1,721,016 research outputs found
Laboratory Hybridization between the Green Lacewings Chrysoperla comanche (Neuroptera: Chrysopidae) and Chrysoperla rufilabris, Predators of the Asian Citrus Psyllid
No full textChrysoperla comanche (Banks) and its sibling species Chrysoperla rufilabris (Burmeister) are voracious predators of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), an invasive pest that vectors a bacterium responsible for the lethal and incurable citrus greening disease. The Comanche lacewing naturally occurs in Southern California, whereas C. rufilabris is currently one of only two commercially available green lacewing in the United States. These sister species can be separated by larval morphological traits, by differences in courtship songs, and possibly by three nuclear genes wingless, PepCK, ATPase, yet they are not distinguishable based on the mitochondrial barcode gene (COI). Releasing in a new area a biological control agent capable of hybridizing with a resident species may pose risks that range from local displacement to irreversible loss of genetic identity. Therefore, we performed no-choice laboratory crosses to assess pre- and postzygotic isolation. We show that fertile and viable hybrid progeny could be readily obtained in interspecific crosses and backcrosses and, although there is a trend toward lower hybrid fitness, postzygotic isolation is overall weak and might not prevent loss of genetic identity under natural conditions. It remains to be determined if differences in courtship songs will prevent hybridization in the wild, as shown for other green lacewings. We also report a low prevalence of Rickettsia infection in both species
Karyotype of Baryscapus silvestrii Viggiani et Bernardo (Hymenoptera: Eulophidae)
No full textThe karyotype of Baryscapus silvestrii Viggiani et Bernardo is described, providing also basic morphometric values such as Centromeric Index (CI) and Relative Length (RL). Comparison with karyotypes of Baryscapus species and other eulophids is also provide
A reevaluation of the generic limits of Pnigalio Schrank (Hymenoptera: Eulophidae) based on molecular and morphological evidence
No full textRatzeburgiola Erdos is a small but phylogenetically interesting genus exhibiting a combination of characters once used to define both the former tribes Elachertini and Eulophini of the subfamily Eulophinae (Hymenoptera: Chalcidoidea: Eulophidae). It was once classified in the tribe Elachertini with genera having scutellar grooves and complete notauli, but in some characters it resembles the genus Pnigalio Schrank from the former tribe Eulophini. As part of a revision of Pnigalio we investigated the phylogenetic relationships between Ratzeburgiola and Pnigalio using both morphological and molecular data. Based on our results we synonymize Ratzeburgiola under Pnigalio n. syn., transfer its two included species to Pnigalio as P. cristatus (Ratzeburg) comb. n. and P. incompletus (Boucek) comb. n., and reassess the phylogenetic and taxonomic value of morphological characters traditionally considered important at the genus level
Cryptic species of the Necremnus tidius complex (Hym.: Eulophidae) revealed through molecules
No full textOngoing COI and 28S+ITS2 analyses indicate four cryptic species exist under the name Necremnus tidius Walker (Chalcidoidea), one in North America, two in Europe, and one in both regions. Study of specimens discriminated using molecular techniques has so far resulted in only partial species resolution using morphology. N. tidius has six junior synonyms. Prior synonymy of N. duplicatus under N. tidius appears to be incorrect, but correct names for the other two species remain to be determined
Figure 1 in Pnigalio agraules (Walker) and Pnigalio mediterraneus Ferrière and Delucchi (Hymenoptera: Eulophidae): two closely related valid species
No full textFigure 1. Comparison of parsimony tree topologies for the two gene regions. (A) One of 28 most parsimonious trees found for the cytochrome oxidase subunit I (COI) dataset; (B) one of four most parsimonious trees found for the 28S-D2 dataset. Bootstrap values>70% are shown in bold above branches.Published as part of Gebiola, M., Bernardo, U., Monti, M.M., Navone, P. & Viggiani, G., 2009, Pnigalio agraules (Walker) and Pnigalio mediterraneus Ferrière and Delucchi (Hymenoptera: Eulophidae): two closely related valid species, pp. 2465-2480 in Journal of Natural History 43 (39-40) on page 2472, DOI: 10.1080/00222930903105088, http://zenodo.org/record/521741
Native, naturalized and commercial predators evaluated for use against Diaphorina citri
No full textDiaphorina citri Kuwayama (Hemiptera: Liviidae), is a key pest of citrus associated with the yet uncurable Huanglongbing (HLB) disease, that is threatening worldwide citrus production. Control of D. citri has hitherto relied on chemical insecticides and on the use of the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). However, use of insecticides is problematic due to environmental and social issues, especially where D. citri is mostly spread in residential areas, and use of T. radiata has resulted in mixed success. Therefore, there is an urgent need to find sustainable and complementary practices to control this pest. Generalist predators, including green lacewings and coccinellids, have been frequently associated to D. citri in field surveys, yet they have rarely been tested. We have tested the predation capability under laboratory, greenhouse and semi-field conditions, of five predators: the green lacewings Chrysoperla comanche (Banks) and C. rufilabris Burmeister (Neuroptera: Chrysopidae), the coccinellids Diomus pumilio Weise and Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and the brown lacewing Sympherobius barberi Banks (Neuroptera: Hemerobiidae). All of them were capable of feeding on D. citri and reduce its populations under laboratory conditions, but critical differences emerged in greenhouse and field cages, with some predators (the green lacewings and D. pumilio) being the most effective. We discuss possible ways of utilizing these predators as an additional biological control tool to address current limitations of D. citri control in commercial groves, in residential areas and at the urban-agricultural interface
Rickettsia Symbionts Cause Parthenogenetic Reproduction in the Parasitoid Wasp Pnigalio soemius (Hymenoptera: Eulophidae)
No full textBacteria in the genus Rickettsia are intracellular symbionts of disparate groups of organisms. Some Rickettsia strains infect vertebrate animals and plants, where they cause diseases, but most strains are vertically inherited symbionts of invertebrates. In insects Rickettsia symbionts are known to have diverse effects on hosts ranging from influencing host fitness to manipulating reproduction. Here we provide evidence that a Rickettsia symbiont causes thelytokous parthenogenesis ( in which mothers produce only daughters from unfertilized eggs) in a parasitoid wasp, Pnigalio soemius (Hymenoptera: Eulophidae). Feeding antibiotics to thelytokous female wasps resulted in production of progeny that were almost all males. Cloning and sequencing of a fragment of the 16S rRNA gene amplified with universal primers, diagnostic PCR screening of symbiont lineages associated with manipulation of reproduction, and fluorescence in situ hybridization ( FISH) revealed that Rickettsia is always associated with thelytokous P. soemius and that no other bacteria that manipulate reproduction are present. Molecular analyses and FISH showed that Rickettsia is distributed in the reproductive tissues and is transovarially transmitted from mothers to offspring. Comparison of antibiotic-treated females and untreated females showed that infection had no cost. Phylogenetic analyses of 16S rRNA and gltA gene sequences placed the symbiont of P. soemius in the bellii group and indicated that there have been two separate origins of the parthenogenesis-inducing phenotype in the genus Rickettsia. A possible route for evolution of induction of parthenogenesis in the two distantly related Rickettsia lineages is discussed
Identificazione morfo-bio-molecolare ed interazioni trofiche degli antagonisti autoctoni di Dryocosmus kuriphilus Yasumatsu in Campania: Metodologia e risultati preliminari
No full textA partire dal 2008, nell’ambito di un progetto triennale finanziato dalla Regione Campania, sono stati raccolti i parassitoidi autoctoni del Dryocosmus kuriphilus introdot- to accidentalmente in questa regione nel 2005. La caratte- rizzazione di questi importanti limitatori naturali è avve- nuta seguendo un approccio integrato, comprendente: caratterizzazione morfologica, caratterizzazione biologica, caratterizzazione molecolare, caratterizzazione filogeneti- ca. Il materiale raccolto in Campania è stato confrontato con esemplari raccolti in altre zone d’Italia, consentendo di valutare la variabilità intraspecifica delle specie più dif- fuse. L’approccio integrato, ed in particolare la caratteriz- zazione molecolare, hanno consentito l’individuazione di specie diverse corrispondenti ad entità morfologiche indi- stinguibili, così come il raggruppamento di entità morfo- logicamente diverse sotto un’unica entità tassonomica. Infine, combinando i dati dei parassitoidi raccolti dal cini- pide del castagno con quelli relativi alle specie raccolte da cinipidi delle querce, è stato possibile identificare i per- corsi trofici che sono alla base dello spostamento di que- sti importanti limitatori naturali tra querce e castagno
A karyological study of the genus Pnigalio Schrank (Hymenoptera: Eulophidae): Assessing the taxonomic utility of chromosomes at the species level
No full textWe provide a karyological study of 12 species of the genus Pnigalio in an attempt to evaluate the taxonomic utility of karyotypes at the species level. For all species of Pnigalio examined the number of chromosome was 2n=12. Karyotype formulae presented mainly metacentric and submetacentric chromosomes, although a pair of acrocentrics or subtelocentrics, shorter than biarmed chromosomes, was present in some species. The analysis of karyotypes of Pnigalio showed frequent but not general interspecific variability of the chromosome traits. Although most of the studied species revealed concordance between morphological and karyological characters (centromeric index and relative length), two other categories have been identified: morphologically distinct species without reciprocal differences in karyotype structure, and morphologically similar species that strongly differ in chromosomal characters
Did the parasitoid Pnigalio mediterraneus (Hymenoptera: Eulophidae) track the invasion of the horse chestnut leafminer?
No full textHow communities of natural enemies, such as parasitoids, adapt to the range expansion of their hosts or the arrival of a novel invasive host is an important question in invasion biology. Do parasitoids track the expansion of their hosts from their shared native range? Do they locally adapt both behaviorally and physiologically to the arrival of a novel species by shifting hosts? Few studies have addressed those questions, yet they are important to develop efficient methods to manage invasive species. Here we focus on Pnigalio mediterraneus Ferri,re and Delucchi (Hymenoptera: Eulophidae), an important parasitoid of two major agricultural and ornamental pests, the olive fruit fly Bactrocera oleae Rossi (Diptera: Tephritidae) and the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae). C. ohridella recently invaded Europe starting from the Southern Balkans, whereas B. oleae has been associated since the Quaternary with wild olives in the Mediterranean, where it largely spread after the domestication of cultivated olives. We used two markers, the ribosomal spacer ITS2 and the mitochondrial gene COI. Although the ITS2 dataset provided little variation and no phylogeographic signal, analysis of mtDNA of 188 individuals of P. mediterraneus from 54 European localities allowed us to identify 53 haplotypes. Both nucleotide and haplotype diversity were higher for Mediterranean samples, and from samples reared from B. oleae. The statistical parsimony network identified one haplotype as the most frequent, ancestral and mainly associated with C. ohridella. Our findings suggest that P. mediterraneus locally host switched to C. ohridella from other hosts in the Balkans and later tracked the horse chestnut leafminer invasion over Europe. Therefore both host-tracking and ecological sorting could explain the current distribution of P. mediterraneus haplotypes
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