Plant water stress and its consequences for herbivorous insects: a new synthesis
TL;DR: Both vote counting and meta-analysis found strong negative effects of water stress on the performance of sap-feeding insects at large and subguilds, respectively.
Abstract: Traditionally, herbivorous insects are thought to exhibit enhanced performance and outbreak dynamics on water-stressed host plants due to induced changes in plant physiology. Recent experimental studies, however, provide mixed support for this historical view. To test the plant-stress hypothesis (PSH), we employed two methods (the traditional vote-counting approach and meta-analysis) to assess published studies that investigated insect responses to experimentally induced water-deficit in plants. For insects, we examined how water deficit affects survivorship, fecundity, density, relative growth rate, and oviposition preference. Responses were analyzed by major feeding guild (sap-feeding insects and chewing insects) and for the subguilds of sap-feeders (phloem, mesophyll, and xylem feeders) and chewing insects (free-living chewers, borers, leaf miners, and gall-formers). Both vote counting and meta-analysis found strong negative effects of water stress on the performance of sap-feeding insects at large and...
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TL;DR: In this paper, the most important potential impacts of climate change on forest goods and services are summarized for the Boreal, Temperate Oceanic, TOC, Mediterranean, and mountainous regions.
1,831 citations
Cites background from "Plant water stress and its conseque..."
...Both, positive responses of insect populations, such as increased development rate, increased chance of survival and reproductive potential and negative effects like decreased growth rate and reduced fecundity are to be expected (Hunter, 2001; Bale et al., 2002; Huberty and Denno, 2004)....
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TL;DR: The keys to sustainable management of this pest include understanding linkages between the soybean aphid and other introduced and native species in a landscape context along with continued development of aphid-resistant varieties.
Abstract: The soybean aphid, Aphis glycines Matsumura, has become the single most important arthropod pest of soybeans in North America. Native to Asia, this invasive species was first discovered in North America in July 2000 and has rapidly spread throughout the northcentral United States, much of southeastern Canada, and the northeastern United States. In response, important elements of the ecology of the soybean aphid in North America have been elucidated, with economic thresholds, sampling plans, and chemical control recommendations widely adopted. Aphid-resistant soybean varieties were available to growers in 2010. The preexisting community of aphid natural enemies has been highly effective in suppressing aphid populations in many situations, and classical biological control efforts have focused on the addition of parasitoids of Asian origin. The keys to sustainable management of this pest include understanding linkages between the soybean aphid and other introduced and native species in a landscape context al...
511 citations
Cites background from "Plant water stress and its conseque..."
...Aphid injury could be exacerbated when plants are under intermittent drought stress (75, 130), but this specific injury has not yet been demonstrated with SBA....
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TL;DR: Insect and fungus feeding behaviour, affected tree part, and water stress severity are proposed as three important predictors of forest damage in drought conditions.
Abstract: In the context of climate change, the effects of prolonged or more severe droughts on pest and pathogen damage are a major concern for forest ecosystems. To date, there is great uncertainty about the direction, magnitude and sources of variation in responses to drought by insects and fungi. We report the outcomes of a meta-analysis of 100 pairwise comparisons of insect pest or pathogen damage to water-stressed and control trees from 40 publications. The type of feeding substrate for insects and fungi and the water stress severity emerged as the main factors influencing the level of damage in water-stressed trees. Overall, primary damaging agents living in wood caused significantly lower damage to the water-stressed trees compared with the control, whereas primary pests and pathogens living on foliage caused more damage to water-stressed trees, in all cases irrespective of stress severity. In contrast, damage by secondary agents increased with stress severity, which was best estimated by the ratio between the predawn leaf water potential in stressed trees and the xylem pressure inducing 50% loss in hydraulic conductance due to cavitation, a species-specific index of drought tolerance. Insect and fungus feeding behaviour, affected tree part, and water stress severity are therefore proposed as three important predictors of forest damage in drought conditions.
384 citations
Cites background from "Plant water stress and its conseque..."
...Generally, bark beetles and wood borers benefit from severe drought (Koricheva et al., 1998; Huberty & Denno, 2004)....
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...…be more susceptible to increased defence compounds in leaf tissues of water-stressed trees than sap feeders (e.g. aphids), phloem and cambium feeders as vascular tissues contain lower amount of allelochemicals (Mattson & Haack, 1987; Larsson, 1989; Awmack & Leather, 2002; Huberty & Denno, 2004)....
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...Several textbooks (Speight & Wainhouse, 1989; Wainhouse, 2005) and review articles (Mattson & Haack, 1987; Koricheva et al., 1998; Huberty & Denno, 2004) have listed examples of forest pest responses to drought....
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...Sap feeding insect would also benefit from this increase in nitrogen concentration (Huberty & Denno, 2004)....
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...In particular, sap suckers were considered as performing better on stressed trees in Koricheva et al. (1998), whereas Huberty & Denno (2004) found the opposite....
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TL;DR: Some of the existing understanding of autumn phenology is synthesized and five areas ripe for future climate change research are identified, to address common pitfalls in autumnal research and to support the conservation and management of vulnerable ecosystems and taxa.
Abstract: Autumn remains a relatively neglected season in climate change research in temperate and arctic ecosystems. This neglect occurs despite the importance of autumn events, including leaf senescence, fruit ripening, bird and insect migration, and induction of hibernation and diapause. Changes in autumn phenology alter the reproductive capacity of individuals, exacerbate invasions, allow pathogen amplification and higher disease-transmission rates, reshuffle natural enemy‐prey dynamics, shift the ecological dynamics among interacting species, and affect the net productivity of ecosystems. We synthesize some of our existing understanding of autumn phenology and identify five areas ripe for future climate change research. We provide recommendations to address common pitfalls in autumnal research as well as to support the conservation and management of vulnerable ecosystems and taxa.
362 citations
TL;DR: In this paper, the impact of the secheresse and the canicule on the populations of infra-forestiers in Europe was investigated. But, the authors only focused on the effect of the stress hydrique on the performance of the infra -forestiers, i.e., their ability to adapt to changes in the environment.
Abstract: Bien que la secheresse affecte directement la physiologie et la croissance des arbres, l'impact de facteurs secondaires (insectes ravageurs, pathogenes et feu) est souvent plus important que le stress original et peut conduire a la mortalite des arbres. En 2003, une secheresse et des vagues de chaleur ont provoque des degâts importants dans les forets d'Europe centrale et occidentale. Cet article rend compte de l'impact de la secheresse et de la canicule sur les populations d'insectes forestiers dans le contexte de cet evenement exceptionnel. Les observations des fluctuations de populations des principaux insectes ravageurs des forets europeennes sont presentees et discutees en regard des connaissances actuelles et des theories des interactions entre secheresse et insectes. Nous avons recherche les effets directs et indirects de la secheresse, respectivement sur les traits d'histoire de vie et au travers des modifications physiologiques induites chez les arbres hotes. Les insectes forestiers ont ete separes en 4 groupes : xylophages, phyllophages, mineuses et suceurs de seve. L'impact du stress hydrique a ete different selon la guilde consideree. Les xylophages ont ete positivement influences par le declin de la resistance de l'hote suite a un stress hydrique prolonge. Au contraire, les phyllophages ont mieux profite de l'augmentation de l'azote dans les tissus de la plante sous un stress hydrique modere ou intermittent. Des observations de terrains ont montre l'importance du statut hydrique du sol sur le niveau de resistance des arbres contre les attaques de ravageurs. En certains sites, la secheresse de 2003 a d'ailleurs mis en evidence des choix d'essences inappropries. Cette secheresse exceptionnelle peut nous donner des indications sur les impacts des evenements climatiques extremes. Cependant les observations des performances au niveau individuel ne permettent pas de predire a long terme les dynamiques des populations, lesquelles dependent d'interactions complexes au niveau local entre facteurs biotiques et abiotiques.
349 citations
Cites background from "Plant water stress and its conseque..."
...In contrast with bark beetles that are known to perform better under prolonged drought, most evidence suggest that leaf chewers are negatively affected by continuous or high water stress, while performances increase under moderate and intermittent water stress [6, 45, 60, 93]....
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...Finally, not all forest insects are immediately concerned by local drought conditions [62] and some, like aphids, must wait for the trees to recover better living conditions [45] to exploit the physiological modifications of the host due to drought....
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...Hence, when temperatures increase above the optimal, growth rates will start to decrease [7, 88] as well as fecundity and survival [5, 45, 48]....
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...Many reviews have looked at the direct or indirect impacts of drought on insects at the individual level [45,48,50,53,60]....
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...Leaf-chewers such as moths, sawflies and beetle, are often more susceptible to the increase in defense compounds in leaf tissues than sap-feeders (aphids) feeding on vascular tissues containing less of these compounds [45, 60]....
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References
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TL;DR: The evidence that N is scarce and perhaps a limiting nutrient for many herbivores, and that in response to this selection pressure, many Herbivores have evolved specific behavioral, morphological, physiological, and other adaptations to cope with and uti lize the ambient N levels of their normal haunts is examined.
Abstract: The nitrogen content of a plant is only one of the many plant characteristics that are vitally important to herbivores. However, because of its central role in all metabolic processes as well as in cellular structure and genetic coding, nitrogen is a critical element in the growth of all organisms. Supplementary N often elicits enhanced health, growth, reproduction, and survival in many organisms. This suggests that N is a limiting factor. Since N makes up a large portion of the earth's atmosphere (about 78%), the problem is not an absolute but a relative shortage-that is, a scarcity of usable or metaboliza ble N during critical growth periods (159, 328). Plants encounter shortages of inorganic nitrogen (nitrate and/or ammonium ions); animals experience shortages of organic nitrogen (specific proteins and/or amino acids). This article reviews and examines the evidence (a) that N is scarce and perhaps a limiting nutrient for many herbivores, and (b) that in response to this selection pressure, many herbivores have evolved specific behavioral, morphological, physiological, and other adaptations to cope with and uti lize the ambient N levels of their normal haunts. McNeill & Southwood (201) and White (328) have also reviewed these general questions. There fore, this review explores additional evidence and further develops the fundamental arguments. The review is organized into three major divisions. The first focuses on important sources of variation in plant N (seasonal and ontogenetic trends, different tissues and species, etc) because such variation may be the basis
3,251 citations
TL;DR: The role of turgor and sensitivity to stress, as well as growth adjustments during and after stress, are studied.
Abstract: OBSERVED RESPONSES TO WATER STRESS....... . . • . • • . . • . . . . • • . • • • • . . . . . • • • • • • • 523 Transpiration and Stomata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 523 Transpiration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523 Leaf temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 524 "Wall" resistance to transpiration.. . . ....... ......... .... . ...... 524 Sensitivity of stomata to stress. .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. 525 Mechanisms of stomatal response..... . . . . . . . . . . . . . . .. . . . . . . . . . .. 526 Aftereffect on stomata . . . . " . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . .. 528 CO, Assimilation in Light.. . . .. .. .. . . . .. .. . . .. . .. . . . . . .. .. . . . . ... 528 At the leaf level. . . . . .. .. . . . . . . .. .. .. .. . . . .. . .. .. .. .. .. .. . .... 528 At the subcellular level. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 532 Lichens, bryophytes, and ferns. . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . .. 533 Respiration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 534 Cell Growth and Cell Wal/ Synthesis..... . . .. . . . . . . . . . . . . . . . . . . . . . .. 535 Role of turgor and sensitivity to stress. . . . . . . . . . . . . . . . . . . . . . . . . .. 535 Growth adjustments during and after stress.... . . . . . . . . . . . . . . . . . . .. 537 Root growth and soil mechanical impedance.. . . . . .. . . . . . . . . . . . . . .. 539 Cel/ wall synthesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 540 Cel/ Division. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 540 Hormones and Ethylene.. . . . . . . . . . . .. . . .... . ... .... .. . ..... .... ... 541 Cytokinin activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 542 Abscissic acid. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 542 Ethylene and abscission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 543 Nitrogen Metabolism...... ........ .. ... . ... . .. .. .... . . .. ..... . . .. 544 Protein synthesis in vegetative tissue. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 544 Protein synthesis in seeds and mosses . . . . . . . . . . . . . . '. . . . . . . . . . . . .. 546 Nucleic acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 547 Proline and other amino acids.... . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. 548 Nitrogen fixation. . . . .. . .. .. . .. .. . . . . .. . .. . . . . . .. .. . . . .. .. . . .. 548 Enzyme Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 548
2,923 citations
TL;DR: The common slope of the fecundity/size relationship is close to 1 and this indicates that female size is a principal constraint on insect potential FECundity.
Abstract: The relationship between intra-specific variation in female body size and potential fecundity was investigated using the published literature on 57 oviparous species of Coleoptera, Diptera, Ephemeroptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera, and Trichoptera, and 11 species of larviparous Aphidina and Diptera. Female body sizes were converted to dry body weight. Variation in body weight and fecundity was expressed as percentage deviation from the median values. The increase in fecundity with body weight was similar in most taxa, with only a few important exceptions. The common regression for oviparous and larviparous species predicts a 0.95% increase in median fecundity for each 1% increase in dry body weight. The number of ovarioles (in 10 species of Coleoptera, Diptera, Hymenoptera and Orthoptera) also increased with body weight. The general relationship predicted a 0.81% increase in ovariole number for each 1% increase in dry body weight. The slope of ovariole number versus weight relationship was greater in species with many ovarioles than in species with few. The common slope of the fecundity/size relationship is close to 1 and this indicates that female size is a principal constraint on insect potential fecundity.
1,504 citations
TL;DR: Four sources of evidence are used to support the Plant Vigor Hypothesis that many herbivore species feed preferentially on vigorous plants or plant modules, as opposed to the Plant Stresshypothesis arguing that stressed plants ae beneficial to herbivores.
Abstract: Four sources of evidence are used to support the Plant Vigor Hypothesis that many herbivore species feed preferentially on vigorous plants or plant modules, as opposed to the Plant Stress Hypothesis arguing that stressed plants ae beneficial to herbivores. Evidence includes patterns of within-plant species utilization by galing insects where females select large plant modules and larvae survive better than on smaller modules. Independent evidence concerns patterns of herbivory between plant species habitually growing in rich resource environments which are heavily utilized, compared with low-resource adapted species. A third source of evidence is the forestry literature in which many cases are known of most attacks by insect herbivores occurring on young and open-grown trees
1,110 citations
TL;DR: It has been postulated that when plants are stressed by certain changes in patterns of weather they become a better source of food for invertebrate herbivores because this stress causes an increase in the amount of nitrogen available in their tissues for young herbivore feeding on them.
Abstract: It has previously been postulated that when plants are stressed by certain changes in patterns of weather they become a better source of food for invertebrate herbivores because this stress causes an increase in the amount of nitrogen available in their tissues for young herbivores feeding on them. And this may cause outbreaks of such phytophagous invertebrates. Evidence is now presented that a similar physiological mechanism appears to operate when a wide variety of apparently unrelated environmental factors impinge on plants or parts of plants in such a way as to perturb their metabolism. A broken branch, lightning strike, fire, nutrient deficiencies or an otherwise adverse site; all may have this effect. With the advent of modern man the available agencies increase and diversify to include pesticides, irradiation and air pollutants. One common metabolic response by plants to all such agents impinging on them seems to be equivalent to that found in senescing plant tissues — the breakdown and mobilization of nitrogen in soluble form away from the senescing/stressed tissues. Young herbivores which chance to feed on such stressed/senescing tissues have a greater and more readily available supply of nitrogen in their food than they would have had if feeding on unstressed plants. As a result many more of them survive, and there is an increase in abundance of their kind. Such increases may be quite localised and short-lived or more widespread and persistent, depending on the extent and duration of the stress experienced by the plants. And in the face of this improved nutrition and survival of the very young, predators and parasites seem to have only a minor influence on subsequent changes in abundance of their herbivorous prey. Another effect of increased mobilization of nitrogen in stressed plants is an increase in the quantity of the seed that they set. This has led to the conclusion that increased abundance of some species of birds at such times is due to a greater supply of seeds as winter food for recent fledglings. But it may be that the increased abundance is due to the synchronous increase in phytophagous insects providing a richer source of protein food for laying hens and growing nestlings.
1,013 citations