植物对虫害的超越补偿作用

阐述了超越补偿作用的本质及其生物学机制,并探讨了超越补偿在生理生态学及栽培学方面的意义,为超越补偿理论在农作物栽培和农、林害虫防治等方面的应用提供科学依据,以进一步提高农、林业生产的经济效益。     

GRF-induced feeding: Evidence for protein selectivity and opiate involvement

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 μl) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 μg/0.5 μl) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 μl) into the PVN. Microinjection of morphine (0, 1, 10, and 17 μg/0.5 μl) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.     

Difference in feeding behaviors of two invasive whiteflies on host plants with different suitability: implication for competitive displacement

In China, Bemisia tabaci Q (commonly known as biotype Q) has rapidly displaced B (commonly known as biotype B) in the past 6 years. The mechanisms underlying such phenomenon have been studied extensively in recent years; however, we have not come to a definitive conclusion yet. In the present study, the differences in host suitability between B and Q whitefly adults to five host plants (cabbage, cotton, cucumber, poinsettia, and tomato) were evaluated based on their respective feeding behaviors using a direct-current electrical penetration graph (DC-EPG) system. Pair-wise comparisons of B. tabaci B and Q feeding on each of the five host plants clearly indicate that Q feeds better than B on tomato, cotton and poinsettia, while B feeds better than Q on cabbage and cucumber. The EPG parameters related to both phloem and non-phloem phases confirm that cabbage and cucumber are best suited to B, while tomato, cotton, and poinsettia are best suited to Q. Our present results support the contention that host suitability and adult feeding behavior contribute to the competitive displacement of biotype B by biotype Q. The discrepancy between field (previous studies) and laboratory results (this study), however, suggests that 1) whitefly displacement is apparently contributed by multiple factors; and 2) factor(s) other than the host plant suitability may play a vital role in dictating the whitefly biotypes in the field.     

Soil biota and invasive plants

Interactions between plants and soil biota resist invasion by some nonnative plants and facilitate others. In this review, we organize research and ideas about the role of soil biota as drivers of invasion by nonnative plants and how soil biota may fit into hypotheses proposed for invasive success. For example, some invasive species benefit from being introduced into regions of the world where they encounter fewer soil-borne enemies than in their native ranges. Other invasives encounter novel but strong soil mutualists which enhance their invasive success. Leaving below-ground natural enemies behind or encountering strong mutualists can enhance invasions, but indigenous enemies in soils or the absence of key soil mutualists can help native communities resist invasions. Furthermore, inhibitory and beneficial effects of soil biota on plants can accelerate or decelerate over time depending on the net effect of accumulating pathogenic and mutualistic soil organisms. These 'feedback' relationships may alter plant-soil biota interactions in ways that may facilitate invasion and inhibit re-establishment by native species. Although soil biota affect nonnative plant invasions in many different ways, research on the topic is broadening our understanding of why invasive plants can be so astoundingly successful and expanding our perspectives on the drivers of natural community organization.     

Evolution in invasive plants: implications for biological control

Evidence is increasing that invasive plants can undergo rapid adaptive evolution during the process of range expansion. Here, we argue that evolutionary change during invasions will also affect plant-antagonist interactions and, thus, will have important implications for biological control programmes targeted at invasive plants. We explore how altered selection in the new range might influence the evolution of plant defence (resistance and tolerance) and life history. The degree to which such evolutionary processes might affect biological control efficacy is largely unexplored. We hope that, by testing the hypotheses that we propose here, a closer link can be established between biological control and evolutionary biology, to the benefit of both disciplines.     

Comparative feeding ecology of invasive Ponto-Caspian gobies

Invasions of Ponto-Caspian gobiid fishes are suspected to cause regime shifts in freshwater ecosystems. This study compared the trophic niche differentiations of Neogobius melanostomus and Ponticola kessleri in the upper Danube River using stable isotope analyses (δ¹³C and δ¹⁵N), gut content analyses and morphometric analyses of the digestive tract. Both species were identified as predacious omnivores with high dietary overlap and a generalistic feeding strategy. Amphipods (especially invasive Dikerogammarus spp.) contributed 2/3 to the index of food importance. δ¹⁵N-signatures of N. melanostomus revealed an ontogenetic diet shift and significantly exceeded those in P. kessleri by ~1.5‰, indicating a niche separation of half a trophic level. P. kessleri had shorter uncoiled intestinal tracts than N. melanostomus, indicating a narrower niche and adaptation to animal food. Trophic niches in both species expanded during the growth period with increasing intraguild predation and cannibalism in P. kessleri and increasing molluscivory in N. melanostomus. P. kessleri showed a higher degree of specialization and more stable feeding patterns across seasons, whereas N. melanostomus adapted its diet according to the natural prey availability. The feeding patterns of both species observed in the upper Danube River strongly differ from those in their native ranges, underlining their great plasticity. Both goby species consumed mainly other non-native species (~92% of gut contents) and seemed to benefit from previous invasions of prey species like Dikerogammarus villosus. The invasive success of gobies and their prey mirror fundamental ecological changes in large European freshwater ecosystems.     

Novel chemistry of invasive exotic plants

Of the many exotic plants that have become naturalized in North America, only a small proportion are pests capable of invading and dominating intact natural communities. In the present study, we tested the hypothesis that the most invasive plants are phytochemically unique in their new habitats. A comparison of exotic plant species that are highly invasive in North America with exotics that are widespread, but non-invasive revealed that the invasive plants were more likely to have potent secondary compounds that have not been reported from North American native plants. On average, the compounds found in the invasive plants were reported from fewer species, fewer genera and fewer families than those from non-invasive plants. Many of the unique phytochemicals from invasive plants have been reported to have multiple activities, including antiherbivore, antifungal, antimicrobial and allelopathic (phytotoxic) effects, which may provide the plants with several advantages in their new environments.     

Zoophytophagous pentatomids feeding on plants and implications for biological control

Zoophytophagous insects can feed on a variety of prey, plants and plant products. By studying the interactions between predatory hemipterans and plants harbouring the prey of these insects, scientists have started to establish two potential outcomes: (1) positive effects like the enhancement of their life history characteristics by acquiring plant contents; and (2) negative effects mediated by plant resistance to herbivores or prey ingesting secondary plant metabolites. Despite this research, there is a lack of information about the feeding sites of predatory hemipterans on their host plants, what they ingest from plants, and whether they cause damage to their host plants. The results presented here indicate that the xylem is one of the feeding sites of predatory hemipterans on plants. The dissection of predators that fed on plants with marked vessels and testing insects for the presence of Cry protein constitutively expressed in the cytoplasm of plant cells revealed that bugs are not able to acquire cytoplasm contents from the plant cell. In addition, we demonstrate that systemic insecticide circulating inside plants from soil applications contaminates these predators. Our results are discussed in the context of zoophytophagous feeding behaviour exhibited by predatory hemipterans and the use of systemic insecticides for the conservation of natural enemies. This interaction contradicts the concept of ecological selectivity obtained for natural enemies through the placement of systemic insecticide in the soil as a selective method of deploying chemical control and predatory hemipteran conservation within the integrated pest management framework.     

Interacting impacts of invasive plants and invasive toads on native lizards

The ecological impacts of an invasive species may be reduced by prior invasions if selective pressures imposed by earlier events preadapt the native biota to deal with the newer arrival. In northwestern Australia, invasion of the cane toad (Rhinella marina) kills many native predators if they ingest the highly toxic toads. Remarkably, the toads' defensive toxins (bufadienolides) are chemically similar to those of another invasive species: an ornamental plant from Madagascar, Bryophyllum spp. (Crassulaceae, mother-of-millions). Omnivorous lizards (bluetongue skinks, Tiliqua scincoides) are imperiled by the invasion of toads in northwestern Australia, but conspecifics from other areas of the continent (those where exotic plants were introduced and including areas where toads have yet to invade) are less affected because they exhibit higher physiological tolerance of toad toxins (and also of plant toxins). The willingness of captive bluetongues to consume both toads and these plants and the high correlation in the lizards' sensitivity to toad toxins versus plant toxins suggest that exotic plants may have imposed strong selection on the lizards' physiological tolerance of bufadienolides. As a result, populations of lizards from areas previously exposed to these alien plants may be preadapted to deal with the toxins of the more recent anuran invader.     

西花蓟马对花卉寄主颜色和挥发物的选择性

【目的】探究寄主颜色、挥发物在西花蓟马Frankliniella occidentalis(Pergande)寄主选择中的作用。【方法】采用叶碟法和Y型嗅觉仪法,测定了西花蓟马对4种寄主(黄花美人蕉、黄花槐、凤尾兰和夹竹桃)的颜色和挥发物的选择性。【结果】颜色选择中,西花蓟马最偏好夹竹桃的叶,黄花槐和黄花美人蕉的花;对叶、花总的偏好性次序为黄花美人蕉(花)、黄花槐(花)>凤尾兰(花)>黄花美人蕉(叶)、夹竹桃(叶)>黄花槐(叶)、凤尾兰(叶)、夹竹桃(花)。挥发物选择中,与空气对照时,西花蓟马都显著偏好寄主的叶和花;叶相互对照中,最为偏好黄花美人蕉和黄花槐;花相互对照中,最为偏好黄花美人蕉;叶与花对照时,西花蓟马对花的偏好性显著强于叶,其对寄主叶、花挥发物总的偏好性为黄花美人蕉(花)>黄花槐(花)>凤尾兰(花)>夹竹桃(花)>黄花美人蕉(叶)≥黄花槐(叶)、夹竹桃(叶)>凤尾兰(叶),与其对颜色的偏好性并不完全一致。【结论】寄主颜色和挥发物对西花蓟马的寄主选择有着重要影响,西花蓟马不仅对不同寄主的颜色和挥发物有不同偏好性,对寄主不同器官的颜色和挥发物也具有不同的偏好性。     

Management of invasive plants through ecological resistance

Despite debates on the real impact of plant invasion on native biodiversity, there remain many situations where exotic invasive plants must be managed and habitats restored. Restoration practices that build on plant community assembly principles could be useful to delay or prevent re-invasion after control, but there are still few syntheses of the biodiversity theory, ecological mechanisms and experimental evidence relevant to invasive plant management, possibly delaying applications. To provide such a synthesis, we review current knowledge on three key determinants of invasion success: biotic resistance, abiotic constraints, and propagule pressure. We elaborate on the ecological mechanisms at play for each determinant and emphasize, using case studies, their relevance for invasive plant management and ecological restoration. We find evidence that restoring a plant cover can enhance invasion resistance, but the challenge for both research and field applications is to understand how multiple determinants interact in relation to species traits in the fields. Failure to recognize these interactions and their effect on community assembly processes may explain some of the mixed species responses observed. While we need control and restoration case studies with local species at different sites, the development of a coherent, dynamic and adaptive framework around biotic/ecological resistance will have to go beyond the idiosyncrasy of the many species and systems being tested. Emphasizing the functional diversity of the restored community seems a promising approach when facing potentially multiple invaders and/or fluctuating abiotic conditions.     

Pre-nesting feeding selectivity of Pink-footed Geese Anser brachyrhynchus in artificial grasslands

The pre-nesting feeding ecology of Pink-footed Geese Anser brachyrhynchus was studied in southern Iceland in April and May 1989–1992. Extensive surveys showed that prior to movement to their nesting areas in the interior, Pink-footed Geese fed mainly on intensively managed grasslands of the southern lowlands. Faecal analysis showed that geese feeding in hayfields foraged almost exclusively on the most commonly reseeded species, Timothy grass Phleum pratense , which made up the majority (41% by number of green shoots) of new growth in studied hayfields. Dropping counts, as an indicator of goose use, were highly significantly correlated in all years with density of growing Phleum shoots in individual field units. Geese showed a response in feeding patterns to changes in Phleum density as a result of reseeding patterns. Analysis of forage quality in 1991 showed that Phleum shoots had a higher protein content than all other grasses present in hayfields, with the exception of Deschampsia caespitosa. The latter species showed similar levels of protein, but its tussocky nature precluded effective grazing by the geese. Phleum was similar in fibre content to other common grasses. Based on removal of tagged plants, geese grazed predominantly on the youngest leaves of Phleum , which also had higher protein content and lower fibre than older leaves and attached dead leaves, which were rarely taken by geese. Geese grazed shorter length classes of youngest leaves, which showed higher protein content than longer, older terminal leaves. Recently created grassland habitat has increased the opportunities for female geese to supplement their reserves during the crucial prelude to clutch initiation by selecting the highest quality plant species and the most nutritious parts of that forage.     

云斑天牛对补充营养寄主的选择性

通过林间调查和室内选择性试验,研究云斑天牛Batocera horsfieldi(Hope)成虫在补充营养阶段对多种寄主植物的选择性。林间调查结果表明,云斑天牛成虫对法国冬青(V.awabuki)和光皮桦(B.luninifera)有较强的嗜食性,林间最高取食选择率分别为100%和92.4%。利用"Y"型嗅觉仪测定云斑天牛成虫对法国冬青、核桃(Jugians regia L.)、光皮桦和杨树(Populus tomentosa)等寄主挥发物的行为反应,生测结果与林间调查及室内选择结果一致,法国冬青和光皮桦的挥发物对云斑天牛引诱效果明显,并且枝条挥发物引诱力高于叶片挥发物,引诱效果最佳的组合为:采用蒸馏法,用二氯甲烷提取的冬青枝叶粗提物;采用浸提法,用乙醚提取的冬青和光皮桦枝叶粗提物和二氯甲烷分别提取的冬青枝和叶的粗提物。     

Nectar feeding by wandering spiders on cotton plants

Spiders are assumed to be strictly carnivorous in assessments of their nutritional and energetic requirements, their habitat preferences, and their potential as biological control agents. However, members of Salticidae (jumping spiders), Thomisidae (crab spiders), and the fast-moving Miturgidae, Anyphaenidae, and Corinnidae, all non-webbuilding wandering spiders, have been observed at floral and extrafloral nectaries of plants, presumably feeding on nectar. To test spiders in the field for nectar feeding, we used a cold anthrone test to detect the presence of ingested fructose, a plant-derived sugar, in wandering spiders occupying cotton plants (Gossypium hirsutum L.), which have floral and extrafloral nectaries. Field collections focused on three ecologically similar, highly active nocturnal spiders: Cheiracanthium inclusum (Hentz) (Miturgidae), Hibana futilis (Banks), and H. arunda (Platnick) (Anyphaenidae). During 2002 and 2003, 27 and 21%, respectively, of all field-collected adults and subadults tested positive for fructose, indicating consumption of extrafloral nectar. In both years, significantly more females were positive than males (38 versus 11% in 2002; 26 versus 12% in 2003). Immatures tested positive at a lower rate than adults (3 and 13%, respectively). Smaller numbers of spiders in the Lycosidae, Oxyopidae, and Thomisidae were also tested. Among the thomisids, 38% in 2002 and 41% in 2003 tested positive for fructose. None of the lycosids (wolf spiders) tested positive; two of nine oxyopids (lynx spiders) did test positive. Oxyopidae is new to the list of nectarivorous spiders. These results suggest that nectarivory is common for foliage wandering spiders and may contribute to fitness.     

Distribution models of invasive plants over-estimate potential impact

Habitat suitability models developed for non-native, invasive species often implicitly assume that projected invasion risk equates to risk of impact. I aim to test to what extent this assumption is true by comparing commonly-used invasive plant distribution datasets to abundance records. I compared herbarium occurrence records (downloaded from an online database) and regional occurrence records (compiled from individual states) to abundance estimates collected from over 300 invasive plant experts for 9 invasive species in the western U.S. I also created habitat suitability models (HSMs) using these datasets and compared the areas of predicted suitability. Sixty percent of the time, herbarium occurrences were located in regions where the species was rare enough to be undetected by experts, while only 26 % coincided with locations identified as having high abundance. Regional occurrences were located in areas where the species was not detected 32 % of the time, and on high abundance 42 % of the time. HSMs based on herbarium records encompassed 89 % of land area at risk of abundance, but overestimated the area of estimated risk (27–46 % false positive rate). HSMs based on regional occurrences had a smaller false positive rate (22–31 %), but encompassed only 67–68 % of area suitable for abundance. Herbarium records are strongly skewed towards locations with low invasive plant abundance, leading to invasion risk models that vastly overestimate abundance risk. Models based on occurrence points should be interpreted as risk of establishment only, not risk of abundance or impact. If HSMs aim to be more management relevant, invasion risk models should include abundance as well as occurrence.     

我国对3种外来入侵植物的利用

主要介绍了我国在防治生物入侵时,对水葫芦、紫茎泽兰、互花米草等入侵植物的综合利用.     

Factors affecting feeding selectivity in herbivorous Ascoglossa (Mollusca: Opisthobranchia)

Food preference and growth were investigated for 13 Florida Ascoglossa. In about half of the species investigated there was a significant preference for one particular food plant. Growth rates were generally highest on the preferred food, and also, species feeding on ephemeral food plants had higher growth rates than species feeding on annual or perennial food plants. A correlation exists between ascoglossan foot width and filament diameter of food plants in species feeding on filamentous algae, and in all species between length and/or diameter of leading radular tooth and size of filaments, utricles or cells of food plants. There was no correlation between food preference and caloric content or ash content of food plants. Thus, structure of food plants seems to be the most important factor in food recognition and preference in Ascoglossa.