Longitarsus Species Research Articles

Ecological characteristic of hermit crabs in Lhokseumawe mangrove forest, Aceh, Indonesia

The study was conducted between August and September of 2021 in order to determine the density, ecological index, distribution pattern, geographic distribution, environmental factors, and the relationship between hermit crabs and environmental factors. Hermit crabs were gathered using a quadratic transect and sample plots, while environmental variables were measured in situ. PCA and CCA multivariate statistics were used to determine the characteristics and correlation between herm...

Discovery and lectotype designation of Longitarsuscalifornicus (Motschulsky) (Coleoptera, Chrysomelidae, Galerucinae, Alticini).

The lectotype of Longitarsuscalifornicus (Motschulsky, 1845) is designated, described, and illustrated. An illustrated key to eight light-colored Longitarsus species known to occur in the western United States is presented. A brief history of Russian entomological collecting in North America during the first half of 19th century, with specimens preserved in Zoological Museum of Moscow University, Moscow and Zoological Institute, St. Petersburg, is provided.

New data on <i>Longitarsus rubellus</i> species group with description of a new species from Western Balkans (Coleoptera: Chrysomelidae: Alticini)

A new Longitarsus species is described from Western Balkans: Longitarsus carolileonardii (Bosnia and Herzegovina: Mojmilo) following the study of five specimens housed at the Hungarian Natural History Museum, Budapest. The new species belongs to the Longitarsus rubellus species group including also L. rubellus (Foudras 1860), L. gruevi Leonardi & Mohr 1974, L. refugiensis Leonardi & Mohr 1974 and L. ibericus Leonardi & Mohr 1974. Altogether, these species have similar habitus, but can be distinguished from each other mainly by the male sexual characters. A comparative table summarizes the diagnostic characters for all the species in the group. New distributional, biological and morphological data are also given.

Notes on Longitarsus aphthonoides Weise 1887 and on the species groups of L. lateripunctatus (Rosenhauer 1856) and L. curtus (Allard 1860) (Coleoptera, Chrysomelidae)

The aim of this study is to deepen the knowledge of five poorly studied Longitarsus species in order to elucidate their taxonomic position within the genus. For each of them further diagnostic characters and many new collecting localities are supplied. One new synonymy and one change of status are proposed: L. callidus Warchalowski 1967 = L. aphthonoides Weise 1887 syn. nov., and L. lateripunctatus personatus Weise 1893 is raised to valid species. The morphologically similar L. curtus (Allard 1860) and L. monticola Kutschera 1863 are also examined, providing new male and female diagnostic characters for their identification, as well as several European and Italian new collecting localities.

Sharpening the DNA barcoding tool through a posteriori taxonomic validation: The case of Longitarsus flea beetles (Coleoptera: Chrysomelidae).

The accuracy of the DNA barcoding tool depends on the existence of a comprehensive archived library of sequences reliably determined at species level by expert taxonomists. However, misidentifications are not infrequent, especially following large-scale DNA barcoding campaigns on diverse and taxonomically complex groups. In this study we used the species-rich flea beetle genus Longitarsus, that requires a high level of expertise for morphological species identification, as a case study to assess the accuracy of the DNA barcoding tool following several optimization procedures. We built a cox1 reference database of 1502 sequences representing 78 Longitarsus species, among which 117 sequences (32 species) were newly generated using a non-invasive DNA extraction method that allows keeping reference voucher specimens. Within this dataset we identified 69 taxonomic inconsistencies using barcoding gap analysis and tree topology methods. Threshold optimisation and a posteriori taxonomic revision based on newly generated reference sequences and metadata allowed resolving 44 sequences with ambiguous and incorrect identification and provided a significant improvement of the DNA barcoding accuracy and identification efficacy. Unresolved taxonomic uncertainties, due to overlapping intra- and inter-specific levels of divergences, mainly regards the Longitarsus pratensis species complex and polyphyletic groups L. melanocephalus, L. nigrofasciatus and L. erro. Such type of errors indicates either poorly established taxonomy or any biological processes that make mtDNA groups poorly predictive of species boundaries (e.g. recent speciation or interspecific hybridisation), thus providing directions for further integrative taxonomic and evolutionary studies. Overall, this study underlines the importance of reference vouchers and high-quality metadata associated to sequences in reference databases and corroborates, once again, the key role of taxonomists in any step of the DNA barcoding pipeline in order to generate and maintain a correct and functional reference library.

Host plant associations in Western Palaearctic Longitarsus flea beetles (Chrysomelidae, Galerucinae, Alticini): a preliminary phylogenetic assessment.

Longitarsus Latreille (Chrysomelidae, Galerucinae, Alticini) is a very large genus of phytophagous insects, with more than 700 species distributed in all zoogeographical regions. Patterns of host use have been a central topic in phytophagous insect research. In this study a first assessment is provided to test the hypothesis that host-plant association is phylogenetically conserved in Western Palaearctic Longitarsus species. Maximum Likelihood and Bayesian Inference methods were used to infer a phylogeny based on DNA sequence data from two mitochondrial genes from 52 Longitarsus species from the Western Palaearctic. In agreement with the host phylogenetic conservatism hypothesis, a strict association between most of the recovered clades and specific plant families was found, except for species associated with Boraginaceae. Low phylogenetic resolution at deep nodes limited the evaluation of whether closely related Longitarsus clades are associated with the same plant family or to closely related plant families.

English

Survey was carried out to study the distribution, infestation and damaging level of insect pests of black pepper during 2013/2014 cropping season in Southwestern Ethiopia. Insect pests were observed and identified at their sites in the surveyed areas. In addition, samples of insect pests and infected plant parts were collected and insect images were taken. The samples were diagnosed in Tepi National Spice Research Center laboratory. A total of twenty two species of insect pests were recorded as black pepper insect pest with different rate of infestation and damage level. Biting black ants (Tetramorium species), black pepper flea beetle (Longitarsus species), leaf gal trips (Liothrips species), and stink bugs (Pentatomidae) were recorded with relatively high infestation and damage level from all surveyed area, while others were considered as intermediate and minor pest due to low infestation and damage level. Therefore, it is important to design control options for these major insect pests to ensure plant health and pest action under economic threshold level. Key words: Survey, black pepper, insect pests, infestation, damage level, spices.

Comparative analysis of microbial diversity in Longitarsus flea beetles (Coleoptera: Chrysomelidae)

Herbivorous beetles comprise a significant fraction of eukaryotic biodiversity and their plant-feeding adaptations make them notorious agricultural pests. Despite more than a century of research on their ecology and evolution, we know little about the diversity and function of their symbiotic microbial communities. Recent culture-independent molecular studies have shown that insects possess diverse gut microbial communities that appear critical for their survival. In this study, we combined culture-independent methods and high-throughput sequencing strategies to perform a comparative analysis of Longitarsus flea-beetles microbial community diversity (MCD). This genus of beetle herbivores contains host plant specialists and generalists that feed on a diverse array of toxic plants. Using a deep-sequencing approach, we characterized the MCD of eleven Longitarsus species across the genus, several of which represented independent shifts to the same host plant families. Database comparisons found that Longitarsus-associated microbes came from two habitat types: insect guts and the soil rhizosphere. Statistical clustering of the Longitarsus microbial communities found little correlation with the beetle phylogeny, and uncovered discrepancies between bacterial communities extracted directly from beetles and those from frass. A Principal Coordinates Analysis also found some correspondence between beetle MCD and host plant family. Collectively, our data suggest that environmental factors play a dominant role in shaping Longitarsus MCD and that the root-feeding beetle larvae of these insects are inoculated by soil rhizosphere microbes. Future studies will investigate MCD of select Longitarsus species across their geographic ranges and explore the connection between the soil rhizosphere and the beetle MCD.

Time course of pyrrolizidine alkaloid sequestration in Longitarsus flea beetles (Coleoptera, Chrysomelidae)

Several species of Longitarsus take up, metabolize and store pyrrolizidine alkaloids (PAs) from their host plants. In feeding experiments using radioactively labeled PAs of different types we examined the time course of the sequestration process in L. jacobaeae and L. aeruginosus. We found that adapted species efficiently store PAs for at least two weeks without major losses. During that time, there is virtually no change in the ratio of tertiary alkaloids to stored non-toxic N-oxides, regardless of chemical form fed to the beetles. This implies a transient N-oxidation process where the alkaloids are only temporarily accessible to the enzyme. A dissection experiment with L. aeruginosus six days after uptake of labeled PAs showed that the tertiary alkaloids are not found in the hemolymph but are stored in the elytra and other body compartments. This conforms with earlier experiments that localized the enzyme’s site of action in the hemolymph. Furthermore we show that different total alkaloid doses in the diet of L. jacobaeae and the potentially less adapted L. succineus do not affect the ratio of recovered N-oxides to tertiary molecules. Thus, the efficiency of the N-oxidizing enzyme is not dependent on the concentration of alkaloids offered.

Uptake and metabolism of pyrrolizidine alkaloids in Longitarsus flea beetles (Coleoptera: Chrysomelidae) adapted and non-adapted to alkaloid-containing host plants.

Several Longitarsus flea beetle species sequester pyrrolizidine alkaloids acquired from their Asteraceae and Boraginaceae host plants. We carried out feeding and injection experiments using radioactively labeled pyrrolizidine alkaloids to investigate the physiological mechanisms of uptake, metabolism and storage of alkaloids in adult beetles. We examined six Longitarsus species belonging to different phylogenetic clades in a comparative approach. All species that accepted pyrrolizidine alkaloids in a preceding food choice study showed the ability both to store pyrrolizidine alkaloid N-oxides and to metabolize tertiary pyrrolizidine alkaloids into their N-oxides. Regardless of whether the beetles' natural host plants contain pyrrolizidine alkaloids or not, these species were found to possess an oxidizing enzyme. This oxygenase appears to be specific to pyrrolizidine alkaloids: [3H]Atropine and [14C]nicotine, two alkaloids not related to pyrrolizidine alkaloids, were neither stored nor N-oxidized by any of the tested species. One species, L. australis, that strictly avoids pyrrolizidine alkaloids behaviorally, exhibited a lack of adaptations to pyrrolizidine alkaloids on a physiological level as well. After injection of tertiary [14C]senecionine, beetles of this species neither N-oxidized nor stored the compounds, in contrast to L. jacobaeae, an adapted species that underwent the same treatment. L. jacobaeae demonstrated the same efficiency in N-oxidation and storage when fed or injected with tertiary [14C]senecionine.

Selective sequestration of iridoid glycosides from their host plants in Longitarsus flea beetles.

We investigated in eight species of the flea beetles genus Longitarsus (Coleoptera, Chrysomelidae) whether the beetles take up iridoid glycosides from their host plants of the Lamiaceae, Plantaginaceae, and Scrophulariaceae. Five of the beetle species, L. australis, L. lewisii, L. melanocephalus, L. nigrofasciatus, and L. tabidus, could be shown to sequester iridoid glycosides in concentrations between 0.40 and 1.55% of their dry weight. Eight different iridoid glycosides, acetylharpagide, ajugol, aucubin, catalpol, 8-epi-loganic acid, gardoside, geniposidic acid, and harpagide could be identified in the host plants, yet only aucubin and catalpol are sequestered by the beetles. No iridoid glycosides could be detected in the beetles if neither aucubin nor catalpol were present in the host plant, as in L. minusculus on Stachys recta (acetylharpagide only) and in L. salviae on Salvia pratensis (no iridoid glycosides). In one beetle species, L. luridus, we could not detect any iridoid glycosides although its field host, Plantago lanceolata, had considerable amounts of aucubin and catalpol plus two further iridoids. The five sequestering Longitarsus species differ in their capacity to store the compounds and in their affinity for catalpol relative to aucubin.

Selective sequestration of pyrrolizidine alkaloids from diverse host plants by Longitarsus flea beetles.

In 11 species of the flea beetle genus Longitarsus we investigated whether the insects sequester the pyrrolizidine alkaloids (PAs) present in their host plants of the families Asteraceae and Boraginaceae. In all cases where PAs could be detected in the leaves of the local host plant, they could also be detected in the corresponding beetles. In one host plant, Pulmonaria officinalis, no PAs could be detected in the leaves, yet were present in the beetles collected from them. We suggest this is due to uptake of PAs during the root-feeding larval stage. By comparing the GC-MS pattern of PAs found in the beetles with those of their hosts, we investigated the specificity of this sequestration. Furthermore, we compared the pattern of sequestered PAs across beetle species that had been feeding on the same plant, and across hosts in Longitarsus species that feed on different plants in the field. This allowed us to analyze to what extent the PA pattern in the insects is specific for the beetle species and depends on the local food plant. Our data indicate that the PAs found in the beetles are largely determined by the host plant, e.g., whether alkaloids typical of the Boraginaceae or Asteraceae are present. However, there are some indications for a selective uptake of PAs and apparently the beetles are able to metabolize them.

Quantitative analysis of pyrrolizidine alkaloids sequestered from diverse host plants in Longitarsus flea beetles (Coleoptera, Chrysomelidae)

Several species of the flea beetles genus Longitarsus are able to sequester pyrrolizidine alkaloids (PAs) from their host plants. In five Longitarsus species we compare the concentration of PAs present in their host plants belonging to the Asteraceae or Boraginaceae with those found in the beetles. To get an estimate of the intrapopulation variability, three samples of five beetles each and five individual plants were analyzed for each comparison. A strong intrapopulation variability could be detected both among plant and beetle samples. The total concentration found in the beetles varied strongly between species. The local host plant and its phenology influence the concentrations present in the beetles as evidenced in comparisons of a single beetle species from two different hosts and of one beetle species collected at the same site at different times of the year. In addition, different beetle species apparently vary in their capacity to sequester the alkaloids, at the lowest extreme the mean PA concentration in the beetles (0.034 μg PA/mg dry weight) was 1/30 of the mean concentration found in the plant leaves (L. aeruginosus from Eupatorium cannabinum), at the highest extreme (2.098 μg PA/mg dw) the concentration in the beetles was a 1000 fold higher than in the plant leaves (L. nasturtii from Symphytum officinale). The highest mean concentration found in the beetles was 3.446 μg/mg dw (L. exoletus from Cynoglossum officinale). The absolute concentrations found in the beetles are comparable to other insects which have been shown to be effectively defended against their potential predators.

On the Biology of some Species of Longitarsus (Col., Chrysom.) living on Ragwort

It appears from the literature that the species of Longitarsus recorded from ragwort (Senecio jacobaea) or its ally the groundsel (S. vulgaris), are L. dorsalis, F., L. suturellus, Duft., L. senecionis, Bris., L. jacobaeae, Wat., L. ochroleucus, Marsh., and L. gracilis, Kutsch.; the last named species is also recorded by Bedel from Tussilago. In addition L. succineus, Foudr., has been associated with various composites, such as Eupatorium cannabinum and Chrysanthemum spp. but, apparently, never before with Senecio.