• Animal cells and systems
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• 제2권1호
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• pp.55-63
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• 1998

The effects of inflorescence herbivory and flowering time on plant architecture and reproductive yields were examined with a perennial herbacious species, Vicia cracca, occurring in Natick, Massachusetts, USA. Natural herbivory on inflorescences was observed among the total of 157 plants during a growing season. Vegetative and reproductive characters were measured in the field as well as in the lab depending on the characters. Approximately 64% of the plants were subjected to herbivory on inflorescences. Plants were classified into three groups; unbrowsed plants, partially browsed, and totally browsed plants, according to the level of herbivory on inflorescences of each plant. Plants were also categorized by their flowering time such as early vs late flowering plants. Herbivores tended to favor inflorescences on rather small plants, resulting in a pattern of totally contact or partially intact inflorescences on taller plants. The mean number of stems, which was assumed to be a direct result of severe herbivory in this population, differed among herbivory groups. There also was a tendency that plants flowering late in the season had more nodes with more leaves, suggesting that herbivory on stem tips early in the season before flowering might have induced growth of side branches or branchlets along the main stems. Comparison between unbrowsed and partially browsed plants showed that the latter compensated for browsing in terms of numbers of inflorescences, fruits, seeds and seed size (weight), though they did not compensate in flower number. The probability of fruit production (presence vs absence of fruits) and seed weight declined toward the end of the season. These results suggest that resources are deficient at the end of the season. Almost complete reproductive failure in totally browsed plants is attributed to the destruction of inflorescence display and the disadvantage of small vegetative size of those plants. After all, in this population, a moderate level of herbivory on inflorescences did not reduce the maternal fitness of the plants. However, severe herbivory on inflorescences resulted in antagonistic interactions between plants and herbivores.

• Fisheries and Aquatic Sciences
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• 제24권12호
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• pp.415-427
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• 2021

Wetland ecosystems act as natural freshwater purification systems, but their rich biodiversity is being threatened with the introduction of the non-native freshwater snail, Pomacea canaliculata. This study was conducted to measure the herbivory effects and growth rate of P. canaliculata on common macrophytes: Ipomoea aquatica, Ipomoea batatas, Pandanus amaryllifolius and Cucurma longa. In separate experiments, the macrophyte species were served as the snails' food as individual species and simultaneously. In the individual treatment, the growth pattern and rate were based on the snails' weight (mg/snail/day; n = 9) while the individual feeding consumption (mg/snail/day) was calculated from the leftover food. In the simultaneous treatment, the herbivory effects were evaluated as the feeding preference (%) from observations every two hours, while the total feeding consumption (mg) was calculated based on the food remaining after a 12-hour experiment (3 replicates: total n = 27). The results indicated that the growth pattern was significant for snails grazing on I. aquatica but not when other macrophyte species were eaten. The individual feeding consumption was higher when using I. aquatica than P. amaryllifolius but the growth rate for snails grazing on I. aquatica and P. amaryllifolius did not differ significantly. Meanwhile, the consumption of C. longa deterred the snails' growth rate. Although the snails consumed all the macrophytes in the individual experiment, when given the species simultaneously, the feeding preference and total feeding consumption were directed significantly more toward I. aquatica than P. amaryfollius and C. longa. We conclude that P. canaliculata is a generalist feeder given a limited choice of food but tends to show a strong feeding preference after being introduced to more food choices. These findings indicate that the introduction of P. canaliculata into wetland ecosystems may increase the herbivory effects on macrophytes, making these ecosystems vulnerable to the impact of eutrophication and biodiversity reduction.

• Journal of Ecology and Environment
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• 제48권3호
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• pp.308-318
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• 2024

Background: Many plants compensate for the damage caused by herbivorous insects through tolerance responses. Besides directly causing plant tissue loss and seed production reduction, herbivory causes phenological changes in the host plant. However, little is known about the fitness costs of phenological changes caused by tolerance responses to herbivorous attacks. Results: The girdling beetle Phytoecia rufiventris caused a short-term decrease in the number of flowers of the host plant Erigeron annuus. However, accelerated growth restored the number of flowers, but after a 2-week delay. With an objective to examine whether the tolerance response with such a delay fully compensates the fitness, we experimentally reproduced a 2-week delay in germination under greenhouse and field settings. Under both conditions, intraspecific competition resulted in serious defects in the growth and reproduction of E. annuus plants which of germination was delayed. However, delayed germination (DG) resulted in better growth when competition and herbivory were eliminated from the field. Thus, we showed that the tolerance response to restore reproductive production does not fully compensate for the fitness loss caused by insect attack; rather, the delay in seed production in attacked plants leads to DG and subsequent inferiority in intraspecific competition. Conclusions: Our results imply that compensation for floral production after an herbivore attack does not fully restore offspring fitness in the presence of intraspecific competition and herbivory. Assessing the ecological consequences of defense traits in an appropriate layer of interaction is critical to interpreting adaptive values.

• 한국습지학회지
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• 제20권2호
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• pp.131-135
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• 2018

식물이 생산하는 꽃외화밀(extrafloral nectar)은 주로 단당류, 이당류로 구성되어 있는 액체로서, 개미나 기생벌 등 초식 곤충의 천적을 유인하는 식물의 간접 방어 수단으로 알려져 있다. 본 연구는 봉선화를 이용하여 봉선화 꽃외화밀의 생산이 곤충의 초식에 의해 어떻게 영향을 받는지 알아보고자 시도하였다. 실험은 곤충 초식 방식 두 가지 (잎을 씹어먹는 타입과 체관 액체를 빨아먹는 타입)를 인위적으로 처리하기 위해, 1) 봉선화 잎을 기계적으로 손상시키는 방법 (simulated herbivory), 2) 봉선화 잎을 기계적으로 손상시킨 후 자스몬산 그리고 나방 애벌레 타액이 섞인 토사물(regurgitate)의 두가지 유도물질(elicitor)을 잎에 처리하는 방법 (simulated herbivory + elicitor application), 3) 초식곤충인 진딧물을 봉선화 잎에 인위적으로 감염시키는 방법 (aphid feeding) 등 총 3가지 방법으로 식물을 처리하고, 이후 나타나는 봉선화의 꽃외화밀 생산량의 변화를 관찰하였다. 실험 결과, 봉선화 꽃외화밀의 생산은 기계적 손상, 기계적 손상+유도물질 처리에 영향을 받지 않았다. 이는 봉선화 꽃외화밀의 생산이 나비나 나방 애벌레 등 잎을 씹어먹는 방식으로 섭식하는 곤충의 초식에 의해서는 영향을 받지 않음을 시사한다. 반면에 진딧물 섭식에 의해서 봉선화 꽃외화밀의 생산량이 감소하였는데, 이는 진딧물 등의 체관 내용물을 빨아먹는 방식으로 섭식하는 곤충의 초식에는 봉선화 꽃외화밀의 생산이 부정적인 영향을 받음을 시사한다. 진딧물의 밀도와 꽃외화밀의 생산량 감소와는 상관성을 발견하지 못했는데, 이는 봉선화 잎의 꽃외화밀 생산에 미치는 진딧물의 영향이 광합성 산물의 일부가 진딧물에 의해 소모되기 때문에 생기는 결과라는 증거는 없다는 것을 시사한다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2021년도 춘계학술대회
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• pp.20-20
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• 2021

• Journal of Ecology and Environment
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• 제45권3호
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• pp.143-151
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• 2021

Background: Plants are able to optimize defense responses induced by various herbivores, which have different feeding strategies. Local and systemic responses within a plant after herbivory are essential to modulate herbivore-specific plant responses. For instance, leaf-chewing herbivores elicit jasmonic acid signaling, which result in the inductions of toxic chemicals in the attacked leaf (tissue-specific responses) and also in the other unattacked parts of the plant (systemic responses). Root herbivory induces toxic metabolites in the attacked root and alters the levels of transcripts and metabolites in the unattacked shoot. However, we have little knowledge of the local and systemic responses against stem-boring herbivores. In this study, we examined the systemic changes in metabolites in the wild tobacco Nicotiana attenuata, when the stem-boring herbivore Trichobaris mucorea attacks. Results: To investigate the systemic responses of T. mucorea attacks, we measured the levels of jasmonic acid (JA), JA-dependent secondary metabolites, soluble sugars, and free amino acids in 7 distinct tissues of N. attenuata: leaf lamina with epidermis (LLE), leaf midrib (LM), stem epidermis (SE), stem pith (SP), stem vascular bundle (SV), root cortex with epidermis (RCE), and root vascular bundle (RV). The levels of JA were increased in all root tissues and in LM by T. mucorea attacks. The levels of chlorogenic acids (CGAs) and nicotine were increased in all stem tissues by T. mucorea. However, CGA was systematically induced in LM, and nicotine was systematically induced in LM and RCE. We further tested the resource allocation by measuring soluble sugars and free amino acids in plant tissues. T. mucorea attacks increased the level of free amino acids in all tissues except in LLE. The levels of soluble sugars were significantly decreased in SE and SP, but increased in RV. Conclusions: The results reveal that plants have local- and systemic-specific responses in response to attack from a stem-boring herbivore. Interestingly, the level of induced secondary metabolites was not consistent with the systemic inductions of JA. Spatiotemporal resolution of plant defense responses against stem herbivory will be required to understand how a plant copes with attack from herbivores from different feeding guilds.

• The Korean Journal of Ecology
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• 제24권6호
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• pp.377-380
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• 2001

Herbivory is an important selective forces on plants by reducing the ability of the plant to compete with its neighbors and to produce offspring. Oak nut weevil(Mechoris ursulus Roelofs) females lay eggs in unmatured acorns and cut off the branch of oviposited acorns. To investigate the influences of branch-cutting behavior of oak nut weevils on oak production, we surveyed the horizontal and vertical distribution ranges of damaged oaks and depth of sites of overwintering larvae and quantified the amounts of biomass and acorn removed by the weevils on deciduous oak species. All of the endemic oak species in Korea were damaged by oak nut weevils in all of the study sites including Mt. Halla and Mt. Seorak. The upper limit of vertical distribution of damaged oaks by the weevils raried from 700 m to 900 m. Mostly their larvae were found in soil from 8.1 cm to 10.0 cm depth in winter. Percentage of annual net primary productivity($720g{\cdot}m^{-2}{\cdot}day^{-1}$) of oak species removed by the weevils was about 7%, which is higher than the percentage removed by all the herbivores in typical temperate forest(5%) and equivalent to that by all the herbivores in tropical forest. The predation percentage of annual acorn production by oak nut weevil was 27% in Q. mongolica and 33% in Q. acutissima. This results indicate that the branch-cutting behavior of oak nut weevil may be the most important factor regulating oak population and affecting other predators dependent on acorns.

• Ocean and Polar Research
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• 제33권4호
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• pp.457-472
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• 2011

To elucidate the trophic role of heterotrophic nano- and microplankton (HNMP), we investigated their biomass, community structure, and herbivory in three different water masses, namely, south of Polar Front (SPF), Polar Front Zone (PFZ), the Sub-Antarcitc Front (SAF) in the Drake Passage in the Southern Ocean, during the austral summer in 2002. We observed a spatial difference in the relative importance of the dominant HNMP community in these water masses. Ciliates accounted for 34.7% of the total biomass on an average in the SPF where the concentration of chlorophyll-a was low with the dominance of pico- and nanophytoplankton. Moreover, the importance of ciliates declined from the SPF to the SAF. In contrast, heterotrophic dinoflagellates (HDFs) were the most dominant grazers in the PFZ where the concentration of chlorophyll-a was high with the dominance of net phytoplankton. HNMP biomass ranged from 321.9 to 751.4 $mgCm^{-2}$ and was highest in the PFZ and lowest in the SPF. This result implies that the spatial dynamic of HNMP biomass and community was significantly influenced by the composition and concentration of phytoplankton as a food source. On an average, 75.6%, 94.5%, and 78.9% of the phytoplankton production were consumed by HNMP in the SPF, PFZ, and SAF, respectively. The proportion of phytoplankton grazed by HNMP was largely determined by the composition and biomass of HNMP, as well as the composition of phytoplankton. However, the herbivory of HNMP was one of the most important loss processes affecting the biomass and composition of phytoplankton particularly in the PFZ. Our results suggest that the bulk of the photosynthetically fixed carbon was likely reprocessed by HNMP rather than contributing to the vertical flux in Drake Passage during the austral summer in 2002.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2011년 학술대회 논문집
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• pp.31-33
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• 2011

화외밀선(EFN)의 형태로 엽연부의 엽맥 끝에 넥타를 분비하는 것은 가막살나무 5 수종에서 모두 관찰되었다. 가막살나무, 산가막살나무에서는 잎 뒷면 선점(pellucid dot)이 분포하는 것이 좋은 방어전략이라 판단된다. 가막살나무의 선점에서 넥타를 먹는 포식응애들이 다수 관찰되었다. 분꽃나무의 잎 뒷면에는 성모 이외에 별모양의 부드러운 털이 있으며, 이를 포식응애가 먹는 것이 관찰되었으며, 이 구조가 가막살나무, 산가막살나무에서의 선점과 같은 역할일 것이라 추정되나 좀더 정밀한 연구가 필요할 것이라 판단된다. 수종별로 독특한 방법으로 초식에 대한 방어전략을 개발하면서 꾸준히 진화하고 있다고 판단된다. 여기에 화학적 방어전략이 추가된다면 식물이 살아남기 위하여 얼마나 열심히 노력하고 있는가를 어느 정도 이해할 수 있을 것이라 기대된다.

• 생태와환경
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• 제47권1호
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• pp.24-31
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• 2014

본 연구는 온대활엽수림에서 초식곤충의 먹이 활동이 계절 및 고도에 따라 어떻게 변하는 가를 알아보기 위하여 수행되었다. 조사는 지난 3년간(2011~2013) 지리산국립공원의 고도가 다른 세 지역(피아골, 시암재, 노고단)에서 이루어졌다. 조사방법은 각 지역에 서식하는 수종(3종)을 선정하여 4월부터 6월까지 1~2주마다 초식곤충의 식흔 활동을 식흔지수를 이용하여 관찰하였다. 조사 결과 고도가 가장 낮은 피아골(${\approx}300m$)에서 가장 먼저 식흔이 나타났고, 중간고도인 시암재(${\approx}900m$)에서는 가장 많은 식흔이 조사되었다. 고도가 가장 높은 노고단(${\approx}1300m$)에서는 식흔이 가장 늦게 나타났지만 짧은 시간에 급속히 식흔의 총량이 증가하였다. 또한 기존에 발표된 연구를 토대로 한 결과 초식곤충의 활동시기는 조류(곤줄박이)의 첫 산란일과 거의 비슷한 것으로 나타나 식물-곤충-2차 소비자(조류)와 밀접한 관련을 보여준다. 기후 환경이 변함에 따라 초식곤충 활동의 기간이 바뀌게 될 것이며 이러한 먹이사슬의 변동을 감시할 수 있는 지속적인 장기 생태 모니터링이 필요하다.