20 research outputs found
Factors limiting the host range of tephritid fruit flies : with particular emphasis on the influence of Dacus tryoni on the distribution and abundance of Dacus jarvisi
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BioTIME: A database of biodiversity time series for the Anthropocene.
MotivationThe BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.Main types of variables includedThe database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.Spatial location and grainBioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).Time period and grainBioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.Major taxa and level of measurementBioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.Software format.csv and .SQL
Role of chemical cues from cotton in mediating host selection and oviposition behaviour in Helicoverpa armigera (Hubner) (Lepidoptera : Noctuidae)
We investigated the role of chemoreception in the host selection and oviposition behaviour of Helicoverpa armigera in the laboratory using five cotton genotypes and synthetic volatile terpenes. Female moths oviposited on substrates treated with methanol, ethanol, acetone and pentane extracts of leaves, squares and flowers of the cotton genotypes. Phytochemicals soluble in pentane were the most efficient in eliciting oviposition behaviour. In a two-way bioassay, pentane extracts of leaves or squares of a Multiple Host-plant Resistance genotype (MHR11), Deltapine commercial (DP90), and Smith Red Leaf (SRL) received significantly more eggs than solvent-treated controls. Extracts of squares of the native genotype Gossypium nelsonii did not receive more eggs. Females preferred DP90 and MHR11 to SRL and G. nelsonii. Female moths also laid more eggs on pentane extracts of MHR11 flowers than MHR11 leaves from preflowering, early flowering and peak-flowering plants. In a flight chamber, female moths used olfactory cues at short range to mediate oviposition and discrimination between host plants. Egg-laying, mated females were attracted at a distance (1.5 m) to volatile compounds released by whole plants and odours emanating from filter papers treated with synthetic volatile terpenes. Individually, the terpenes did not stimulate any significant oviposition response. However, there was a significant oviposition response to a mixture of equal volumes of the terpenes (trans-beta-caryophyllene, alpha-pinene, beta-pinene, myrcene, beta-bisabolol, and alpha-humulene). Conversely, antennectomised (moths with transected antennae), egg-laying, mated females did not stimulate any significant oviposition response. The significance of these findings in relation to H. armigera hostplant selection are discussed
Size of the first spring generation of Helicoverpa punctigera (Wallengren) (Lepidoptera : Noctuidae) and winter rain in central Australia
Serious infestations of Helicoverpa punctigera are experienced yearly in the eastern cropping regions of Australia. Regression analysis was used to determine whether the size of the first generation in spring (G(1)), which is comprised mostly of immigrants from inland Australia, was related to monthly rainfall in inland winter breeding areas. Data from two long series of light-trap catches at Narrabri in New South Wales (NSW) and Turretfield in South Australia (SA) were used in the analyses. The size of G1 at Narrabri in each year was significantly regressed on the amount of rainfall in western Queensland and NSW in May and June. The size of G1 at Turretfield each year was significantly regressed on the amount of rain in May, June and July in western Queensland and NSW and also in the desert of central Western Australia. Low r(2) values of the regressions suggest that rainfall data for more sites, as well as biological and other physical factors, such as temperature, evaporation, and prevailing wind systems, may need to be included to improve forecasts of the potential magnitude of the infestations in coastal cropping regions
A simulation model of wind-driven dispersal of Helicoverpa moths
A simulation model is described that simulates the dispersal of Helicoverpa spp. moths over a heterogeneous landscape. The model divides the region under consideration into a scalable grid of square cells, each of which may contain one or more landuse units. Moth flight between cells and their component landuse units is largely governed by wind speed and direction. Flight is simulated for each cell in turn, once each day. For each cell, the flight paths of emigrating moths are distributed into sectors radiating from the cell centre and flanking the wind direction. The proportion of moths allocated into each sector is based on an assumed normal distribution, where the arc of each sector represents one standard deviation from the mean wind direction. The angle of the flight sectors on either side of the wind direction is inversely proportional to wind speed. If wind conditions are calm, the flight sectors encompass a full 360° arc and are allocated equivalent numbers of moths. The moths within each flight sector are moved out from the cell centre on a front which forms the arc of the sector. As the arc intersects with cells on the underlying grid, a proportion of moths land in each cell. The proportion of moths alighting is determined on the basis of the overall attractiveness of the habitats within each cell, and the proportion of the cell that is intersected by the flight sector. Alighting moths are distributed into the landuse units in target cells according to the relative attractiveness of each landuse, and its relative area within the cell. Wind velocities may vary between cells or time steps
Host plants and habitats of Helicoverpa punctigera and H. armigera (Lepidoptera: Noctuidae) in inland Australia
For Helicoverpa punctigera (Wallengren), and to a lesser extent Helicoverpa armigera (Hübner), native host plants in non-cropping regions of inland Australia are believed to be contributors to populations which migrate in spring to infest cropping regions of south-east Australia, and southwestern Australia. Non-crop hosts were sampled using sweep nets in 71 survey trips in 19 years between 1987 and 2017 for larvae of H. punctigera and H. armigera, over about 2.4 million km in inland Australia. Of 1976 samples, H. punctigera larvae were present in 50.5%, distributed throughout the study area. Larvae were found on 106 host plant species in 24 families, including 61 new host records. H. armigera larvae were found on 33 plant species from eight families, including 14 new host records. However, only 4.3% of samples were positive for this species, and they were mostly in the east of the study area and had fewer larvae than the positive H. punctigera samples. H. punctigera larvae were found in each of six habitats, being, in order of mean numbers per sample: sandy deserts > floodplains > mulga, grasslands and saltbush > stony downs. Host status was determined for both species by plotting relative incidence against relative abundance, and the good hosts for H. punctigera differed between habitats. We discuss the value and limitations of this approach for identifying key hosts in broad scale population dynamics, and primary hosts which may have close co-evolutionary histories with the insects
Host plants and habitats of Helicoverpa punctigera and H. armigera (Lepidoptera: Noctuidae) in inland Australia
For Helicoverpa punctigera(Wallengren), and to a lesser extent Helicoverpa armigera(Hübner), native hostplants in non-cropping regions of inland Australia are believed to be contributors to populations which migratein spring to infest cropping regions of south-east Australia, and southwestern Australia. Non-crop hosts were sam-pled using sweep nets in 71 survey trips in 19 years between 1987 and 2017 for larvae of H. punctigera and H. armigera, over about 2.4 million km2in inland Australia. Of 1976 samples, H. punctigeralarvae were presentin 50.5%, distributed throughout the study area. Larvae were found on 106 host plant species in 24 families, in-cluding 61 new host records. H. armigeralarvae were found on 33 plant species from eight families, including1 4 new host records. However, only 4.3% of samples were positive for this species, and they were mostly inthe east of the study area and had fewer larvae than the positive H. punctigera samples. H. punctigeralarvae were found in each of six habitats, being, in order of mean numbers per sample: sandy deserts> flood plains > mulga,grasslands and salt bush > stony downs. Host status was determined for both species by plotting relative incidence against relative abundance, and the good hosts for flood plains > mulga,grasslands and salt bush > stony downs. Host status was determined for both species by plotting relative incidence against relative abundance, and the good hosts for mulga,grasslands and salt bush > stony downs. Host status was determined for both species by plotting relative incidence against relative abundance, and the good hosts for stony downs. Host status was determined for both species by plotting relative incidence against relative abundance, and the good hosts for H. punctigera differed between habitats. We discuss the value and limitations of this approach for identifying key hosts in broad scale population dynamics, and primary hostswhich may have close co-evolutionary histories with the insects
A review on biological interactions and management of the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)
Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is one of the most damaging insect pests globally, causing estimated global economic losses of over 3 billion US dollars annually. Crops most affected include cotton, tomato, soybean, grain crops such as corn and sorghum, chickpea and other pulses. Adults of this species possess strong migratory abilities (>2000 km), high fecundity and rapid reproductive rates; completing 4–6 generations per year in most cropping regions. Furthermore, the larvae are polyphagous, with a wide and diverse host range and possess the ability to enter diapause in order to survive adverse climatic conditions. At present, it is distributed across most of Oceania, Asia, Africa and southern Europe and has recently spread to South America. Various control measures have been trialled or proposed for the treatment of this pest, including synthetic insecticides, phytopesticides, microbial pesticides, macro‐biocontrol agents (both parasitoids and predators) and the development of genetically modified crops (e.g. Bt cotton). Successful control necessitates the use of an integrated pest management (IPM) approach, wherein biological, chemical and physical control measures are combined for the greatest control efficacy