High level of extra-pair paternity in the socially monogamous Marsh Tits (Poecile palustris)

Background Extra-pair copulation behavior has been widely studied among socially monogamous birds. Many species revealed high rates of extra-pair paternity. But few of the studies have been carried out in the Asian population. Methods From 2012 to 2019, we explored the extra-pair paternity of Marsh Tits (Poecile palustris) in Xianrendong National Nature Reserve, Liaoning Province, China. During the study, adult Marsh Tits were captured with mist nets and parental birds, with nest-box traps. Blood samples were taken from the brachial vein. Parentage analyses were carried out using nine highly variable microsatellite loci through Cervus 3.0 software and maximum likelihood approach. Results Forty-nine offspring (15.08%) from 20 nests (45.45%) were the results of extra-pair fertilization out of a total of 325 offspring in 44 nests. The average extra-pair offspring ratio was 33.54%, with a set varying from 11.11 to 71.43%. Nine extra-pair fathers had been successfully identified, four of whom were the close neighbors of the focus nest while the nests of the remaining five were relatively far. No significant difference was found in the genetic similarity between the social and extra-pair mates of the female, nor in the heterozygosis among the maternal half-siblings. Conclusions In general, our study proved that the extra-pair paternity in Marsh Tits and its extra-pair mating is independent of the genetic compatibility hypothesis. This complements the understudied bird’s extra-pair paternity in Asian area and contributes to the comprehensive insight of birds’ extra-pair paternity behaviors.

Effects of Heat Stress on Mating Behavior and Colony Development in Bombus terrestris (Hymenoptera: Apidae)

Climate change is related to an increase in the frequency and intensity of extreme events such as heatwaves. In insect pollinators, heat exposure is associated with direct physiological perturbations, and in several species, could lead to a decrease of fitness related to a decrease in fertility. Here we developed a new experimental protocol in controlled conditions to assess if the exposure to high temperatures could modify the attractiveness and fertility of Bombus terrestris males. Our results show that virgin queens of B. terrestris do not have preferences between the pheromonal secretions of heat-exposed and control males. Moreover, mating with a heat-exposed male has no impact on the copulation behavior and the development of the nest (brood composition). We advise to extend trials to cover a range of wild and heat-sensitive species on multiple generations to better understand the impact of heat waves on the bumblebee communities.

Similar Is Not the Same – Mate Recognition in a Parasitoid Wasp

Finding and recognizing a suitable mate is a key prerequisite to reproductive success. Insects often recognize prospective mates using chemical cues and signals. Among these, cuticular lipids commonly serve for mate recognition at close range. The lipid layer on the surface of insects is comprised predominantly of cuticular hydrocarbons (CHCs), though more polar compounds may also be present. While the composition of the cuticular profile is typically species specific, many species additionally show differentiation between the sexes by sex specific compounds and/or compound ratios. It is often assumed that a clear sexual dimorphism of cuticular lipid profiles is a prerequisite for a potential function as sex pheromones. Both, sex specific single compounds or the profiles as a whole have been shown to serve as sex pheromones in parasitoid wasps. Here, we studied parasitoid wasps of the species Tachinaephagus zealandicus (Encyrtidae, Hymenoptera). Chemical analyses revealed that this species presents a case where males and females produce the same set of CHCs in similar relative amounts. To test whether these wasps nonetheless can use the cuticular lipids for close range mate recognition, we tested the reaction of males toward freeze-killed conspecifics. Males showed copulation behavior exclusively toward dead females, but not toward dead males. Dead females from which the cuticular lipids had been removed did not elicit copulation behavior by tested males. Reapplication of female whole body extracts restored bioactivity, and males reacted with copulation attempts as often as toward the freeze-killed females. Bioassays with lipid fractions revealed that only the CHC fraction was bioactive on its own. Here, again, males reacted to female, but not to male CHCs. Our results indicate that these wasps are capable of using CHCs for close range sex recognition despite the similarity of male and female profiles.

On the Production, Mating and Behavior of Males in Synoeca surinama (Vespidae: Polistinae: Epiponini)

In colonies of Neotropical swarm-founding wasps (Epiponini), males are thought to be produced only in periods when there are many queens present. Little information is available regarding male behavior in and out of the nest, and male mating strategies are poorly understood. Here, a behavioral study of males of Synoeca surinama is provided and copulation behavior inside a nest is described for the first time. A description of an aggregation of non-natal males at a nest is also provided. The behavior of males was observed in three colonies subjected to removal of queens for another study. Nest envelope was partially removed, and the observations were made directly (seen by “the naked eye”) and indirectly (through camcorder recordings), daily. Production of males occurred in large colonies with number of workers being more relevant than the number of the queens. Males of the aggregation were marked and filmed. The aggregation of non-natal males was observed for seven consecutive days next to the largest colony; some of the males attended the aggregation on consecutive days. The males were observed accessing the comb by the opening in the envelope and courting new queens. One successful copulation on the comb of the nest was observed. In the colony where the male aggregation was observed, 47.6% of the new queens were inseminated while in the other two colonies, no new queens were inseminated. These observations suggest males are attracted to, aggregate and seek mating opportunities at non-natal colonies that are producing young adult queens.

Males evolve to be more harmful under increased sexual conflict intensity in a seed beetle

One conspicuous manifestation of sexual conflict is traumatic mating, in which male genitalia damage the female during copulation. The penis of the seed beetle, Callosobruchus maculatus, is covered in spines that damage the female reproductive tract. Females kick males ostensibly to shorten these harmful copulations. How these iconic conflict behaviors coevolve in response to sexual conflict intensity can provide insight into the economics of these traits. We examined whether male harm and female resistance coevolved in response to elevated sexual conflict. We quantified copulation behavior and female reproductive tract damage of individuals from replicated populations evolving for 32 generations under low or high sexual conflict (female- and male-biased treatments, respectively). First, we permitted females ad libitum matings with males from either sex-ratio treatment, recording her tract damage and longevity. Second, we performed a full-factorial cross of matings by males and females from each of the replicate populations, recording mating and kicking duration and reproductive output. We found manipulation of sexual conflict intensity led to the evolution of male harmfulness, but not female resistance to harm. We also demonstrate that female kicking does not respond to sexual conflict intensity, suggesting it does not function to mitigate male harm in this species. Our findings demonstrate the complexities of behavioral and morphological coevolutionary responses to sexual conflict intensity in an important model species.

Genetic monogamy despite frequent extrapair copulations in “strictly monogamous” wild jackdaws

“Monogamy” refers to different components of pair exclusiveness: the social pair, sexual partners, and the genetic outcome of sexual encounters. Avian monogamy is usually defined socially or genetically, whereas quantifications of sexual behavior remain scarce. Jackdaws (Corvus monedula) are considered a rare example of strict monogamy in songbirds, with lifelong pair bonds and little genetic evidence for extrapair (EP) offspring. Yet jackdaw copulations, although accompanied by loud copulation calls, are rarely observed because they occur visually concealed inside nest cavities. Using full-day nest-box video surveillance and on-bird acoustic bio-logging, we directly observed jackdaw sexual behavior and compared it to the corresponding genetic outcome obtained via molecular parentage analysis. In the video-observed nests, we found genetic monogamy but frequently detected forced EP sexual behavior, accompanied by characteristic male copulation calls. We, thus, challenge the long-held notion of strict jackdaw monogamy at the sexual level. Our data suggest that male mate guarding and frequent intrapair copulations during the female fertile phase, as well as the forced nature of the copulations, could explain the absence of EP offspring. Because EP copulation behavior appeared to be costly for both sexes, we suggest that immediate fitness benefits are an unlikely explanation for its prevalence. Instead, sexual conflict and dominance effects could interact to shape the spatiotemporal pattern of EP sexual behavior in this species. Our results call for larger-scale investigations of jackdaw sexual behavior and parentage and highlight the importance of combining social, sexual, and genetic data sets for a more complete understanding of mating systems.

Effects of nest boxes in natural mating colony cages on fear, stress, and feather damage for layer breeders123

Colony cages are commonly used in China for the natural mating of layer breeders. However, feather pecking (FP) is a major problem in this system, and feather damage mainly due to FP needs to be alleviated. The objective of this study was to investigate the effects of nest boxes provided in colony cages. Each colony cage confined 10 roosters and 90 laying hens. The use of nest boxes as it relates to age, feather damage, sexual behavior, fertility, and fearfulness was evaluated. Thyroid hormones, which are considered to be physiological indicators of various forms of stress in poultry and may be correlated with the quality of feather coverage, were also tested. The control group and the nest box group each had 12 replicates, totaling 24 identical cages. Analyses were conducted using the linear mixed models procedure of SPSS Statistics 22.0. The results showed that the control group had a significantly higher proportion of hens with feather damage to 4 specific body regions (back, rump, tail, and belly) compared to the nest box group (P < 0.05). Increasing the use of the nest boxes took place from weeks 41 to 47 and at 53 wk of age, as seen by the percentage of eggs and number of sitting events in the nests, number of hens using the nests, and frequency of visits. There were no significant differences in fertility, the occurrence of mounting, or full copulation behavior between the 2 groups. Hens in the control group showed a significantly longer duration of tonic immobility at 43, 49, and 55 wk of age (P < 0.05). No significant differences were found between groups for the concentration of triiodothyronine or thyroxine, but a significantly higher concentration of corticosterone was measured in the control group than in the nest box group (P < 0.05). In conclusion, hens with access to nest boxes during the laying period had a decreased FP frequency, fewer damaged feathers, lower plasma corticosterone secretion, and were less fearful. This information contributes to the understanding of the FP behavior and stress sensitivity of layer breeders, which will provide a basis for the development and optimization of the colony cage equipment.

Perubahan perilaku Callosobruchus maculatus Faaabricius terhadap warna cahaya pada kacang-kacangan di penyimpanan

Callosobruchus maculatus (Fab.) adalah salah satu species serangga dari ordo Coleoptera, family Brucidae yang merupakan hama kacang-kacangan di gudang penyimpanan. Kerusakan kacang selama penyimpanan diawali dengan perilaku oviposisi telur serangga betina dewasa pada kotiledon biji kacang. Serangga C. maculatus (Fab.) tidak menyukai tempat dengan cahaya terang. Penelitian ini bertujuan untuk mengamati perubahan perilaku oviposisi dan kopulasi serangga dewasa pada kacang-kacangan dengan penerangan empat warna cahaya pada ruang penyimpanan. Pengamatan dan analisis data menggunakan Rancangan Acak Lengkap Faktorial. Faktor petama menggunakan cahaya lampu merah, kuning, hijau dan putih, sedangkan faktor kedua terdiri dari tiga jenis kacang (Fabaceae) yaitu kacang hijau, kacang kedelai dan kacang merah. Hasil penelitian menunjukkan perilaku oviposisi telur terjadi pada cahaya lampu kuning, sedangkan perilaku kopulasi terjadi pada cahaya lampu merah. Cahaya lampu merah dan kuning dapat memengaruhi perilaku oviposisi dan kopulasi Callosobruchus maculatus (Fab.).ABSTRACTCallosobruchus maculatus (Fab.) is one of the insect species of the order Coleoptera, family Brucidae which is a pest for stored beans. Damage to beans during the storage starts with the behavior of the egg oviposition of adult female insects on bean seed cotyledons. C. maculatus (Fab.) do not like to be in a bright place. This study aimed to observe changes in the behavior of oviposition and copulation of adult insects in beans with four-colour lighting in the storage. The observation and analysis of data used factorial completely randomized design. The first factor were light colors; red, yellow, green, and white light while the second factor consists of three types of beans (Fabaceae); green beans, soybeans and red beans. The results showed that copulation behavior occurred in red light. While the oviposition behavior of eggs occured in yellow light. The red and yellow lights can affect the behavior of oviposistion and copulation of C.maculatus (Fab.).

Cuticular Hydrocarbon Recognition in the Mating Behavior of Two Pissodes Species

Two sibling weevil species, Pissodes strobi Peck and P. nemorensis Germar (Coleoptera: Curculionidae), can form reduced-fitness hybrids in the laboratory, but neither their premating isolation mechanisms nor mating behaviors are well-understood. Cuticular hydrocarbons (CHCs) have been reported as crucial chemical cues in mating recognition in many insects, including weevils, and, thus, may also mediate the mating behavior of P. strobi and P. nemorensis. We conducted a series of behavioral observations, bioassays, and chemical analyses to investigate the role of CHCs in their mating behavior. Copulation behavior of both species followed similar steps: approaching, mounting, tapping, aedeagus extrusion, and copulation. In P. strobi, hexane extraction significantly reduced the number of successful male copulations compared with freeze-killed females. Conversely, significantly fewer P. nemorensis males copulated with dead females compared with live females. No significant differences were detected among hexane-extracted, freeze-killed or recoated female carcasses to P. nemorensis. These findings suggested that female cuticular extracts contain important cues in mate recognition in P. strobi but not in P. nemorensis. We identified 21 CHCs from both species with variation in abundances between sexes and seasons. Discriminant analysis revealed incomplete overlap of CHC compositions in females of the two species in summer, when hybridization potentially occurs.