Wild-caught Females Research Articles

Olfactory sensitivity of the marine flatfish Solea senegalensis to conspecific body fluids.

Chemical communication is better understood in freshwater fish than marine fish. The Senegalese sole (Solea senegalensis) is a marine flatfish wherein one of the problems in aquaculture is the poor reproductive performance of hatchery-bred males. Is chemical communication involved in the reproduction of this species? Urine, intestinal fluid and mucus samples were taken from adult fish (wild-caught and hatchery-bred) over the spawning season (March-May), and assessed for olfactory potency using the electro-olfactogram (EOG). The effect of stimulation of the olfactory system with adult female urine on circulating luteinizing hormone (LH) levels was also tested in males. Intestinal fluid and urine were potent olfactory stimuli for both juvenile and adult conspecifics, evoking large-amplitude, concentration-dependent EOG responses, with thresholds of detection at approximately 1:106 However, the amplitude of the response to urine depended on the sex and state of maturity of both the donor and the receiver. Most olfactory activity could be extracted by C18 solid-phase cartridges. Urine from mature females evoked a slight, but significant, increase in circulating LH levels in mature males 30 min after exposure. Furthermore, the olfactory potency of urine differed between wild-caught and hatchery-bred fish; however, contrary to expectations, urine from wild-caught females was less potent than that from hatchery-bred females. Taken together, these results strongly suggest that faeces- and urine-released odorants are involved in reproduction in the Senegalese sole, and establish a basis for further investigation into pheromonal communication in marine teleosts.

Incomplete offspring sex bias in Australian populations of the butterfly Eurema hecabe.

Theory predicts unified sex ratios for most organisms, yet biases may be engendered by selfish genetic elements such as endosymbionts that kill or feminize individuals with male genotypes. Although rare, feminization is established for Wolbachia-infected Eurema butterflies. This paradigm is presently confined to islands in the southern Japanese archipelago, where feminized phenotypes produce viable all-daughter broods. Here, we characterize sex bias for E. hecabe in continental Australia. Starting with 186 wild-caught females, we reared >6000 F1-F3 progeny in pedigree designs that incorporated selective antibiotic treatments. F1 generations expressed a consistent bias across 2 years and populations that was driven by an ~5% incidence of broods comprising ⩾80% daughters. Females from biased lineages continued to overproduce daughters over two generations of outcrossing to wild males. Treatment with antibiotics of differential strength influenced sex ratio only in biased lineages by inducing an equivalent incomplete degree of son overproduction. Brood sex ratios were nevertheless highly variable within lineages and across generations. Intriguingly, the cytogenetic signature of female karyotype was uniformly absent, even among phenotypic females in unbiased lineages. Molecular evidence supported the existence of a single Wolbachia strain at high prevalence, yet this was not clearly linked to brood sex bias. In sum, we establish an inherited, experimentally reversible tendency for incomplete offspring bias. Key features of our findings clearly depart from the Japanese feminization paradigm and highlight the potential for more subtle degrees of sex distortion in arthropods.

Comparison of nutritional quality of three edible tissues of the wild-caught and pond-reared swimming crab (Portunus trituberculatus) females

The nutritional values of three edible tissues (i.e. hepatopancreas, ovary and muscle) of both wild-caught and pond-reared swimming crab females were investigated and compared. Contents of moisture, total lipid and carbohydrate were higher in both hepatopancreas and ovary of wild-caught crab than in these two tissues of pond-reared crab while content of protein was significantly lower; moisture content of muscle in the wild-caught crab was significantly higher than in the pond-reared crab with other contents comparable. For fatty acid profile, wild-caught crab's hepatopancreas had more ΣSFA, ΣPUFA, Σn-3PUFA, Σn-6PUFA and ΣHUFA but less ΣMUFA than the pond-reared crab's; moreover, both ovary and muscle of wild-caught crab contained significantly higher ΣSFA but lower ΣMUFA, ΣPUFA and ΣHUFA. For amino acid profile, contents of seventeen types of amino acids (Gly excluded) were all lower in wild-caught crab than in pond-reared crab, including EAA, NEAA and TAA. Additionally, contents of most nutritious minerals in wild-caught crab were higher than those in pond-reared crab; but notably, toxic mineral contents were also detected to be far higher in the former, especially Cu, Cd and As. To summarize, the pond-reared swimming crab female is thought to have a higher nutritious value for healthy diets.

A Nightmare for Males? A Maternally Transmitted Male-Killing Bacterium and Strong Female Bias in a Green Lacewing Population

For maternally transmitted microbes, a female-biased host sex ratio is of reproductive advantage. Here we found a strong female bias in a field population of the green lacewing, Mallada desjardinsi (Insecta; Neuroptera). This bias was attributed to the predominance of individuals harboring a maternally inherited male-killing bacterium that was phylogenetically closely related to the plant-pathogenic Spiroplasma phoeniceum and Spiroplasma kunkelii. Among 35 laboratory-reared broods produced by wild-caught females, 21 broods (60%)—all infected with Spiroplasma—consisted of only females (940 individuals). Among 14 broods consisting of both males and females (516 and 635 individuals, respectively), 4 broods were doubly infected with Spiroplasma and Rickettsia, 6 broods were singly infected with Rickettsia, and 3 broods were uninfected (remaining one brood was unknown). Mortality during embryonic and larval development was prominent in all-female broods but not in normal sex ratio broods. Following antibiotic treatment on all-female broods, mortality was significantly reduced and the sex ratio was restored to 1:1. Strong expression and high prevalence of this male-killer is remarkable considering its low density (~10−5–10−4 cells per host mitochondrial gene copy based on quantitative PCR). In addition, a bacterium closely related to Rickettsia bellii was present in 25 of 34 broods (73.5%), irrespective of the sex ratio, with the infection density comparable to other cases of endosymbiosis (~10−2–10−1 cells per mitochondrial gene copy). Higher density of Rickettsia than Spiroplasma was also demonstrated by electron microscopy which visualized both Spiroplasma-like cells and Rickettsia-like cells inside and outside the ovarian cells.

Changes in tissue composition in Brazilian mojarraEugerres brasilianus(Cuvier, 1830) females at different stages of gonadal development as a starting point for development of broodstock diets

Summary Thie study evaluated the changes in proximate composition and fatty acid profile in the muscle, liver and ovarian tissues of wild-caught Brazilian mojarra Eugerres brasilianus females during sexual maturation as a starting point for the development of broodstock diets. A total of 114 females captured in the Santa Cruz Canal, Itapissuma, PE, north-eastern Brazil, from August 2012 to April 2013, were classified into four stages of gonadal development by histological analyses. Ovarian protein and total lipid levels increased with maturation, and a simultaneous decrease in liver protein and lipid levels was observed. The levels of arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) also increased in the ovary as the gonadal development proceeded; they represented 96.4% of the total highly unsaturated fatty acids (HUFA) in the ovaries of fully mature females. These findings highlight the need to include protein and lipid-rich sources containing n-6 HUFA, particularly ARA, and n-3 HUFA (EPA, DPA and DHA) in the diets of Brazilian mojarra breeders.

An exploration of the fungal assemblage in each life history stage of the butterfly, Lycaeides melissa (Lycaenidae), as well as its host plant Astragalus canadensis (Fabaceae)

Abstract Understanding the ecological role of symbiotic microbes is an area of increasing interest. With regard to mediating plant–insect interactions, it has become apparent that symbiotic microbes are of fundamental importance. However, elucidation of the roles of symbiotic microbes in these systems has been hampered by a lack of knowledge regarding microbial community structure; with fungi, in particular, being understudied components of symbiont assemblages. Here, we present one of the first studies to characterize fungi associated with each life history stage of a lepidopteran herbivore (egg, larva, pupa, and adult) and the leaves of its host plant. We used a culture-independent approach and explored the possibility that plant-associated fungi may colonize butterflies. The fungal assemblage recovered from each butterfly life history stage was a subset of the fungi that occurred on host plant leaves. The most diverse fungal assemblage recovered from a butterfly life history stage was associated with eggs of wild-caught females. Because fungi recovered from all butterfly life history stages were also found on host plant tissues, our study raises the possibility that butterflies could disperse fungi between individual plants. Additionally, we observed a marked reduction in fungal diversity during pupation. As one of the first studies examining the fungal microbiome of a holometabolous insect throughout its life history, our results highlight the diversity of fungi associated with insect herbivores and their hosts and suggest possibilities for further work examining plant–insect–fungal interactions.

Life cycle of Amblyomma integrum (Acari: Ixodidae) under laboratory conditions.

Amblyomma integrum is a hard tick infesting mainly buffalo and cattle and has been identified as an agent of human otoacariasis in Sri Lanka. Data on the life cycle pattern of A. integrum were collected by experimental infestation on New Zealand white rabbits under laboratory conditions. Wild-caught females laid 55-7389 eggs for 2-35days after spending a latent period of 10-25days. Egg incubation period was 31-105days and the newly emerged larvae started feeding after 4-11days. Larvae dropped off after feeding and they moulted into nymphs after 10-16days. Nymphs actively fed on rabbits for 4-8days and dropped off. Engorged nymphs took 11-25days for moulting before emerging as adults. The male:female sex ratio of the adults moulted under laboratory conditions was 11:9. All the stages showed periodicity in engorgement and dropping off. The three-host life cycle was completed within 74-245days with an average of 152.9days. The mean Reproductive Efficiency Index (REI) and Reproductive Aptitude Index (RAI) were 3.6 and 1.1, respectively. Females hatched in the laboratory did not successfully feed on New Zealand white rabbits. The wild-caught females which fed on buffaloes had prolonged pre-oviposition and oviposition periods, low REI, low RAI and low eclosion under controlled laboratory conditions compared to other tick species. Although larva and nymphs of A. integrum successfully fed on New Zealand white rabbits under laboratory conditions, full life cycle was not completed because the adult females did not feed on rabbits.

Rearing history and allostatic load in adult western lowland gorillas (Gorilla gorilla gorilla) in human care.

Disrupted rearing history is a psychological and physical stressor for nonhuman primates, potentially resulting in multiple behavioral and physiological changes. As a chronic, soma-wide stressor, altered rearing may be best assessed using a holistic tool such as allostatic load (AL). In humans, AL estimates outcomes of lifetime stress-induced damage. We predicted mother-reared gorillas would have lower AL than nursery-reared and wild-caught conspecifics. We estimated AL for 27 gorillas housed at the Columbus Zoo and Aquarium between 1956 and 2014. AL estimates were calculated using biomarkers obtained during previous anesthetic events. Biomarkers in the high-risk quartile were counted toward a gorilla's AL. Rearing history was categorized as mother-reared, nursery-reared, and wild-caught. Using ANCOVA, rearing history and AL are significantly associated when age and sex are entered as covariates. Wild-caught gorillas have significantly higher AL than mother-reared gorillas. Neither wild-caught nor mother-reared gorillas are significantly different from nursery-reared gorillas. When examined by sex, males of all rearing histories have significantly lower AL than females. We suggest males face few stressors in human care and ill effects of rearing history do not follow. Wild-caught females have significantly higher AL than mother-reared females, but neither is significantly different from nursery-reared females. Combined with our previous work on AL in this group, wherein females had twofold higher AL than males, we suggest females in human care face more stressors than males. Disrupted rearing history may exacerbate effects of these stressors. Providing opportunities for females to choose their distance from males may help reduce their AL.

Female reproductive activity and its endocrine correlates in the African lesser bushbaby, Galago moholi.

Steroid hormones play an important role in female reproductive physiology and behaviour and are often used to monitor important female reproductive events. However, such studies are often attempted on captive populations alone, delivering limited data. One such example is the African lesser bushbaby, Galago moholi, for which contradicting observational data exist between captive and free-ranging populations, while hormonal analyses have only been obtained from a single captive population. To extend and rectify the limited information, we monitored faecal progestagen and oestrogen metabolite levels across various important life history stages of both captive and free-ranging G. moholi. We additionally recorded changes in vaginal state as well as the occurrence of reproductive and aggressive behaviour throughout the study. Data from our captive population revealed an ovarian cycle length of 33.44 ± 0.59 days (mean ± SD), with follicular and luteal phases of 14.2 ± 1.0 and 19.1 ± 1.5 days, respectively, and an average pregnancy length of 128 ± 3.3 days. The initiation of female reproductive activity was closely linked to an oestrus-related increase in faecal oestrogen metabolite levels. Four of the seven captive females monitored in our study conceived during the May mating period, with one additional female fertilised in September, supporting the idea that the September mating period functions as a back-up for female G. moholi. Identified benchmark faecal progestagen metabolite levels (non-pregnant: >1 µg/g dry weight (DW), pregnant: >9 µg/g DW) should help researchers to determine pregnancy status of randomly wild-caught females in even a cross-sectional study setup.

The emergence of insecticide resistance in the major malaria vector Anopheles funestus (Diptera: Culicidae) from sentinel sites in Mutare and Mutasa Districts, Zimbabwe.

BackgroundInsecticide resistance in major malaria vectors poses severe challenges for stakeholders responsible for controlling the disease. During the 2013/14 season, malaria vector sentinel sites in Mutare and Mutasa Districts, Zimbabwe, experienced high presence of gravid malaria vector mosquitoes resting indoors in recently pyrethroid-sprayed structures. Subsequently, an evaluation of insecticide resistance in Anopheles funestus populations, the major malaria vector, was conducted to better inform the Zimbabwe National Malaria Control Programme.MethodsIndoor-resting mosquitoes were collected in randomly selected pyrethroid-sprayed houses around Burma Valley and Zindi sentinel sites in Mutare and Mutasa Districts, respectively, using prokopac aspirator in February 2014. A. funestus mosquitoes were identified in the field using morphological keys and divided into two cohorts. One cohort was used immediately for WHO susceptibility tests and the other batch was transferred to the National Institute of Health Research insectary in Harare for oviposition. Susceptibility and intensity resistance assays were carried out on polymerase chain reaction-assayed, 3–5 days old, A. funestus s.s. F1 progeny females.ResultsEight-hundred and thirty-six A. funestus and seven Anopheles gambiae complex mosquitoes were collected resting inside living structures. Wild caught females showed resistance to lambda-cyhalothrin (3.3 % mortality), deltamethrin (12.9 % mortality), etofenprox (9.2 % mortality), and bendiocarb (11.7 % mortality). F1 A. funestus female progeny indicated resistance to deltamethrin (14.5 % mortality), lambda-cyhalothrin (6.9 % mortality), etofenprox (8.3 % mortality), and bendiocarb (16.8 % mortality). Wild caught and female progeny were susceptible to DDT and pirimiphos-methyl (100 % mortality). Intensity resistance assay to bendiocarb was 100 % mortality, while deltamethrin, lambda-cyhalothrin, and etofenprox had increased knockdown times with mortalities ranging between 66.7 and 92.7 % after 24-h exposures.ConclusionThis study is the first report of pyrethroid and carbamate resistance in A. funestus populations from Burma Valley and Zindi areas and indicates a major threat to the gains made in malaria vector control in Zimbabwe. In view of the current extension and intensity of such resistance, there is urgent need to set up a periodic and systematic insecticide resistance-monitoring programme which will form the basis for guiding the selection of insecticides for indoor residual spraying and distribution of pyrethroid-treated mosquito nets.

Sirex woodwasp range expansion in Australia: performance and parasitism on two commercial pine species

Sirex woodwasp was detected in Queensland in 2009 and rapidly established in softwood plantations (Pinus radiata and P. taeda) in southern border regions. Biocontrol inoculations of Deladenus siricidicola began soon after, and adults were monitored to assess the success of the programme. Wasp size, sex ratios, emergence phenology and nematode parasitism rates were recorded, along with the assessment of wild-caught females. Patterns varied within and among seasons, but overall, P. taeda appeared to be a less suitable host than P. radiata, producing smaller adults, lower fat body content and fewer females. Sirex emerging from P. taeda also showed lower levels of nematode parasitism, possibly due to interactions with the more abundant blue-stain fungus in this host. Sirex adults generally emerged between November and March, with distinct peaks in January and March, separated by a marked drop in emergence in early February. Temperature provided the best correlate of seasonal emergence, with fortnights with higher mean minimum temperatures having higher numbers of Sirex emerging. This has implications for the anticipated northward spread of Sirex into sub-tropical coastal plantation regions. Following four seasons of inundative release of nematodes in Queensland, parasitism rates remain low and have resulted in only partial sterilization of infected females.

Paternity analyses in wild-caught and laboratory-reared Caribbean cricket females reveal the influence of mating environment on post-copulatory sexual selection.

Polyandry is ubiquitous in insects and provides the conditions necessary for male- and female-driven forms of post-copulatory sexual selection to arise. Populations of Amphiacusta sanctaecrucis exhibit significant divergence in portions of the male genitalia that are inserted directly into the female reproductive tract, suggesting that males may exercise some post-copulatory control over fertilization success. We examine the potential for male-male and male-female post-copulatory interactions to influence paternity in wild-caught females of A. sanctaecrucis and contrast our findings with those obtained from females reared in a high-density laboratory environment. We find that female A. sanctaecrucis exercise control by mating multiple times (females mount males), but that male-male post-copulatory interactions may influence paternity success. Moreover, post-copulatory interactions that affect reproductive success of males are not independent of mating environment: clutches of wild-caught females exhibit higher sire diversity and lower paternity skew than clutches of laboratory-reared females. There was no strong evidence for last male precedence in either case. Most attempts at disentangling the contributions of male-male and male-female interactions towards post-copulatory sexual selection have been undertaken in a laboratory setting and may not capture the full context in which they take place--such as the relationship between premating and post-mating interactions. Our results reinforce the importance of designing studies that can capture the multifaceted nature of sexual selection for elucidating the role of post-copulatory sexual selection in driving the evolution of male and female reproductive traits, especially when different components (e.g. precopulatory and post-copulatory interactions) do not exert independent effects on reproductive outcomes.

La Crosse Encephalitis Virus Infection in Field-Collected Aedes albopictus, Aedes japonicus, and Aedes triseriatus in Tennessee.

La Crosse virus (LACV) is a mosquito-borne virus and a major cause of pediatric encephalitis in the USA. La Crosse virus emerged in Tennessee and other states in the Appalachian region in 1997. We investigated LACV infection rates and seasonal abundances of the native mosquito vector, Aedes triseriatus, and 2 recently introduced mosquito species, Ae. albopictus and Ae. japonicus, in an emerging disease focus in Tennessee. Mosquitoes were collected using multiple trapping methods specific for Aedes mosquitoes at recent human case sites. Mosquito pools were tested via reverse transcriptase-polymerase chain reaction (RT-PCR) of the S segment to detect multiple Bunyamwera and California serogroup viruses, including LACV, as well as real-time RT-PCR of the M segment. A total of 54 mosquito pools were positive, including wild-caught adult females and laboratory-reared adults, demonstrating transovarial transmission in all 3 species. Maximum likelihood estimates (per 1,000 mosquitoes) were 2.72 for Ae. triseriatus, 3.01 for Ae. albopictus, and 0.63 for Ae. japonicus. We conclude that Ae. triseriatus and Ae. albopictus are important LACV vectors and that Ae. japonicus also may be involved in virus maintenance and transmission.

Comparison of ovarian maturation and spawning after unilateral eyestalk ablation of wild-caught and pond-reared Penaeus monodon

The present study compares the efficiency of ovarian maturation and spawning success between wild-caught and pond-reared Penaeus monodon females after unilateral eyestalk ablation. The earliest spawning time after eyestalk ablation was 5.9 days in wild-caught females, which is significantly shorter than the spawning time in pond-reared females (10.5 days). Both wild-caught and pond-reared females repeatedly spawned after eyestalk ablation. On average, each wild-caught female spawned 2.94 times while each pond-reared female spawned only 1.09 times. The spawning induction rate, egg hatching rate, and the number of eggs per spawning were significantly greater in wild-caught females than in pond-reared females. However, the egg size was not significantly different between wild-caught and pond-reared females. Four shrimp sizes (60, 80, 100 and 120 (± 1.0) g) were tested in this study and body weight significantly affected ovarian induction in pond-reared females but not in wild-caught females. Within the same body-weight class, the egg number per spawn in wild-caught females was significantly greater than that in pond-reared females. The egg production per spawn of the pond-reared females in the 120-g size group was two times higher than that in the pond-reared females in the 80-g size group. In conclusion, the fecundity of wild-caught P. monodon females is significantly higher than that of pond-reared P. monodon females. In breeding pond-reared P. monodon, the recommended minimum body weight of females is over 80 g, and the desirable body weight is over 100 g.

Birth sex ratio, infant mortality and rearing type in captive western lowland gorillas

One of the main challenges for the successful captive breeding programme for the western lowland gorilla is the management of males surplus to the population. In addition, infant mortality and rearing type can have a large effect on the development of the population. A better understanding of factors influencing sex ratio, infant mortality and rearing could be advantageous for the management of the captive population. We analysed 1286 births from 378 different dams living in zoos participating in the international breeding programme. Our results show that there is a trend for a male-biased sex ratio with increasing maternal age, but the relationship is not significant and we conclude that limiting reproduction in older females would not sufficiently reduce the surplus of males to warrant the possible negative effects on population genetics and social development. None of the following factors had a significant effect on infant mortality within 30 days after birth: maternal age at conception, birth order, rearing type of the mother, sex of the offspring, survivorship of the previous offspring or population. However, there was a significant decrease in infant mortality over the years, probably reflecting improved captive husbandry practices. Infants born to a hand-reared female had to be hand reared significantly more often as opposed to those of parent-reared and wild-caught females. The ratio of hand-reared offspring showed a significant decrease throughout the study period, showing again the positive results of current management strategies. The study confirms that over the years the management of gorillas in captivity has been considerably improved. Selective breeding with young females will not resolve the problem of surplus males and other solutions will have to be investigated. Neither maternal age at conception, nor birth order, rearing type of the mother, sex of the offspring, survivorship of the previous offspring or population did have a significant effect on infant mortality within 30 days after birth. However, there was a significant decrease of infant mortality through the years, probably reflecting improved captive husbandry practices. Infants born to a hand reared female had to be hand reared significantly more often as opposed to those of parent reared and wild caught females. The ratio of hand reared offspring showed a significant decrease throughout the study period, showing again the positive results of current management strategies. The study confirms that through the years the management of gorillas in captivity has been improved considerably. Selective breeding with young females will not resolve the problem of surplus males and other solutions will have to be investigated.

Revisiting the link between breeding effort and oxidative balance through field evaluation of two sympatric sibling insect species.

The idea that oxidative stress could be a major force governing evolutionary trade-offs has recently been challenged by experimental approaches in laboratory conditions, triggering extensive debates centered on theoretical and methodological issues. Here, we revisited the link between oxidative stress and reproduction by measuring multiple antioxidant and oxidative damages in wild-caught females of two sibling weevil species (Curculio elephas, C. glandium). The strength of our study arised from (1) studied species that were sympatric and exploited similar resource, but displayed contrasting reproductive strategies and (2) individuals were sampled throughout adult life so as to relate oxidative status to breeding effort. We found that the short-lived C. elephas sacrifices red-ox homeostasis for immediate reproduction upon emergence as characterized by low antioxidant defenses and elevated oxidative damage. Comparatively, C. glandium massively invests in antioxidant and maintains low oxidative damage, which may contribute to their extended prereproductive period. Intriguingly, we also reveal, for the first time in a field study, an unexpected reactivation of antioxidant defenses with the onset of reproduction. Our results thus support the existence of a strong, but complex relationship between oxidative stress and life-history evolution and highlight the need for a finer-scale picture of antioxidant strategies.

Triple insecticide resistance in Anopheles culicifacies: A practical impediment for malaria control in Odisha State, India.

Background & objectives:In Odisha State, the control of malaria vectors has become dependent on synthetic pyrethroids, which are used for treatment of all approved long-lasting insecticidal nets (LLINs). The vast use of just one class of insecticide has led to the problem of resistance to insecticides in malaria vectors. One of the major malaria vectors in Odisha State is Anopheles culicifacies Giles. The aim of this study was to determine the resistance status of An. culicifacies to deltamethrin, a synthetic pyrethroid and other common insecticides used by the National Vector Borne Diseases Control Programme (NVBDCP) for indoor residual spraying in Odisha State.Methods:Mosquitoes were collected during April 2014 - June 2014 from 15 randomly selected villages in five Plasmodium falciparum endemic southern districts of Odisha State. The blood-fed wild caught females were exposed to the diagnostic dosage of DDT (4.0%), malathion (5.0%) and deltamethrin (0.05%) for one hour. Mortality was recorded at 24 h after the exposure.Results:Results indicated that An. culicifacies was resistant to all the three insecticides used in the malaria control programme in the five districts of Odisha State.Interpretation & conclusions:Resistance management strategy by appropriate rotation of different groups of insecticides including carbamates and incorporating a synergist with synthetic pyrethroids for treating mosquito nets should be considered for the control of malaria vectors in the area, especially where An. culicifacies is predominant. Periodical monitoring of susceptibility/resistance status of An. culicifacies to different insecticides is warranted.

Life expectancy and longevity of varanid lizards (Reptilia:Squamata:Varanidae) in North American zoos.

In zoos, life expectancy-the average lifespan of individuals within a population, and longevity-the maximum lifespan within a population, can be useful parameters for evaluating captive husbandry and animal welfare. Using life history and demographic data derived from regional studbooks, this study examined life expectancy and longevity in a total of 782 wild-caught (WC) and captive-bred (CB) varanid lizards of seven species maintained in North American zoos since 1926. The average lifespans for WC and CB animals were 6.3 ± 0.3 and 9.3 ± 0.4 years, respectively, with CB males living significantly longer than females (P = 0.009). A total of 26.4% of WC and 22.5% of CB animals experienced mortality during their first 2 years in captivity, with mortality during this period greatest among Varanus rudicollis and V. prasinus. A positive correlation was observed between life expectancy and adult body mass in captive-bred individuals (r = 0.981; P = 0.002). Wild-caught females with a history of successful reproduction had a significantly greater average lifespan than non-reproducing females (P < 0.0001). Results from this study suggest that varanids have not been reaching their lifespan capacities in North American zoos. In light of these findings, several husbandry-related factors which may be affecting the welfare and lifespans of varanids in zoos are identified and discussed. This study also highlights the utility of demographic and life history data in captive animal management, and offers a general framework for future herpetological studies of a similar nature.

Cytogenetic, cross-mating and molecular evidence of four cytological races of Anopheles crawfordi (Diptera: Culicidae) in Thailand and Cambodia

Twenty-nine isolines of Anopheles crawfordi were established from wild-caught females collected from cow-baited traps in Thailand and Cambodia. Three types of X (X1, X2, X3) and four types of Y (Y1, Y2, Y3, and Y4) chromosomes were identified, according to differing amounts of extra heterochromatin. These sex chromosomes represent four metaphase karyotypes, i.e., Forms A (X1, X2, X3, Y1), B (X1, X2, X3, Y2), C (X2, Y3) and D (X2, Y4). Forms C and D are novel metaphase karyotypes confined to Thailand, whereas forms A and B appear to be common in both Thailand and Cambodia. Cross-mating experiments between the four karyotypic forms indicated genetic compatibility in yielding viable progenies and synaptic salivary gland polytene chromosomes. The results suggest that the forms are conspecific and A. crawfordi comprises four cytological races, which is further supported by very low intraspecific variation (mean genetic distance=0.000–0.018) of the nucleotide sequences in ribosomal DNA (ITS2) and mitochondrial DNA sequences (COI, COII).

Sex ratio bias caused by endosymbiont infection in the dwarf spiderOedothorax retusus

Spiders exhibit a remarkable variety of reproductive phenotypes such as induced parthenogenesis and reproductive skew in primary sex ratio. However, observations of distorted sex ratios are mainly inferred from field catches of adult individuals, whereas detailed information on clutch primary sex ratio and sex ratio inheritance, resulting from multiple generations of laboratory rearing, is scarce. One of the potential causes of sex ratio variation is infection with maternally inherited endosymbiont bacteria that alter a mother's offspring sex ratio to increase their own fitness. Although studies show that spiders are infected with several endosymbiont species, it was only recently discovered that endosymbiont bacteria can cause a female sex ratio bias in this order. To explore the distribution of biased sex ratios and endosymbiont infection patterns, we investigated sex ratio variation and bacterial presence in Oedothorax retusus Westring 1851. Significant sex ratio variation was detected in six matrilines originating from wild-caught females, one of which consistently showed a female bias in offspring production. Congruent with a bacterial effect, the sex ratio bias showed a clear maternal inheritance, and treatment with antibiotics reversed the sex ratio to equal numbers of males and females. Female-biased clutches were found to exhibit a significantly lower number of hatched spiderlings than unbiased clutches, suggesting the occurrence of male-killing. All matrilines showed infection with the Cardinium endosymbiont, while two matrilines, including the female biased one, were additionally infected with Wolbachia and Rickettsia. These findings indicate that bacterial endosymbionts are responsible for the sex ratio variation in this species, and suggest that effects of endosymbiont bacteria in the order Araneae could be more widespread than previously assumed.