The response of leaf resin to artificial herbivory in Eriodictyon californicum

Herbivore damage induces the production of defensive chemicals in many plant species. However, defensive chemicals sometimes have functions other than protection from herbivores, and these chemicals may respond to hervibory differentialy than those which are primarily defensive. A well-studied group of leaf constituents with multiple functions is the phenolic leaf resins, which protect leaves from herbivores, UV radiation, and possibly excess water loss. The effects of herbivory on phenolic leaf resins were investigated in the chapparral shrub Eriodictyon californicum by artificially damaging leaves during the growing season and subsequently measuring resin content and composition. We found that (i) resin content declined in leaves damaged by artificial herbivory; (ii) resin declined (at the P < 0.1 level) in undamaged leaves present on the same plant as those heavily damaged; and (iii) resin composition, as measured by the ratio of the major components, was unaffected by artificial herbivory.     

The seasonal dynamics of leaf resin,nitrogen, and herbivore damage in Eriodictyon californicum and their parallels in Diplacus aurantiacus

Summary The chaparral shrub Eriodictyon californicum produces a flavonoid leaf resin with a chemically similar composition to that previously reported for the sympatric shrub Diplacus aurantiacus. We determined the phenology, resin content, and nitrogen content of Eriodictyon leaves and the leaf area lost to herbivores. Nitrogen content and resin content were both negatively correlated with leaf age at each sampling date, but nitrogen decreased during the growing season while resin increased. The fraction of leaf area lost during the growing season averaged less than 7% and was highest on the oldest leaves. The seasonal pattern of resin production in Eriodictyon corresponds to that in Diplacus, indicating that the similar environments of Eriodyctyon and Diplacus have led to convergent leaf resins. This convergence in these two plants has implications for chemicals of similar function in other chaparral shrubs.     

Phylogeny and host-plant association in the leaf beetle genus Trirhabda LeConte (Coleoptera: Chrysomelidae)

The leaf beetle genus Trirhabda contains 26 described species from the United States and Canada, feeding on host plants from the families Asteraceae and Hydrophyllaceae. In this study, we present a phylogeny for the genus that was reconstructed from mitochondrial COI and 12S rRNA fragments, nuclear ITS2 rRNA, and morphological characters. Both parsimony and mixed-model Bayesian likelihood analyses were performed. Under both methods, the mitochondrial and nuclear partitions support the same backbone phylogeny, as do the combined data. The utility of the molecular data is contrasted with the low phylogenetic signal among morphological characters. The phylogeny was used to trace the evolution of the host-plant association in Trirhabda. The recovered phylogeny shows that although the host-plant association is phylogenetically conservative, Trirhabda experienced one shift to a distantly related host-plant family, 6 shifts between host-plant tribes, and 6 between genera within tribes. The phylogeny reveals that Trirhabda were plesiomorphically adapted to tolerate complex secondary compounds of its host plants and this adaptation is retained in Trirhabda species, as evidenced by multiple shifts from chemically simpler host plants back to the more complex host plants.     

Interactions between goldenrod (Solidago altissima L.) and its insect herbivore (Trirhabda virgata) over the course of succession

Consumers can mediate the composition of plant communities and alter ecosystem processes. Although herbivores usually increase N availability in the short term, they might decrease it in the long term. I investigated the long-term effect of insect herbivores on leaf tissue quality and soil N availability in goldenrod (Solidago altissima) fields using two approaches: (1) I compared plots from which herbivores had been excluded for 17 years with adjacent plots that had experienced normal levels of herbivory, and (2) I examined a chronosequence of nine goldenrod fields representing three successional stages: early, middle, and late. These parallel approaches showed that, in the long term, herbivores decrease the quality of leaf litter and soil N availability in goldenrod fields. These long-term effects appear to compensate for various short-term effects that increase N availability in the soil (e.g., added frass, increased light penetration). Furthermore, herbivores decrease leaf litter quality and N availability by reducing the quality of leaf tissue within the same species. This pattern may result from insect herbivores preferentially grazing on plants with a high N content thereby increasing the amount of recalcitrant litter over the course of succession. Received: 4 May 1999 / Accepted: 24 September 1999     

Anthophagy in the leaf beetles (Coleoptera,Chrysomelidae)

Laboratory experiments were performed on leaf beetles collected on flowers. Flower consumption (anthophagy) was demonstrated for adults of Donacia bicolora, D. brevitarsis, D. obscura, D. thalassina, Plateumaris discolor, Cryptocephalus laetus, C. sericeus, C. solivagus, Labidostomis longimana, Hydrothassa marginella, Phaedon concinnus, Galerucella nymphaeae, Neocrepidodera femorata, Altica oleracea, Aphthona lutescens, Longitarsus pellucidus, and larvae of Entomoscelis adonidis, H. marginella, and G. nymphaeae for the first time for all the species except for P. discolor, L. longimana, and C. sericeus. The feeding behavior was described, and the mouthparts of adults were studied. The mandibles and maxillae of the Donacia, Plateumaris, and Orsodacne species mentioned are adapted to consuming pollen. Some questions of ecology and evolution of anthophagy are discussed. An overview of literature on anthophagy in the leaf beetles is presented.     

Variation in leaf trichomes and nutrients of Wigandia urens (Hydrophyllaceae) and its implications for herbivory

Leaf trichome variation was studied in a population of Wigandia urens (Hydrophyllaceae) in relation to water availability, diversity of herbivorous insects, and grazing rates. Plants of W. urens have glandular and urticant (stinging hairs) trichomes, and it is possible to distinguish two types of leaves: smooth leaves with only glandular trichomes and bristly leaves with both types of trichomes. Density of urticant trichomes was negatively correlated with weekly mean precipitation. Fourteen species of insects in five different orders feed on leaves of W. urens throughout the year. Grazing rates varied according to type and age of leaves. Grazing rates were lower in smooth than bristly young leaves but the rates were similar for mature leaves. Secondary metabolites, screened using qualitative methods, showed similar classes of compounds in both types of leaves. Bristly leaves had significantly higher concentrations of nitrogen, phosphorous and water and these nutritional differences were well correlated with the differences in grazing rates between bristly and smooth leaves.     

Small-scale distributional dynamics of the yellow water-lily and its herbivore Galerucella nymphaeae (Coleoptera: Chrysomelidae)

Summary I followed the within-generation distribution of a chewing specialist herbivore, the water-lily beetle, on individually marked leaves of the yellow water-lily. Yellow water-lilies produced new leaves steadily throughout the growth season. Average leaf longevity was 3–4 weeks, much shorter than the developmental time of the beetle. The average egg-load of leaves was about 120. Leaf longevity was independent of egg density, but migration rate of the first instar larvae was density-dependent. Beetles occurred in every leaf, but consumed only a fraction (17%) of the available leaf area. However, this caused the leaf to lose its floating ability, so even this low rate of consumption made the leaf unavailable to herbivores. The herbivore population had to redistribute itself throughout the summer, escaping from the drowning leaves to fresh ones. No beetle could survive from egg to adult on a single leaf. The small-scale redistribution of the herbivore strongly affected the damage experienced by the host plant. In general, ability to redistribute depends on the dispersal ability of the herbivore, and thus migration ability may strongly affect the plant-herbivore interaction.     

Feeding behavior of leaf beetles (Coleoptera,Chrysomelidae)

The feeding behavior of adult leaf beetles (41 species from 18 genera and 8 subfamilies) was studied for the first time. Beetles of the genera Chrysolina, Chrysomela, Cryptocephalus, Galeruca, Gastrophysa, Labidostomis, Leptinotarsa, Timarcha, and Cassida stigmatica gnaw a leaf from the edge, whereas the representatives of Donacia, Galerucella, Lema, Lilioceris, Oulema, Phyllobrotica, Plagiodera, Zeugophora, Hypocassida, and most species of Cassida gnaw the leaf plane. In addition, adults of Lilioceris merdigera and Donacia clavipes feed on young leaves rolled into a tube. New host plants are reported for the first time: Hyoscyamus niger for the larvae of the Colorado potato beetle and Naumburgia thyrsiflora for Galerucella grisescens.     

Endemism patterns in the Italian leaf beetle fauna (Coleoptera,Chrysomelidae)

In this contribution the results of a zoogeographical analysis, carried out on the 123 endemic leaf beetle species (Coleoptera: Chrysomelidae) occurring in Italy and its immediately adjacent regions, are reported. To assess the level of faunistic similarity among the different geographic regions studied, a cluster analysis was performed, based on the endemic component. This was done by calculating the Baroni Urbani & Buser’s similarity index (BUB). Finally, a parsimony analysis of endemicity (PAE) was used to identify the most important areas of endemism in Italy.     

Larva of the leaf beetle Labidostomis longimana (Coleoptera, Chrysomelidae, Clytrinae)

The first- and the last-instar larvae of the leaf-beetle Labidostomis longimana are described in detail for the first time. The last instar larva is morphologically close to L. sibirica larva and differs from it in the absence of a projection in the medial emargination of the labrum, in the presence of 7 spiniform setae on the tibiotarsus ventrally, 11–13 narrow simple setae on the tibiotarsus dorsally, and fine rugae on the larval case.     

To the knowledge of the leaf beetle genus Cystocnemis (Coleoptera, Chrysomelidae)

Four subspecies of Cystocnemis discoidea are distinguished; two subspecies are described as new to science based on investigation of intraspecific variation in different parts of the species range, and ssp. gebleri was resurrected from synonymy. The ways of speciation in highland-hollow landscapes are discussed. The alpine subspecies C. discoidea oreas ssp. n. has an altibiome disjunction with the nominotypical subspecies. Similarity of the alpine subspecies of C. discoidea to the species from the subgenus Entomomela was found to be the reason of permanent confusion of representatives of these taxa. The subgenus Entomomela is transferred from the genus Oreomela to the genus Cystocnemis. A key to species and subspecies of the genus Cystocnemis is given.     

Patch colonization by Trirhabda canadensis (Coleoptera: Chrysomelidae): effects of plant species composition and wind

Summary The goldenrod leaf beetle, Trirhabda canadensis, is known to respond to odors of host and non-host species in the laboratory. Here we report movements of T. canadensis in the field in response to volatile odors from monocultures and polycultures of host plants. Overall, beetles preferentially colonized plots with a higher density of host plants and lower diversity of allelochemicals, but under some wind conditions there were marked exceptions. At high windspeeds, they colonized whichever plot(s) was upwind. At low windspeeds, beetles colonized preferred plots even when they were not upwind. The data suggest that odor dispersion varies in a complex way with windspeed: at low windspeeds beetles received information from a wide are of vegetation and made choices while at high windspeeds information was available only from upwind plot(s).     

Contributions to the knowledge of the leaf beetles (Coleoptera, Chrysomelidae) of Russia

A new species, Macroplea skomorokhovi sp. n., is described from the Russian Far East, and a key to species of the genus Macroplea Curtis is given. Cryptocephalus oxysternus Jacobson (Primorskii Territory) and Longitarsus truncatellus Weise (northern Caucasus) are recorded for the Russian fauna for the first time.     

The influence of vegetational diversity on the population ecology of a specialized herbivore,Phyllotreta cruciferae (Coleoptera: Chrysomelidae)

Summary The population ecology of Phyllotreta cruciferae Goeze, a flea beetle which is an important pest of cole crops (Brassica oleracea) in central New York was studied in experimental gardens of differing vegetational diversity over a three year period. Adult beetles were more abundant on collards (B. oleracea var. acephala) grown in monocultures than on those grown adjacent to natural vegetation. The emergence of individuals forming the new annual generation was also greater in the pure stands. Predators and parasites appeared to have a negligible influence on the adult beetles in both habitats. Further experiments demonstrated that monocultures were colonized more rapidly and experienced greater feeding damage than stands in which collards had been interplanted with tomatoes and tobacco. Choice experiments in the laboratory showed that chemical stimuli given off by non-host plants (tomato, Lycopersicon esculentum, and ragweed, Ambrosia artemisiifolia) interfered with the host finding and feeding behaviour of P. cruciferae. These results indicate that vegetational diversity can exert a direct influence on populations of phytophagous insects.We conclude that the environmental capacity (Determination in Schwerdtfeger's terminology) of diverse natural communities is lower than that of natural or man-made monocultures. The associational resistance resulting from the higher taxonomic and microclimatic complexity of natural vegetation tends to reduce outbreaks of herbivores in diverse communities.     

Relationships of herbivore feeding and plant flavonoids (Coleoptera: Chrysomelidae and Anacardiaceae: Rhus)

Summary Eighteen leaf flavonoid compounds were isolated from several populations of Rhus tripartita from xeric habitats in Israel, ornamental Schinus terebinthifolius from Israel, and three species of Rhus (vulgaris, natalensis, tenuinervis) from mesic habitats in Kenya. Foodplant preference testing of Rhus-feeding Leaf Beetles (Blepharida sacra from Israel and B. marginalis and B. conradsi from Kenya) correlated well with the flavonoid composition of the different foodplants. Blepharida sacra and B. marginalis foodplant preferences demonstrated an herbivore sibling relationship but there is evidence, including foodplant ecology and distribution, that they are separate species. The herbivorefoodplant coevolution of the xeric B. sacra-R. tripartita is distinct from that of the mesic B. marginalis-R. vulgaris/natalensis, however, this study also indicates possible ancestral relationships between the herbivore species as well as between the plant species.     

New species of the leaf beetles (Coleoptera,Chrysomelidae) from China: VII

The following new taxa of leaf beetles are described from Chinese provinces Gansu, Sichuan, and Xinjiang based on the material of the Zoological Institute, Russian Academy of Sciences, St. Petersburg, where the types are deposited: Chrysolina confucii sp. n., Ch. daosana sp. n., Ch. infernalis sp. n., Ch. gruevi sp. n., Ch. songpana sp. n., Phratora alternata sp. n., Taipinus rotundatus gen. et sp. n., Oreomela milae sp. n. (Chrysomelinae) and Zangastra sichuanica sp. n. (Galerucinae).     

Spatial distribution of the cereal leaf beetle (Coleoptera: Chrysomelidae) in wheat

A 2-yr study was conducted in wheat fields in South Carolina involving weekly sampling of cereal leaf beetle, Oulema melanopus (L.). In each of the six fields of this study, temporal patterns showed two distinct peaks in March and in May of adult O. melanopus. Populations decreased as wheat plants matured. In 2009, larval populations had one peak in April in between the two adult peaks. The χ(2) statistics for observed and Poisson predicted distributions of O. melanopus indicated nonrandom distribution for adults and larvae. In addition, the values of I(D) were >1 for adults and larvae in both years across sampling dates. These results indicate that the sampling distributions of both adult and larval populations of O. melanopus were aggregated. Slopes of Taylor power's law (b) and patchiness regressions (β) were significantly (P < 0.05) different than one in all cases, except for b in 2008 for adults. Across sampling dates, the distance from field border had a significant effect on adult O. melanopus in both years, but not on larval O. melanopus. Densities of adult O. melanopus were greatest at 0 m (the field edge), and decreased at 5-25 m from the field edge. The inverted distance weighted interpolation method showed considerable levels of spatial variability in densities within fields. High densities along the edge of wheat fields suggests that localized control methods in wheat may be effective in reducing migration of O. melanopus and damage in corn, Zea mays L.     

Characterization and chromosome location of satellite DNA in the leaf beetle Chrysolina americana (Coleoptera, Chrysomelidae)

This paper is the first record of the satellite DNA of the specialized phytophagous genus Chrysolina. The satellite DNA of Chrysolina americana is organized in a tandem repeat of monomers 189 bp long, has a A + T content of 59.6 % and presents direct and inverted internal repeats. Restriction analysis of the total DNA with methylation sensitive enzymes suggests that this repetitive DNA is undermethylated. In situ hybridization with a biotinylated probe of the satellite DNA showed the pericentromeric localization of these sequences in all meiotic bivalents. The presence of this repetitive DNA in other species of the genus was also tested by Southern analysis. The results showed that this satellite DNA sequence is specific to the C. americana genome and has not been found in three other species of Chrysolina with a different choice of host plants than in the former. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ovipositional biology of Viburnum leaf beetle, Pyrrhalta viburni (Coleoptera: Chrysomelidae)

Pyrrhalta viburni Paykull, a new landscape pest in the United States, feeds in both the larval and adult stages on foliage of plants in the genus Viburnum. We measured lifetime oviposition capacity of mated and unmated females reared in the laboratory versus field-collected females, as well as ovipositional response to physical characteristics of the host plant. Both mated and unmated females produced eggs, but at different rates. Field-collected females and mated females reared in the laboratory laid similar numbers of egg masses containing similar numbers of eggs, but unmated females laid approximately one half as many eggs, the result primarily of smaller clutch size. Mated females reared in the laboratory had a preovipositional period of 11.4 +/- 1.7 versus 29 + 11.7 d for unmated females, and unmated females lived significantly longer than mated females. The angle and diameter of stems of V. trilobum, a very susceptible host, both greatly influenced oviposition; females laid most eggs on vertically oriented stems, and those of smallest diameter; when these factors were combined, stem diameter predominated. Females also had a very strong geotactic response, preferring to lay eggs on portions of stems toward gravity, even when stems were at fairly shallow angles.