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Hereward J.P.,University of Queensland | Hereward J.P.,Australian Cotton Research Institute | Walter G.H.,University of Queensland | Debarro P.J.,CSIRO | And 3 more authors.
Ecology and Evolution | Year: 2013

Creontiades dilutus (Stål), the green mirid, is a polyphagous herbivorous insect endemic to Australia. Although common in the arid interior of Australia and found on several native host plants that are spatially and temporally ephemeral, green mirids also reach pest levels on several crops in eastern Australia. These host-associated dynamics, distributed across a large geographic area, raise questions as to whether (1) seasonal fluctuations in population size result in genetic bottlenecks and drift, (2) arid and agricultural populations are genetically isolated, and (3) the use of different host plants results in genetic differentiation. We sequenced a mitochondrial COI fragment from individuals collected over 24 years and screened microsatellite variation from 32 populations across two seasons. The predominance of a single COI haplotype and negative Tajima D in samples from 2006/2007 fit with a population expansion model. In the older collections (1983 and 1993), a different haplotype is most prevalent, consistent with successive population contractions and expansions. Microsatellite data indicates recent migration between inland sites and coastal crops and admixture in several populations. Altogether, the data suggest that long-distance dispersal occurs between arid and agricultural regions, and this, together with fluctuations in population size, leads to temporally dynamic patterns of genetic differentiation. Host-associated differentiation is evident between mirids sampled from plants in the genus Cullen (Fabaceae), the primary host, and alternative host plant species growing nearby in arid regions. Our results highlight the importance of jointly assessing natural and agricultural environments in understanding the ecology of pest insects.© 2013 The Authors. Ecology and Evolution.


Ghosh S.,University of New England of Australia | Lockwood P.,University of New England of Australia | Hulugalle N.,Australian Cotton Research Institute | Daniel H.,University of New England of Australia | And 2 more authors.
Soil Science Society of America Journal | Year: 2010

In Australia, the surface and subsurface soils of the majority of cotton (Gossypium hirsutum L)-growing regions are sodic. Application of organic amendments can be an option to stabilize the structure of sodic Vertisols due to their potential positive effect on soil physical properties. An incubation experiment was conducted for 4 wk in a temperature-controlled (30°C) growth chamber to study the effect of organic amendments on the properties of two Vertisols with different sodicity levels. The exchangeable Na percentages (ESPs) in these Vertisol soils collected from the Australian Cotton Research Institute (ACRI) near Narrabri, New South Wales, and a commercial cotton farm near Dalby, Queensland, were modified such that three different sodicity levels resulted, i.e., nonsodic (ESP < 6), moderately sodic (ESP 6-15), and strongly sodic (ESP > 15). The organic amendments used were cotton gin trash (60 Mg ha -1), cattle manure (60 Mg ha -1), and composted chicken manure (18 Mg ha -1), as well as an unamended control. The organic amendments improved the physical properties of both Vertisols by decreasing clay dispersion. In the Dalby soil, cotton gin trash produced the largest decrease (29%) in the dispersion index over the control at the moderate sodicity level, whereas in the strongly sodic soil, the lowest dispersion index resulted from the application of chicken manure. Nutrient availability (N, P, and K) was also increased significantly at higher sodicity levels for both the ACRI and Dalby soils by using organic amendments. These results indicate that using organic amendments can be beneficial for the amelioration of sodic Vertisols and also to sustain soil quality. © Soil Science Society of America.


Bahar M.H.,University of New England of Australia | Backhouse D.,University of New England of Australia | Gregg P.C.,University of New England of Australia | Mensah R.,Cotton Catchment Communities | Mensah R.,Australian Cotton Research Institute
Biocontrol Science and Technology | Year: 2011

A strain of the fungus Cladosporium sp. (RM16) from an egg of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was assessed as a potential biocontrol agent for this pest. Pathogenicity of the fungus was tested against H. armigera eggs and larvae, cotton aphids (Aphis gossypii Glover; Homoptera: Aphididae), and silverleaf whitefly type B (Bemisia tabaci Gennadius; Hemiptera: Aleyrodidae). The pathogenicity of the fungus to the predatory red and blue beetles (Dicranolaius bellulus Guérin-Méneville; Coleoptera: Melyridae), transverse ladybird beetles (Coccinella transversalis Fabricius; Coleoptera: Coccinellidae), green lacewings (Mallada signatus Schneider; Neuroptera: Chrysopidae) and damsel bugs (Nabis kinbergii Reuter; Hemiptera: Nabidae), was also assessed in the laboratory. Fungus treatment resulted in failure to hatch of up to 64% of H. armigera eggs (compared with 11% in the controls) and mortality of 54% of first instar H. armigera larvae (compared with 5% in the controls). In contrast, it was not pathogenic to later instar H. armigera larvae. Cladosporium RM16 was also efficacious against the sap-sucking insect pests of cotton that were tested. No significant harmful effect of the fungus was found on any of the four beneficial predatory insects assessed in this study. Cladosporium RM16 has the potential as biological control agent to support integrated pest management in cotton farming systems, although this needs intensive study. © 2011 Copyright Taylor and Francis Group, LLC.


Mensah R.K.,Australian Department of Primary Industries and Fisheries | Mensah R.K.,Australian Cotton Research Institute | Vodouhe D.S.,Organisation Beninoise pour la Promotion de lAgriculture Biologique OBEPAB | Assogba G.,Organisation Beninoise pour la Promotion de lAgriculture Biologique OBEPAB
International Journal of Pest Management | Year: 2012

Organic cotton is considered a high-value crop in Benin, West Africa, but problems of high costs and reduced yield arising from the lack of effective pest control have left cotton farmers with low profit margins. We have developed a novel supplementary food spray product (Benin Food Product, BFP) to attract and retain beneficial insects on these crops to improve the management of pests. Applications of BFP to organic cotton, with and without other biological control agents, attracted and increased the densities of predatory insects, significantly reducing pest insect numbers and producing higher yields than in cotton treated with neem extract or in cotton that was untreated. In economic terms, the average gross profit margin on the BFP-treated plot was 125,340 FCFA (French Communaute Financiere Africaine; USA $1 1/4 483 FCFA) with 80,248, 89,450 and 968 FCFA on plots treated with neem extract, synthetic insecticides, and no control agent, respectively. These results clearly show that a supplementary food spray, combined with biological pesticides such as neem extract, sugar, and nuclear polyhedrosis virus, could have a positive economic impact on organic cotton production in Benin. © 2012 Taylor & Francis.


Lategan M.J.,University of Technology, Sydney | Lategan M.J.,Cooperative Research Center for Contamination Assessment and Remediation of the Environment | Korbel K.,University of Technology, Sydney | Korbel K.,Australian Cotton Research Institute | And 2 more authors.
Marine and Freshwater Research | Year: 2010

The cotton strip assay uses the loss of tensile strength of cotton strips as a measure of microbial cellulolytic activity. Its suitability for measuring general microbial activity in groundwater was tested by examining the relationship of tensile strength, abundance of cellulolytic organisms and general microbial activity on cotton strips deployed in bores. The hypothesis was that the strength of cotton strips would decline with increasing abundance and activity of cellulolytic organisms, and as cellulolysis makes resources available to other microbial groups, cotton strength loss should also be related to increased overall microbial activity. The correlation between the abundance of cellulolytic organisms and cotton strength was not significant. Two main factors influenced this relationship: (i) effectiveness of the media in detecting cellulolytic moulds and (ii) inter-community interactions. After accounting for the presence of moulds through partial correlation, the relationship between tensile strength and abundance of cellulolytic organisms was stronger and significant. Both cotton strength and abundance of cellulolytic organisms correlated significantly with general microbial activity. These results support the use of the cotton strip assay, and cotton tensile strength as a surrogate for microbial activity in groundwater. © 2010 CSIRO.


Bianchi F.J.J.A.,CSIRO | Bianchi F.J.J.A.,Australian Cotton Research Institute | Bianchi F.J.J.A.,Crop and Weed Ecology Group | Bianchi F.J.J.A.,Wageningen University | And 4 more authors.
Agricultural and Forest Entomology | Year: 2013

1 Landscape management for enhanced natural pest control requires knowledge of the ecological function of the habitats present in the landscape mosaic. However, little is known about which habitat types in agricultural landscapes function as reproduction habitats for arthropod pests and predators during different times of the year. 2 We studied the arthropod assemblage on six crops and on the seven most abundant native plant species in two landscapes over 1 year in Australia. Densities of immature and adult stages of pests and their predators were assessed using beat sheet sampling. 3 The native plants supported a significantly different arthropod assemblage than crops. Native plants had higher predator densities than crops over the course of the year, whereas crops supported higher pest densities than the native plants in two out of four seasonal sampling periods. Crops had higher densities of immature stages of pests than native plants in three of four seasonal sampling periods, implying that crops are more strongly associated with pest reproduction than native plants. Densities of immature predators, excluding spiders, were not different between native plants and crops. Spiders were, however, generally abundant and densities were higher on native plants than on crops but, because some species disperse when immature, there is less certainty in identifying their reproduction habitat. 4 Because the predator to pest ratio on native plant species showed little variation, and spatial variation in arthropod assemblages was limited, the predator support function of native vegetation may be a general phenomenon. Incentives that maintain and restore native remnant vegetation can increase the predator to pest ratio at the landscape scale, which could enhance pest suppression in crops. © 2012 CSIRO Agricultural and Forest Entomology © 2012 The Royal Entomological Society.


Downes S.,CSIRO | Mahon R.J.,CSIRO | Rossiter L.,Australian Cotton Research Institute | Kauter G.,Cotton Australia Ltd | And 3 more authors.
Evolutionary Applications | Year: 2010

In Australia, monitoring Helicoverpa species for resistance to the Cry2Ab toxin in second generation Bacillus thuringiensis (Bt) cotton has precisely fulfilled its intended function: to warn of increases in resistance frequencies that may lead to field failures of the technology. Prior to the widespread adoption of two-gene Bt cotton, the frequency of Cry2Ab resistance alleles was at least 0.001 in H. armigera and H. punctigera. In the 5years hence, there has been a significant and apparently exponential increase in the frequency of alleles conferring Cry2Ab resistance in field populations of H. punctigera. Herein we review the history of deploying and managing resistance to Bt cotton in Australia, outline the characteristics of the isolated resistance that likely impact on resistance evolution, and use a simple model to predict likely imminent resistance frequencies. We then discuss potential strategies to mitigate further increases in resistance frequencies, until the release of a third generation product. These include mandating larger structured refuges, applying insecticide to crops late in the season, and restricting the area of Bollgard II® cotton. The area planted to Bt-crops is anticipated to continue to rise worldwide; therefore the strategies being considered in Australia are likely to relate to other situations. © 2010 Blackwell Publishing Ltd.


Bianchi F.J.J.A.,CSIRO | Bianchi F.J.J.A.,Australian Cotton Research Institute | Schellhorn N.A.,CSIRO | Buckley Y.M.,University of Queensland | And 2 more authors.
Ecological Applications | Year: 2010

Agricultural pest control often relies on the ecosystem services provided by the predators of pests. Appropriate landscape and habitat management for pest control services requires an understanding of insect dispersal abilities and the spatial arrangement of source habitats for pests and their predators. Here we explore how dispersal and habitat configuration determine the locations where management actions are likely to have the biggest impact on natural pest control. The study focuses on the early colonization phase before predator reproduction takes place and when pest populations in crops are still relatively low. We developed a spatially explicit simulation model in which pest populations grow exponentially in pest patches and predators disperse across the landscape from predator patches. We generated 1000 computer-simulated landscapes in which the performance of four typical but different predator groups as biological control agents was evaluated. Predator groups represented trait combinations of poor and good dispersal ability and densityindependent and density-dependent aggregation responses toward pests. Case studies from the literature were used to inform the parameterization of predator groups. Landscapes with a small nearest-neighbor distance between pest and predator patches had the lowest mean pest density at the landscape scale for all predator groups, but there can be high variation in pest density between the patches within these landscapes. Mobile and strongly aggregating predators provide the best pest suppression in the majority of landscape types. Ironically, this result is true except in landscapes with small nearest-neighbor distances between pest and predator patches. The pest control potential of mobile predators can best be explained by the mean distance between a pest patch and all predator patches in the landscape, whereas for poorly dispersing predators the distance between a pest patch and the nearest predator patch is the best explanatory variable. In conclusion, the spatial arrangement of source habitats for natural enemies of agricultural pest species can have profound effects on their potential to colonize crops and suppress pest populations. © 2010 by the Ecological Society of America.


Hereward J.P.,University of Queensland | Hereward J.P.,Australian Cotton Research Institute | Debarro P.J.,CSIRO | Walter G.H.,University of Queensland
Bulletin of Entomological Research | Year: 2013

Following the global uptake of transgenic cotton several Hemipteran pests have emerged as primary targets for pesticide control. Previous research on one such emergent pest: the green mirid, Creontiades dilutus, indicated differential use of two crop hosts, cotton (Gossypium hirsutum, Malvaceae) and lucerne (alfalfa) (Medicago sativa, Fabaceae). We tested the hypothesis that this apparent demographic independence of lucerne and cotton inhabiting mirids is the result of cryptic species being associated with these two crops. We assessed gene flow using microsatellite markers across adjacent cotton and lucerne crops at three geographically separated sites (up to 900 km apart). We also analysed the recent feeding behaviour of these insects by amplifying chloroplast markers from their gut contents. We find high gene flow between these two crops (mean pair wise F ST between host plants=0.0141 within localities), and no evidence of cryptic species. Furthermore, the gut analyses revealed evidence of substantial recent movement between these two crops. We discuss the implications of these results for interpreting multiple host use in this species and setting future research priorities for this economically important pest. © Cambridge University Press 2013.


Hereward J.P.,University of Queensland | Hereward J.P.,Australian Cotton Research Institute | Walter G.H.,University of Queensland
PLoS ONE | Year: 2012

The way in which herbivorous insect individuals use multiple host species is difficult to quantify under field conditions, but critical to understanding the evolutionary processes underpinning insect-host plant relationships. In this study we developed a novel approach to understanding the host plant interactions of the green mirid, Creontiades dilutus, a highly motile heteropteran bug that has been associated with many plant species. We combine quantified sampling of the insect across its various host plant species within particular sites and a molecular comparison between the insects' gut contents and available host plants. This approach allows inferences to be made as to the plants fed upon by individual insects in the field. Quantified sampling shows that this "generalist" species is consistently more abundant on two species in the genus Cullen (Fabaceae), its primary host species, than on any other of its numerous listed hosts. The chloroplast intergenic sequences reveal that C. dilutus frequently feeds on plants additional to the one from which it was collected, even when individuals were sampled from the primary host species. These data may be reconciled by viewing multiple host use in this species as an adaptation to survive spatiotemporally ephemeral habitats. The methodological framework developed here provides a basis from which new insights into the feeding behaviour and host plant relationships of herbivorous insects can be derived, which will benefit not only ecological interpretation but also our understanding of the evolution of these relationships. © 2012 Hereward, Walter.

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