We examined the relationship between social network structure based on egocentric social network and physical activity. MethodsFrom 6799 middle-aged Korean adults, we assessed the social network density and proportion of closed triads, using the name generator module. Self-reported physical activity for functional and leisure purposes was calculated in metabolic equivalent of task (MET)-min/week. We employed sex-stratified, multivariable linear regression to assess the association between each network structure variable and total physical activity, adjusting for age, network size, socioeconomic status, and comorbidities. We also examined the association with moderate-to-vigorous physical activity (MVPA) and wrist-worn accelerometer assessed physical activity. ResultsThe network members of female participants were more likely to be of same sex and family member compared to those of males. There were no sex differences in average network size. Network density based on affiliation was sex-differentially associated with physical activity (male β −346.7, p 0.2221 and female β −528.6, p 0.0002). In parallel, the proportion of closed triads was negatively associated with physical activity only in females (male β −542.6, p 0.0551 and female β −641.51, p < 0.0001). However, network density and closed triads were insignificantly yet positively associated with MVPA in male (density β 229.7, p 0.3193 and closed triad β 109.21, p 0.6333). Network structure by contact frequency or emotional closeness and accelerometer-assessed physical activity showed inconsistent results. ConclusionUnderstanding the role of social network structures can help to achieve ideal physical activity level in the context of primary prevention of cardiometabolic disorders.