17 research outputs found
Spot form of net blotch resistance in barley is under complex genetic control
Key message: Evaluation of resistance toPyrenophora teresf.maculatain barley breeding populations via association mapping revealed a complex genetic architecture comprising a mixture of major and minor effect genes. Abstract: In the search for stable resistance to spot form of net blotch (Pyrenophora teres f. maculata, SFNB), association mapping was conducted on four independent barley (Hordeum vulgare L.) breeding populations comprising a total of 898 unique elite breeding lines from the Northern Region Barley Breeding Program in Australia for discovery of quantitative trait loci (QTL) influencing resistance at seedling and adult plant growth stages. A total of 29 significant QTL were validated across multiple breeding populations, with 22 conferring resistance at both seedling and adult plant growth stages. The remaining 7 QTL conferred resistance at either seedling (2 QTL) or adult plant (5 QTL) growth stages only. These 29 QTL represented 24 unique genomic regions, of which five were found to co-locate with previously identified QTL for SFNB. The results indicated that SFNB resistance is controlled by a large number of QTL varying in effect size with large effects QTL on chromosome 7H. A large proportion of the QTL acted in the same direction for both seedling and adult responses, suggesting that phenotypic selection for SFNB resistance performed at either growth stage could achieve adequate levels of resistance. However, the accumulation of specific resistance alleles on several chromosomes must be considered in molecular breeding selection strategies
Evaluation of the Effect of Hydrated Lime on the Scavenging of Feral Swine (\u3ci\u3eSus Scrofa\u3c/i\u3e) Carcasses and Implications for Managing Carcass-Based Transmission of African Swine Fever Virus
African swine fever (ASF) is a devastating hemorrhagic disease marked by extensive morbidity and mortality in infected swine. The recent global movement of African swine fever virus (ASFV) in domestic and wild swine (Sus scrofa) populations has initiated preparedness and response planning activities within many ASF-free countries. Within the US, feral swine are of utmost concern because they are susceptible to infection, are wide-spread, and are known to interact with domestic swine populations. African swine fever virus is particularly hardy and can remain viable in contaminated carcasses for weeks to months; therefore, carcass-based transmission plays an important role in the epidemiology of ASF. Proper disposal of ASF-infected carcasses has been demonstrated to be paramount to curbing an ASF outbreak in wild boar in Europe; preparedness efforts in the US anticipate carcass management being an essential component of control if an introduction were to occur. Due to environmental conditions, geographic features, or limited personnel, immediately removing every carcass from the landscape may not be viable. Hydrated lime converts to calcium carbonate, forming a sterile crust that may be used to minimize pathogen amplification. Any disturbance by scavenging animals to the sterile crust would nullify the effect of the hydrated lime; therefore, this pilot project aimed to evaluate the behavior of scavenging animals relative to hydrated lime-covered feral swine carcasses on the landscape. At two of the three study sites, hydrated limetreated carcasses were scavenged less frequently compared to the control carcasses. Additionally, the median time to scavenging was 1 d and 6 d for control versus hydrated lime-treated carcasses, respectively. While results of this study are preliminary, hydrated lime may be used to deter carcass disruption via scavenging in the event that the carcass cannot be immediately removed from the landscape
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Movements of Feral Hogs in Response to Warfarin Bait Consumption
The distribution of feral hogs throughout North American has increased dramatically since their introduction. The use of toxicants has proven to be a n effective tool in controlling feral hog numbers in several countries. Using data from 13 GPS hogs, we compared movements and space use of control and treated hogs between pre-baiting and baiting phases of 3 feral hog toxicant field tests. Generalized linear mixed models were used to explain prospective changes in movements. In addition, we evaluated the distance of toxicant-killed feral hog carcasses from bait stations, roads, and cultivated crop plots. The mean distances traveled by treatment hogs between the pre-baiting and baiting periods was reduced by 43.9%, 32.1%, and 48.8% for daily, diurnal, and nocturnal periods, respectively. Daily and nocturnal movements exhibited a significant decrease between pre-baiting and baiting phases by feral hogs as a result of bait consumption. Mean space use size between the pre-baiting and baiting periods for treatment hogs was reduced by 37.5% and 30.0% for 95% MCP and 50% MCP, respectively but was not a result of bait consumption. Toxicant-killed feral hog carcass distance from bait stations, cultivated crops, and roads averaged (± SE) 919.4 ± 68.1 m, 908.9 ± 72.1 m, and 120.7 ± 34.9 m, respectively. These carcasses were never recovered from crop plots or near roads and were typically found in natural land cover types. The toxicant warfarin reduced movements of feral hogs, which in turn can reduce their damage to crop and reduce the spread of disease
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Movements of Feral Hogs in Response to Warfarin Bait Consumption
The distribution of feral hogs throughout North American has increased dramatically since their introduction. The use of toxicants has proven to be a n effective tool in controlling feral hog numbers in several countries. Using data from 13 GPS hogs, we compared movements and space use of control and treated hogs between pre-baiting and baiting phases of 3 feral hog toxicant field tests. Generalized linear mixed models were used to explain prospective changes in movements. In addition, we evaluated the distance of toxicant-killed feral hog carcasses from bait stations, roads, and cultivated crop plots. The mean distances traveled by treatment hogs between the pre-baiting and baiting periods was reduced by 43.9%, 32.1%, and 48.8% for daily, diurnal, and nocturnal periods, respectively. Daily and nocturnal movements exhibited a significant decrease between pre-baiting and baiting phases by feral hogs as a result of bait consumption. Mean space use size between the pre-baiting and baiting periods for treatment hogs was reduced by 37.5% and 30.0% for 95% MCP and 50% MCP, respectively but was not a result of bait consumption. Toxicant-killed feral hog carcass distance from bait stations, cultivated crops, and roads averaged (± SE) 919.4 ± 68.1 m, 908.9 ± 72.1 m, and 120.7 ± 34.9 m, respectively. These carcasses were never recovered from crop plots or near roads and were typically found in natural land cover types. The toxicant warfarin reduced movements of feral hogs, which in turn can reduce their damage to crop and reduce the spread of disease
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Field Testing of a New Feral Hog Feeder to Minimize Bait Exposure to Non-target Wildlife
The feral hog is an invasive species that inflicts billions of dollars in agricultural damage every year in the U.S. Hog-specific baits have shown promise in reducing feral hog abundance but require species-specific feeders to exclude domestic animals and non-target wildlife. Four feeder types were tested during 2016 and 2017 field studies, including commercial feeders, prototype feeders, and a new species-specific feral hog feeder. Commercial feeders with 2.3 kg, 4.5 kg, and 6.8 kg weighted doors were used in 2016 and raccoons were observed on camera opening doors 10 times out of 164 camera observed visitations (6.1%). No other non-target species were observed entering the feeders. The following year, new feeders with 7.7 kg double-sided guillotine doors were used in a field study and no raccoons opened doors during 153 camera-observed visitations. Out of over 1,600 non-target camera images recorded, only one mouse was observed inside the feeders. Results of this study suggest the new hog feeder may provide reduced-risk to non-target species and a promising tool for controlling hog populations
Pathogenic variation of Pyrenophora teres f. teres in Australia
Pyrenophora teres f. teres (Ptt) is the causal agent of net form of net blotch (NFNB) – a major foliar disease of barley (Hordeum vulgare) crops worldwide. Deployment of genetic resistance in cultivars is the preferred method of control, but requires knowledge of the pathogenic variation of Ptt to be effective as spatial and temporal variation is common. In this study, 123 Ptt isolates collected from five states across Australia were examined for pathogenic variation using a set of 31 barley genotypes, composed of 11 international genotypes and 20 Australian cultivars. Barley seedlings were inoculated with spore suspensions from monoconidial isolate cultures and scored for infection response. Phenotypes were used to perform hierarchical cluster analysis for barley genotypes and Ptt isolates. Cluster analysis identified seven line groups, each containing barley genotypes that displayed similar responses to the Ptt isolates. Isolates clustered into four distinct isolate groups shown to harbour differential virulence to four key genotypes: Maritime, Prior, Skiff and Tallon. Isolates with virulence to any one of these genotypes accounted for 96.7% of the samples. Differential virulence was observed on a range of genotypes within each isolate group. The composition of isolate groups in eastern Australia was distinct from Western Australia, whereas all isolate groups were detected in southern Australia. Results suggest that cultivation of regionally adapted barley cultivars has led to regional evolution of Ptt, where the pathogen acquires virulence specific for resistance factors deployed in local cultivars. Detection of Ptt modern isolates that were highly virulent to historic cultivars indicates the long-term survival of virulence gene combinations in the pathogen population