• Asian-Australasian Journal of Animal Sciences
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• v.6 no.4
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• pp.569-576
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• 1993

A feeding trial was conducted to determine the effectivity of microbial treatment on eliminating the toxicity of weevil-infested sweet potato roots, and to assess intake level and performance of broilers fed microbiologically-treated, weevil-infested sweet potato meal. Weevil-infested sweet potato meal was treated with Aspergillus awamori (terpene-degrading fungus), dried, and mixed with other ingredients. One hundred twenty (120) broiler chicks were randomly distributed to treatment diets containing 3 types of sweet potato meal (healthy, weevil-infested, and microbiologically-treated, weevil-infested) incorporated at 2 levels (12% and 24%) in the ration, following the $2{\times}3$ factorial in CRD with 4 replicates per treatment. Voluntary intake was high with healthy sweet potato meal, even at 24% in the ration, especially at later stage of broiler development. Weevil infestation of sweet potato meal, even at 24% in the ration, especially at later stage of broiler development. Weevil infestation of sweet potato roots significantly reduced voluntary intake and broiler performance even at 12% level in the diet, much more at 24% level (p<0.01). Microbial treatment, however, was found to alleviate such problem, especially at 24% level of incorporation (p<0.01). "Toxicity" of weevil infestation, in terms of enlargement of liver and spleen, in the absence of mortality, was only apparent at 24% level of incorporation in the ration. Again, this was minimized by microbial treatment (p<0.01), and is therefore recommended at high levels of incorporating weevil-infested sweet potato meal in broiler diets. Microbial treatment constitutes an added cost, so that economic analyses should be done to find out whether increases in broiler performance, or reduction in the toxic effects of terpenoid compounds, outweigh the cost of treatment before a definite recommendation can be made for its commercial application.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.505-518
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• 2023

The key to invasive pest management lies in preemptive action. However, most current research using species distribution models is conducted after an invasion has occurred. This study modeled the potential distribution of the globally notorious sweet potato pest, the sweet potato weevil(Cylas formicarius), that has not yet invaded Korea using MaxEnt. Using global occurrence data, bioclimatic variables, and topsoil characteristics, MaxEnt showed high explanatory power as both the training and test areas under the curve exceeded 0.9. Among the environmental variables used in this study, minimum temperature in the coldest month (BIO06), precipitation in the driest month (BIO14), mean diurnal range (BIO02), and bulk density (BDOD) were identified as key variables. The predicted global distribution showed high values in most countries where the species is currently present, with a significant potential invasion risk in most South American countries where C. formicarius is not yet present. In Korea, Jeju Island and the southwestern coasts of Jeollanam-do showed very high probabilities. The impact of climate change under shared socioeconomic pathway (SSP) scenarios indicated an expansion along coasts as climate change progresses. By applying the 10th percentile minimum training presence rule, the potential area of occurrence was estimated at 1,439 km² under current climate conditions and could expand up to 9,485 km² under the SSP585 scenario. However, the model predicted that an inland invasion would not be serious. The results of this study suggest a need to focus on the risk of invasion in islands and coastal areas.