Peak Mating Research Articles

Identification and characterization of circadian clock genes in the head transcriptome of Conopomorpha sinensis Bradley

Conopomorpha sinensis Bradley is the most detrimental pest to litchi and longan in China. Adult eclosion, locomotion, mating and oviposition of C. sinensis usually occur at night, regulated by a circadian rhythm. Nevertheless, our understanding of the linkages between adult circadian rhythms and clock genes remains inadequate. To address this gap, transcriptomic analysis was conducted on female and male heads (including antennae) of C. sinensis using the Illumina HiSeq 6000 platform to identify major circadian clock-related genes. The annotated sequences were analyzed by BLASTx, and candidate clock genes were classified based on conservation, predicted domain architectures, and phylogenetic analysis. The analysis revealed a higher conservation of these genes among the compared moths. Further, the expression profile analysis showed a significant spatiotemporal and circadian rhythmic accumulation of some clock genes during development. The candidate clock genes were predominantly expressed in the head, highlighting their crucial function in circadian rhythm regulation. Moreover, CsinPer, CsinTim1, and CsinCry1 displayed similar dynamic expressions with a peak expression level in the 4th age adults, suggesting their involvement in regulation of courtship and mating behaviors. The CsinPer and CsinTim1 mRNA oscillated strongly with a similar phase, containing a peak expression just before the female mating peak. This work will greatly contribute to understanding the circadian clock system of C. sinensis and provide valuable information for further studies of the molecular mechanisms involved in rhythmicity in fruit-boring pests.

Singing silver‐haired bats (Lasionycteris noctivagans)

AbstractCharacterizing sounds produced by animals can lead to better understanding of their behavioral ecology and conservation. While considerable focus has been on signals used by bats for echolocation, there has been less emphasis on nonecholocation sounds. We describe songs (i.e., acoustic vocalizations with distinctive syllable types in series or in complex motifs) produced by silver‐haired bat (Lasionycteris noctivagans). Songs, characterized by a sequence (song phrase) of 3 distinct vocalization types, were confirmed by observing free‐flying, silver‐haired bats at mine hibernacula in British Columbia, Canada. The song patterns were relatively consistent with each song phrase consisting of a lead call, followed by a droplet call, and finishing with a series of multiple chirp calls. The function of the songs is unknown, however, as other bat species produce songs for mating, we propose silver‐haired bat songs may similarly be associated with courtship or mating. Alternative functions cannot be ruled out, particularly because we recorded some songs outside of the accepted mating period. Other research has determined peak mating of silver‐haired bats occurs in fall, and spring mating has been documented. Here we additionally provide evidence of winter mating in British Columbia. The proportion of silver‐haired bat songs recorded relative to echolocation recordings varied across locations and seasons. While we recorded songs in all months of the year, more than half of the songs were produced during winter, and 93.4% (of 1,857) were produced outside of summer months. Song production in summer could be associated with other behaviors such as learning or practice, establishing or maintaining social bonds, or male‐male competition. To provide landscape and temporal context, we summarize acoustic datasets from numerous locations in western North America where recordings were made between 2005 and 2022.

Long-term video and genetic data yield insights into complex sociality of a solitary large carnivore

American black bears (Ursus americanus) may be more social than currently understood. We used long-term video and genetic data to evaluate social interactions among wild, independent-aged black bear on a conservation property in western Montana, USA. We used multinomial logistic regression to evaluate predictions about male-male interactions within the context of individual fitness, female-female interactions within the context of inclusive fitness, and male-female interactions within the context of female counterstrategies to infanticide. Overall, our findings challenged the assumption that independent-aged bears interact only during the mating season or when concentrated feeding sites are present. We documented 169 interaction events by at least 66 bear pairs, 92 (54%) of which occurred outside of the peak mating season and in the absence of concentrated feeding sites. The probability that male-male pairs engaged in play and other non-agonistic behaviours was higher than that for female-female pairs. Conversely, the probability that female-female pairs engaged in chase behaviour was higher than that for male-male and male-female pairs. We documented evidence of female mate choice, female resource defense, sexually selected infanticide (SSI), and female counterstrategies to avoid SSI. Our findings improve our understanding of ursid ethology and underscore the complexity of ursid sociality.

An OBP gene highly expressed in non-chemosensory tissues affects the phototaxis and reproduction of Spodoptera frugiperda.

Insect odorant binding proteins (OBPs) were initially regarded as carriers of the odorants involved in chemosensation. However, it had been observed that a growing number of OBP genes exhibited broad expression patterns beyond chemosensory tissues. Here, an OBP gene (OBP31) was found to be highly expressed in the larval ventral nerve cord, adult brain and male reproductive organ of Spodoptera frugiperda. An OBP31 knockout strain (OBP31-/- ) was generated by CRISPR/Cas9 mutagenesis. For OBP31-/- , the larvae needed longer time to pupate, but there was no difference in the pupal weight between OBP31-/- and wild type (WT). OBP31-/- larvae showed stronger phototaxis than the WT larvae, indicating the importance of OBP31 in light perception. For mating rhythm of adults, OBP31-/- moths displayed an earlier second mating peak. In the cross-pairing of OBP31-/- and WT moths, the mating duration was longer, and hatchability was lower in OBP31-/- group and OBP31+/- ♂ group than that in the WT group. These results suggested that OBP31 played a vital role in larval light perception and male reproductive process and could provide valuable insights into understanding the biological functions of OBPs that were not specific in chemosensory tissues.

Identification of sex pheromone in Macdunnoughia crassisigna Warren (Lepidoptera: Noctuidae) and field optimization of the sex attractant.

Sex pheromones have proven to be a viable tool for monitoring and controlling pests and is an important part of integrated pest management (IPM). The noctuid moth Macdunnoughia crassisigna Warren poses a significant threat as a defoliator pest, impacting soybean and cruciferous vegetable production and quality in East Asia. However, a lack of comprehensive knowledge about its sexual chemical signaling hampers the development of semiochemical-based IPM approaches for M. crassisigna. We first determined the mating rhythms of M. crassisigna. We then collected pheromones from the sex glands of virgin females at the mating peak and analyzed their components using gas chromatography-electroantennogram detection analysis. The results showed that three components elicited significant electrophysiological responses in male antennae. Gas chromatography-mass spectrometry analysis characterized these components as (Z)-7-dodecene acetate (Z7-12:OAc), (Z)-9-tetradecene acetate (Z9-14:OAc), and (Z)-11-hexadecen-1-ol (Z11-16:OH). Further field experiments indicated that the mixture of Z7-12:OAc and Z9-14:OAc at a ratio of 3:1 displayed significant attractivity to males, confirming its role as a putative sex pheromone of M. crassisigna. Long-term monitoring tests showed that traps baited with these pheromone lures effectively mirrored the population dynamics of M. crassisigna. This study successfully identified and validated the sex pheromone released by female M. crassisigna and formulated potent sex lures for field-based pest monitoring. These findings enriched our understanding of chemical communication in Noctuidae and laid a foundation for developing practical monitoring and control methods against M. crassisigna. © 2023 Society of Chemical Industry.

Specific mating behavior of Malayan pangolin (Manis javanica) in captivity

Pangolin is a mysterious animal in the Family Pholidota, Mammalia. Malayan pangolin (Manis javanica) is one of eight existing species and is listed in Manis. With the number of wild pangolins (Manis spp.) rapidly decreasing, captive breeding has become an important way to protect them from extinction. The research on mating behavior of pangolins is an important content to understand its reproductive characteristics and develop breeding management. From 2016 to 2022, a total of 360 mating events were observed in six males and 24 females through closed circuit television (CCTV) surveillance. The results show that males do not engage in complex courtship behavior before mating. In addition, we found that male pangolins adopted a ventrolateral mating position. Once males selected the side (left/right) of the female pangolin from which to approach to mate, they usually remained on the same side for subsequent mating, suggesting that male pangolins may have a preference in mating position. Finally, all mating events were observed at 1.72 ± 1.47 (n = 83, Mean ± SD) days after cohabitation and adjustment time before mating (from the male touching the female to intromission) took 4.98 ± 3.86 mins (n = 323). During mating, males hugged females and remained still for 47.37 ± 10.08 seconds (n = 323), which is the ejaculation and post-ejaculation quiescent time. Remarkably, we observed for the first time two peak mating times, 19:00 to 22:00 and 1:00 to 3:00, suggesting that they may have a preference for mating times. This study provides new insight into the mating behavior of M. javanica and contributes to the development of scientific conservation measures to improve the reproductive capacity of M. javanica.

Time estimation for mating peak and calving of Bali cattle in semi-arid area in Netemnanu village Kupang district

Bali cattle have advantages in terms of adaptation and fertilization rates, but tend to have slow growth rate because the rearing system is still grazing so that livestock growth becomes uncontrollable. This study aims to determine the peak of mating and calving estimation of Bali cattle (Bos sondaicus) that did not experience reproductive disorders, aged 4-7 years, belonging to smallholder farmers. The cattle were reared in semi-arid area of Netemnanu village, South Amfoang district, Kupang regency, Nusa Tenggara Timur. The method used was interviews with farmers, diagnosis of pregnancy through rectal palpation and ultrasonography. The results showed that the pregnancy rate was 86.20% (50/58). Based on pregnancy data, it was known that the peak of mating would occur in December 2021 and estimated calving would reach its peak in September 2022.

Time estimation for mating peak and calving of Bali cattle in semi-arid area in Netemnanu village Kupang district

Bali cattle have advantages in terms of adaptation and fertilization rates, but tend to have slow growth rate because the rearing system is still grazing so that livestock growth becomes uncontrollable. This study aims to determine the peak of mating and calving estimation of Bali cattle (Bos sondaicus) that did not experience reproductive disorders, aged 4-7 years, belonging to smallholder farmers. The cattle were reared in semi-arid area of Netemnanu village, South Amfoang district, Kupang regency, Nusa Tenggara Timur. The method used was interviews with farmers, diagnosis of pregnancy through rectal palpation and ultrasonography. The results showed that the pregnancy rate was 86.20% (50/58). Based on pregnancy data, it was known that the peak of mating would occur in December 2021 and estimated calving would reach its peak in September 2022.

Clock genes regulate mating activity rhythms in the vector mosquitoes, Aedes albopictus and Culex quinquefasciatus.

Endogenous circadian rhythms result from genetically-encoded molecular clocks, whose components and downstream output factors cooperate to generate cyclic changes in activity. Mating is an important activity of mosquitoes, however, the key aspects of mating rhythm patterns and their regulatory mechanisms in two vector mosquito species, Aedes albopictus and Culex quinquefasciatus, remain unclear. We determined and compared the diel mating activity rhythms of these two mosquito species and discovered that Ae. albopictus had mating peaks in the light/dark transition periods (ZT0-3 and ZT9-12), while Cx. quinquefasciatus only had a mating peak at ZT12-15. Knockouts of the clock (clk) orthologous genes (Aalclk and Cxqclk) resulted in phase delay or phase reversal of the mating peaks in Ae. albopictus and Cx. quinquefasciatus, respectively. In addition, the temporal expression pattern of the desaturase orthologous genes, desat1, in both mosquito species was also different in respective wild-type strains and showed phase changes similar to the mating rhythms in clk mutant strains. Inhibition of desat1 expression resulted in decreased mating activity in male mosquitoes of both species but not females. In addition, desat1 regulated cuticular hydrocarbons' synthesis in both species. Silencing desat1 in male Ae. albopictus resulted in decreases of nonadecane and tricosane, which promoted mating, with concomitant increases of heptacosane, which inhibited mating. Silencing desat1 in male Cx. quinquefasciatus also resulted in decreases of tricosane, which promoted mating. These results suggest that Aalclk and Cxqclk have significant roles in the mating activity rhythms in both Ae. albopictus and Cx. quinquefasciatus by regulating the temporal expression of the desat1 gene under LD cycles, which affects sex pheromone synthesis and mating. This work provides insights into the molecular regulatory mechanism of distinct mating rhythm of Ae. albopictus and Cx. quinquefasciatus and may provide a basis for the control of these two important vector mosquitoes.

Harvesters (Arachnida: Opiliones) mate more at cooler temperatures, but the effect of temperature on mating varies across years

AbstractTemperature impacts a wide range of mating behaviors, particularly in ectothermic organisms that tend to have body temperatures similar to ambient thermal conditions. Here, we test the effects of thermal variation on precopulatory and copulatory behavior in the harvester Leiobunum politum Weed 1889, which belongs to the group commonly known as daddy longlegs. We ran single choice mating trials across temperatures commonly experienced in the field during the mating season (18–34°C) for 2 years. We tested how temperature affected the likelihood to move, attempt to mate, and successfully mate, as well as the duration of copulation. Mating was highest at low to intermediate temperatures, and the temperature at which peak mating rates occurred varied across years. The wide range of temperatures across which L. politum is found to mate reflects thermal variability in the field and the flexibility in mating behavior in this fascinating animal.

Reproductive strategy of bachelors in a snub-nosed monkey (Rhinopithecus bieti) all-male unit.

Snub-nosed monkeys exhibit a rare multilevel social system composed of several one-male units (OMU) and at least one all-male unit (AMU). The AMU comprises males who are blocked from access to females by resident males in the OMUs, and how these satellite males achieve reproductive success is still unclear. To investigate their reproductive strategies, we focused on the AMU in a band of provisioned black-and-white snub-nosed monkeys (Rhinopithecus bieti) in Yunnan, China. Behaviors that AMU males use to gain access to females (i.e. immigration, male takeover, and sexual interaction with females) were recorded and compared with resident OMU males to explore how AMU bachelors achieve reproductive success when they are denied stable access to females. We found that in response to solicitation from females, adult and sub-adult members of the AMU responded more actively than resident males, and the bachelors actively initiated mating with females when the latter's resident male was temporarily absent. These mating opportunities mostly coincided with the peak mating season in OMUs, and probably allowed bachelors to sire some offspring. We also found that for some AMU adults, taking over an OMU is the main strategy used to gain stable access to females, and these males repeatedly migrate between bands. AMU members therefore show multiple strategies that allow them to gain some degree of reproductive success.

The reproductive behavior and evaluation of sex pheromone gland extracts of Ectropis grisescens (Lepidoptera: Geometridae)

The geometrid, Ectropis grisescens Warren, is one of the most serious defoliators of the green tea, Camellia sinensis. In the present study, adult emergence, calling behavior, mating activities, and oviposition patterns were observed and the effect of female sex pheromone was evaluated under laboratory conditions (25 ± 1 °C, 14:10 light/dark and 70–75% RH). Adult emergence and calling behavior occurred only at the scotophase. The peak emergence occurred 2 h into the scotophase for males and 3 h for females. Female calling behavior occurred during 1–4 days after eclosion, with most callings among the 1-day-old and the calling gradually decreasing by the age. Mating behavior was first observed at the 2 h into the scotophase. While the mating peak time was similar, 6–8 h into the scotophase for single-pair and multiple-pair groups, the peak of oviposition was 3 days after mating. The pheromone gland extracts from the abdominal tips of 1–2 days virgin female moths were more attractive than the virgin females or the control in the wind tunnel tests. Our findings provide scientific basis to ecological control of E. grisescens.

Male residency and dispersal triggers in a seasonal breeder with influential females

Males in female-philopatric social groupings leave their natal groups to pursue successive reproductive opportunities in one or more other groups. In vervet monkeys, Chlorocebus pygerythrus, adult males coexist and physical eviction is not a driver of male movement. Migratory decisions are expected to turn on an evaluation of future reproductive opportunity, as indexed principally by local operational sex ratio and relative competitive ability. Although vervet males' reproductive success is correlated with dominance, they are distinctive in that the attainment of rank is contingent on integration into female sociospatial networks and we expect decisions about continued residency to reflect this. We used 8 years' data from three groups to confirm that male dispersal between groups is seasonal in our population, with a peak that is coterminous with androgen levels and precedes peak mating and conception by 4 weeks. The average length of completed residency was 459 days, with an increase in the logged rate of departure after 1428 days, which is 150 days longer than the estimated modal age at first conception by putative daughters. There were positive correlations between a male's initial and highest rank, and between his highest rank and the length of time to reach it. We found that a male's residency was positively and independently associated with his highest achieved rank and both his grooming centrality and proximity degree. Additionally, increasing rank and proximity degree also had positive effects on residency length subsequent to the attainment of his highest rank. The probability of emigration was associated negatively with both female number and grooming centrality scores. We conclude that emigration from a group is linked to male rank attainment and mediated by a male's integration into female sociospatial networks. We found no evidence that emigration preceded the sexual maturity of putative daughters.

Bat Swarming in the Eastern Palaearctic (Eastern Siberia)

Bat swarming in Siberia and the Russian Far East has not yet been studied. Therefore, the purpose of the present research was to obtain information about bat swarming (species composition, sex ratio and age structure) as it relates to mating at several sites in Siberia. The study of bat swarming was carried out in July–September 2015, 2016 and 2017 in the eastern Palaearctic at the entrances to three large karstic caves: Okhotnichya, Mechta and Dolganskaya Yama, located in the Baikal rift zone. We captured 1,604 bats belonging to seven species: Plecotus ognevi, Murina hilgendorfi, Myotis petax, Myotis sibirica, Myotis ikonnikovi, Myotis [frater] longicaudatus and Eptesicus nilssonii. In all swarming sites P. ognevi predominated (40–85%). The second most abundant species was M. hilgendorfi (except for Mechta Cave, where high numbers of M. petax were observed). In all the caves, males predominated (70–88%), except for Dolganskaya Yama Cave in September where the sex ratio was close to 1:1. Adult individuals were more numerous than juveniles, which reached the maximum proportion (30%) in Dolganskaya Yama Cave in September due to the inflow of juvenile females of P. ognevi. The maximum body mass and BCIvp (body condition index taking into account observed to expected body mass) of adult males of dominant species were recorded in September for P. ognevi in Dolganskaya Yama Cave and M. hilgendorfi in Dolganskaya Yama and Okhotnichya caves. Based on the observations, it appears that the peak of mating of P. ognevi and M. hilgendorfi occurs in mid-August, when the ratio of males and females was 7:3. Moreover, in the case of P. ognevi the peak of mating is apparently more dependent on climatic conditions than in M. hilgendorfi. The abundance of species during the swarming season and hibernation in the same caves differed — P. ognevi and M. hilgendorfi occurred as singletons in winter, and Myotis spp. (mostly M. sibirica) predominated. Our results support the hypothesis that swarming is typical for bats of the temperate zone throughout the entire Holarctic (Europe, North America and Asia).

Temporal pattern of adult emergence and sexual behavior of Scopula subpunctaria (Lepidoptera: Geometridae)

The objective of this research was to study the reproductive behavior (emergence, calling, mating and oviposition) of Scopula subpunctaria (Lepidoptera: Geometridae) under laboratory conditions (26 ± 1 °C, 12 h photophase and 75 ± 1% RH). The emergence occurred during the scotophase and photophase, but mainly during the scotophase. Females and males simultaneously emerged during the 1st to 12th h of scotophase. However, the calling and mating behavior were limited to nocturnal hours. Adults were engaged in sexual activity (calling) as soon as one day after emergence. Virgin females began calling actively at 2.5 h–3 h into the scotophase, and with a peak occurring at 7.5 h of the scotophase. The maximum number of mating occurred when the couple was 2-d-old, the longest mating duration occurred when the couple was 5-d-old (230 ± 20.2 min), and the mating peak occurred from 6 h to 8 h of scotophase. The males could mate twice and females only mate once. Oviposition behavior also occurred during the scotophase. Females laid eggs from the first day after mating until the eighth day, with a peak occurring at the second day (111 ± 5.6). The emergence, calling, mating and oviposition patterns of S. subpunctaria are discussed and future research is outlined. New technology is currently available for the control of this pest, possibly involving the use of pheromones for trapping or disrupting the mating cycle of the insect.

One for all: Mating compatibility among various populations of olive fruit fly (Diptera: Tephritidae) for application of the sterile insect technique.

The olive fruit fly, Bactrocera oleae (Rossi), is the most important insect pest for the cultivation of olives worldwide. Considerable research efforts have been invested in the past decades to develop eradication or suppression tactics for use within an area-wide integrated pest management (AW-IPM) approach that includes a sterile insect technique (SIT) component. One of the major obstacles encountered in the development of SIT for olive fruit fly was the inferior quality of the mass-reared flies, expressed among others evident primarily by sterile males having a different timing of peak mating and a lower mating propensity in comparison with their wild counterparts. In this study we assessed the mating behaviour and mating compatibility of olive fruit flies originating from four countries of the Mediterranean region (Croatia, France, Italy, Spain) in walk-in field cages and post zygotic compatibility (expressed as % egg hatch) under laboratory conditions. Furthermore, we tested the hypothesis whether a hybrid strain (Greece (domesticated)/Israel (wild)) adapted to laboratory rearing conditions showed any mating barriers with all the four “wild” populations. Finally, we examined the effect of colonization on the mating compatibility of the four newly established populations over three consecutive generations. The results showed no pre-zygotic (mating barriers) or post-zygotic isolations (measured by egg hatch%) among the olive fruit fly populations from the four countries tested. Also, there was no evidence of mating barriers between the hybrid strain and the wild populations of the Mediterranean region.

Linking plasma sex steroid hormone levels to the condition of external genitalia in European badgers (Meles meles): A critical evaluation of traditional field methodology

Field biologists often rely on examination of external genitalia as a proxy for mammalian reproductive condition. In seasonally breeding European badgers, scrotal testes are used as an indicator of spermatogenesis, while a pink and swollen vulva with mucosal secretion is assumed to indicate oestrus. Systematic validation of these assumptions is lacking. Here we analysed sex steroid hormones from plasma samples collected from sexually mature adults during the winter mating season, the spring post-weaning period, the summer minor mating peak, and autumn reproductive quiescence, to compare circulating testosterone levels in males (n = 216), and oestrone (n = 143) and oestradiol (n = 36) levels in females with concurrent external genitalia condition (males: descended, intermediate, ascended testes, as well as testes volume; females: swollen, intermediate, normal vulva). Sex-steroid levels exhibited seasonal patterns, broadly reflecting the seasonal variation in genital condition. Nevertheless, on an individual level, male testosterone levels correlated significantly with testes condition and testes volume only during the mating season in spring, and neither oestrone nor oestradiol differed between female EGM categories. We thus conclude that, in males, EGM is a reliable indicator of reproductive activity during the mating season, but can provide only a tentative indication of physiological reproductive status outside this period, while in females EGM is generally less precise for assessing female reproductive status.

Male-Male Mounting Behaviour in Free-Ranging Golden Snub-Nosed Monkeys (Rhinopithecus roxellana)

An all-male band of golden snub-nosed monkeys (Rhinopithecus roxellana) was observed for 3 months in the Qinling Mountains of China, in order to collect data on the frequencies and contextual significance of male-male mounting behaviour. Mounts occurred in a variety of affiliative, dominance-related and sexual contexts, which differed depending upon the ages of the males involved. Mounting behaviour in this group was mainly initiated by adults. Juveniles mounted each other in affiliative contexts (during play and prior to grooming). Adult males mounted subadult and juvenile partners in a greater variety of sociosexual contexts (dominance/rank-related interactions; reconciliation following agonistic encounters, and sometimes as a prelude to receiving grooming). However, subadults and juveniles were never observed to mount adults. In one dyad, involving an adult male and a subadult partner, mounting was more frequent and prolonged, and included bouts of deep pelvic thrusting. Two mounts resulted in anal intromissions and, in 1 case, the subadult partner exhibited seminal emission. Given that the study took place during the annual mating peak period of R. roxellana, it is possible that this unusual male-male sexual activity was related to the absence of mating opportunities for those adults that were excluded from 1-male units.

Non-Pleiotropic Coupling of Daily and Seasonal Temporal Isolation in the European Corn Borer.

Speciation often involves the coupling of multiple isolating barriers to produce reproductive isolation, but how coupling is generated among different premating barriers is unknown. We measure the degree of coupling between the daily mating time and seasonal mating time between strains of European corn borer (Ostrinia nubilalis) and evaluate the hypothesis that the coupling of different forms of allochrony is due to a shared genetic architecture, involving genes with pleiotropic effects on both timing phenotypes. We measure differences in gene expression at peak mating times and compare these genes to previously identified candidates that are associated with changes in seasonal mating time between the corn borer strains. We find that the E strain, which mates earlier in the season, also mates 2.7 h earlier in the night than the Z strain. Earlier daily mating is correlated with the differences in expression of the circadian clock genes cycle, slimb, and vrille. However, different circadian clock genes associate with daily and seasonal timing, suggesting that the coupling of timing traits is maintained by natural selection rather than pleiotropy. Juvenile hormone gene expression was associated with both types of timing, suggesting that circadian genes activate common downstream modules that may impose constraint on future evolution of these traits.

Exposure to Persistent Organic Pollutants Reduces Testosterone Concentrations and Affects Sperm Viability and Morphology during the Mating Peak Period in a Controlled Experiment on Farmed Arctic Foxes (Vulpes lagopus).

We investigated testosterone production and semen parameters in farmed Arctic foxes by dietary exposure to persistent organic pollutants (POPs) for 22 months. Eight male foxes were given a diet of POP-contaminated minke whale blubber, whereas their eight male siblings were fed a control diet containing pig fat as the main fat source. The minke whale-based feed contained a ∑POPs concentration of 802 ng/g ww, whereas the pig-based feed contained ∑POPs of 24 ng/g ww. At the end of the experiment, ∑POP concentrations in adipose tissue were 8856 ± 2535 ng/g ww in the exposed foxes and 1264 ± 539 ng/g ww in the control foxes. The exposed group had 45-64% significantly lower testosterone concentrations during their peak mating season compared to the controls (p ≤ 0.05), while the number of dead and defect sperm cells was 27% (p = 0.07) and 15% (p = 0.33) higher in the exposed group. Similar effects during the mating season in wild Arctic foxes may affect mating behavior and reproductive success. On the basis of these results, we recommend testosterone as a sensitive biomarker of POP exposure and that seasonal patterns are investigated when interpreting putative endocrine disruption in Arctic wildlife with potential population-level effects.