Selection of large host plants for oviposition by a monophagous leaf beetle: nutritional quality or enemy-free space?

The ecological factors controlling the distribution and abundance of the folivorous marsupials endemic to the rainforests of northern Australia are not understood. In this study, we surveyed folivore abundance at 40 sites stratified by altitude and geology in rainforests of the Atherton Tableland, north Queensland. All five species of folivore that inhabit the study area were more abundant in highland (800–1200 m) than in upland (400–800 m) forests. Allowing for the effects of altitude, four species of folivore were more abundant in forests on nutrient-rich basalts than in forests on nutrient-poor acid igneous or metamorphic rocks. The abundance of two folivore species also varied inversely with rainfall. Altitudinal variation in folivore abundance in the study area has been attributed to habitat destruction, Aboriginal hunting, the distribution of host plants and climate; however, none of these hypotheses has been tested. Variation in folivore abundance with geology is plausibly explained as a response to the nutritional quality of foliage. Foliage quality may also explain the inverse relationship between two of the folivores and rainfall. The results of this study show that only a relatively small proportion of north Queensland rainforests support abundant populations of the endemic folivorous marsupials.

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Direct and indirect effects of herbivores influencing plant invasions.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0226 ◽

2020 ◽

pp. 226-240

Author(s):

Peter M. Kotanen

Keyword(s):

Indirect Effects ◽

Free Space ◽

Native Plants ◽

Plant Invasions ◽

Evolutionary Change ◽

Range Shifts ◽

The Novel ◽

Direct And Indirect Effects ◽

Enemy Free Space ◽

New Distribution

Abstract Non-native plants rarely escape damage by herbivores. Instead, upon arrival in a new region, they begin to acquire new enemies, replacing those they have lost during their migration. These herbivores can include both natives to the new region and species that have themselves been accidentally or deliberately introduced from elsewhere, potentially including examples originating from the invader's original range. Shifts of new enemies from other hosts can occur over a range of timescales, depending in part on whether evolutionary change is required, but are likely to be faster for plants that are widespread and phylogenetically related to a herbivore's original host, and faster for generalist herbivores than for specialists. The occurrence of herbivores is not necessarily uniform across an invader's range; instead, they may be less diverse or abundant in host populations that are geographically or ecologically marginal, though existing evidence is mixed. Collectively, these new suites of herbivores can affect the growth and fitness of invaders, both directly by damaging them and indirectly by attacking their competitors. Studies comparing the demographic consequences of herbivory for successful vs unsuccessful invaders may help to clarify how often such impacts limit invasiveness. The view that an invader enters 'enemy-free' space is inaccurate; instead, persistence and spread of non-native plants often may be affected by the novel and changing assemblage of herbivores that they acquire within their new distribution.

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Direct and indirect effects of herbivores influencing plant invasions.

Plant invasions: the role of biotic interactions ◽

10.1079/9781789242171.0012 ◽

2020 ◽

pp. 226-240

Author(s):

Peter M. Kotanen ◽

Keyword(s):

Indirect Effects ◽

Free Space ◽

Native Plants ◽

Plant Invasions ◽

Evolutionary Change ◽

Range Shifts ◽

The Novel ◽

Direct And Indirect Effects ◽

Enemy Free Space ◽

New Distribution

Non-native plants rarely escape damage by herbivores. Instead, upon arrival in a new region, they begin to acquire new enemies, replacing those they have lost during their migration. These herbivores can include both natives to the new region and species that have themselves been accidentally or deliberately introduced from elsewhere, potentially including examples originating from the invader's original range. Shifts of new enemies from other hosts can occur over a range of timescales, depending in part on whether evolutionary change is required, but are likely to be faster for plants that are widespread and phylogenetically related to a herbivore's original host, and faster for generalist herbivores than for specialists. The occurrence of herbivores is not necessarily uniform across an invader's range; instead, they may be less diverse or abundant in host populations that are geographically or ecologically marginal, though existing evidence is mixed. Collectively, these new suites of herbivores can affect the growth and fitness of invaders, both directly by damaging them and indirectly by attacking their competitors. Studies comparing the demographic consequences of herbivory for successful vs unsuccessful invaders may help to clarify how often such impacts limit invasiveness. The view that an invader enters 'enemy-free' space is inaccurate; instead, persistence and spread of non-native plants often may be affected by the novel and changing assemblage of herbivores that they acquire within their new distribution.

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Witchweed Control by Herbicides Translocated Through Host Plants

Weed Science ◽

10.1017/s0043174500048797 ◽

1971 ◽

Vol 19 (3) ◽

pp. 240-244 ◽

Cited By ~ 1

Author(s):

Paul F. Sand ◽

Grant H. Egley ◽

W. L. Gould ◽

C. A. Kust

Keyword(s):

Zea Mays ◽

Grain Yield ◽

Host Plants ◽

Herbicide Application ◽

Kernel Development ◽

Optimum Treatment ◽

Delayed Emergence ◽

Anisic Acid ◽

Selection Of

Dicamba (3,6-dichloro-o-anisic acid) and 2,3,6-trichlorobenzoic acid (2,3,6-TBA) applied in lanolin pastes to leaves or roots of host plants growing in soil were translocated acropetally and affected witchweed (Striga lutea Lour.) plants parasitizing roots of host plants. Emerged witchweed plants exhibited characteristic epinastic responses while emergence of other witchweed plants was delayed. Broadcast foliar treatments of dicamba and 2,3,6-TBA to corn (Zea mays L.) applied before witchweed emergence generally reduced the intensity of the infestation and delayed emergence. However, injury to corn, expressed as failure of kernel development and grain yield decreases, sometimes occurred. Injury was greater when herbicide application was delayed until corn was in the early tassel stage. Dicamba was more effective than 2,3,6-TBA for witchweed control. However, no treatment gave season-long control of witchweed. Yearly variations in corn injury precluded a selection of optimum treatment dates and rates for control of witchweed by this technique.

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Changing Host Plants Causes Structural Differences in the Parasitoid Complex of the Monophagous Moth Yponomeuta evonymella, but Does Not Improve Survival Rate

Insects ◽

10.3390/insects10070197 ◽

2019 ◽

Vol 10 (7) ◽

pp. 197 ◽

Cited By ~ 3

Author(s):

Łukowski ◽

Janek ◽

Baraniak ◽

Walczak ◽

Karolewski

Keyword(s):

Survival Rate ◽

Host Plant ◽

Free Space ◽

Total Mortality ◽

Larval Rearing ◽

Primary Host ◽

New Host ◽

Parasitoid Complex ◽

Significant Difference ◽

Enemy Free Space

Recently in Poland, cases of host expansion have frequently been observed in the typically monophagous bird-cherry ermine moth (Yponomeuta evonymella), which has moved from its native host plant, bird cherry (Prunus padus), to a new, widely distributed plant that is invasive in Europe, black cherry (P. serotina). We attempted to verify the reasons behind this host change in the context of the enemy-free space hypothesis by focusing on parasitoids attacking larval Y. evonymella on one of three host plant variants: The primary host, P. padus; initially P. padus and later P. serotina (P. padus/P. serotina); or the new host, P. serotina. This experiment investigated if changing the host plant could be beneficial to Y. evonymella in terms of escaping from harmful parasitoids and improving survival rate. We identified nine species of parasitoids that attack larval Y. evonymella, and we found that the number of parasitoid species showed a downward trend from the primary host plant to the P. padus/P. serotina combination to the new host plant alone. We observed a significant difference among variants in relation to the percentage of cocoons killed by specific parasitoids, but no effects of non-specific parasitoids or other factors. Total mortality did not significantly differ (ca. 37%) among larval rearing variants. Changing the host plant caused differences in the structure of the parasitoid complex of Y. evonymella but did not improve its survival rate. This study does not indicate that the host expansion of Y. evonymella is associated with the enemy-free space hypothesis; we therefore discuss alternative scenarios that may be more likely.

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