How do insect herbivores cope with the extreme oxidative stress of phototoxic host plants?

SynopsisBracken in Britain is a host for 27 species of insect herbivores, with a further 11 species that either feed below ground (and are poorly studied), or appear to be only rarely associated with the plant. A typical site in northern England has an average of 15–16 of these species in any one year. Compared with perennial herbaceous angiosperms with similar wide distributions, bracken is not noticeably depauperate in the number of insect species that feed upon it. Bracken in others parts of the world is attacked by a wide variety of insects, with more species present in the geographical areas where bracken is most common.The ‘feeding niches’ of some of these insects are reviewed. Most are very rare relative to the biomass of their host plants, probably because of the impact of natural enemies; the effect of most of the insects upon their host-plant is consequently negligible.Reverse effects, of host-plant upon the insects, are subtle but poorly understood. Experiments to elucidate these effects are briefly outlined.

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Phenotypic plasticity in chemical defence allows butterflies to diversify host use strategies

10.1101/2020.04.07.030122 ◽

2020 ◽

Author(s):

Érika C. P. de Castro ◽

Jamie Musgrove ◽

Søren Bak ◽

W. Owen McMillan ◽

Chris D. Jiggins

Keyword(s):

Phenotypic Plasticity ◽

Host Plants ◽

Niche Partitioning ◽

Chemical Defence ◽

Host Use ◽

Insect Herbivores ◽

Cyanogenic Glucosides ◽

Chemical Defences ◽

Biochemical Responses ◽

Heliconius Cydno

AbstractHostplant specialization is a major force driving ecological niche partitioning and diversification in insect herbivores. The cyanogenic defences of Passiflora plants keeps most herbivores at bay, but not larvae of Heliconius butterflies, which can both sequester and biosynthesize cyanogenic compounds. Here, we demonstrate that both Heliconius cydno chioneus, a host plant generalist, and H. melpomene rosina, a specialist, have remarkable plasticity in their chemical defence. When feeding on Passiflora species with cyanogenic compounds they can readily sequester, both species downregulate the biosynthesis of these compounds. In contrast, when fed on Passiflora plants that do not contain cyanogenic glucosides that can be sequestered, both species increase biosynthesis. This biochemical plasticity comes at a significant fitness cost for specialist like H. m. rosina, as growth rates for this species negatively correlate with biosynthesis levels, but not for a generalist like H. c. chioneus. In exchange, H. m rosina has increased performance when sequestration is possible as on its specialised hostplant. In summary, phenotypic plasticity in biochemical responses to different host plants offers these butterflies the ability to widen their range of potential host within the Passiflora genus, while maintaining their chemical defences.

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Plant-associated CO2 mediates long-distance host location and foraging behaviour of a root herbivore

eLife ◽

10.7554/elife.65575 ◽

2021 ◽

Vol 10 ◽

Author(s):

Carla CM Arce ◽

Vanitha Theepan ◽

Bernardus CJ Schimmel ◽

Geoffrey Jaffuel ◽

Matthias Erb ◽

...

Keyword(s):

Host Plants ◽

Host Location ◽

Foraging Behaviour ◽

Larval Growth ◽

Insect Herbivores ◽

Long Distance ◽

Herbivore Interactions ◽

Root Herbivore ◽

Plant Herbivore ◽

Dose Dependent

Insect herbivores use different cues to locate host plants. The importance of CO2 in this context is not well understood. We manipulated CO2 perception in western corn rootworm (WCR) larvae through RNAi and studied how CO2 perception impacts their interaction with their host plant. The expression of a carbon dioxide receptor, DvvGr2, is specifically required for dose-dependent larval responses to CO2. Silencing CO2 perception or scrubbing plant-associated CO2 has no effect on the ability of WCR larvae to locate host plants at short distances (<9 cm), but impairs host location at greater distances. WCR larvae preferentially orient and prefer plants that grow in well-fertilized soils compared to plants that grow in nutrient-poor soils, a behaviour that has direct consequences for larval growth and depends on the ability of the larvae to perceive root-emitted CO2. This study unravels how CO2 can mediate plant–herbivore interactions by serving as a distance-dependent host location cue.

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Enhancement of oxidative stress contributes to increased pathogenicity of the invasive pine wood nematode

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2018.0323 ◽

2019 ◽

Vol 374 (1767) ◽

pp. 20180323 ◽

Cited By ~ 7

Author(s):

Wei Zhang ◽

Lilin Zhao ◽

Jiao Zhou ◽

Haiying Yu ◽

Chi Zhang ◽

...

Keyword(s):

Oxidative Stress ◽

Invasive Species ◽

Host Plants ◽

Bursaphelenchus Xylophilus ◽

Theme Issue ◽

Insulin Pathway ◽

Introduced Populations ◽

Virulent Strains ◽

The Usa ◽

Plant Pathogen Interactions

Reactive oxygen species (ROS) play important roles in defence response of host plants versus pathogens. While generation and detoxification of ROS is well understood, how varied ability of different isolates of pathogens to overcome host ROS, or ROS contribution to a particular isolate's pathogenicity, remains largely unexplored. Here, we report that transcriptional regulation of the ROS pathway, in combination with the insulin pathway, increases the pathogenicity of invasive species Bursaphelenchus xylophilus . The results showed a positive correlation between fecundity and pathogenicity of different nematode isolates. The virulent isolates from introduced populations in Japan, China and Europe had significantly higher fecundity than native avirulent isolates from the USA. Increased expression of Mn-SOD and reduced expression of catalase / GPX-5 and H 2 O 2 accumulation during invasion are associated with virulent strains. Additional H 2 O 2 could improve fecundity of Bu. xylophilus . Furthermore, depletion of Mn-SOD decreased fecundity and virulence of Bu. xylophilus , while the insulin pathway is significantly affected. Thus, we propose that destructive pathogenicity of Bu. xylophilus to pines is partly owing to upregulated fecundity modulated by the insulin pathway in association with the ROS pathway and further enhanced by H 2 O 2 oxidative stress. These findings provide a better understanding of pathogenic mechanisms in plant–pathogen interactions and adaptive evolution of invasive species. This article is part of the theme issue ‘Biotic signalling sheds light on smart pest management’.

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Herbivory in gingers from latest Cretaceous to present: is the ichnogenus Cephaloleichnites (Hispinae, Coleoptera) a rolled-leaf beetle?

Journal of Paleontology ◽

10.1666/07-089.1 ◽

2008 ◽

Vol 82 (5) ◽

pp. 1035-1037 ◽

Cited By ~ 18

Author(s):

Carlos García-Robledo ◽

Charles L. Staines

Keyword(s):

Host Plants ◽

Current Knowledge ◽

Leaf Beetle ◽

Insect Herbivores ◽

Early Eocene ◽

Leaf Beetles ◽

Plant Herbivore Interaction ◽

Plant Herbivore ◽

Herbivore Interaction ◽

Rolled Leaf

It is suggested that rolled-leaf hispine beetles (Hispinae, Coleoptera) and plants from the order Zingiberales maintained a highly specialized plant-herbivore interaction for >60 My. The evidence supporting this old and conservative interaction are herbivory marks found on leaves of the genus Zingiberopsis (Zingiberaceae) from the latest Cretaceous and early Eocene. This fossil herbivory was described as the ichnotaxon Cephaloleichnites strongii (Hispinae, Coleoptera), based on the assumption that this type of herbivory can be solely attributed to extant rolled-leaf beetles. This ichnotaxon has been a key element in several analyses on the origin, radiation and diversification of tropical insect herbivores. In this paper we report feeding patterns equivalent to those described in Zingiberopsis fossils but produced by larvae of Pyralidae and Choreutidae (Lepidoptera) and Anopsilus weevils (Curculionidae, Coleoptera) in four families of extant Zingiberales. We discuss the implications of C. strongii not being a rolled leaf beetle and how this may affect the current knowledge of the co-diversification of rolled-leaf beetles and their host plants from the order Zingiberales.

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Interaction between ants and plants bearing extrafloral nectaries in cerrado vegetation

Anais da Sociedade Entomológica do Brasil ◽

10.1590/s0301-80591998000200001 ◽

1998 ◽

Vol 27 (2) ◽

pp. 161-176 ◽

Cited By ~ 22

Author(s):

Paulo S. Oliveira ◽

Marcio R. Pie

Keyword(s):

Plant Species ◽

Host Plants ◽

Field Experiments ◽

Extrafloral Nectaries ◽

Insect Herbivores ◽

Cerrado Vegetation ◽

Plant Parts ◽

The Past ◽

Plant Foliage ◽

Herbivore Species

Extrafloral nectaries (EFNs) are nectar-secreting glands not directly involved with pollination which may occur on virtually all above-ground plant parts of angiosperms. Recent studies revealed that such glands are widely distributed amongst the woody flora of the Brazilian cerrados. Plants bearing EFNs are visited day and night by a diverse assemblage of nectarivorous ants. In this review we present the data gathered during the past 15 years on the interaction between ants and EFN-bearing plants in cerrado vegetation. Field experiments indicate that ants visiting EFNs may prey or attack insect herbivores on the plant foliage, significantly reducing herbivore damage to leaves, buds or flowers. As a response, some herbivore species have developed an array of mechanisms to circumvent the ants' deterring capacities on their host plants. Ant-derived benefits to plants, however, may vary with the species of visiting ant, with the defensive tactics of the associated herbivores, as well as with the plant species. We discuss the results obtained for different cerrado plant species, and suggest some promising topics for future experimental investigation.

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Should I Eat or Should I Go? Acridid Grasshoppers and Their Novel Host Plants: Potential for Biotic Resistance

Plants ◽

10.3390/plants7040083 ◽

2018 ◽

Vol 7 (4) ◽

pp. 83 ◽

Cited By ~ 1

Author(s):

Alina Avanesyan

Keyword(s):

Host Plants ◽

Biotic Resistance ◽

Life Stage ◽

Experimental Studies ◽

Feeding Preference ◽

Insect Herbivores ◽

Plant Interactions ◽

Grasshopper Species ◽

Native Communities ◽

Introduced Plants

Novel, non-coevolved associations between introduced plants and native insect herbivores may lead to changes in trophic interactions in native communities, as well as to substantial economic problems. Although some studies in invasion ecology demonstrated that native herbivores can preferentially feed on introduced plants and therefore contribute to the biotic resistance of native communities to plant invasions, the role of acridid grasshoppers as native generalist insect herbivores is largely overlooked. This systematic review aimed to identify patterns of grasshopper feeding preferences for native versus introduced plants and, consequently, a potential of grasshoppers to provide biotic resistance of native communities. The analysis of 63 records of feeding preference trials for 28 North-American grasshopper species (retrieved from 2146 studies published during 1967–2017) has demonstrated a preference of grasshoppers for introduced host plants, and identified 12 preferred introduced plants with high or middle invasive ranks. A significant effect of the life stage (p < 0.001), but not the experimental environment, plant material, and measurements, on grasshopper preferences for introduced plants was also detected. Overall, results suggest a potential of acridid grasshoppers to contribute to the biotic resistance of native communities. The review also provides methodological recommendations for future experimental studies on grasshopper-host plant interactions.

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