Angiosperm to Gymnosperm host‐plant switch entails shifts in microbiota of the Welwitschia bug,Probergrothius angolensis (Distant, 1902)

The adaptation of herbivorous insects to new host plants is key to their evolutionary success in diverse environments. Many insects are associated with mutualistic gut bacteria that contribute to the host's nutrition and can thereby facilitate dietary switching in polyphagous insects. However, how gut microbial communities differ between populations of the same species that feed on different host plants remains poorly understood. Most species of Pyrrhocoridae (Hemiptera: Heteroptera) are specialist seed‐feeders on plants in the family Malvaceae, although populations of one species, Probergrothius angolensis, have switched to the very distantly related Welwitschia mirabilis plant in the Namib Desert. We first compared the development and survival of laboratory populations of Pr. angolensis with two other pyrrhocorids on seeds of Welwitschia and found only Pr. angolensis was capable of successfully completing its development. We then collected Pr. angolensis in Namibia from Malvaceae and Welwitschia host plants, respectively, to assess their bacterial and fungal community profiles using high‐throughput amplicon sequencing. Comparison with long‐term laboratory‐reared insects indicated stable associations of Pr. angolensis with core bacteria (Commensalibacter, Enterococcus, Bartonella and Klebsiella), but not with fungi or yeasts. Phylogenetic analyses of core bacteria revealed relationships to other insect‐associated bacteria, but also found new taxa indicating potential host‐specialized nutritional roles. Importantly, the microbial community profiles of bugs feeding on Welwitschia versus Malvaceae revealed stark and consistent differences in the relative abundance of core bacterial taxa that correlate with the host‐plant switch; we were able to reproduce this result through feeding experiments. Thus, a dynamic gut microbiota may provide a means for insect adaptation to new host plants in new environments when food plants are extremely divergent.     

The fatty acid compositions of predator Piocoris luridus （Heteroptera： Lygaeidae） and its host Monosteria unicostata （Heteroptera： Tingidae） reared on almond

The changes in fatty acid compositions during nutritional interaction among almond Amygdalus communis Linnaeus （Rosales： Rosaceae） （host plant）, lacebug Monosteria unicostata （Mulsant and Rey） （Heteroptera： Tingidae） and its predator Piocoris luridus Fieber （Heteroptera： Lygaeidae） were determined by gas chromatography and gas chromatography-mass spectrometry analyses. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. Unlike the general observations for virtually most terrestrial insects, arachidonic and eicosapentaenoic acids were detected in high proportions of phospholipid fractions in both insects, especially in P. luridus. Also the almond tissues provide very little oleic acid to the herbivore diet, yet both insect species developed high proportions of this component. Our data reveals instances of specific accumulation of fatty acid biosynthesis, elongation/desaturation, and not incorporating selected fatty acids into cellular lipids.     

Niche use patterns among some Stenodemini (Heteroptera: Miridae) of limestone grassland,and an investigation of the possibility of interspecific competition between Notostira elongata Geoffroy and Megaloceraea recticornis Geoffroy

Summary It was suggested in a previous paper that mortality patterns in two species of Stenodemini (M. recticornis and N. elongata) could be explained by interspecific competition (Gibson 1976a)Such competition would have been generated by seasonal changes in the foodplants used by the two species resulting in both species using virtually the same range of plants at one time of year.As with a number of phytophagous insects (McNeill and Southwood 1978) many changes in foodplant use could be explained by differential seasonal changes in nitrogen content of the plant part (leaves) that the bugs were using in different plant species. Each bug had an ideal food nitrogen range which it used whenever possible. Lack of fit to this mechanism could often be explained by defensive chemistry and physical properties of some grass species.Although the total bug population was taking under 1% of the area's primary production, a potential refuge foodplant for one bug species was very heavily eaten where it was rare, and behavioural interference between bug species suggested that space to feed in was a limiting resource.Laboratory and semi-field culture experiments showed that the presence of one bug species adversely affected the growth and/or survival of the other, although the outcome of competition was different to that in the field, probably due to the different relative and absolute densities used.Although one cannot be completely certain without field manipulation experiments, it is extremely likely that interspecific competition was occurring and could be stabilised by the losing species (N. elongata) having a refuge generation.Competition between stenodemine species on the study area could usually be avoided by separation along a number of resource axes e.g. foodplant species, plant part, nitrogen level of food or emergence timing. In the present circumstance, a particular combination of bug and plant species in the area has forced one species pair into overlap. It should be possible to predict the guild structure and competition relations in other areas from this.     

Grass flowers in the diet of Megaloceraea recticornis (Heteroptera: Miridae): plant structural defences and interspecific competition reviewed

ABSTRACT. 1. Megaloceraea recticornis (Geoffroy) is the most common of seven species of stenodemine bugs on a calcareous grassland in Oxfordshire. Previous work indicated that it competed with a related species, Notostira elongata Geoffroy, by behavioural interference at the feeding site. Both bugs were thought to eat only grass leaves.
2. The importance of grass flowers in the diet of M.recticornis was studied in the laboratory. This bug completes its development only by feeding on grass flowers; grass leaves do not suffice.
3. M.recticornis is unusual among phytophagous insects in that its later instars can eat flowers of the grass Brachypodium pinnatum L. The hard lemma and palea surrounding these flowers inhibit feeding by young bugs. The age of the flowers also affect bug feeding success.
4. The result of field experiments, which previously appeared to show competition between M.recticornis and N.elongata , are discussed in the light of the present findings. It now seems that M.recticornis may not suffer from competition with N.elongata.     

Flowers for better pest control? The effects of apple orchard ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), their predators and the canopy insect community

Effects of habitat diversification through ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), woolly apple aphid (Eriosoma lanigerum [Haussmann]) (Hemiptera: Aphididae), their insect natural enemies and the most abundant canopy insects (in the Neuroptera, Fulgoromorpha, Cicadomorpha, Heteroptera, Coleoptera and Formicidae) were studied in an apple orchard over 6 years. The composition and diversity of the main functional groups of canopy insects was also compared. Habitat diversification was achieved by changing ground cover conditions within the orchard. In the treatment termed FLOWER, annual and/or perennial flowering plants were sown in the alleys of an apple orchard. Other ground cover treatments were weed-free bare ground (termed BAREgr) and orchard plots with alleys of mowed grass (termed GRASS), which served as control treatments. We found no evidence that habitat diversification enhanced the biological control of green apple aphids compared to the control treatments. However, the greater plant cover in FLOWER resulted in increased woolly apple aphid infestations compared to BAREgr or GRASS. The abundance of various beneficial or neutral canopy insects – Chrysoperla carnea sensu lato (Neuroptera, Chrysopidae) adults, leafhoppers and treehoppers, planthoppers, herbivorous (non-apple feeding) beetles, dipterans and parasitoid wasps – also increased in FLOWER as compared to BAREgr, with GRASS being intermediate between the other treatments. Significantly greater species richness and diversity was found in FLOWER than in BAREgr for most of the functional groups sampled, although the number of predacious insect species was similar among treatments. The composition of the studied functional groups showed high similarity in FLOWER and GRASS, but these treatments were different from BAREgr. Effects of groundcover management on the dominant insect species are discussed.     

Health food versus fast food: the effects of prey quality and mobility on prey selection by a generalist predator and indirect interactions among prey species

1. In order to understand the relative importance of prey quality and mobility in indirect interactions among alternative prey that are mediated by a shared natural enemy, the nutritional quality of two common prey for a generalist insect predator along with the predator's relative preference for these prey was determined. 2. Eggs of the corn earworm Helicoverpa zea (Lepidoptera: Noctuidae) were nutritionally superior to pea aphids Acyrthosiphum pisum (Homoptera: Aphididae) as prey for big‐eyed bugs Geocoris punctipes (Heteroptera: Geocoridae). Big‐eyed bugs survived four times as long when fed corn earworm eggs than when fed pea aphids. Furthermore, only big‐eyed bugs fed corn earworm eggs completed development and reached adulthood. 3. In two separate choice experiments, however, big‐eyed bugs consistently attacked the nutritionally inferior prey, pea aphids, more frequently than the nutritionally superior prey, corn earworm eggs. 4. Prey mobility, not prey nutritional quality, seems to be the most important criterion used by big‐eyed bugs to select prey. Big‐eyed bugs attacked mobile aphids preferentially when given a choice between mobile and immobilised aphids. 5. Prey behaviour also mediated indirect interactions between these two prey species. The presence of mobile pea aphids as alternative prey benefited corn earworms indirectly by reducing the consumption of corn earworm eggs by big‐eyed bugs. The presence of immobilised pea aphids, however, did not benefit corn earworms indirectly because the consumption of corn earworm eggs by big‐eyed bugs was not reduced when they were present. 6. These results suggest that the prey preferences of generalist insect predators mediate indirect interactions among prey species and ultimately affect the population dynamics of the predator and prey species. Understanding the prey preferences of generalist insect predators is essential to predict accurately the efficacy of these insects as biological control agents.     

Structure of aquatic assemblages of Coleoptera and Heteroptera in relation to habitat type and flood dynamic structure

The abundance and taxonomic composition of the aquatic insect fauna were investigated, with focus on adult water bugs, water beetles and water scavenger beetles (Heteroptera: Nepomorpha and Gerromorpha, and Coleoptera: Hydradephaga and Hydrophilidae) in two different freshwater habitats: (1) a periodically flooded area of the Special Zoological Reserve in Kopa?ki rit Nature Park, Croatia; and (2) melioration canals in the wider area of the Nature Park during 2005. Aquatic insects are generally abundant in various water systems, including floodplains that are exposed to water level fluctuations. Our aims were (1) to determine abundance and species richness in relation to habitat type; (2) to determine the influence of high flood peaks and oscillations during high water levels on the diversity of aquatic Coleoptera and Heteroptera in the flooded area; and (3) to identify characteristic species associated with each habitat type. We collected 71 species; 41 were captured at canals and 64 at the flooded area. Diversity of the two habitat types varied depending on the months but there were remarkable differences in species pool and their abundance. Both high and low water levels as well as oscillations during high water levels had major influence on species assemblages at the flooded area. Diversity of aquatic Coleoptera and Heteroptera was higher when the water level decreased after high water level peaks. A total of 11 species fulfilled the criteria for specificity and were sufficiently abundant to be suitable species characteristic for these two habitats. A higher proportion of significant characteristic species was present in the flooded area than in the canals. The presence of two Red List species of water beetles (Graphoderus bilineatus De Geer, 1774 and Berosus geminus Reiche et Saulcy, 1856) and nine significant characteristic species at the flooded area clearly indicates that the contribution of floodplains in maintaining freshwater biodiversity is not only important regionally but also at the international level. Also, our results suggest that the power of high water levels is an important factor that can be used in analyses on aquatic Coleoptera and Heteroptera assemblages, showing the uniqueness of large floodplain areas.     

Differential effects of foliar endophytic fungi on insect herbivores attacking a herbaceous plant

Foliar endophytic fungi appear to be ubiquitous in nature, occurring in a very wide range of herbaceous plants. However, their ecological role within forbs is very poorly known and interactions with foliar-feeding insects virtually unexplored. In this study, leaves of Cirsium arvense were infected with different combinations of endophyte fungi that had been previously isolated from this plant species. Two months later, leaf material was fed to larvae of a generalist insect, Mamestra brassicae, and adults of a specialist feeder, Cassida rubiginosa. Endophytes had different effects on the two insects; one species, Chaetomium cochliodes, reduced growth of M. brassicae but increased feeding by C. rubiginosa. Another species, Cladosporium cladosporioides, increased beetle feeding also, but had no effect on M. brassicae. Interactions were also seen between fungal species and dual infection with C. cladosporioides and Trichoderma viride greatly reduced beetle feeding. It is concluded that endophytes have significant effects on foliar feeding insects that differ with degree of specialism of the herbivore. We suggest that these effects are due to chemical changes in the host, brought about by fungal infection. These fungi have received remarkably little attention in the study of insect–plant interactions and yet could be important determinants of insect growth and even population dynamics.     

How granivorous Coreus marginatus (Heteroptera: Coreidae) recognises its food

Phytophagous insects select their host plant using multiple sensory modalities including vision, olfaction, gustation and mechanoreception. In the laboratory, we investigated the role of vision, olfaction and gustatory sense in the perception of cues released by seeds of different plant species in granivorous Coreus marginatus (Heteroptera: Coreidae). Juvenile insects were put in a choice arena and offered with different seeds on which they feed naturally (Polygonum, Rumex) and seeds which are not their natural food (Stellaria). Individual bugs were manipulated in one of three ways: 1. blackened compound eyes, 2. coated sensillae on antennae, 3. coated tip of labial pouch. Control individuals were not manipulated. The behaviour of each bug was observed for 12 h. Control bugs fed for a significantly longer time than manipulated ones. Individuals with any senses impaired fed on Stellaria, whereas, the control individuals ignored it. The results suggested that seed selection requires information from all three sensory organs: compound eyes, antennae and sensillae on labial pouch. Further research is required to unravel the importance of each sense for the seed selection.     

When did the ancestor of true bugs become stinky? Disentangling the phylogenomics of Hemiptera–Heteroptera

The phylogeny of true bugs (Hemiptera: Heteroptera), one of the most diverse insect groups in terms of morphology and ecology, has been the focus of attention for decades with respect to several deep nodes between the suborders of Hemiptera and the infraorders of Heteroptera. Here, we assembled a phylogenomic data set of 53 taxa and 3102 orthologous genes to investigate the phylogeny of Hemiptera–Heteroptera, and both concatenation and coalescent methods were used. A binode-control approach for data filtering was introduced to reduce the incongruence between different genes, which can improve the performance of phylogenetic reconstruction. Both hypotheses (Coleorrhyncha + Heteroptera) and (Coleorrhyncha + Auchenorrhyncha) received support from various analyses, in which the former is more consistent with the morphological evidence. Based on a divergence time estimation performed on genes with a strong phylogenetic signal, the origin of true bugs was dated to 290–268 Ma in the Permian, the time in Earth's history with the highest concentration of atmospheric oxygen. During this time interval, at least 1007 apomorphic amino acids were retained in the common ancestor of the extant true bugs. These molecular apomorphies are located in 553 orthologous genes, which suggests the common ancestor of the extant true bugs may have experienced large-scale evolution at the genome level.     

Die rolle der speichelsekrete im wechselverhaltnis zwischen tier und Nahrungspflanze bei homopteren und heteropteren

Zusammenfassung Im Speichel der Rhynchoten gibt es verschiedene Verdauungsenzyme, die eine weitgehende Anpassung hinsichtlich der Art der Nahrung aufweisen und bei der Verdauung wichtig sind. Zugleich gibt es im Rhynchotenspeichel auch Pflanzenwuchs hemmende Stoffe Auxine und Viren, die alle Krankheitszustände bei den Nahrungspflanzen verursachen welche ihrerseits die Lebensbedingungen der Schädlinge fördern.

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Summary The above article is a short survey of the relation between the salivary secretions of the Hemiptera and their host plants.In analyses of the composition secretions in the salivary glands of phytophagous Homoptera and Heteroptera, the most extensive work has been done on the digestive enzymes. Proteases, amylases, saccharase, maltase, pectinase and lipase have been detected, but most commonly only 2–3 of these occurs in any one species. An adaptation of the enzyme complement to the diet is evident and in this respect the feeding site used by the insect is especially decisive to the enzyme composition of the saliva. Proteases and amylases occur in the saliva of mesophyll feeders, but are absent in phloem feeders, for which they are useless because, from the insect's point of view, the food is already digested. The adaptation of the salivary enzymes to the nature of the food seems to be largely inherited for a diet containing nothing but sucrose does not induce adaptive changes in the enzyme content of the salivary glands. By contrast, papain seems to be transferred from a synthetic food to the salivary glands.The disease symptoms caused in plants by the salivary toxins of Homoptera and Heteroptera have many similarities to those caused by abnormal amounts of growth hormones. Indole-tri-acetic acid has been detected in extracts of crushed aphids and leafhoppers, although no growth stimulating hormones have been detected in salivary glands dissected from several heteropterous bugs and one aphid. On the contrary, substances inhibiting plant growth exist in the salivary glands of many Heteroptera and in at least one aphid. In some experiments with a heteropterous bug, indole-triacetic was observed to have been transferred from a synthetic diet to the salivary glands. It seems possible that auxins, enzymes and other phytotoxic substances occurring in the salivary glands of insects may at last in some cases originate from the host plant and are not produced by the insect.The salivary enzymes without doubt play an important role in the digestion of the insects secreting them. They are important also in the differentation of Homoptera and Heteroptera to different modes of life. The auxins or auxin inhibitors, as wel as all phytotoxic substances in the salivary glands of Homoptera and Heteroptera are significant for these animals by changing the physiological state of the host plant in such a direction that its suitability as a source of food increases.

     

THE COMPOSITION AND BEHAVIOUR OF SOME MIXED-SPECIES BIRD FLOCKS IN SARAWAK

Mixed-species flocks of birds feeding on insects were observed mainly in forest in Sarawak at a time of year when insect availability is known to be near its annual minimum. The approximate individual and specific composition of most flocks were noted. Twenty-six species occurring in 25% of flocks were regarded as occasional members, 15 species occurring in 40% of flocks being classed as regular members. Recording species' feeding behaviour was the main priority and few observations of inter- and intra-specific interactions within the flock, horizontal distribution or vertical stratification were made, although the last proved to be of potential significance. From the analysis of feeding behaviour two groups of species were distinguished. The larger group contained those usually having an exclusive common feeding pattern and showing very little overlap with the other such species. Fewer species used a wide range of feeding methods, all of which were shared with other species, but the least overlap was with other members of the same category. The observed composition of these flocks, in terms of regular members, might be interpreted as ensuring a low level of inter-specific competition and it is suggested that the less specialized foragers may occur in the flocks by utilizing the ‘gaps’ between, and absences of, specialists. The possible advantages of membership of mixed-species flocks are briefly considered and the likelihood of the selective advantage in any situation being the result of a balance of factors emphasized. In the apparent absence of regular potential predators the existence of these flocks is interpreted primarily as an adaptation for augmenting available insect food, particularly perhaps at critical times of year, by flushing insects as a result of the foraging activities of flock members. It is suggested that the varied responses of insects on being disturbed coupled with the different and fairly specialized feeding techniques of the birds could ensure benefit for all members of the flock.     

Effects of elevated atmospheric CO<Subscript>2</Subscript> on the nutritional ecology of C<Subscript>3</Subscript> and C<Subscript>4</Subscript> grass-feeding caterpillars

It is plausible that the nutritional quality of C₃ plants will decline more under elevated atmospheric CO₂ than will the nutritional quality of C₄ plants, causing herbivorous insects to increase their feeding on C₃ plants relative to C₄ plants. We tested this hypothesis with a C₃ and C₄ grass and two caterpillar species with different diet breadths. Lolium multiflorum (C₃) and Bouteloua curtipendula (C₄) were grown in outdoor open top chambers at ambient (370 ppm) or elevated (740 ppm) CO₂. Bioassays compared the performance and digestive efficiencies of Pseudaletia unipuncta (a grass-specialist noctuid) and Spodoptera frugiperda (a generalist noctuid). As expected, the nutritional quality of L. multiflorum changed to a greater extent than did that of B. curtipendula when grown in elevated CO₂; levels of protein (considered growth limiting) declined in the C₃ grass, while levels of carbohydrates (sugar, starch and fructan) increased. However, neither insect species increased its feeding rate on the C₃ grass to compensate for its lower nutritional quality when grown in an elevated CO₂ atmosphere. Consumption rates of P. unipuncta and S. frugiperda were higher on the C₃ grass than the C₄ grass, the opposite of the result expected for a compensatory response to the lower nutritional quality of the C₄ grass. Although our results do not support the hypothesis that grass-specialist insects compensate for lower nutritional quality by increasing their consumption rates more than do generalist insects, the performance of the specialist was greater than that of the generalist on each grass species and at both CO₂ levels. Mechanisms other than compensatory feeding, such as increased nutrient assimilation efficiency, appear to determine the relative performance of these herbivores. Our results also provide further evidence against the hypothesis that C₄ grasses would be avoided by insect herbivores because a large fraction of their nutrients is unavailable to herbivores. Instead, our results are consistent with the hypothesis that C₄ grasses are poorer host plants primarily because of their lower nutrient levels, higher fiber levels, and greater toughness.     

Carotenoids of hemipteran insects,from the perspective of chemo-systematic and chemical ecological studies

Carotenoids of 47 species of insects belonging to Hemiptera, including 16 species of Sternorrhyncha (aphids and a whitefly), 11 species of Auchenorrhyncha (planthoppers, leafhoppers, and cicadas), and 20 species of Heteroptera (stink bugs, assassin bugs, water striders, water scorpions, water bugs, and backswimmers), were investigated from the viewpoints of chemo-systematic and chemical ecology. In aphids, carotenoids belonging to the torulene biosynthetic pathway such as β-zeacarotene, β,ψ-carotene, and torulene, and carotenoids with a γ-end group such as β,γ-carotene and γ,γ-carotene were identified. Carotenoids belonging the torulene biosynthetic pathway and with a γ-end group were also present in water striders. On the other hand, β-carotene, β-cryptoxanthin, and lutein, which originated from dietary plants, were present in both stink bugs and leafhoppers. Assassin bugs also accumulated carotenoids from dietary insects. Trace amounts of carotenoids were detected in cicadas. Carotenoids of insects belonging to Hemiptera well-reflect their ecological life histories.     

The influence of host plant diversity and food quality on larval survival of plant feeding heteropteran bugs

Abstract. 1. In a laboratory experiment, the influence of host plant diversity and food quality, in terms of nitrogen content, on the larval survival of two oligophagous bug species (Heteroptera, Miridae: Leptopterna dolobrata L., Notostira erratica L.) was investigated. Both species are strictly phytophagous and capable of feeding on a wide range of grass species. Moreover, they typically change their host plants during ontogenesis; it has been suggested that this behaviour is a response to the changing protein content of the hosts.
2. To investigate the importance of host plant diversity for these insects, the development of insects reared on grass monocultures was compared with that on mixtures of four grass species. In addition, the host grasses were grown under two nitrogen regimes to test whether nitrogen content is the key factor determining host plant switching.
3. Both species had a significantly higher survival rate when feeding on several host plants but only L. dolobrata showed a significant response to food nitrogen content. Furthermore, there was no correlation between the nitrogen content of the host plants and the survival rate of N. erratica larvae.
4. The study suggests that at least some Stenodemini need a variety of host plants during larval development but that the level of host plant nitrogen is not the main factor responsible for the observed diversity effect.     

No competition for resources between two tick species at their parapatric boundary

Summary Aponomma hydrosauri and Amblyomma limbatum are tick species with the same major host species, the sleepy lizard Trachydosaurus rugosus, but parapatric distributions in South Australia. Near Mt. Mary one species is abruptly replaced by the other over one kilometre. There is substantial overlap in feeding sites on the hosts. This suggested that interspecific competition, during feeding, may be an important mechanism preventing further overlap of the distributions of the two species. However, in the overlap region there was no resource shortage, and each species infested hosts independently of the other species. Also in laboratory experiments at the highest densities encountered in the field, larvae and nymphs of each species attached and engorged equally well whether alone or mixed with the other species. These data refuted the, hypothesis of interspecific competition between the two species while feeding.     

Colonization of eucalypts in New Zealand by Australian insects

Since the 1860s, Australian insects have steadily colonized eucalypts in New Zealand. The rate of colonization has increased markedly over the last two decades. This increase may be related to increasing trade between the two countries. Currently there are 26 specialist eucalypt insect species and approximately 31 polyphagous insect species that can feed on Eucalyptus in New Zealand. The specialist eucalypt insects endemic to Australia have generally caused more damage than polyphagous or native insects. Eucalypt‐specific insects are dominated by sap sucking bugs, particularly psyllids, and defoliating Coleoptera and Lepidoptera. In some cases the major insect pest species have been those that are only occasional pests in Australia, for example Gonipterus scutellatus, Ctenarytaina eucalypti, Eriococcus coriaceus and Phylacteophaga froggatti. Some important insect pests have been rare, or even not described from Australia, prior to their appearance as a pest in New Zealand, for example Paropsis charybdis and Ophelimus eucalypti. Invading eucalypt insects are more likely to establish in the Auckland region than anywhere else in New Zealand.     

Relationship of different feeding groups of true bugs (Hemiptera: Heteroptera) with habitat and landscape features in Pannonic salt grasslands

Eastern European grasslands are still inhabited by a rich arthropod fauna, but the drivers and mechanisms influencing their communities have to be understood to ensure their future survival. Heteroptera communities were studied in 20 plot-pairs in Pannonic salt steppe–salt marsh mosaics in Hungary. The effects of vegetation characteristics, landscape diversity and the proportion of surrounding grasslands on the composition, species richness and abundance of different feeding groups of true bugs (carnivores, specialist and generalist herbivores) were examined using ordinations and mixed-effect models. We found distinct herbivorous assemblages corresponding to microtopography-driven differences in water regime and vegetation between steppe and marsh plots, but this pattern was less pronounced in carnivorous assemblages. A higher species richness of true bugs was found in the more diverse steppe vegetation than in the salt marsh vegetation, while the abundance pattern of true bugs was opposite. Landscape diversity had a positive effect on the species richness and abundance of generalist herbivores and carnivores. Our results suggested that generalist herbivores and carnivores appear to drive diversity patterns in the local landscape due to their high dispersal abilities and the broader range of resources they can utilize. Specialist herbivores strongly influence the local insect biomass in relation to the distribution and density of their host plants. The present study highlights the importance of both habitat and landscape diversity for local insect diversity in Pannonic salt grasslands and suggests that the main threats for arthropod diversity are those processes and activities that homogenize these areas.     

Fungal loline alkaloids in grass–endophyte associations confer resistance to the rice leaf bug, Trigonotylus caelestialium

Plant symbiotic fungi (endophytes) of the genus Neotyphodium [anamorphs, asexual derivatives of Epichloë (Ascomycota: Clavicipitaceae)] often associate with grass species of the subfamily Pooideae, which includes important forage and turf species. These endophytes are known to produce a range of alkaloids that enhance their host's resistance to insects or are toxic to grazing animals. Among the alkaloids, loline alkaloids (saturated 1‐aminopyrrolizidines) are generally observed in the highest concentrations in many Neotyphodium–grass symbiotic associations, and are known to be toxic to insects but not to mammals. Some Neotyphodium‐infected grasses have enhanced resistance to rice leaf bug, Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae), one of the major pests for rice production in Japan. Our laboratory experiments quantified the effects of purified loline (N‐formylloline) and in planta synthesis of loline alkaloids by meadow fescue [Lolium pratense (Huds.) S.J. Darbyshire (syn. Festuca pratensis Huds.)]–Neotyphodium uncinatum (Gams, Petrini & Schmidt) Glenn, Bacon & Hanlin and Italian ryegrass (Lolium multiflorum Lam.)–Neotyphodium occultans Moon, Scott & Christensen associations on the development and survival of T. caelestialium. No‐choice feeding assays with laboratory populations of the insect revealed that their growth was significantly decreased by the infected grasses, and the effect was greater for N. uncinatum than for N. occultans, in keeping with differences in N‐formylloline concentrations in the plants. Artificial feeding of N‐formylloline through feeding sachets indicated that the chemical has an adverse effect on survival of larvae, even at the lowest concentration tested (50 µg/g), which was considerably lower than the typical concentrations in many Neotyphodium–grass associations. The results confirmed the ability of Neotyphodium‐infected forage grasses to control T. caelestialium propagation in meadows, which may cause damages to nearby rice paddies.