Speciation in Passerina buntings: introgression patterns of sex-linked loci identify a candidate gene region for reproductive isolation

Sex-chromosomes are thought to play an important role in speciation, but few studies of non-model organisms have investigated the relative influence of multiple sex-linked markers on reproductive isolation. We collected 222 individuals along a geographical transect spanning the hybrid zone between Passerina amoena and P. cyanea (Aves: Cardinalidae). Using maximum-likelihood cline fitting methods, we estimated locus-specific introgression rates for 10 z-linked markers. Although the cline width estimates ranged from 2.8 to 584 km, eight of 10 loci had cline widths between 224 and 271 km. We also used coalescent-based estimates of locus-specific divergence times between P. amoena and P. cyanea to test a recently proposed hypothesis of an inverse relationship between divergence time and cline width but did not find a significant association. The narrow width (2.8 km) of the cline estimated from the VLDLR9 locus indicates strong selection retarding introgression of alleles at this locus across the hybrid zone. Interestingly, a mutation in the very low density lipoprotein receptor ( VLDLR ) gene, in which VLDLR9 is an intron, is known to reduce the egg-laying ability of some chickens, suggesting a possible link between this gene region and reproductive isolation between P. amoena and P. cyanea . These results underscore the importance of sampling multiple loci to investigate introgression patterns across a chromosome or genome and support previous findings of the importance of sex-linked genes in speciation.     

Netguns: a technique for capturing Black‐backed Woodpeckers

ABSTRACT Effective capture techniques are essential for studying bird populations, but commonly used techniques have proven ineffective for capturing Black‐backed Woodpeckers (Picoides arcticus) during the nonbreeding period. As a result, little is known about the winter ecology of Black‐backed Woodpeckers. We used two netguns, one powered with a 0.308 cartridge and another with CO₂ propellant, to capture 101 Black‐backed Woodpeckers (N= 75 initial captures and 26 recaptures) in the Black Hills of South Dakota from 2008 to 2011. Captures with the 0.308 netgun resulted in an impact mortality probability of 0.061 ± 0.034 (SE), whereas no impact mortalities were associated with the CO₂ netgun. We also tracked birds for 72 h post‐release, and determined a capture‐related mortality rate of 0.102 ± 0.04 with the 0.308 netgun and 0.038 ± 0.027 with the CO₂ netgun. With the CO₂ netgun, we captured woodpeckers in 31 of 43 net deployments (72%), with an average of 7.2 ± 0.4 h of capture effort for each bird. Many unsuccessful attempts were caused by tree branches that prevented net deployment. Netguns powered by CO₂ provide an effective capture technique that we recommend for studies of Black‐backed Woodpeckers and possibly other species of birds that forage low on trees.     

Suppression of populations of Australian sheep blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae), with a novel blowfly trap

The Australian sheep blowfly, Lucilia cuprina , initiates more than 85% of fly strikes on sheep in Australia with an estimated average annual cost of A$280 million to the Australian sheep industry. LuciTrap^® is a commercially available, selective trap for L. cuprina consisting of a plastic bucket with multiple fly entry cones and a synthetic attractant. The impact of LuciTrap on populations of L. cuprina on sheep properties in five Australian states was evaluated by comparing L. cuprina populations on paired properties with and without LuciTraps over seasons when significant fly populations could be expected. Twenty-four comparisons (trials) were conducted over 4 years. During times of 'higher fly density' (when the 48 h geometric mean of trap catches on the control property was greater than five L. cuprina ), the overall geometric mean trap catches for control and trapped properties differed significantly ( P  < 0.001) with mean trap catches of 19.4 and 7.74 L. cuprina , respectively. The selectivity of the LuciTrap was confirmed with 59% of all trapped flies being L. cuprina . Chrysomya spp. and Calliphora spp. constituted 9.3% and 1.1% of the catches with a variety of other flies (mainly Sarcophagidae and Muscidae ) providing the remainder (31%). Lucilia sericata was only trapped in Tasmania and made up 7.7% of the Lucilia spp. catch in that state. Seventy-two per cent of the trapped L. cuprina were female. The deployment of LuciTrap on sheep properties at one trap per 100 sheep from the beginning of the anticipated fly season suppressed the populations of L. cuprina by 60% compared with matched control properties. The LuciTrap is a selective and easy to use fly trap and constitutes an effective, non-insecticidal tool for use in integrated management programs for L. cuprina .     

Haldane's rule in an avian system: using cline theory and divergence population genetics to test for differential introgression of mitochondrial, autosomal, and sex-linked loci across the Passerina bunting hybrid zone

Using cline fitting and divergence population genetics, we tested a prediction of Haldane's rule: autosomal alleles should introgress more than z-linked alleles or mitochondrial haplotypes across the Passerina amoena/Passerina cyanea (Aves: Cardinalidae) hybrid zone. We screened 222 individuals collected along a transect in the Great Plains of North America that spans the contact zone for mitochondrial (two genes), autosomal (four loci) and z-linked (two loci) markers. Maximum-likelihood cline widths estimated from the mitochondrial (223 km) and z-linked (309 km) datasets were significantly narrower on average than the autosomal cline widths (466 km). We also found that mean coalescent-based estimates of introgression were larger for the autosomal loci (0.63 genes/generation, scaled to the mutation rate mu) than for both the mitochondrial (0.27) and z-linked loci (0.59). These patterns are consistent with Haldane's rule, but the among-locus variation also suggests many independently segregating loci are required to investigate introgression patterns across the genome. These results provide the first comprehensive comparison of mitochondrial, sex-linked, and autosomal loci across an avian hybrid zone and add to the body of evidence suggesting that sex chromosomes play an important role in the formation and maintenance of reproductive isolation between closely related species.     

Field evaluation of effectiveness of the BG-Sentinel, a new trap for capturing adult Aedes aegypti (Diptera: Culicidae)

In recent years, the development of new tools to gather field information about vector ecological parameters has increased. This report evaluated the BG-Sentinel Trap (BGS-Trap), a promising new attempt to improve collection of the dengue vector, Aedes aegypti. The efficacy of the BGS-Trap was compared with the CDC backpack aspirator, one of the commonest used methods for capturing adult mosquitoes. BGS-Traps captured significantly more Ae. aegypti males (chi2 = 21.774, df = 1, P < 0.05) and females (chi2 = 56.007, df = 1, P < 0.05) than CDC aspirator during all days of field collection. However, CDC aspirator was significantly more efficient to capture Culex quinquefasciatus males (chi2 = 5.681, df = 1, P < 0.05) and females (chi2 = 6.553, df = 1, P < 0.05). BGS-Traps captured host-seeking females (varying between 68.75 to 89.8%) in detriment of females in other behavioral and physiological stages. BGS-Traps proved to be efficient and can be used for monitoring adult mosquito populations.     

Apomorphine as an emetic for insectivorous songbirds: effectiveness and post‐release effects on survival and mass change

Emetics can be used to obtain food samples from birds, but they can harm birds during or after treatment. Studies to date suggest that apomorphine is a safe emetic for songbirds, but information is needed about possible post‐release deleterious effects. From March to July 2012, we collected food samples from insectivorous songbirds using apomorphine. We treated 67 Moustached Warblers (Acrocephalus melanopogon), 56 Reed Warblers (Acrocephalus scirpaceus), 15 Great Reed Warblers (Acrocephalus arundinaceus), and 12 Savi's Warblers (Locustella luscinoides). Effectiveness in inducing regurgitation was high (76.7%) and varied among species, being significantly more effective with Reed Warblers (91.1%). No birds died during treatment. To check for possible post‐release negative effects, we considered 53 treated Moustached Warblers and 37 treated Reed Warblers and selected an equal number of untreated individuals (simply captured, banded, and measured). We found no support for differences in survival or recapture probabilities between treated and untreated birds of either species within 21 d after administering apomorphine. We calculated body mass changes of all Moustached Warblers subsequently recaptured (within 21 d) and found no difference between treated (N = 8) and untreated (N = 22) birds, suggesting normal foraging activity after release. Our results suggest that apomorphine is a safe emetic, with no negative effect on survival at least in the short term. The effectiveness of apomorphine with insectivorous songbirds in our study contrasts with the results of some previous studies and confirms the differences in effectiveness among different taxa of songbirds. As with differences in effectiveness among species in our study, this variability in sensitivity to the emetic could be caused by morphological and physiological differences among different taxa.     

A new method for catching cavity‐nesting birds during egg laying and incubation

ABSTRACT The physiological condition of female birds during the egg‐laying and incubation periods is of considerable interest and yet is relatively understudied in wild birds, primarily due to the difficulty of catching birds during this period without causing nest desertion. We therefore developed a box‐net to capture cavity‐nesting birds using sections of a mist‐net placed around a metal cubic frame. We captured female Great Tits (Parus major) as they left nest boxes during the egg‐laying and incubation periods and measured desertion rates. Using box‐nets, we captured 108 of 119 (90%) females during egg laying and 10 of 12 (83%) during incubation. Our recapture rate over two consecutive days during incubation was 50% (5 of 10). Females not captured left nest boxes before we attempted to capture them, escaped through a hole in the mist‐net, or remained in nest boxes for more than 2 h, after which we ended capture attempts. Overall, 22% of egg‐laying females deserted, with desertion rates highest early in the egg‐laying period. Desertion rates of females captured using box‐nets did not differ from those of undisturbed females. One of 10 females captured in a box‐net deserted during the incubation period. Box‐nets are portable, can be set up and taken down quickly and easily, and could potentially be used with nest boxes or natural cavities at any height. Box‐nets are easy to construct and adaptable for use with an array of cavity‐nesting birds, and can be an important tool for studying female physiology during egg laying and incubation.     

Experimental evaluation of a minnow trap for small lotic fish

A minnow trap that operates in various flow regimes in streams and allows sampling of small fish from stream bed microhabitats was developed. In laboratory and field tests, the most efficient trap design for capturing and retaining various species of fish had one funnel oriented downstream, a plexiglass body, and commercial trout food as bait. These lightweight traps can be set in a wide range of current velocities and depths, and can be useful in investigations that examine the microhabitat use, diel activity patterns or population densities of small lotic fish. Guidelines for the trap's use and for quick verification of capture success in new situations are suggested.     

Assessing trap and lure effectiveness for the monitoring of Sirex noctilio

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Pitfall trap design affects the capture efficiency of harvestmen (Opiliones) and millipedes (Diplopoda)

Pitfall trapping is one of the standard methods used for the capture of ground‐active arthropod groups. Despite being frequently used, the standardization of this method is problematic due to the large range of combinations of the individual parameters of pitfall traps with varying efficacy under different environmental conditions. We evaluated the effects of the trap diameter, the fixing fluid, and their combination on the capture efficacy for harvestmen (Opiliones) and millipedes (Diplopoda). We used pitfall traps with three different diameters: 3 cm, 5 cm, and 12 cm, filled with three types of fixing fluids (saturated fluid of NaCl, 10:1 mixture of 70% ethanol and glycerol and 4% formaldehyde). Altogether, 90 traps representing nine combinations of trap diameters and fixing fluid were placed on a mown meadow in spring and autumn intervals for a total of 45 days. We sampled 1,488 individuals representing 11 harvestmen species and 881 individuals representing 11 millipede species. Large (d = 12 cm) and medium (5 cm) traps captured significantly more millipede species and individuals than the small‐sized traps (3 cm). The same effect was observed for harvestmen species richness, whereas the medium traps (d = 5 cm) captured the highest mean activity of harvestmen. By analyzing the differences in the body sizes of the studied arthropods in relation to the trap diameter and fluid, we found that larger traps, as well as traps filled with NaCl solution, captured larger harvestmen more frequently than the other trap types. Our results revealed that the combination of larger traps (d = 5 and 12 cm) and formaldehyde was most effective in the capture of both studied groups. However, the disadvantage of formaldehyde is its toxicity.     

Evaluation of trap designs and food attractants for trapping Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae)*

Eucryptorrhynchus scrobiculatus (Motschulsky) is a serious pest of tree of heaven, Ailanthus altissima (Mill.) Swingle in China. Laboratory choice tests were conducted to compare attractiveness of vinegar, ethanol, apple juice, the vinegar-ethanol mixture (VE), vinegar-apple mixture (VA), ethanol-apple mixture (EA) and vinegar-ethanol-apple mixture (VEA) to E. scrobiculatus. VEA showed significantly higher attractiveness to E. scrobiculatus than vinegar, ethanol, apple juice alone, VE, VA or EA. The field experiments were conducted to evaluate the efficiency of commercial pitfall traps baited with different ratios of VEA (Apple: VE, m:m) for trapping E. scrobiculatus. Field evaluations showed that the number of marked and wild E. scrobiculatus in traps baited with the VEA (Apple: VE, 30:70 ratio, m:m) was significantly higher than traps baited with other ratios of VEA. Further testing of four types of trap baited with this VEA (Apple: VE, 30:70 ratio, m:m) indicated that captures in homemade pitfall trap design were significantly higher than in any other trap design (commercial pitfall traps, cross-vane versus traps and six-unit-funnel traps). The results demonstrated that homemade pitfall traps baited with the VEA (Apple: VE, 30:70 ratio, m:m) have potential for E. scrobiculatus monitoring.     

Comparative efficacy of five types of trap for woodborers in the Cerambycidae, Buprestidae and Siricidae

1 Traps of four new designs were tested against the conventionally used multiple‐funnel trap to determine whether trapping of large wood‐boring insects can be improved in western Canada. All four new traps used a large collecting receptacle containing detergent‐laced water, and three presented a prominent visual silhouette above the receptacle. 2 In total, 27 336 large woodborers were captured from 10 June to 30 September in an experiment in the southern interior of British Columbia, and 4737 from 6 June to 27 July in an experiment in northern Alberta. The woodborers captured in the British Columbia experiment were mainly beetles in the families Cerambycidae (79%) and Buprestidae (15%), and woodwasps in the family Siricidae (6%). Most woodborers, e.g. three Monochamus spp. and Xylotrechus longitarsus (the predominant cerambycids), were captured throughout the summer, with peak captures in August. 3 Cross‐vane, pipe and stacked‐bottomless‐flower‐pot traps were generally superior to pan and multiple‐funnel traps for insects in nine taxa, but cross‐vane traps were the most effective overall, trapping 32% of all insects captured. 4 The large number of target insects captured in a relatively small number of traps in the two experiments suggests that employment of an efficacious trap with a large vertical silhouette and a wide, escape‐proof collecting receptacle could make mass trapping of large woodborers in timber processing areas operationally feasible. 5 Because the most effective traps were unstable in the wind, and the detergent‐laced water captured unacceptably high numbers of small mammals, design modifications are necessary. We are currently developing a wind‐firm trap, with a prominent vertical silhouette, a wide collecting surface, and an escape‐proof, but dry collecting receptacle.     

水盆与饮水瓶诱捕器诱捕棉铃虫雄蛾效果的比较

2005年在北疆棉区棉铃虫Helicoverpa armigera2代成虫期田间试验表明,水盆诱捕器每个每晚平均诱捕头数是饮水瓶的6.3倍(瓶竖放)和18.4倍(瓶斜放),差异均达显著水准(P=0.05)。比较单个诱捕器1晚最大诱蛾数,水盆是饮水瓶的8.0倍(瓶竖放)和24.0倍(瓶斜放),差异均达显著水准(P=0.05)。比较逐日平均诱蛾数,水盆是饮水瓶的9.44倍,差异达极显著水准(P=0.01)。综合考虑经济成本,在此条件下用饮水瓶制作棉铃虫诱捕器是不可取的。     

Host plant selection behaviour of Chilo partellus and its implication for effectiveness of a trap crop

Female lepidopterans can display a hierarchy of preference among potential host species, a trait thought to arise from the balance between attractants and deterrents to which the insects respond. Host plant ranking by moths and larvae of Chilo partellus Swinhoe (Lepidoptera: Crambidae), an important pest of cereals in Africa, was investigated, and whether eggs deposited on specific host plants yield larvae of particular host preferences. Trap plants are used in management of this pest. However, any ‘disagreement’ in host ranking between moths and larvae could potentially reduce effectiveness of trap crops as larvae emigrate to the main crop from the parent’s preferred trap plant. We also investigated whether host plant preference is influenced by the diet upon which larvae fed as part of an integrated assessment of the relationship between host plant selection and learning in C. partellus. Five host plants (all Poaceae) were used: maize (Zea mays L.), sorghum (Sorghum bicolor Moench), Napier grass (Pennisetum purpureum Schumach), and two varieties of signal grass [Brachiaria brizantha (A. Rich.) Stapf], viz., local (henceforth signal grass) and improved (‘Mulato’). In multiple choice tests, C. partellus female moths preferentially oviposited on Napier grass, followed by sorghum, maize, and signal grass, and least preferred ‘Mulato’. Larvae however equally orientated and settled on leaf cuts of maize, sorghum, signal grass, and Napier grass, but least preferred ‘Mulato’. Moreover, eggs from specific host plants did not yield larvae of particular host preferences. Furthermore, oviposition preference was not altered by the larval food. These results imply only a slight ‘disagreement’ in host ranking behaviour between moths and larvae, which is beneficial for trap cropping as larvae would not ‘reject’ the trap plant and appreciably disperse to the neighboring plants. Moreover, absence of larval learning behaviour indicates that regardless of the larval food C. partellus moths would still be attracted to the selected trap plant.     

A novel mitochondria-localizing nitrobenzene derivative as a donor for photo-uncaging of nitric oxide

We report a novel green-fluorescent NO donor, NBDNO, bearing a 2,6-dimethylnitrobenzene moiety for photocontrollable NO release and a triphenylphosphonium moiety for targeting to mitochondria. Photorelease of NO from NBDNO was confirmed by means of ESR analysis in aqueous solution. Intracellular release of NO from NBDNO was confirmed by using DAR-4M AM, an NO-specific fluorescence probe. NBDNO was colocalized with MitoRed, a mitochondrial stain, in HCT116 colon cancer cells. Our results indicate that NBDNO is an effective NO donor for time-controlled, mitochondria-specific NO treatment.     

糖醋液和乙二醇对地表甲虫的诱集效率比较

2006～2007年分别以糖醋液和乙二醇作为陷阱溶液对天然紫胶林、人工紫胶林和旱地的地表甲虫群落进行了抽样。糖醋液诱到19科66种522头地表甲虫,乙二醇诱到19科68种690头 共同诱到29种,占全部种类的27.6%。糖醋液诱到的拟步甲、金龟、步甲个体数少于乙二醇,而糖醋液诱到的小蠹则多于乙二醇。天然林中,糖醋液诱到的地表甲虫个体数显著少于乙二醇,种类数无显著差异。结果表明：这2种溶液诱到的地表甲虫种类数接近,但乙二醇诱到的个体数多 使用单一溶液进行抽样往往会损失一定的多样性信息。     

No evidence for environmental filtering of cavity‐nesting solitary bees and wasps by urbanization using trap nests

Spatial patterns in biodiversity are used to establish conservation priorities and ecosystem management plans. The environmental filtering of communities along urbanization gradients has been used to explain biodiversity patterns but demonstrating filtering requires precise statistical tests to link suboptimal environments at one end of a gradient to lower population sizes via ecological traits. Here, we employ a three‐part framework on observational community data to test: (I) for trait clustering (i.e., phenotypic similarities among co‐occurring species) by comparing trait diversity to null expectations, (II) if trait clustering is correlated with an urbanization graient, and (III) if species'' traits relate to environmental conditions. If all criteria are met, then there is evidence that urbanization is filtering communities based on their traits. We use a community of 46 solitary cavity‐nesting bee and wasp species sampled across Toronto, a large metropolitan city, over 3 years to test these hypotheses. None of the criteria were met, so we did not have evidence for environmental filtering. We do show that certain ecological traits influence which species perform well in urban environments. For example, cellophane bees (Hylaeus: Colletidae) secrete their own nesting material and were overrepresented in urban areas, while native leafcutting bees (Megachile: Megachilidae) were most common in greener areas. For wasps, prey preference was important, with aphid‐collecting (Psenulus and Passaloecus: Crabronidae) and generalist spider‐collecting (Trypoxylon: Crabronidae) wasps overrepresented in urban areas and caterpillar‐ and beetle‐collecting wasps (Euodynerus and Symmorphus: Vespidae, respectively) overrepresented in greener areas. We emphasize that changes in the prevalence of different traits across urban gradients without corresponding changes in trait diversity with urbanization do not constitute environmental filtering. By applying this rigorous framework, future studies can test whether urbanization filters other nesting guilds (i.e., ground‐nesting bees and wasps) or larger communities consisting of entire taxonomic groups.