Age-specific survivorship analysis ofHeliothis spp. Populations on cotton

Population dynamics of Heliothis virescens (F.) and Heliothis zea (Boddie ) (Lepidoptera: Noctuidae) eggs and larvae were studied for two years in a small plot of cotton, Gossypium hirsutum (L.). Due to morphological and ecological similarities, the pooled Heliothis population was considered for most of the analyses. Two generations of Heliothis eggs and larvae were completed during each year. Stage recruitment was estimated for the eggs and larval instars 2–6, and recruitment variances were estimated by a Monte Carlo method. A modified form of the Weibull distribution was developed and used as a model to characterize survivorship curves for each of the four Heliothis generations. A Type I survivorship curve (mortality rate increasing with age) was inferred for both Generation 1 (early season) data sets, whereas a Type II survivorship curve (mortality rate constant and thus independent of age) was inferred for both Generation 2 (late season) data sets. The shapes of the survivorship curves for the individual H. virescens and H. zea populations were inferred to be the same as those for the pooled populations. Analysis of the contributions of various factors to Heliothis stage-specific mortality indicated that natural enemies (predators and parasites) and the availability of food for larvae were responsible for between-generation differences in survivorship patterns.     

Contemporary evolution of a Lepidopteran species,Heliothis virescens,in response to modern agricultural practices

Adaptation to human‐induced environmental change has the potential to profoundly influence the genomic architecture of affected species. This is particularly true in agricultural ecosystems, where anthropogenic selection pressure is strong. Heliothis virescens primarily feeds on cotton in its larval stages, and US populations have been declining since the widespread planting of transgenic cotton, which endogenously expresses proteins derived from Bacillus thuringiensis (Bt). No physiological adaptation to Bt toxin has been found in the field, so adaptation in this altered environment could involve (i) shifts in host plant selection mechanisms to avoid cotton, (ii) changes in detoxification mechanisms required for cotton‐feeding vs. feeding on other hosts or (iii) loss of resistance to previously used management practices including insecticides. Here, we begin to address whether such changes occurred in H. virescens populations between 1997 and 2012, as Bt‐cotton cultivation spread through the agricultural landscape. For our study, we produced an H. virescens genome assembly and used this in concert with a ddRAD‐seq‐enabled genome scan to identify loci with significant allele frequency changes over the 15‐year period. Genetic changes at a previously described H. virescens insecticide target of selection were detectable in our genome scan and increased our confidence in this methodology. Additional loci were also detected as being under selection, and we quantified the selection strength required to elicit observed allele frequency changes at each locus. Potential contributions of genes near loci under selection to adaptive phenotypes in the H. virescens cotton system are discussed.     

Handling time, prey preference, and functional response for Chrysoperla rufilabris in the laboratory

The predaceous larvae of Chrysoperla rufilabris (Burmeister) exhibited some success-motivated searching, particularly when feeding on Heliothis virescens (F.) eggs, but handling time did not decrease with experience. Handling time for H. virescens larvae was more than twice that for eggs. H. virescens larvae were preferred to cotton aphids (Aphis gossypii (F.)) while aphids were preferred to H. virescens eggs. C. rufilabris larvae exhibited a linear functional response to the three prey types tested, over the prey densities tested.USDA, ARS, Retire. Present address: 200 Highland, College Station, TX 77840, USA     

Identification, Mapping, and In Vitro Translation of Campoletis sonorensis Virus mRNAs from Parasitized Heliothis virescens Larvae

Expression of Campoletis sonorensis virus (CsV) in parasitized Heliothis virescens larvae was investigated by Northern blot analysis of poly(A)⁺ mRNAs isolated from H. virescens larvae at various times after parasitization by C. sonorensis. At least 12 CsV mRNAs were detected in parasitized H. virescens larvae. Injection of nonparasitized H. virescens larvae with purified CsV resulted in a pattern of viral mRNAs similar to that observed in naturally parasitized larvae. With CsV DNA restriction fragments which contained expressed sequences, individual CsV mRNAs were mapped to the superhelical DNAs of the viral genome. Two gene-specific probes, which consisted of cloned S1 nuclease-protected restriction fragments, each hybridized to several CsV superhelical DNAs, suggesting that some CsV genes may be shared on several superhelical DNAs. Cloned restriction fragments containing sequences which flank the expressed sequences also hybridized to numerous CsV superhelical DNAs. Some CsV proteins were identified by in vitro translation of hybrid-selected CsV mRNAs.     

Competition between laboratory populations of green leafhoppers,Nephotettix spp. (Homoptera: Cicadellidae)

Intra- and interspecific competition between laboratory populations of four green leafhoppers, Nephotettix spp. was studied in the laboratory under three different temperature regimes of 24°C, 27°C and 30°C. For the single-species population of the three tropical species, the equilibrium density increased as the temperature increased. On the other hand, for the temperature species N. cincticeps, the highest equilibrium density was at the intermediate temperature and the lowest at high temperature. Interspecific interactions between two tropical (N. virescens vs. N. nigropictus), a tropical and a temperature (N. virescens vs. N. cincticeps) and a rice-feeding and a grass-inhabiting (N. virescens vs. N. malayanus) Nephotettix species were also studied in the laboratory at the three temperature regimes. Temperature differentially affected the outcome of competition between two Nephotettix species. Between N. virescens and N. nigropictus, the latter was more successful over the former at low and intermediate temperatures, while the former was more successful at high temperature. Between N. virescens and N. cincticeps, the temperate species inhibited the growth of the tropical species at low temperature while the tropical species inhibited the growth of the temperate species at high temperature. At intermediate temperature, the population of N. virescens persisted at a slightly higher density over the population of N. cincticeps. Between the rice-feeding N. virescens and the grass-inhabiting N. malayanus, regardless of temperature the population density of the latter was greatly reduced and later became extinct while the population of the former continued its growth. These consequences of competition between two Nephotettix species conformed fairly well to those predicted by theLotka-Volterra model using demographic parameters specified for each species.     

Piscivore Responses to Enhancement of the Channelized Kissimmee River,Florida, U.S.A.

Evaluation of the success of ecosystem restoration projects requires identification of appropriate ecological metrics. Comparison of reconstructed food webs (or subsets thereof) from restored and non‐restored habitats may be a valuable tool to evaluate restoration success because food webs help identify critical predator–prey relationships, keystone species, relative importance of direct and indirect trophic interactions, and other aspects of ecological function. We compared the diets of apex predatory fishes collected from enhanced and non‐enhanced portions of the channelized Kissimmee River, Florida, USA to determine whether food web structure responded to experimental hydrologic manipulations. Diets were reconstructed for black crappie (Pomoxis nigromaculatus), bowfin (Amia calva), chain pickerel (Esox niger), Florida gar (Lepisosteus platyrhincus), largemouth bass (Micropterus salmoides), and warmouth (Lepomis gulosus) collected from enhanced and non‐enhanced portions of the Kissimmee River. Prey eaten by apex predatory fishes in the enhanced portion of the Kissimmee River were quantitatively and qualitatively different from prey eaten in non‐enhanced portions of the river. Predators in the enhanced portion of the river had fewer empty stomachs, more prey items per individual, more prey types per individual, more fish prey per individual, greater overall richness of prey, and a multivariate suite of prey distinct from predators in non‐enhanced portions of the river. Results from hydrologic manipulations suggest that large‐scale restoration of hydrologic linkages between the main channel and floodplain habitats will positively affect food web structure and ecosystem function in the Kissimmee River.     

Impact of white-spotting alleles,including W20, on phenotype in the American Paint Horse

The American Paint Horse Association (APHA) records pedigree and performance information for their breed, a stock-type horse valued as a working farm or ranch horse and as a pleasure horse. As the name implies, the breed is also valued for its attractive white-spotting patterns on the coat. The APHA utilizes visual inspections of photographs to determine if coat spotting exceeds threshold anatomical landmarks considered characteristic of desirable patterns. Horses with sufficient white patterning enter the ‘Regular’ registry, rather than the ‘Solid Paint-Bred’ division, providing a threshold modeled phenotype. Genetic studies previously defined sequence variants corresponding to 35 alleles for white spotting in the horse. Here, we calculate the allele frequencies for nine common white-spotting alleles in the American Paint Horse using a sample of 1054 registered animals. The APHA spotting phenotype is altered by additive interactions among spotting loci, and epistatically by the MC1R and ASIP genes controlling pigment production. The W20 allele within the KIT gene, independent of other known spotting alleles, was strongly associated with the APHA-defined white-spotting phenotype (P = 1.86 × 10⁻¹⁸), refuting reports that W20 acts only as a modifier of other underlying white-spotting patterns. The parentage of an individual horse, either American Paint or American Quarter Horse, did not alter the likelihood of its entering the APHA Regular Registry. An empirical definition of the action of these genetic loci on the APHA-defined white-spotting phenotype will allow more accurate application of genome-assisted selection for improving color production and the marketability of APHA horses.     

Seasonal development of five Cephaleuros species (Trentepohliaceae,Chlorophyta) on the leaves of woody plants and the behaviors of their gametes and zoospores

The infection cycle of five Cephaleuros species – C. aucubae, C. biolophus, C. japonicus, C. microcellularis, and C. virescens – was clarified by investigating seasonal development and gamete and zoospore behavior at study sites in Matsue, Shimane Prefecture, Japan. Fresh thalli or lesions appeared on the leaves of various woody plants from August and continued to develop in general from April to September in the following year. Gametangia and zoosporangia matured on 2‐ and 3‐year‐old leaves. Gametes were released in C. microcellularis samples collected from late March to late May and in samples of the other four species collected from late April to late July. Zoospores were released in C. biolophus, C. japonicus, and C. virescens samples collected from mid‐May to early August. In the present study, gametes did not conjugate but germinated like zoospores to produce new plants. After inoculation with zoospores and gametes that behave as asexual spores, fresh thalli or lesions became evident in 2–5 months following inoculation and gametes and zoospores were produced on the developed thalli or lesions the following year; one cycle of the infection was completed per year in the study area.     

Morphological features and chromosome numbers in cultures of five Cephaleuros species (Trentepohliaceae,Chlorophyta) from Japan

The morphological features and chromosome numbers were examined in cultures of five species of Cephaleuros; C. aucubae, C. biolophus, C. japonicus, C. microcellularis, and C. virescens, collected from Japan. On agar media of Bold's basal medium and CA medium, radial growth of the algal colonies was vigorous in C. virescens, moderate in C. aucubae, and poor in C. microcellularis, but varied from poor to moderate in isolates of C. biolophus and C. japonicus. Filaments of C. virescens branched at an angle less than 40° and just below the cross walls, while those of the other species branched at an angle greater than 40° without relation to the cross walls. The length of filamentous cells was significantly smaller in C. microcellularis than in the other species. The chromosome number differed with the species: n = 22 in C. aucubae, n = 34 in C. biolophus, n = 18 in C. japonicus, n = 12 in C. microcellularis, and n = 24 in C. virescens. The chromosome number did not vary between isolates from filaments and gametes in C. aucubae and C. biolophus and among those from filaments, gametes, and zoospores in C. japonicus and C. virescens.     

Genetic population structure of Japanese river sculpin Cottus pollux (Cottidae) large-egg type,inferred from mitochondrial DNA sequences

The geographic distribution of mitochondrial DNA haplotypes from Japanese river sculpin Cottus pollux large-egg type (LE), collected from 55 locations in 22 rivers over most of the species’ range in Japan, was examined to assess for patterns of population genetic structure. The 87 haplotypes observed from C. pollux LE were distinguishable from C. pollux middle-egg type and small-egg type haplotypes from previously published research. Cottus pollux LE from each river were largely represented by diagnostic mtDNA haplotypes, with limited geographical associations of haplotypes, suggesting that each river must be treated as a separate management unit.     

Physiology and glomerular projections of olfactory receptor neurons on the antenna of female Heliothis virescens (Lepidoptera: Noctuidae) responsive to behaviorally relevant odors

The neurophysiology and antennal lobe projections of olfactory receptor neurons housed within short trichoid sensilla of female Heliothis virescens F. (Noctuidae: Lepidoptera) were investigated using a combination of cut-sensillum recording and cobalt-lysine staining techniques. Behaviorally relevant odorants, including intra- and inter-sexual pheromonal compounds, plant and floral volatiles were selected for testing sensillar responses. A total of 184 sensilla were categorized into 25 possible sensillar types based on odor responses and sensitivity. Sensilla exhibited both narrow (responding to few odors) and broad (responding to many odors) response spectra. Sixty-six percent of the sensilla identified were stimulated by conspecific odors; in particular, major components of the male H. virescens hairpencil pheromone (hexadecanyl acetate and octadecanyl acetate) and a minor component of the female sex pheromone, (Z)-9-tetradecenal. Following characterization of the responses, olfactory receptor neurons within individual sensilla were stained with cobalt lysine (N=39) and traced to individual glomeruli in the antennal lobe. Olfactory receptor neurons with specific responses to (Z)-9-tetradecenal, a female H. virescens sex pheromone component, projected to the female-specific central large female glomerulus (cLFG) and other glomeruli. Terminal arborizations from sensillar types containing olfactory receptor neurons sensitive to male hairpencil components and plant volatiles were also localized to distinct glomerular locations. This information provides insight into the representation of behaviorally relevant odorants in the female moth olfactory system. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Isolation, identification and synthesis of host-seeking stimulants for Cardiochiles nigriceps, a parasitoid of tobacco budworm

Several methyl-branched saturated C₃₂, C₃₃, and C₃₄ hydrocarbons have been identified from larvae and mandibular glands of Heliothis virescens (F.) (Lepidoptera, Noctuidae) that trigger a short-range host-seeking response of its parasitoid, Cardiochiles nigriceps, Viereck (Hymenoptera: Branconidae). Although the individual components elicited a response, a mixture of the most active C₃₂, C₃₃, and C₃₄ hydrocarbons was significantly more active than the individual components; some mixtures were as active as the contents of the mandibular gland of the host.

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Zusammenfassung Isomere Monomethylalkane in den Larven und in der Mandibeldrüse von Heliothis virescens, die bei ihrem Parasitoid, Cardiochiles nigriceps, nach Kontakt eine wirtsuchende Wirkung besitzen, wurden identifiziert. Mischungen mehrerer, als aktiv erkannter Substanzen (z.B. 12-Methyl C₃₁+12-Methyl C₃₂+13-Methyl C₃₃, optimal zusammen 500 ng) wirkten stärker als die einzelnen Komponenten und konnten die Wirkung des Mandibulardrüseninhalts erreichen.

     

Susceptibility of Helicoverpa zea and Heliothis virescens (Lepidoptera: Noctuidae) to Vip3A insecticidal protein expressed in VipCot™ cotton

Susceptibility of laboratory and field colonies of Helicoverpa zea (Boddie) and Heliothis virescens F. to Vip3A insecticidal protein was studied in diet incorporation and diet overlay assays from 2004 to 2008. Responses of field populations were compared to paired responses of University of Arkansas laboratory susceptible H. zea (LabZA) and H. virescens (LabVR) colonies. After 7 d of exposure, observations were made on number of dead larvae (M) and the number of larvae alive but remaining as first instars (L1). Regression estimates using M (LC₅₀) and M plus L1 (MIC₅₀) data were developed for laboratory and field populations. Susceptibility of laboratory and field populations exposed to Vip3A varied among different batches of protein used over the study period. Within the same batch of Vip3A protein, susceptibilities of laboratory colonies of both species (LabZA and LabVR) were similar. Field colonies were significantly more susceptible to Vip3A than the respective reference colonies of both species. Within field populations, susceptibility to Vip3A varied up to 75-fold in H. zea and 132-fold in H. virescens in LC₅₀ estimates. Variabilities in MIC₅₀s were up to 59- and 11-fold for H. zea and H. virescens, respectively.     

Alkanes of four related moth species,Helicoverpa and Heliothis

Comparison of the presence and quantities of cuticular hydrocarbons has been used successfully for identifying sibling species and races of several groups of insects. This approach has been extended to four species of moths previously regarded as belonging to the same genus, Heliothis. Gas chromatography was used to quantify the numerous high-molecular weight alkanes found on the cuticle of two pairs of closely related species: Helicoverpa zea and Helicoverpa armigera, and Heliothis virescens and Heliothis subflexa. Both sexes of H. zea and H. armigera contained different quantities of several alkanes that could be used for unambiguous identification. Similar comparisons of H. subflexa and H. virescens showed four peak ratios that were different for each species. Sexual dimorphism was minor in H. subflexa and H. virescens.     

Detection of the threatened snail darter Percina tanasi in the Tennessee River system using environmental DNA

The distribution of many fishes that occupy large rivers is poorly known, in part due to the difficulties of sampling for them. This is especially true for small-bodied or rare species, such as the snail darter Percina tanasi, 44, 469–488; 1976). This federally listed (threatened) species has a limited distribution in the Tennessee River system in Alabama and Tennessee, where it is known from a few large tributaries or small rivers. In Alabama, P. tanasi was previously known from only one locality, but has recently been found in two additional, widely separated systems. These new records raise questions regarding the accuracy of our current understanding of the range for this species. Particularly, is P. tanasi present throughout the main stem Tennessee River, and is this species dispersing into new areas from source populations in the river? To clarify the distribution of P. tanasi in Alabama, 83 unique sites were surveyed using environmental DNA analysis. This cost-effective detection tool reduces the difficulty associated with empirically sampling large rivers for small fishes. Approximately 42% of sites sampled were positive for P. tanasi DNA. This study confirmed the known localities of P. tanasi in the Bear Creek, Elk River and Paint Rock River. Several new localities were also discovered throughout the main stem Tennessee River and in Shoal Creek, near Florence, Alabama. These findings can inform biologists about where to prioritize conservation efforts and further could lead to studies assessing movement and relatedness between populations in this system.     

Comparison of dispersal ability between the green leafhoppers,Nephotettix virescens andN. cincticeps (hemiptera: Cicadellidae) by tethered flight

Dispersal propensity of green leafhoppers was compared between a tropical species, Nephotettix virescens, and a temperate species, N. cincticeps. The flight ability was measured with tethered flight technique under laboratory conditions (25°C, 16L-8D). The pre-flight period was shorter and the flight duration was longer in N. virescens than in N. cincticeps in both sexes. No significant correlations were found between the flight activity and morphometric characters for either of the two species. The results suggested that dispersal propensity of N. virescens is higher than that of N. cincticeps.     

Degradation of diclofenac,trimethoprim, carbamazepine,and sulfamethoxazole by laccase from Trametes versicolor: Transformation products and toxicity of treated effluent

Abstract

The degradation of diclofenac (DCF), trimethoprim (TMP), carbamazepine (CBZ), and sulfamethoxazole (SMX) by laccase from Trametes versicolor was investigated. Experiments were conducted using the pharmaceuticals individually, or as a mixture at different initial concentrations (1.25 and 5?mg/L each). The initial enzymatic activity of all the treated samples was around 430–460?U_(DMP)/L. The removal of the four selected pharmaceuticals tested individually was more effective than when tested in mixtures under the same conditions. For example, 5?mg DCF/L was completely removed to below its detection limit (1?µg/L) within 8?h in the individual experiment vs. after 24?h when dosed as a mixture with the other pharmaceuticals. A similar trend was visible with other three pharmaceuticals, with 95 vs. 39%, 82 vs. 34% and 56 vs. 49% removal after 48?h with 5?mg/L of TMP, CBZ, and SMX tested individually or as mixtures, respectively. In addition, at the lower initial concentration (1.25?mg/L each), the removal efficiency of TMP, CBZ, and SMX in mixtures was lower than that obtained at the higher initial concentrations (5?mg/L each) during both the individual and combined treatments. Four enzymatic transformation products (TPs) were identified during the individual treatments of DCF and CBZ by T. versicolor. For TMP and SMX, no major TPs were observed under the experimental conditions used. The toxicity of the solution before and after enzymatic treatment of each pharmaceutical was also assessed and all treated effluent samples were verified to be non-toxic.     

Protocol for assessing soybean antixenosis to Heliothis virescens

Larvae of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) often infest soybean crops, Glycine max (L.) (Fabaceae), causing significant yield losses in important soybean-producing regions. The use of soybean varieties resistant to lepidopteran larvae is a major approach in soybean integrated pest management. However, standardization and optimization of bioassays that are used to screen genotypes for insect resistance are essential for high-throughput phenotyping. Methodologies for screening were assessed to determine the most effective method for discriminating levels of antixenosis to H. virescens in soybean plants. Feeding and oviposition preference assays were performed to determine optimal densities of larvae and adults, and optimal plant structures and growth stages for conducting assays. In addition, trichome densities, and fiber and lignin contents were quantified in plant structures of soybean cultivars differing in resistance. Resistance levels of cultivars were best differentiated using nine neonate larvae and two 6-day-old larvae, and by using young leaves of plants at the vegetative stage. This was likely due to the more pronounced differences in lignin and fiber contents in young leaves of vegetative-stage plants. Density of adult pairs, plant structure, and growth stage did not affect ability to distinguish differences in oviposition preference by H. virescens. Higher numbers of eggs were found on the leaves, which were the plant structures that exhibited the lowest trichome densities. The protocol developed in this work will benefit future evaluations of soybean genotypes for antixenosis against H. virescens.     

Rearing of two predators,Thanasimus dubius andTemnochila virescens, for the biological control ofIps grandicollis in Australia

Rearing methods for two coleopterous predators,Thanasimus dubius andTemnochila virescens, imported into Australia for the biological control ofIps grandicollis, were developed. Bionomic data obtained from laboratory rearings between 1982–1987 showed thatT. dubius eggs took about 7 days to hatch and that duration of the larval stage was about 42 days. Observations showed thatT. dubius had a prolonged prepupal stage (x=56.4 days, range 14–274 days), which was probably non-diapausal in nature. Mean adult longevity was 50 days (range 1–358 days).Temnochila virescens eggs took almost 9 days to hatch, and a lengthy larval stage (x=155.4 days, range 73–333 days) was observed. Mean duration of the pupal stage was 14 days (range 7–28 days). A long preoviposition period (x=141 days, range 47–206 days) was observed, and adults were very long-lived (x=232.7 days, range 14–667 days). Capacity for increase (r_c) calculated from rearing data suggested that numbers ofT. dubius could be increased faster thanT. virescens. Mortality between 1982–1987 averaged about 70% for both species. However, mortality ofT. dubius in 1987 increased significantly, suggesting that inbreeding or other methodological factors could be responsible. A mass-rearing method usingIps-infested pine billets was developed as a cheaper alternative to laboratory rearing, and was shown to be effective in producing large numbers of insects for release.