• Title/Summary/Keyword: herbivore

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Plant Diversity and Density, Driving Forces of the Feeding Activity of Herbivores in a Temperate Forest of Southern South Korea (한국 남부 온대림 초식 곤충 식흔량에 영향을 주는 식물 다양성과 밀도)

  • Kim, Nang-Hee;Choi, Sei-Woong
    • Korean Journal of Ecology and Environment
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    • v.51 no.4
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    • pp.322-330
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    • 2018
  • Herbivory is a major functional component of forest ecosystems, and herbivorous insects comprise about 25% of all insect species. Increasing plant diversity is related to herbivore abundance and diversity, which affects the level of leaf damage caused by insects. This study was conducted to identify plant-related variables such as plant diversity and number of leaves and density-related variables, basal area, and diameter at breast height (DBH) in a temperate forest of southern South Korea. To assess the level of leaf damage caused by leaf chewing insects, we set up two 0.1 ha plots in a temperate deciduous forest on Mt. Jirisan National Park. Plant richness differed between two sites: 16 species in 14 families(site 1) and 19 species in 15 families (site 2). Fisher's alpha index based on plant species richness and abundance resulted in 4.41 (site 1) and 6.57 (site 2). However, the sum of basal area of each site was higher in site 1 ($6.6m^2$) than site 2 ($3.7m^2$). The total surveyed leaves at two sites were 3,832 and 4,691, respectively and the damage leaves were 1,544 and 2,136, respectively. The mean leaf damage level was 11.2% (${\pm}1.76%$) in two study sites: the leaf damage level of the site 1 (11.99%) was significantly higher than site 2 (10.59%). Stepwise regression analysis showed that species diversity and evenness were the significant variables for leaf damages by chewing herbivores. NMDS ordination also identified that high tree density and low species diversity were the significant variables. This suggested that the level of damage was significantly higher in plots with low plant diversity and high tree density. In the future, we will investigate other guilds of herbivores such as sap-suckers, miners and gallers in temperate deciduous forests.

Biochemical Adaptation of the Oriental Tobacco Budworm, Helicoverpa assulta, to Host-plant Defensive Compounds (기주식물 방어물질에 대한 담배나방의 생화학적 적응)

  • Ahn, Seung-Joon
    • Korean journal of applied entomology
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    • v.61 no.1
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    • pp.143-154
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    • 2022
  • Plant secondary metabolites play an important role in insect-plant interactions. Herbivorous insects have various strategies to cope with the plant defensive compounds. Polyphagous insects feed on a wide variety of plant species, and their detoxification mechanisms are more complex since they tend to respond to a large array of different plant-derived chemicals. Alternatively, oligophagous insects specialize on only a few related plant species and may be expected to have a more efficient form of adaptation. This adaptation could involve either the production of large quantities of enzymes to detoxify their defensive compounds or the sequestration of the compounds or their metabolites. The oriental tobacco budworm, Helicoverpa assulta, is a specialist herbivore, feeding on a few plants of Solanaceae, such as tobacco and hot pepper. Understanding its host-plant adaptation not provides an important insight on physiology, ecology and evolution of specialist herbivores, but also gives a clue to develop management strategies of the pest species such as H. assulta. This paper briefly reviews the specialist, H. assulta, focusing on its host range, larval associations with the host plants, and detoxification mechanisms to nicotine and capsaicin, two characteristic defensive compounds derived from its two major host plants, tobacco and hot pepper, respectively. It summarizes the relevant research over the last half century and provides a future perspective on this subject.

Composting Method and Physicochemical Characteristics of By-products from Home Garden Plants and Small Herbivore Feces (옥수수 부산물과 토끼 분변의 이화학적 성분특성 및 퇴비 제조조건)

  • Kim, Dae-Gyun;Kim, Jin-Young;Lee, Won-Suk;Kim, Hye-Hyeong;Seo, Myung-Whoon;Park, In-Tae;Hyun, Junge;Yoo, Gayoung
    • Journal of Environmental Impact Assessment
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    • v.27 no.6
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    • pp.695-703
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    • 2018
  • This study was conducted to suggest a sustainable farming practice forresource recycling in vegetable gardens of North Korea. In North Korea, farmers are allowed to own private vegetable gardens less than $100m^2$. However, usage of fertilizers in private vegetable gardens is very limited due to economic sanctions by UN security council. If North and South Korea initiated the cooperative action in the near future, agricultural sector would be the highest priority cooperation area. Considering the current North Korean situation in agriculture, we would like to suggest a method for producing organic fertilizer manure. For raw materials for producing manure, we selected corn byproduct, which is the most abundant material, and rabbits' feces, which are easily obtained from individual private farms in North Korea. As we cannot get corn byproducts and rabbits' feces from North Korea, we prepared samples of corn byproducts and rabbits; feces from many places in South Korea. After statistical analysis of variance, there was no significant difference in the T-N contents of corn byproducts from Gyeonggi, Gangwon, Chungnam, Chungbuk, Jeollabuk and Gyeongsangnam-dos, which indicates that the fertilizing quality of corn byproducts does not vary significantly in the spatial scale of South. Korea. In this sense, if we use corn samples from Gyeonggi province, they would not be very different from those of North Korean regions. Physicochemical properties of rabbits' feces were different between those eating feed grains and those eating plants only. Hence, we used rabbits' feces of the rabbits from Yeonchun area, which were fed by plants only. Using three different mixing ratios of corn byproducts and rabbits' feces, composting was conducted for 60 days. The mixing ratio of 1:1 produced the manure with % T-N of 1.98% and OM/N ratio of 31.7 after 30 days of composting, which is comparable to the quality of commercial manure.

Interaction between Invertebrate Grazers and Seaweeds in the East Coast of Korea (동해안 조식성 무척추동물과 해조류 간 상호작용)

  • Yoo, J.W.;Kim, H.J.;Lee, H.J.;Lee, C.G.;Kim, C.S.;Hong, J.S.;Hong, J.P.;Kim, D.S.
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.12 no.3
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    • pp.125-132
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    • 2007
  • We estimated the distribution of predator-prey interaction strengths for 12 species of herbivores (including amphipods, isopods, gastropods, and sea urchins) and made a regression model that may be applicable to other species. Laboratory experiments were used to determine per capita grazing rate (PCGR; g seaweeds/individual/day). Relationship between the biomass of individual grazers and fourth-root transformed PCGR was fitted to power curve ($y=0.2310x^{0.3290}$, r=0.8864). This finding supported that the grazing efficiency was not even as individual grazers increase in size (biomass). Therefore, the biomass-normalized PCGR was estimated and revealed that smaller size herbivores were more effective grazers. Grazing impact considering density of each taxon was calculated. The sea hare Aplysia kurodai had greatest grazing impact on the seaweed bed and the sea urchin Strongylocentrotus nudus and S. intermedius were ranked in descending order of the impact. The amount of seaweed grazed by the amphipod Elasmopus sp. (>4,000 $ind./m^2$) and Jassa falcata (>2,000 $ind./m^2$) were 3.435 and $1.697mg/m^2/day$ respectively. The combined grazing amount of herbivores was $5,045mg/m^2/day$ in the seaweed bed. Although sea hare and sea urchin had strong impacts on seaweeds, the effects of dense, smaller species could not be seen as negligible. Surprisingly, the calculated grazing potential of sea urchins with a mean density of 3 $ind./m^2$ exceeded the mean production of seaweed cultured in domestic coastal waters in Korea (ca., 5 ton/ha). Small crustaceans were also expected to consume up to 16% of the seaweed production if their densities were rising under weak predation conditions. Considering that the population density of herbivores are strongly controlled by fish, human interference like overfishing may have strong negative effects on persistence of seaweeds communities.