Game theoretic model of brood parasitism in a dung beetle Onthophagus taurus

We present a game theoretic model of brood parasitism in the dung beetle Onthophagus taurus. Female O. taurus engage in brood parasitism when they attack a brood ball made by another female, destroy the existing egg and place one of their own eggs to develop within the existing dung ball. Brood parasitism is more costly than other forms of kleptoparasitism because an individual loses the total investment in an offspring. In this paper, we outline the behaviors involved in brood ball production and provide time estimates of those behaviors. The model is then used to predict when it is beneficial to steal the brood ball created by another female and when it is beneficial for a female to create her own. We also investigate how long a female should guard her eggs.     

Brood Ball-Mediated Transmission of Microbiome Members in the Dung Beetle,Onthophagus taurus (Coleoptera: Scarabaeidae)

Insects feeding on plant sap, blood, and other nutritionally incomplete diets are typically associated with mutualistic bacteria that supplement missing nutrients. Herbivorous mammal dung contains more than 86% cellulose and lacks amino acids essential for insect development and reproduction. Yet one of the most ecologically necessary and evolutionarily successful groups of beetles, the dung beetles (Scarabaeinae) feeds primarily, or exclusively, on dung. These associations suggest that dung beetles may benefit from mutualistic bacteria that provide nutrients missing from dung. The nesting behaviors of the female parent and the feeding behaviors of the larvae suggest that a microbiome could be vertically transmitted from the parental female to her offspring through the brood ball. Using sterile rearing and a combination of molecular and culture-based techniques, we examine transmission of the microbiome in the bull-headed dung beetle, Onthophagus taurus. Beetles were reared on autoclaved dung and the microbiome was characterized across development. A ~1425 bp region of the 16S rRNA identified Pseudomonadaceae, Enterobacteriaceae, and Comamonadaceae as the most common bacterial families across all life stages and populations, including cultured isolates from the 3^rd instar digestive system. Finer level phylotyping analyses based on lepA and gyrB amplicons of cultured isolates placed the isolates closest to Enterobacter cloacae, Providencia stuartii, Pusillimonas sp., Pedobacter heparinus, and Lysinibacillus sphaericus. Scanning electron micrographs of brood balls constructed from sterile dung reveals secretions and microbes only in the chamber the female prepares for the egg. The use of autoclaved dung for rearing, the presence of microbes in the brood ball and offspring, and identical 16S rRNA sequences in both parent and offspring suggests that the O. taurus female parent transmits specific microbiome members to her offspring through the brood chamber. The transmission of the dung beetle microbiome highlights the maintenance and likely importance of this newly-characterized bacterial community.     

Evolution of kleptoparasitism as a war of attrition

Previous models of kleptoparasitism (resource stealing) assume that contests over resource items are of fixed duration. Here we suggest that such contests will often be well represented as a war of attrition, with the winner being the individual who is prepared to contest for the longer time. Given that time spent in contests cannot be used to search for other resource items, we provide an analytical expression for the evolutionarily stable distribution of contest times. This can be used to investigate the circumstances under which we would expect kleptoparasitism to evolve. In particular, we focus on situations where searching for conspecifics to kleptoparasitize can only be achieved at a cost of reduced resource discovery by other means; under such circumstances we show that kleptoparasitism is not evolutionarily stable.     

Kleptoparasitism of freshwater crabs by cichlid fishes endemic to Lake Barombi Mbo,Cameroon, West Africa

Synopsis Although kleptoparasitism, or food-stealing, is common in birds and some carnivorous mammals, reported instances are exceedingly rare in fishes. We studied the behaviour and ecology of the 11 endemic tilapiine cichlids of Lake Barombi Mbo, Cameroon, West Africa. Here we report that six of the Barombi cichlids (Stomatepia mariae, S. pindu, Konia eisentrauti, Pungu maclareni, Sarotherodon lohbergeri, andS. linnellii) kleptoparasitize freshwater crabsPotamon africanus.     

An experimental analysis of joint nesting in the salamander Hemidaetylium scutatum (Caudata: Plethodontidae): the effects of population density

Three nesting behaviour patterns are documented in the plethodontid salamander Hemidactylium scutatum. A female may lay eggs (1) in a solitary nest and brood them, (2) in a joint nest and brood them as well as eggs of other females, or (3) in a joint nest that is brooded by another female. The hypothesis that population density was positively associated with joint nesting was tested by following two populations for 5 years and by experimentally manipulating the population density of nesting females in artificial habitats for the latter 2 years. The proportion of joint nests did not vary with density, although joint nests tended to contain eggs of more females at the high population density. Joint nests were usually brooded by one female; thus, most females that laid eggs in joint nests did not brood them at high density. The reproductive success, as measured by survival of embryos, of solitary and joint nesters was equivalent. Joint nests were deserted less often, however, which decreased the probability of catastrophic mortality. The number of days of brooding was significantly positively correlated with loss of body mass of females, suggesting a cost to brooding behaviour. Joint nesting with solitary brooding is not explained by aggressive usurpation of nests or by brood parasitism.     

Interspecific kleptoparasitism in Audouin's Gull Lams audouinii at the Ebro Delta, northeast Spain: a behavioural response to low food availability

Kleptoparasitism of Audouin's Gull Lams audouinii on other seabirds, a foraging behaviour previously unrecorded for the species, was studied in the Ebro Delta, northeast Spain, during 1992. The relationship between kleptoparasitism and trawler activity was assessed through changes in the availability offish discards brought about by a trawling moratorium. When trawlers are not active, Audouin's Gulls use different feeding strategies, such as interspecific kleptoparasitism. Audoin's Gulls appeared to prefer to kleptoparasitize terns rather than gulls, but the success rate on gulls was higher. Most of the attacks rather than gulls, but the success rate on gulls was higher. Most of the attacks were performed by single Audouin's Gulls, although success per attack improved with group size. During the trawling moratorium, the existence of large seabird colonies in the Ebro Delta acted as a buffer for Audouin's Gull through kleptoparasitism, compensating partly for the reduced food supply.     

Identification of Cu/Zn superoxide dismutase in cattle and river buffaloes

All air-living organisms produce superoxide dismutase (SOD) and several antioxidant enzymes that limit oxidative stress by detoxifying reactive oxygen species. SOD1 gene has been investigated in Egyptian native cattle and buffalos at the level of genomic DNA and cDNA that were extracted from leucocytes. An unexpected band at approximately 370 bp was obtained in cattle genomic DNA and cDNA as well as in buffalo cDNA. SOD1 amplified sequence of native cattle genomic DNA and cDNA showed a 93% alignment. Native cattle genomic DNA SOD1 amplicon shares sequence homology with mRNAs of Bos taurus “similar to superoxide dismutase” (SOD1) sequence of the GeneBank database. It also shares sequence homology with “similar to superoxide dismutase” on B. taurus chromosome BTA13. The results indicate that the genomic DNA of Egyptian native cattle contains SOD1 processed pseudo gene. SOD1 primers amplified three fragments in buffalo genomic DNA which indicates that buffalo genome has different copies of SOD1 due to alternative splicing. It failed to produce the 370 bp fragments found in cattle DNA. The protein analysis revealed no differences between Egyptian native cattle and B. taurus SOD1 mRNA. However, one amino acid, aspartic acid (Asp), in Egyptian native cattle and B. taurus SOD1, is substituted with asparagine (Asn) (D26N) in buffaloes. This amino acid substitution may be due to non-synonymous single nucleotide polymorphisms (nsSNPs). The nsSNPs detected in buffaloes may affect the function of the encoded protein. This study is the first investigation reporting that the resistance of the buffalo to diseases and parasites that afflict cattle may not be acquired but may have a genetic basis.     

Sex-role reversed nuptial feeding reduces male kleptoparasitism of females in Zeus bugs (Heteroptera; Veliidae)

Males of a variety of taxa occasionally steal food secured by their mates. In some spiders and insects, males rely entirely on this form of intraspecific kleptoparasitism for their subsistence. However, this male strategy may be costly for females and a variety of different female counteradaptations have been proposed. In Zeus bugs (Phoreticovelia spp.), males ride on the back of their mates for extended periods and females produce a gland secretion that males feed on. By experimentally occluding the dorsal glands in females and varying food availability, we show that nuptial feeding by females reduces the extent to which the males kleptoparasitize their mates. We suggest that females have, at least in part, evolved this unique form of nuptial feeding as a counteradaptation to reduce the rate of kleptoparasitism by males.     

Brood Parasitism in Two Species of Spider Wasps (Hymenoptera: Pompilidae, Dipogon), with Notes on a Novel Reproductive Strategy

A trap-nesting study provided the first documentation of brood parasitism in Dipogon nagasei and in D. iwatai. Dipogon nagasei was found to brood parasitize D. sperconsus, D. conspersus, D. inconspersus, and D. bifasciatus. Dipogon iwatai brood parasitized D. sperconsus, D. conspersus, D. romankovae, and Auplopus carbonarius. Both brood parasitic species are with the subgenus Nipponodipogon, whereas all five Dipogon hosts are in the subgenus Deuteragenia. Comparison of their ecological features revealed that brood parasitism in D. nagasei is considerably more derived than in D. iwatai. Of particular note is the fact that in D. nagasei the female routinely lays up to five eggs on a single host spider, all of which develop into adult wasps without larval cannibalism; almost all Pompilidae previously studied lay only one egg on a host spider.     

Differential hygienic behavior of Apis cerana F. and Apis mellifera L. to Sacbrood virus infection

Beekeeping with Apis cerana of Korean apiculture is facing with serious colony collapse caused by invasive Sacbrood virus (SBV) disease. This fatal brood disease was the main reason of more than 90% colony lost in Korea leading almost the extinct crisis. Sacbrood virus can infect either larvae or adult honeybees, with a higher sensibility of larvae to the infection. Since SBV has spread to all over the country, efforts have been made to treat and prevent this devastating disease although no effective results have so far been obtained. Several studies have demonstrated that Apis mellifera bee colonies that express an efficient hygienic behavior exhibit a higher resistance to the brood disease. In this study we demonstrated that the differences of hygienic behavior between A. cerana and A. mellifera. A. cerana more efficiently removed the pin-killed brood than A. mellifera. On the other hand, A. mellifera more efficiently removed SBV-infected larvae and SBV-dead brood than A. cerana. However, it remains unclear whether the advantage of hygienic bee could have efficacy against Sacbrood disease on A. cerana colonies.     

Differences of skin morphology in Bos indicus,Bos taurus,and their crossbreds

Cutaneous evaporation is the main avenue by which cattle dissipate heat via the involvement of sweat glands and other skin components. The difference in skin morphology between B. indicus and B. taurus has been recognized, as well as differences in their ability to tolerate heat. The objective of this study was to compare skin morphology between B. indicus, B. taurus, and their crossbreds. Skin samples of Sahiwal (B. indicus) (n?=?10, reddish brown skin) and Holstein Friesian (HF) (B. taurus) (n?=?10, black and white skin) and crossbred of HF75% (n?=?10, black and white skin) and HF87.5 % (n?=?10, black and white skin) were biopsied for histological study, followed by measurement of skin components. The results indicated that breed significantly affected sweat gland morphology. The shape of the sweat gland, as indicated by the ratio of length/diameter, in Sahiwal was baggier in shape compared to HF (5.99 and 9.52) while values for crossbreds were intermediate (7.82, 8.45). The density and volume of sweat glands in Sahiwal (1,058 glands/cm²; 1.60 μ³?×?10^?6) were higher than in HF (920 glands/cm²; 0.51 μ³x10^?6) and crossbreds, both HF 75 % (709 glands/cm²; 0.68 μ³?×?10^?6) and HF 87.5 % (691 glands/cm²; 0.61 μ³?×?10^?6) respectively. However, capillary surface area was greater for HF (2.07 cm²) compared to Sahiwal (1.79 cm²); accordingly, the lower genetic fraction of HF in crossbred cattle showed less capillary surface area (1.83 and 1.9 cm² for HF75% and HF87.5 %) (P?<?0.01). Nerve density was not significantly different between Sahiwal and HF but was higher in the crossbred (P?<?0.01) cattle. Moreover, the effect of skin color (black and white) was evaluated and it was found that there was an interaction (P?<?0.01) between breed and skin color on the skin components. This study reveals that there are differences in skin morphology among B. indicus, B. taurus and their crossbreds, with these differences being more or less related to the genetic fraction of HF. This may imply that capability for cutaneous evaporative heat loss and tolerance to heat in crossbred cattle could be related to skin morphology.     

Revisiting the Life Cycle of Dung Fungi,Including Sordaria fimicola

Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem to challenge the view that they are obligate to dung. However, endophyte status is controversial because surface-sterilization protocols could fail to kill dung fungus ascospores stuck to the plant surface. Thus, we first tested the ability of representative isolates of three common genera of dung fungi to affect plant growth and fecundity given that significant effects on plant fitness could not result from ascospores merely stuck to the plant surface. Isolates of S. fimicola, Preussia sp., and Sporormiella sp. reduced growth and fecundity of two of three populations of Bromus tectorum, the host from which they had been isolated. In further work with S. fimicola we showed that inoculations of roots of B. tectorum led to some colonization of aboveground tissues. The same isolate of S. fimicola reproduced sexually on inoculated host plant tissues as well as in dung after passage through sheep, thus demonstrating a facultative rather than an obligate life cycle. Finally, plants inoculated with S. fimicola were not preferred by sheep; preference had been expected if the fungus were obligate to dung. Overall, these findings make us question the assumption that these fungi are obligate to dung.     

Do climatic conditions affect host and parasite phenotypes differentially? A case study of magpies and great spotted cuckoos

Climatic conditions, through their effects on resource availability, may affect important life history strategies and trade-offs in animals, as well as their interactions with other organisms such as parasites. This impact may depend on species-specific pathways of development that differ even among species with similar resource requirements (e.g., avian brood parasites and their hosts). Here we explore the degree of covariation between environmental-climatic conditions and nestling phenotypes (i.e., tarsus length, body mass, immune response to phytohemagglutinin injection) and ectoparasite loads of great spotted cuckoos (Clamator glandarius) and those of their magpie (Pica pica) hosts, both within and among 11 study years (1997–2011). Our main results were that (1) nestling phenotypes differed among years, but differently for great spotted cuckoos and magpies; (2) nestling phenotypes showed significant among-year covariation with breeding climatic conditions (temperature and precipitation); and (3) these associations differed for cuckoos and magpies for some phenotypic traits. As the average temperature at the beginning of the breeding season (April) increased, body mass and tarsus length increased only for cuckoos, but not for magpie hosts, while immune response decreased in both species. Finally, (4) the strength of the within-year relationships between the probability of ectoparasitism by Carnus hemapterus flies and laying date (used as an estimate of the within-year variation in climatic conditions) was negatively affected by the annual accumulated precipitation in April. These results strongly suggest that variation in climatic conditions would result in asymmetric effects on different species with respect to the probability of ectoparasitism, immunity and body size. Such asymmetric effects may affect animal interactions in general and those of brood parasites and their hosts in particular.     

Tick-susceptible Bos taurus cattle display an increased cellular response at the site of larval Rhipicephalus (Boophilus) microplus attachment, compared with tick-resistant Bos indicus cattle

Cattle demonstrate divergent and heritable phenotypes of resistance and susceptibility to infestation with the cattle tick Rhipicephalus (Boophilus) microplus. Bos indicus cattle are generally more resistant to tick infestation than Bos taurus breeds although large variations in resistance can occur within subspecies and within breed. Increased tick resistance has been previously associated with an intense hypersensitivity response in B. taurus breeds; however, the mechanism by which highly resistant B. indicus cattle acquire and sustain high levels of tick resistance remains to be elucidated. Using the commercially available Affymetrix microarray gene expression platform, together with histological examination of the larval attachment site, this study aimed to describe those processes responsible for high levels of tick resistance in Brahman (B. indicus) cattle that differ from those in low-resistance Holstein-Friesian (B. taurus) cattle. We found that genes involved in inflammatory processes and immune responsiveness to infestation by ticks, although up-regulated in tick-infested Holstein-Friesian cattle, were not up-regulated in Brahman cattle. In contrast, genes encoding constituents of the extracellular matrix were up-regulated in Brahmans. Furthermore, the susceptible Holstein-Friesian animals displayed a much greater cellular inflammatory response at the site of larval R. microplus attachment compared with the tick-resistant Brahman cattle.     

Kleptoparasitism in gulls Laridae at an urban and a coastal foraging environment: an assessment of ecological predictors

Capsule: Kleptoparasitism in gulls occurred at a greater rate at an urban compared with a coastal site. Population density and prey size predicted the rate of kleptoparasitism at the urban site.

Aims: To investigate and assess the ecological variables associated with kleptoparasitism among gulls at urban and rural sites.

Methods: Field observations were conducted at Brancaster (coastal rural) and Billingsgate Market (urban) to examine differences in the rate of kleptoparasitism in mixed-species flocks of gulls. Four key variables (prey size, population density, season and species) were assessed as predictors of kleptoparasitism.

Results: Generalized linear models revealed significant effects on kleptoparasitism rate of site, population density and prey size, and two-way interactions between these main terms. Population density and prey size differed significantly between sites, but population density appeared to predict the rate of kleptoparasitism.

Conclusion: Kleptoparasitism may well aid invasion and increase the range of environments a gull can tolerate by helping them meet their energy needs in novel environments where normal foraging behaviours are difficult to implement.     

The effect of multi‐species host density on superparasitism and sex ratio in a gregarious parasitoid

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Evolution of sex ratios in social hymenoptera: Consequences of finite brood size

Evolutionarily stable sex ratios are determined for social hymenoptera under local mate competition (LMC) and when the brood size is finite. LMC is modelled by the parameterd. Of the reproductive progeny from a single foundress nest, a fractiond disperses (outbreeding), while (l-d) mate amongst themselves (sibmating). When the brood size is finite,d is taken to be the probability of an offspring dispersing, and similarly,r, the proportion of male offspring, the probability of a haploid egg being laid. Under the joint influence of these two stochastic processes, there is a nonzero probability that some females remain unmated in the nest. As a result, the optimal proportion of males (corresponding to the evolutionarily stable strategy, ESS) is higher than that obtained when the brood size is infinite. When the queen controls the sex ratio, the ESS becomes more female biased under increased inbreeding (lowerd). However, the ESS under worker control shows an unexpected pattern, including anincrease in the proportion ofmales withincreased inbreeding. This effect is traced to the complex interaction between inbreeding and local mate competition.     

When and how did Bos indicus introgress into Mongolian cattle?

The Mongolian cattle are one of the most widespread breeds with strictly Bos taurus morphological features in northern China. In our current study, we presented a diversity of mitochondrial DNA (mtDNA) D-loop region and Y chromosome SNP markers in 25 male and 8 female samples of Mongolian cattle from the Xinjiang Uygur autonomous region in Western China, and detected 21 B. taurus and four Bos indicus (zebu) mtDNA haplotypes. Among four B. indicus mtDNA haplotypes, two haplotypes belonged to I1 haplogroup and the remaining two haplotypes belonged to I2 haplogroup. In contrast, all 25 male Mongolian cattle samples revealed B. taurus Y chromosome haplotype and no B. indicus haplotypes were found. Historical and archeological records indicate that B. taurus was introduced to Xinjiang during the second millennium BC and B. indicus appeared in this region by the second century AD. The two types of cattle coexisted for many centuries in Xinjiang, as depicted in clay and wooden figurines unearthed in the Astana cemetery in Turfan (3rd–8th century AD). Multiple lines of evidence suggest that the earliest B. indicus introgression in the Mongolian cattle may have occurred during the 2nd–7th centuries AD through the Silk Road around the Xinjiang region. This conclusion differs from the previous hypothesis that zebu introgression to Mongolian cattle happened during the Mongol Empire era in the 13th century.