Lack of avoidance of the fungal entomopathogen, Metarhizium brunneum, by male Agriotes obscurus beetles.

Fungal entomopathogens can greatly reduce the fitness of their hosts, and it is therefore expected that susceptible insects will be selected to avoid exposure to pathogens. Metarhizium brunneum is a fungal pathogen that can infect Agriotes obscurus, which in its larval form is a destructive agricultural pest and is repelled by the presence of M. brunneum conidia.

The effect of synthetic female sex pheromone on the transmission of the fungus Metarhizium brunneum by male Agriotes obscurus click beetles.

Autodissemination techniques can potentially be used to distribute insecticides, including microbial insecticides, to cryptic pests. This approach is reliant on the target insect either passing the pathogen passively to other insects or the pathogen cycling within the population after the initial host dies. Here we examine, in small scale experiments, whether male Agriotes obscurus click beetles passively transmit the spores of the fungus Metarhizium brunneum directly, or indirectly via the environment, and whether this is influenced by exposure to synthetic female pheromone.

Effect of Collection Month, Visible Light, and Air Movement on the Attraction of Male L. (Coleoptera: Elateridae) Click Beetles to Female Sex Pheromone.

Elaterid female sex pheromone, while currently used for monitoring the adult life stage (click beetle), has only recently been explored as a potential management tool. Consequently, there is little understanding of how abiotic and biotic conditions influence the response of click beetles to the pheromone. We examined whether the response of male L.

Modification of reproductive schedule in response to pathogen exposure in a wild insect: Support for the terminal investment hypothesis.

Trade-offs in the time and energy allocated to different functions, such as reproductive activities, can be driven by alterations in condition which reduce resources, often in response to extrinsic factors such as pathogens or parasites. When individuals are challenged by a pathogen, they may either reduce reproduction as a cost of increasing defence mechanisms or, alternatively, modify reproductive activities so as to increase fecundity thereby minimizing the fitness costs of earlier death, a behaviour consistent with the terminal investment hypothesis (TIH). The TIH predicts that individuals with decreased likelihood of future reproduction will maximize current reproductive effort, which may include shifts in reproductive timing.

Resistance of Trichoplusia ni populations selected by Bacillus thuringiensis sprays to cotton plants expressing pyramided Bacillus thuringiensis toxins Cry1Ac and Cry2Ab.

Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca.

Effect of low levels of Bacillus thuringiensis exposure on the growth, food consumption and digestion efficiencies of Trichoplusia ni resistant and susceptible to Bt.

It is becoming increasingly clear that the impact of low doses of an environmental stressor, such as Bacillus thuringiensis, can often not be predicted from high dose experiments, and the impact of these effects on the evolution of resistance has received little attention. In the present study, we examined the effect of low levels of B. thuringiensis exposure on the growth, food consumption and digestion efficiencies of Trichoplusia ni resistant and susceptible to Bt.

Response of a red clone of Myzus persicae (Hemiptera: Aphididae) to sublethal concentrations of imidacloprid in the laboratory and greenhouse.

Background: Pest resurgence following a pesticide application may occur owing to a stimulatory (hormetic) response to sublethal insecticide concentrations. The objective of the present study was to examine the potential for a greenhouse-derived red clone of Myzus persicae to exhibit resurgence owing to a hormetic response following a systemic imidacloprid treatment in a bell pepper greenhouse.

Results: No differences in mortality and fecundity were observed among apterous adults exposed to sublethal imidacloprid concentrations on excised pepper leaves fed aqueous solutions of imidacloprid.

Genetic variation in fitness parameters associated with resistance to Bacillus thuringiensis in male and female Trichoplusia ni.

Resistance of insects to insecticides is often associated with reduced fitness in the absence of selection. We examined fitness trade-offs associated with resistance to the microbial insecticide, Bacillus thuringiensis (Bt), across full-sib families in a resistant population of Trichoplusia ni. Significant genetic variation in and heritability of susceptibility to Bt occurred among the full-sib families.

Modified Bacillus thuringiensis toxins and a hybrid B. thuringiensis strain counter greenhouse-selected resistance in Trichoplusia ni.

Resistance of greenhouse-selected strains of the cabbage looper, Trichoplusia ni, to Bacillus thuringiensis subsp. kurstaki was countered by a hybrid strain of B. thuringiensis and genetically modified toxins Cry1AbMod and Cry1AcMod, which lack helix alpha-1.

Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

We studied the immune response to Bacillus thuringiensis kurstaki (Btk) in susceptible (Bt-RS) and resistant (Bt-R) Trichoplusia ni after exposure to low doses of Btk and injection with Escherichia coli. We measured the levels of resistance, the expression profiles of hemolymph proteins, the phenoloxidase (PO) activity, and the differential number of circulating hemocytes in resistant and susceptible individuals. Individuals from the Bt-RS line became more resistant following a previous exposure to sub lethal concentrations of Btk, but the resistance to Btk of the Bt-R line did not change significantly.

Host-plant effects the expression of resistance to Bacillus thuringiensis kurstaki in Trichoplusia ni (Hubner): an important factor in resistance evolution.

Pathogens are thought to exert strong selection on their hosts leading to increased host resistance. Bacillus thuringiensis kurstaki (Bkt) is a ubiquitous entomopathogen that has become the mainstay of nonchemical control of Lepidopteran pests and thus, the potential exists for the evolution of resistance in targeted host insects. We have studied the expression of Btk resistance in the cabbage looper, Trichoplusia ni (Hubner).

Mechanism of resistance to Bacillus thuringiensis toxin Cry1Ac in a greenhouse population of the cabbage looper, Trichoplusia ni.

The cabbage looper, Trichoplusia ni, is one of only two insect species that have evolved resistance to Bacillus thuringiensis in agricultural situations. The trait of resistance to B. thuringiensis toxin Cry1Ac from a greenhouse-evolved resistant population of T.

Clinical variation in melioidosis in pigs with clonal infection following possible environmental contamination from bore water.

An outbreak of melioidosis occurred in pigs on a rural property in the tropical north of the Northern Territory of Australia. The pigs were mostly asymptomatic but lesions in the parotid glands suggested an oral route of infection. Skin lesions were also common and one piglet had disseminated infection.

The cost of resistance to Bacillus thuringiensis varies with the host plant of Trichoplusia ni.

Selection for resistance to insecticides, diseases and parasitoids is assumed to be costly and often requires tradeoffs with reproductive fitness. The costs of resistance, however, are often difficult to measure. Cabbage looper, Trichoplusia ni, a generalist Lepidopteran herbivore, has become highly resistant following the extensive use of the microbial insecticide, Bacillus thuringiensis kurstaki (Bt) in vegetable greenhouses.

Inheritance of resistance to Bacillus thuringiensis Cry1Ac toxin in a greenhouse-derived strain of cabbage looper (Lepidoptera: Noctuidae).

A population of cabbage looper, Trichoplusia ni (Hübner), collected from commercial greenhouses in the lower mainland of British Columbia, Canada, in 2001 showed a resistance level of 24-fold to Dipel, a product of Bacillus thuringiensis (Bt) subspecies kurstaki. This population was selected with Cry1Ac, the major Bt Cry toxin in Dipel, to obtain a homogenous population resistant to Cry1Ac. The resulting strain of T.

Inheritance of resistance to Bacillus thuringiensis subsp. kurstaki in Trichoplusia ni.

The genetic inheritance of resistance to a commercial formulation of Bacillus thuringiensis subsp. kurstaki was examined in a Trichoplusia ni colony initiated from a resistant population present in a commercial vegetable greenhouse in British Columbia, Canada. Progeny of F(1) reciprocal crosses and backcrosses between F(1) larvae and resistant (P(R)) and susceptible (P(S)) populations were assayed at different B.

Percutaneous absorption of m-xylene vapour in volunteers during pre-steady and steady state.

Percutaneous absorption of m-xylene (XYL) was determined in volunteers exposed to 29.4 microg cm(-3) XYL vapour on the forearm and hand for 20, 45, 120 and 180 min. The internal exposure was assessed by measuring the concentration of XYL in exhaled air.

Rapid evolution and the cost of resistance to Bacillus thuringiensis in greenhouse populations of cabbage loopers, Trichoplusia ni.

The microbial insecticide Bacillus thuringiensis (Bt) has become the mainstay of non-chemical control of Lepidopteran pests, either as sprays or through the incorporation of Bt toxins into transgenic crops. Given the wide use of Bt, it is striking that currently only one pest species, Plutella xylostella, has been reported to have developed significant resistance to Bt outside the laboratory. By contrast, we report here the frequent and rapid development of resistance to B.

An estimate of specificity for a Johne's disease absorbed ELISA in northern Australian cattle.

Objective: To estimate the specificity of an absorbed enzyme-linked immunosorbent assay kit for Johne's disease (JD) when used in mature cattle populations resident in northern Australia.

Design: Blood samples were collected from beef cattle in northern Queensland, the Northern Territory and northern Western Australia, and from dairy cattle in northern Queensland. The specificity of a serological test for JD was estimated by testing the blood samples with an absorbed ELISA kit.

Enhanced fumigant toxicity of p-cymene against Frankliniella occidentalis by simultaneous application of elevated levels of carbon dioxide.

The fumigant toxicity of the essential oil component p-cymene was assessed against Western Flower Thrips, Frankliniella occidentalis. F occidentalis adult females, first- and second-instar larvae and eggs were exposed for 2, 24 and 48 h to combinations of three p-cymene doses and two carbon dioxide levels (ambient, 10%). Additional experiments were conducted on F occidentalis adult females with lower carbon dioxide levels (ambient, 2%, 4%, 6%) applied in combination with p-cymene.

Animal melioidosis in Australia.

Melioidosis was first diagnosed in Australia in sheep in 1949. While it has been considered endemic in tropical Australia, there have been animal outbreaks in southwest Western Australia and southern Queensland. Infection occurs in many species, with both latency and a wide range of clinical manifestations.

Reference ranges for biochemical and haematological values in farmed saltwater crocodile (Crocodylus porosus) yearlings.

Objective: To determine reference ranges for healthy yearling farmed saltwater crocodiles by performing routine biochemical and haematological laboratory tests on blood samples.

Design: A clinico-pathological study.

Procedure: Blood samples were collected from 120 healthy yearlings from four Northern Territory crocodile farms and body weight and length were measured.

Subdivision of Burkholderia pseudomallei ribotypes into multiple types by random amplified polymorphic DNA analysis provides new insights into epidemiology.

Ribotyping has previously been used for epidemiological studies of Burkholderia pseudomallei (previously Pseudomonas pseudomallei). We show here that random amplified polymorphic DNA (RAPD) analysis allows subdivision of strains of the same ribotype. With five different primers, no two epidemiologically unrelated isolates of any single ribotype in this study of 102 isolates from humans, goats, cats, and soil had identical RAPD patterns.