Emergence of blackflies (Diptera: Simuliidae) from a small forested stream in Ontario

Three species of blackflies were found in emergence-trap samples taken overa period of 8 months from a second-order, forested, cold-stenothermal stream in southern Ontario. The emergence phenologies of the two common species, Prosimulium mixtum and Stegopterna mutata, are described and compared with their phenologies in other streams in North America. Hypotheses are presented for the poor faunal diversity and prolonged emergence of the two species in the stream studied. Emergence data are used to describe the pupal distribution in the stream.Wing-length measurements showed a distinct dimorphism in P. mixtum: females were larger than males. Adult size (except of P. mixtum females) varied among sampling sites in the stream and, in the case of S. mutata, this variation was time dependent.     

Species richness and spatial distribution of blackflies (Diptera: Simuliidae) in streams of Central Amazonia, Brazil

1. The spatial distribution and species richness of blackflies were evaluated at 58 stream sites in Central Amazonia, Brazil. Samples were taken along a north–south axis of approximately 130 km and a east–west axis of approximately 220 km.
2. Based on stream-site characteristics, the occurrence of larvae of the six most frequently collected species was highly predictable (79.3–91.5% accuracy in prediction of occurrence). The predictive value of stream size and the presence of impoundments agrees with results of similar work in the Holarctic Region, suggesting a general responses of blackflies to environmental parameters.
3. Although only 19.0% of interstream variation in species richness was explained by a regression model, results suggested that species richness was greater in larger, cooler, faster, covered streams with rocky beds than in smaller, warmer, slower, open streams with sandy bottoms. Overall, the species richness of blackflies (11 species in total) was lower than in the temperate zone suggesting, for some taxa at least, that aquatic communities do not follow the terrestrial pattern of greater species richness in the tropics.     

Higher differentiation among subspecies of the house mouse (Mus musculus) in genomic regions with low recombination

In the early stages of reproductive isolation, genomic regions of reduced recombination are expected to show greater levels of differentiation, either because gene flow between species is reduced in these regions or because the effects of selection at linked sites within species are enhanced in these regions. Here, we study the patterns of DNA sequence variation at 27 autosomal loci among populations of Mus musculus musculus, M. m. domesticus, and M. m. castaneus, three subspecies of house mice with collinear genomes. We found that some loci exhibit considerable shared variation among subspecies, while others exhibit fixed differences. We used an isolation-with-gene-flow model to estimate divergence times and effective population sizes (N(e) ) and to disentangle ancestral variation from gene flow. Estimates of divergence time indicate that all three subspecies diverged from one another within a very short period of time approximately 350,000 years ago. Overall, N(e) for each subspecies was associated with the degree of genetic differentiation: M. m. musculus had the smallest N(e) and the greatest proportion of monophyletic gene genealogies, while M. m. castaneus had the largest N(e) and the smallest proportion of monophyletic gene genealogies. M. m. domesticus and M. m. musculus were more differentiated from each other than either were from M. m. castaneus, consistent with greater reproductive isolation between M. m. domesticus and M. m. musculus. F(ST) was significantly greater at loci experiencing low recombination rates compared to loci experiencing high recombination rates in comparisons between M. m. castaneus and M. m. musculus or M. m. domesticus. These results provide evidence that genomic regions with less recombination show greater differentiation, even in the absence of chromosomal rearrangements.     

Detection of Onchocerca volvulus (Nematoda: Onchocercidae) infection in vectors from Amazonian Brazil following mass Mectizan distribution

Detection of Onchocerca volvulus in Simulium populations is of primary importance in the assessment of the effectiveness of onchocerciasis control programs. In Brazil, the main focus of onchocerciasis is in the Amazon region, in a Yanomami reserve. The main onchocerciasis control strategy in Brazil is the semi-annually mass distribution of the microfilaricide ivermectin. In accordance with the control strategy for the disease, polymerase chain reaction (PCR) was applied in pools of simuliids from the area to detect the helminth infection in the vectors, as recommended by the Onchocerciasis Elimination Program for the Americas and the World Health Organization. Systematic sampling was performed monthly from September 1998 to October 1999, and a total of 4942 blackflies were collected from two sites (2576 from Balawaú and 2366 from Toototobi). The molecular methodology was found to be highly sensitive and specific for the detection of infected and/or infective blackflies in pools of 50 blackflies. The results from the material collected under field conditions showed that after the sixth cycle of distribution of ivermectin, the prevalence of infected blackflies with O. volvulus had decreased from 8.6 to 0.3% in Balawaú and from 4 to 0.1% in Toototobi.     

Populational fluctuation and spatial distribution of Alphitobius diaperinus (Panzer) (Coleoptera; Tenebrionidae) in a poultry house, Cascavel, Parana state, Brazil.

Knowledge of the population fluctuation and spatial distribution of pests is fundamental for establishing an appropriate control method. The population fluctuation and spatial distribution of the Alphitobius diaperinus in a poultry house in Cascavel, in the state of Parana, Brazil, was studied between October, 2001 and October 2002. Larvae and adults of the lesser mealworm were sampled weekly using Arends tube traps (n = 22) for six consecutive flock grow-outs. The temperature of the litter and of the poultry house was measured at the same locations of the tube traps. Beetle numbers increased continuously throughout all the sampling dates (average 5,137 in the first week and 18,494 insects on the sixth week). Significantly greater numbers of larvae were collected than adults (1 to 20 times in 95% of the sampling points). There was no correlation between temperature and the number of larvae and adults collected, therefore no fluctuation was observed during the sampling period. The population growth was correlated to litter re-use. The highest temperatures were observed in deep litter. The spatial distribution of larvae and adults in the poultry house was heterogeneous during the whole period of evaluation. Results suggest that monitoring in poultry houses is necessary prior to adopting and evaluating control measures due to the great variability of the insect distribution in the poultry house.     

Social behavior, foraging strategies, and fecal glucocorticoids in female blue monkeys (Cercopithecus mitis): potential fitness benefits of high rank in a forest guenon

Socioecological theory predicts that aggressive feeding competition is associated with linear dominance hierarchies and reproductive advantages for high-ranking females. Female blue monkeys contest fruits and have a linear dominance hierarchy, yet previous research has shown no evidence that high-ranking females benefit from greater feeding success or fertility. Here, we assess whether individuals differ in fecal glucocorticoid (fGC) excretion and examine proximate determinants of such differences to infer potential fitness correlates of rank, using data collected from two study groups in the Kakamega Forest, Kenya. We found that higher ranking females had preferential access to fruits in both groups, although the behavioral mechanisms leading to this effect varied between groups. Despite a consistent rank difference in feeding on fruits, an overall rank effect on fGCs emerged in only one group; females of this group spent comparatively more time feeding on fruits, fruits accounted for a greater proportion of the diet, and females engaged in more frequent food-related agonism. In addition, more females in this group were lactating during a period of low fruit availability, when rank effects on fGCs were particularly strong. Regardless of fruit availability, among lactating females of both groups higher rank was associated with lower fGC levels, indicating lower energetic stress in higher ranking females when energy demands were particularly high. Individual rates of agonism, a potential psychological stressor, were unrelated to fGCs at all times. After we accounted for rates of agonism and feeding on fruits, females of one group who groomed others more had lower fGCs, suggesting that variable social coping behavior can contribute to fGC variation in some groups. This study provides the first empirical evidence that high-ranking female blue monkeys may obtain fitness benefits from their social status, by gaining priority of access to fruits during critical times in the reproductive cycle.     

Social correlates of variation in urinary cortisol in wild male bonobos (Pan paniscus)

Cortisol excretion in males of group living species is often associated with social rank and competition for oestrous females. Rank-related patterns of cortisol levels can be used to study mechanisms of rank maintenance and costs associated with mate competition. Bonobos (Pan paniscus) are interesting because males form a linear dominance hierarchy but are not dominant over females and therefore aggressive male-male competition over access to females alone is not considered to be a successful reproductive strategy. In this study on social correlates of urinary cortisol in wild male bonobos, we investigated the relationship between cortisol levels and several aspects of mate competition, including male rank, aggression rates, and association time with oestrous females. We found that cortisol levels correlated positively with dominance rank when oestrous females were present, but not when they were absent. This result is consistent with the idea that aggressive behaviour plays a minor role in maintenance of high rank. While aggression received from males and females explained within-individual variation in cortisol levels, it was the time spent in association with oestrous females that best explained between-individual variation in male cortisol levels. The observed increase in male cortisol may be associated with spatial proximity to oestrous females and could result from anticipated aggression from other group members, reduced feeding time in the males, or a combination of both.     

Sampling Techniques for Bloodsucking Dipterans (Diptera: Culicidae,Simuliidae, Ceratopogonidae,Tabanidae)

Entomological Review - Techniques for sampling and preserving bloodsucking dipterans: mosquitoes, blackflies, biting midges, and horseflies (Diptera: Culicidae, Simuliidae, Ceratopogonidae,...     

Folliculogenesis, onset of puberty and fecundity of mink (Mustela vision Schreb) selectively bred for docility or aggressiveness

It has been suggested that selective breeding of animals for docile behavior is correlated with early onset of puberty and improved fertility. We wished to test the hypothesis that mink bred for docility would show earlier onset of puberty and greater fecundity than mink bred for aggressiveness. We used farm-raised, 7-mo-old mink females that had been selectively bred for 7 to 10 generations on the basis of behavior towards humans. Onset of puberty was estimated once (between 15 and 20 December) by vaginal smears and was said to start wtih preponderance of cornified epithelial cells in the cytological specimen. Fecundity was measured by litter size and rate of folliculogenesis, with and without hCG stimulation, by histomorphometric examination of ovaries and uteri. A total of 43/100 (43%) docile females achieved proestrus and estrus as compared to 16/136 (12%) of the aggressive ones. Overall pregnancy rate, survival to 5 d after whelping and litter size did not differ between the docile and aggressive females. Docile females showed significantly higher numbers (P < 0.05 and < 0.001) of growing, maturing and atretic follicles than the aggressive ones, however the latter showed a highly significant (P < 0.001) folliculogenic response to hCG. The response of the ovary of aggressive females to hCG is particularly dramatic because in most aggressive females the ovaries contained none or only few follicles of any kind. The inhibition of folliculogenesis in aggressive mink is similar to that reported in Silverblue and Sapphire mink homozygous for the Stuart factor. The paradoxical response to hCG may be an indication that selective breeding for aggression may be correlated with the disturbance at the early stages of folliculogenesis which creates a deficiency of follicles that are sensitive to LH-type stimulation.     

DNA probes for the identification of members of the Simulium damnosum complex (Diptera: Simuliidae)

Genomic libraries in plasmid have been constructed from various sibling species of blackflies of the Simulium damnosum complex from West Africa. Three cloned repetitive sequences, which show variation in copy number between sibling species, have been isolated. These clones can be used as probes for the dot-blot identification of larvae, pupae or adults into the three main West African subcomplexes, i.e. damnosum, squamosum and sanctipauli subcomplexes. The sequences also show some intraspecific variation in copy number.     

Breeding Season Aggression of Female and Male Eastern Bluebirds (Sialia sialis) to Models of Potential Conspecific and Interspecific Egg Dumpers

Naturally occurring aggression between female eastern bluebirds (Sialia sialis) is dramatic, resulting in severe injuries and even death. Furthermore, aggression among bluebirds is usually sex specific: males attack males, females attack females. We hypothesized that the primary function of female-female aggression is to guard against the threat of intraspecific egg dumping and that, in this context, same sex aggression is related to the possibility of advantages for males of parasitism (egg dumping) of their nests. Our hypotheses to explain variation in naturally occurring aggression predict temporal variation in aggressive tendency within nest cycles and between the sexes depending on asymmetries in threats to the residents. We report the results of experimental trials in the field designed to determine temporal variation in the aggressive tendencies of resident females to models of intruder females of two species, eastern bluebirds and brown-headed cowbirds (Molothrus ater). Both species dump eggs in the nests of bluebirds. Female aggression to eastern bluebird models is greatest during early stages of nest cycles; the patterns are most consistent with protection against egg dumping and protection of nest sites from usurpation. Male residents seldom attack female eastern bluebird models, but often attack models of female brown-headed cowbirds, a result inconsistent with the hypothesis that patterns of differential parental care control aggression of female and male residents.     

Growth Rates and Body Condition in Norops polylepis (Polychrotidae) Vary with Respect to Sex but not Mite Load1

Norops polylepis is a common anoline lizard that occupies both forest and pasture habitats at various elevations in southern Costa Rica. Previous studies have documented significant spatial variation in mite loads (Eutrombicula chiggers) on N. polylepis. My objective was to investigate whether mite load has a negative impact on growth rates and body condition. Growth rates were estimated in three sites using mark‐recapture with three intensive sampling periods over 12 mo. Nine hundred and forty lizards were captured and 200 individuals were recaptured across sampling periods. Mite load was significantly higher in forests than in pastures, and varied significantly among study sites. Males grew faster than females, and females and juveniles had higher body condition than males. I was unable, however, to detect any influence of mite load on growth rates or body condition. I conclude that Eutrombicula chiggers are either largely benign for N. polylepis or, if they do exert a negative effect on fitness, it is mediated through a trait other than growth or body condition.     

Differences in development time,mortality and water loss between eggs from laboratory and wild populations ofDermatophagoides pteronyssinus (Trouessart, 1897) (Acari: Pyroglyphidae)

A total of four microcultures of adults ofDermatophagoides pteronyssinus, two each from laboratory and wild populations, were fed on separate diets of house dust and yeast granules. A total of 35 eggs of known age from each of the four microcultures were harvested and incubated at 15°C, 60% RH for 16 h/day and 30°C, 75% RH for 8 h/day to simulate diurnal microclimatic fluctuations in a bed. Eggs from females fed on yeast were larger and underwent more rapid rates of water loss, estimated by measurements of reduction in visible surface area (VSA), than eggs from females fed on house dust. There were no significant differences in mean egg development time between the four microcultures (range 6.0–6.88 days). Mortality of the eggs was as follows: from laboratory females fed on yeast, 31.4%; laboratory females fed on house dust, 11.5%; wild females fed on yeast, 2.9%; wild females fed on house dust, 0%. Thus diet and egg size at oviposition had no effect on mortality. Since the microclimates at which eggs from both populations were oviposited and incubated were identical, it is hypothesized that mortality was higer in eggs from laboratory cultures because the mites had become acclimated to the optimal conditions at which they had been kept and were less able to withstand the diurnal fluctuations in microclimate, similar to those imposed upon wild mites in their natural habitats.     

Within-group female-female agonistic interactions in Taiwanese macaques (Macaca cyclopis)

Feeding-related agonism among wild female Taiwanese macaques was investigated in two study groups at ecologically diverse sites (Fu-shan and Ken-ting) to determine whether contest-feeding competition was present in these groups. Females that contest for food within a primate group are hypothesized to form dominance hierarchies and tend to be philopatric. In this study we tested 1) whether Taiwanese macaque females show higher agonism in a feeding context, 2) whether they exhibit stronger agonism over higher-quality foods, and 3) whether higher agonism rates occur in smaller food patches. Female Taiwanese macaques at both study sites showed similar agonism rates in a feeding context (0.30 events/hr). They exhibited higher agonism rates inside food patches than outside food patches in the spring. Higher agonism rates occurred during seasons of higher fruit availability, and a lower agonism rate occurred in winter when the macaques switched to feeding on fallback foods. Females in the Fu-shan group exhibited higher proportions of aggressive interactions over higher-quality foods, such as animal matter and the reproductive parts of plants. In the Ken-ting group, 95.8% of feeding-related agonistic interactions among females occurred over fruits. Agonistic interactions that occurred in small food patches tended to result in the agonism recipient leaving the food patch. We conclude that female Taiwanese macaques show contest feeding competition in certain contexts. The patterns we observed have also been documented in other primate species in which females are philopatric and form linear dominance hierarchies.     

Territorial behaviour in corn mice, <Emphasis Type="Italic">Calomys musculinus</Emphasis> (Muridae: Sigmodontinae), with regard to mating system

We studied territorial behaviour of Calomys musculinus, a promiscuous-polygynous species, in order to test the predictions that during the breeding period, home-range-owner females are more aggressive than home-range intruders and that males do not display territorial behaviour. At the core of the breeding season, we conducted 136 intrasexual and 66 intersexual encounters. The study was carried out in four 0.25-ha enclosures, each containing one independent population. We studied territorial behaviour utilising focal animal sampling to record behaviour. Encounters were conducted in a circular opaque arena (COA) near the home-range’s activity mathematical centre (AMC). Amicable behaviour was not observed in any of the 78 trials among females. The rates of aggressive and submissive behaviour per female–female encounters varied in relation to whether they were home-range owners or intruders, the former being aggressive, the latter submissive. So we could link these drives to the territorial behaviour of C. musculinus. This result fits well with the already known territoriality of C. musculinus during the breeding season. In contrast, the 58 intrasexual male encounters did not show direct aggressive interactions between them. The rates of the different behaviours between males did not vary in relation to whether they were home-range owners or intruders. In our study, which took place during the breeding period, C. musculinus males were nonterritorial, and they never exhibited aggressiveness towards females.     

The effects of habitat complexity on aggression and fecundity in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

Female zebrafish housed in aquaria with spatial complexity (plastic plants) over a 13–16-week period showed reduced levels of aggressive behavior compared to females in bare tanks. In tanks with plants, there was no relationship between levels of aggression and fecundity but, in bare tanks, females experiencing the highest levels of aggression showed reduced fecundity. Our results suggest that it may be beneficial, when maintaining zebrafish at moderate to high densities or working with especially aggressive strains, to house them in spatially complex conditions.     

Effects of male group size,parity, and cycle stage on female chimpanzee copulation rates at Ngogo,Kibale National Park,Uganda

Chimpanzees have complex and variable mating strategies, but most copulations occur when females with full sexual swellings are in parties with multiple males and mate with most or all of those males. Daily copulation rates for fully swollen females vary at different times of a female’s cycle, among females, and across communities and populations. Variation in female age, parity, and cycle stage underlie some of this variation, but possible demographic effects on copulation rates have not been systematically investigated. Demographic variation can affect many aspects of behavior and ecology, including the frequency and success of different mating tactics. Analysis of data from the unusually large chimpanzee community at Ngogo produces two results that are consistent with the hypothesis that demographic variation affects female copulation rates. Copulation rates were high compared with those reported from other research sites, where females had fewer potential mates available. Daily copulation rates of fully swollen females were also positively related to the number of males with whom they associated. Ngogo data also re-confirm results from other studies, of both wild and captive populations, showing that female copulation rates increase during periovulatory periods. This is consistent with the hypothesis that sexual swellings and extended receptivity and proceptivity help to protect females against infanticide by helping to ensure they mate with all potential sires. As at some other sites, parous females at Ngogo copulated at higher rates than nulliparous females. Possible effects of demography on sexual behavior should be considered in assessments of differences between chimpanzees and bonobos and of variation across chimpanzee populations.     

Seasonal variation of mortality,detectability, and body condition in a population of the adder (Vipera berus)

We analyzed seasonal variation in mortality rates in adult males and females of the European adder (Vipera berus), using data collected during a 13‐year capture–recapture study (2005–2017) in a large population. We concurrently obtained quantitative information on the seasonal variation in the detectability and body condition of adders. Our results show strong seasonality in body condition, encounter, and capture rates of adult adders, and these patterns differ markedly between sexes and between breeding and nonbreeding females. Seasonal variation in mortality rates was however virtually nonexistent in males and moderately low in both breeding and nonbreeding females. In addition, we found no evidence for among‐year differences in the seasonal mortality schedules of males and females. During periods of intensive basking, both males and pregnant females are highly visible for humans, but are not subject to strong natural mortality. This low susceptibility to predation is presumably induced by various factors, including the limitation of overt exposure to short periods of time and specific microhabitats, the dorsal coloration pattern that provides cryptic protection and possibly also an aposematic warning signal, and presumed seasonal differences in the foraging behavior and food requirements of natural predators. Our data provide some evidence that female adders, but not males, are relatively vulnerable to predation during the seasonal migrations between the hibernation and feeding habitats. Mortality in the females was not much elevated during their breeding years, but was notably highest in the spring of the ensuing nonbreeding year. After giving birth, reproductive females are extremely emaciated and have a weakened general condition. They then run the risk of dying from starvation either before, during, or after hibernation. The higher mortality after giving birth, that is sustained over a period of ca. 9 months, should be considered as an indirect and delayed survival cost of reproduction.     

Male sexual attractiveness and aggressiveness in rodents having different mating systems

Male aggressiveness can affect male reproductive success both directly by increasing competitiveness and indirectly through female preference. Assuming that significance of male aggressiveness in species having different mating systems can be different, we studied how male aggressiveness relates to sexual attractiveness in polygynous rodents, the water vole (Arvicola terrestris) and the house mouse (Mus musculus), and in a monogamous species, the steppe lemming (Lagurus lagurus). Our analysis revealed that the relation between odor attractiveness and aggressiveness is nonlinear. In polygynous species, males are more aggressive, so females opt for aggressive, albeit not too aggressive, males. In the monogamous steppe lemming, males show low level of intermale aggressiveness, and the most attractive are slightly aggressive males who have greater reproductive potential.     

Patterns of spatio-temporal variation in the survival rates of a viviparous lizard: the interacting effects of sex,reproductive trade-offs,aridity, and human-induced disturbance

Examination of the spatial and temporal variation in survival rates provides insight on how the action of natural selection varies among populations of single species. In this study, we used mark-recapture data from seven populations of the viviparous lizard Sceloporus grammicus in Central Mexico and a multi-model inference framework to examine interpopulation variation in the survival of adult males and females. We aimed to analyze the potential effects of aridity, human-induced disturbance, and reproductive costs on the survival rates of these lizards. For females in particular, we also searched for a negative relationship between litter size (adjusted for female size) and female survival. Our results demonstrate seasonal changes in survival for males and females. In three out of our seven study sites female survival decreased during the birthing season. In contrast, male survival did not appear to decrease during the mating season. We found an interaction between site-specific aridity and reproductive season affecting female survival. A decrease in female survival during the birthing season was observed in relatively arid sites. In one of these arid sites we found a negative effect of size-adjusted litter size on female survival: females producing more offspring than those expected for their size were more likely to die. This result represents evidence of a physiological trade-off for gravid females occurring in at least one of the studied populations. Interpopulation variation in the degree of human-induced disturbance could not explain the observed patterns of spatial variation in survival rates. Our results demonstrate wide variation in sex-specific survival patterns of this viviparous lizard and provide evidence that negative associations between reproduction and survival are highly dependent on the local environmental conditions.