Seasonal variation in defence compounds: A case study on pyrrolizidine alkaloids of clones of Jacobaea vulgaris, Jacobaea aquatica and their hybrids.

Concentration of plant secondary metabolites (SMs) show seasonal variations. However, it is still not well understood how these abiotic and biotic factors influence the seasonal variations of SMs. In addition, it is of interest to know if and how SMs are reallocated to the different plant organs, in particular whether SMs are reallocated to the remaining tissues when biomass is lost, e.g., during winter. Here we used Jacobaea vulgaris, Jacobaea aquatica, two F1 and four F2 hybrids that differed in their pyrrolizidine alkaloids (PAs) bouquet as a study system. A series of clones of these genotypes were investigated during their vegetative stage spanning 14 months in a semi-natural environment. We found that the total PA concentration in roots and shoots showed a gradual increase until the spring of the second year, whereafter it dropped substantially in shoots. The variation in PA composition due to seasonal changes was significant but relatively small. Senecionine-like PAs were the dominant PAs in roots, while jacobine-/erucifoline-like PAs were dominant in shoots. The variation of PA concentration was significantly correlated with temperature, day length, and plant age. A correlation analysis showed that PAs were not reallocated when biomass was lost in winter. Overall, our study showed that PA composition of each genotype changed over seasons in a different manner but seasonal variation did not overrule the differences in PA composition among genotypes.

Temperature and altitude modulate feeding attributes of Mexican beetle, Zygogramma bicolorata Pallister on Parthenium hysterophorus.

Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is an effective biocontrol agent of Parthenium hysterophorus L. which is an alien invasive herbaceous weed with a pan-tropical distribution. The present study aimed to assess the effects of temperature and altitude on feeding attributes (consumption rate, conversion efficiency and growth rate) of adults from the wild populations of Z. bicolorata inhabiting India and Nepal. Results revealed that adults inhabiting areas of low temperature (24°C ‒ 25°C) and high altitude (415 m ‒1400 m) were large and had higher food consumption rates. In contrast, those inhabiting areas of high temperature (34°C ‒ 36°C) and low altitude (81 m ‒ 229 m) were smaller and had higher food utilization efficiencies. In all the eco-climatic regions, females were larger than males and had higher feeding attributes than their counterparts. Temperature between 27°C and 30°C was found optimal for Z. bicolorata adults to convert and utilize the food biomass to body mass. Above the optimal temperature the feeding attributes decreased. Present results suggest that there exists a possibility for decrease in body size, and thereby weed biocontrol efficiency of Z. bicolorata adults with an increase in temperature due to global climate change.

In vitro nematicidal activity of natural and semisynthetic cadinenes from Heterotheca inuloides against the plant-parasitic nematode Nacobbus aberrans (Tylenchida: Pratylenchidae).

BACKGROUND: Nacobbus aberrans (Tylenchida: Pratylenchidae) is one of the main plant-parasitic nematodes species that affects crops in Mexico, generating substantial economic losses. Traditionally, the control of the nematodes is carried out using chemical products; however, research efforts are presently focused on the search for new methods for the control of this pest. Natural products derived from plants are an alternative for the control of populations of plant-parasitic nematodes. The genus Heterotheca (Asteraceae) is characterized by containing sesquiterpenes with cadinane skeleton, and some species of this genus exert nematicidal activity. RESULTS: We determined the effects of selected Heterotheca inuloides plant metabolites and some semisynthetic derivatives on the hatching of eggs isolated from the gelatinous matrix and infective second-stage juveniles (J2) of the false root-knot nematode N. aberrans using an in vitro experimental model. Among the evaluated compounds, nematodes were more susceptible to hydroxylated and quinone compounds, whereas the remaining compounds showed moderate or no activity. The presence of the hydroxyl group is essential for nematicidal potential, with changes at the hydroxyl group modifying the nematicidal activity. CONCLUSION: Flowers of Heterotheca inuloides contain bioactive compounds that showed nematicidal activity against N. aberrans. Here we report the nematicidal activities of cadinenes isolated from the flowers of H. inuloides and their semisynthetic derivatives against the false root-knot nematode N. aberrans. © 2018 Society of Chemical Industry.

Differential responses of body growth to artificial warming between parasitoids and hosts and the consequences for plant seed damage.

Temperature increase may disrupt trophic interactions by differentially changing body growth of the species involved. In this study, we tested whether the response of body growth to artificial warming (~2.2 °C) of a solitary koinobiont endo-parasitoid wasp (Pteromalus albipennis, Hymenoptera: Pteromalidae) differed from its main host tephritid fly (Tephritis femoralis, Diptera: Tephritidae; pre-dispersal seed predator), and whether the plant seed damage caused by wasp-parasitized and unparasitized maggots (larval flies) were altered by warming. In contrast to the significant and season-dependent effects of warming on body growth of the host tephritid fly reported in one of our previous studies, the effect of artificial warming on body growth was non-significant on the studied wasp. Moreover, the warming effect on seed damage due to unparasitized maggots was significant and varied with season, but the damage by parasitized maggots was not altered by warming. Distinct responses of body growth to warming between parasitoids studied here and hosts assessed in a previous study indicate that temperature increase may differentially affect life history traits of animals along food chains, which is likely to affect trophic interactions.

Persistence of Trichomonas gallinae in Birdseed.

Trichomonas gallinae has emerged worldwide as a cause of mortality in songbirds (passerines). The congregation of numerous birds, including the reservoir hosts, pigeons and doves (columbids), at backyard feeding and watering sources has been suggested as a potential driver for the outbreaks. Evidence supporting a role for water in transmission has been established, but the role of birdseed in the transmission of trichomoniasis remained to be investigated. We assessed the survival of T. gallinae in three commercial birdseeds (mixed seed, black-oil sunflower seed, and niger seed) routinely used to attract passerine birds to local properties. Trichomonad suspensions were inoculated (low dose: 1 × 103; high dose: 1 × 105) into each of the three seed types in petri dishes, using both dry and moist (water-soaked) conditions, in triplicate. Petri dishes were incubated at 37 C and monitored for T. gallinae survival for 48 hr by wet-mount microscopy and by InPouch™ TF medium culture for 10 days. Surviving trichomonads were not detected in any of the dry birdseed treatments. In moist conditions, however, trichomonads were found to survive ≤24 hr in all three seed types and ≤48 hr in the mixed seed that contained organic debris. We demonstrate that T. gallinae has the ability to survive in moist birdseed, which suggests that public bird-feeding sites may play a significant role in the transmission of trichomoniasis.

Effects of Thermal Regimes, Starvation and Age on Heat Tolerance of the Parthenium Beetle Zygogramma bicolorata (Coleoptera: Chrysomelidae) following Dynamic and Static Protocols.

Temperature and resource availability are key elements known to limit the occurrence and survival of arthropods in the wild. In the current era of climate change, critical thermal limits and the factors affecting these may be of particular importance. We therefore investigated the critical thermal maxima (CTmax) of adult Zygogramma bicolorata beetles, a biological control agent for the invasive plant Parthenium hysterophorus, in relation to thermal acclimation, hardening, age, and food availability using static (constant) and dynamic (ramping) protocols. Increasing temperatures and exposure times reduced heat survival. In general, older age and lack of food reduced heat tolerance, suggesting an important impact of resource availability. Acclimation at constant temperatures did not affect CTmax, while fluctuating thermal conditions resulted in a substantial increase. Hardening at 33°C and 35°C improved heat survival in fed young and mid-aged but only partly in old beetles, while CTmax remained unaffected by hardening throughout. These findings stress the importance of methodology when assessing heat tolerance. Temperature data recorded in the field revealed that upper thermal limits are at least occasionally reached in nature. Our results therefore suggest that the occurrence of heat waves may influence the performance and survival of Z. bicolorata, potentially impacting on its field establishment and effectiveness as a biological control agent.

Three new genera and three new species of Nearctic Lasiopteridi (Diptera: Cecidomyiidae: Cecidomyiinae) from Asteraceae and Caprifoliaceae, and the tribe Rhopalomyiini subsumed under Oligotrophini.

Three new Nearctic genera of gall midges (Diptera: Cecidomyiidae), each with a new species, are described: Helianthecis Gagné for Helianthecis capitum Gagné, new species, that lives in flower heads of Helianthus spp. (Asteraceae) from North Dakota to Texas; Lonicerae Gagné for Lonicerae russoi Gagné, new species, and Lonicerae lonicera (Felt), new combination, that form bud galls on Lonicera spp. (Caprifoliaceae) in California; and Chiosperma Gagné for Chiosperma turgidum Gagné, new species, that forms a bud gall on Symphoricarpos albus (L.) S.F. Blake (Caprifoliaceae) in Washington. The three new genera belong to the supertribe Lasiopteridi and are placed in the tribe Oligotrophini. The tribes Oligotrophini and Rhopalomyiini are combined.

First description of leaf-mining Nepticulidae and Tischeriidae (Insecta, Lepidoptera) feeding on the Chilean endemic plant genus Podanthus Lag. (Asteraceae).

Despite taxonomic and conservation interest in the Chilean endemic plant genus Podanthus Lag. (Asteraceae: subfamily Asteroideae, tribe Heliantheae), no Podanthus-feeding Nepticulidae or Tischeriidae have ever been recorded. Here, on the basis of material reared from Podanthus from central Mediterranean Chile, we present the description of Stigmella podanthae sp. nov. (Nepticulidae) and a re-description of Astrotischeria chilei Puplesis & Diskus, 2003. Females and host-plant of the latter species were previously unknown. Both treated species are illustrated with numerous photographs of the leaf-mines, adults of both sexes, and male and female genitalia.

Eriophyoid mites from Eastern India: description of three new species (Acari: Prostigmata: Eriophyoidea).

Three new eriophyoid mite species, namely Dichopelmus puncti n. sp. (Eriophyidae) from cogan grass, Imperata cylindrica (Poaceae); Calacarus kalyaniensis n. sp. (Eriophyidae) from Siam weed, Chromolaena odorata (Asteraceae) and Neorhynacus bidhanae n. sp. (Diptilomiopidae) from Croton caudatus (Euphorbiaceae), are described and illustrated from West Bengal, India. The new species are vagrants on the leaves of their respective host plants with no visible damage observed. Keys to the known species of Dichopelmus and Neorhynacus are provided along with a checklist of eriophyoid mites species present in West Bengal.

Palearctic species of the genus Tephritis (Diptera, Tephritidae) associated with plants of the tribe Senecioneae (Asteraceae).

Tephritis arnicae (Linnaeus, 1758) from Europe was the hitherto only Palearctic species of the genus Tephritis known to infest flowerheads of asteraceous plants of the tribe Senecioneae. An additional species with similar biology, Tephritis arsenii, new species, recently discovered in Iran and Armenia is described. It is very similar to T. arnicae in the shape of the aculeus and spermathecae, as well as the wing with darkened anal lobe and abdominal tergites with black setulae, but differs from it by the white posterior orbital and notopleural setae, and also by details of the wing pattern. Larvae of T. arsenii feed in flowerheads of Doronicum dolichotrichum Cavill of the tribe Senecioneae (Asteraceae).

The first description of the leaf-mining Nepticulidae (Lepidoptera) feeding on the South American plant genus Liabum, Asteraceae.

First Liabum Adans. (Asteraceae) feeding Nepticulidae are reported. Two new new species from the Andes (Ecuador) are described: Stigmella serpantina Diskus & Stonis, sp. nov. and S. pangorica Diskus & Stonis, sp. nov. The male genitalia of both species and the female genitalia, as well the leaf-mines of S. serpantina sp. nov. are illustrated.

Phytoseiidae (Acari: Mesostigmata) from rubber tree crops in the State of Bahia, Brazil, with description of two new species.

The current study describes the results of a survey of Phytoseiidae mites conducted on a rubber tree plantation in the State of Bahia, Brazil. We present 22 species, two of which are new to science, Amblydromalus insolitus n. sp. Nuvoloni & Lofego, and Typhlodromips paramilus n. sp. Nuvoloni & Lofego, and three new records for this host are presented. The species composition was more related with the records of the northern Brazilian Region, than with that of Southeastern and Midwestern.

Morphological and Molecular Revision of the Genus Ozirhincus (Diptera: Cecidomyiidae)-Long-Snouted Seed-Feeding Gall Midges on Asteraceae.

The Palaearctic gall-midge genus Ozirhincus is unique among the Cecidomyiidae for its morphology and biology. Unlike most other phytophagous gall midges, species in this genus do not induce galls but develop inside achenes of Asteraceae plants. The heads of adults are characterized by an unusually elongate proboscis, the function of which is unclear. Despite a lot of attention from taxonomists in the 19th and early 20th century, a proper revision of the genus has been hindered by complex host associations, the loss of most relevant type material, and the lack of a thorough comparative study of all life stages. The present revision integrated morphological, molecular, and life-history data to clearly define species boundaries within Ozirhincus, and delimit host-plant ranges for each of them. A phylogenetic analysis based on the mitochondrial COI and 16S genes confirmed the validity of four distinct species but did not resolve the relationships among them. All species are oligophages, and some may occur together on the same host plant. Species with wider host-plant ranges have wider European and circum-Mediterranean distribution ranges, whereas species with narrower host ranges are limited to Europe and the Russian Far East. As part of the present work, O. hungaricus is reinstated from synonymy, O. tanaceti is synonymized under O. longicollis, neotypes are designated for O. longicollis and O. millefolii, and a lectotype is designated for O. anthemidis.

Phylogeny, evolution and classification of gall wasps: the plot thickens.

Gall wasps (Cynipidae) represent the most spectacular radiation of gall-inducing insects. In addition to true gall formers, gall wasps also include phytophagous inquilines, which live inside the galls induced by gall wasps or other insects. Here we present the first comprehensive molecular and total-evidence analyses of higher-level gall wasp relationships. We studied more than 100 taxa representing a rich selection of outgroups and the majority of described cynipid genera outside the diverse oak gall wasps (Cynipini), which were more sparsely sampled. About 5 kb of nucleotide data from one mitochondrial (COI) and four nuclear (28S, LWRh, EF1alpha F1, and EF1alpha F2) markers were analyzed separately and in combination with morphological and life-history data. According to previous morphology-based studies, gall wasps evolved in the Northern Hemisphere and were initially herb gallers. Inquilines originated once from gall inducers that lost the ability to initiate galls. Our results, albeit not conclusive, suggest a different scenario. The first gall wasps were more likely associated with woody host plants, and there must have been multiple origins of gall inducers, inquilines or both. One possibility is that gall inducers arose independently from inquilines in several lineages. Except for these surprising results, our analyses are largely consistent with previous studies. They confirm that gall wasps are conservative in their host-plant preferences, and that herb-galling lineages have radiated repeatedly onto the same set of unrelated host plants. We propose a revised classification of the family into twelve tribes, which are strongly supported as monophyletic across independent datasets. Four are new: Aulacideini, Phanacidini, Diastrophini and Ceroptresini. We present a key to the tribes and discuss their morphological and biological diversity. Until the relationships among the tribes are resolved, the origin and early evolution of gall wasps will remain elusive.

Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts.

In parasitoid-herbivore-plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed-predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre-dispersal seed predators (tephritid fly larvae) and koinobiont parasitoids using field observations, a field experiment and a microcosm study. We first compared observed seed production in (i) non-infected capitula, (ii) capitula infected only by seed predators (tephritid flies) and (iii) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. This effect was replicated in a controlled field experiment focusing on the most common parasitoid-seed predator-plant interaction chain in our system, in which confounding factors (e.g. density and phenology) were excluded. Here, we show that parasitoids indirectly decreased plant seed production by changing the behaviour of seed predators. In a microcosm study, we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. In contrast to the typical predator-induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators. Future studies on trophic interactions should consider the net effect of both increased consumption by seed predators and their death after development of parasitoids.

A new species and record of Aceria (Acari: Prostigmata: Eriophyoidea) on Carlina spp. (Asteraceae) from Serbia.

A new species of eriophyoid mite, Aceria utzkae n. sp., inhabiting Carlina acanthifolia subsp. utzka (Hacq.) Meusel & Kästner (Asteraceae) is described and illustrated. It is compared with Aceria carlinae (Nalepa), the only other species known to inhabit Carlina spp., and a differential diagnosis is provided. Both species are recorded from Serbia for the first time and a new host plant, Carlina vulgaris (Asteraceae) L., is also documented for Aceria carlinae.

Geometric morphometric study of geographic and host-related variability in Aceria spp. (Acari: Eriophyoidea) inhabiting Cirsium spp. (Asteraceae).

The russet mite, Aceria anthocoptes (Nalepa), is the only eriophyoid that has been recorded on Cirsium arvense (L.) Scop. It has been noted in several European countries and recently in the USA. In this study we explored the geographic and host-related variability of Aceria spp. inhabiting different Cirsium spp. We applied landmark-based geometric morphometric methods to study morphological variability of three body regions (ventral, coxigenital and prodorsal) of 13 Aceria spp. populations inhabiting five Cirsium spp. in Serbia (Europe) and four Cirsium spp. in Colorado (North America). Analyses of size and shape variation revealed statistically significant differences between Aceria spp. living on European native and North American native Cirsium spp., as well as between A. anthocoptes s.s. inhabiting European C. arvense and North American C. arvense. The coxigenital region was the most informative when considering inter-population shape differences. European Aceria spp. dwelling on Cirsium spp., including A. anthocoptes s.s. from C. arvense, are characterized by higher inter-population size and shape variability than their North American counterparts. This finding supports a Eurasian origin of A. anthocoptes, presumed to consist of a complex of cryptic taxa probably coevolved with host plants in the native environment. Morphological similarity among Aceria spp. inhabiting North American native Cirsium spp. may indicate that speciation of A. anthocoptes started relatively soon after the host shift to plants different from C. arvense in the invaded region.

Strength in numbers? Effects of multiple natural enemy species on plant performance.

While plants are invariably attacked by numerous insects and pathogens, the consequences of multiple enemies for plant performance are poorly understood. In particular, a predictive framework is lacking for when to expect enemies to have independent versus non-independent effects on their host plant. This is problematic for weed biological control programmes where multiple enemies are frequently released with the possibility of antagonistic interactions that may reduce control. Here, we conduct an analysis of 74 unique plant-enemy-enemy combinations from 51 studies to determine the frequency of non-independent effects of natural enemies on host plant performance, and test a number of a priori predictions for determinants of independent and antagonistic effects of multiple enemies. For three-quarters of plant response measurements, enemies had independent effects on plant performance. In most of the remainder, multiple enemies led to less reduction in performance than that predicted from each enemy alone. Antagonistic effects occurred when enemies attacked the same plant part concurrently or attacked plant reproductive structures. These two predictors explained why antagonistic effects were particularly prevalent for weeds, plants in the family Asteraceae and enemies in the order Diptera. Our results suggest that a few simple rules about avoiding particular combinations of multiple enemies could improve biological control success.

Herbivore damage-induced production and specific anti-digestive function of serine and cysteine protease inhibitors in tall goldenrod, Solidago altissima L. (Asteraceae).

Plant protease inhibitors (PIs) are among the most well-studied and widely distributed resistance traits that plants use against their herbivore attackers. There are different types of plant PIs which putatively function against the different types of proteases expressed in insect guts. Serine protease inhibitors (SPIs) and cysteine protease inhibitors (CPIs) are hypothesized to differentially function against the predominant gut proteases in lepidopteran and coleopteran herbivores, respectively. Here, we test the hypothesis that tall goldenrod, Solidago altissima, can specifically respond to damage by different herbivores and differentially induce SPIs and CPIs in response to damage by lepidopteran and coleopteran herbivores. Moreover, we ask if the concerted induction of different types of PIs accounts for variation in induced resistance to herbivory. We altered and optimized a rapid and effective existing methodology to quantitatively analyze both SPI and CPI activity simultaneously from a single tissue sample and to use the same plant extracts directly for characterization of inhibitory effects on insect gut protease activity. We found that both SPIs and CPIs are induced in S. altissima in response to damage, regardless of the damaging herbivore species. However, only SPIs were effective against Spodoptera exigua gut proteases. Our data suggest that plant PI responses are not necessarily specific to the identity of the attacking organism but that different components of generally induced defense traits can specifically affect different herbivore species. While providing an efficient and broadly applicable methodology to analyze multiple PIs extracted from the same tissue, this study furthers our understanding of specificity in induced plant resistance.

The gall midge Asphondylia borrichiae (Diptera: Cecidomyiidae): an indigenous example of host-associated genetic divergence in sympatry.

Speciation usually is conceptualized as occurring via three biogeographic modes: allopatry, parapatry, and sympatry. Sympatric speciation has been the most controversial because of the difficulty of developing plausible theoretical models in which the homogenizing effects of gene flow are sufficiently overcome to permit genetic divergence to occur in the absence of geographic barriers restricting gene flow. Recently, a number of hypothetical models for sympatric speciation have been advanced and several candidate study systems have provided evidence of sympatric divergence, although many of the systems so identified involve introduced species, especially in the cases of host-race formation in phytophagous insects, which expand their host range and use a novel host. Although these cases demonstrate the reality of sympatric divergence, they do not address which mode of speciation predominates in indigenous communities. Asphondylia borrichiae Rossi & Strong has been proposed as a potential example of sympatric divergence in a fully indigenous system, based on the results of a host-choice experiment involving three host-plant species. In the current study, we report significant differences in the genetic composition of midge populations collected from each host in situ, supporting the hypothesis of sympatric genetic divergence among the morphologically identical host-associated populations of A. borrichiae and consistent with host fidelity in oviposition choice.