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Characterization of electrical penetration graphs of Bucephalogonia xanthophis, a vector of Xylella fastidiosa in citrus

MIRANDA, M. P.; FERERES, A.; APPEZZATO-DA-GLORIA, B.; LOPES, J. R. S.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
Português
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36.91%
The sharpshooter Bucephalogonia xanthophis (Berg) (Homoptera: Cicadellidae) is a vector of the xylem-limited bacterium, Xylella fastidiosa (Wells, Raju, Hung, Weisburg, Mandelco-Paul, and Brenner), which causes citrus variegated chlorosis. Despite the importance of citrus variegated chlorosis, the probing behavior of vectors on citrus and its implications for transmission of X. fastidiosa have not been studied. Here we studied electrical penetration graph (EPG-DC system) waveforms produced by B. xanthophis on Citrus sinensis (L.) Osbeck (Rutaceae), and their relationships with stylet activities and xylem ingestion. Electrical penetration graph waveforms were described based on amplitude, frequency, voltage level, and electrical origin of the observed traces during stylet penetration on plant tissues. The main waveforms were correlated with histological observations of salivary sheaths in plant tissues and excretion analysis, in order to determine stylet activities and their precise position. Six waveforms and associated activities are described: (S) secretion of salivary sheath and intracellular stylet pathway, (R) resting during stylet pathway, (Xc) contact of stylets with xylem vessels, (Xi) active xylem ingestion, (N) interruption within the xylem phase (during Xc or Xi)...

Effect of contact and systemic insecticides on the sharpshooter Bucephalogonia xanthophis (Hemiptera: cicadellidae), a vector of Xylella fastidiosa in citrus

Bezerra-Silva, Gerane Celly Dias; Silva, Márcio Alves; Miranda, Marcelo Pedreira de; Lopes, Joao Roberto Spotti
Fonte: FLORIDA ENTOMOLOGICAL SOC; LUTZ Publicador: FLORIDA ENTOMOLOGICAL SOC; LUTZ
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.66%
The knockdown and toxic effects of insecticides of different chemical groups and modes of action registered for citrus in Brazil were investigated for effective control of Bucephalogonia xanthophis, a sharpshooter vector of Xylella fastidiosa in citrus. The active ingredients dimethoate (1.2 mL/1.2L), imidacloprid (0.24 mL/1.2L) and lambda-cyhalothrin (0.24 mL/1.2L), as well as a control (water), were sprayed onto branches of potted-citrus nursery trees to evaluate the effect of residual contact. The insects were confined on sprayed branches by using sleeve cages, in groups of 10 per branch (5 branches/treatment). Lambdacyhalothrin showed a knockdown effect on B. xanthophis (>70% mortality within 2 h of exposure), and the residues were effective for approximately one wk. Imidacloprid, lambdacyhalothrin and dimethoate suppressed the vector populations for up to 3 wk after application, when the insects were exposed to sprayed plants for at least 24 h. In another experiment, 2 neonicotinoid insecticides (thiamethoxam and imidacloprid) were applied by soil drench to potted nursery trees, in order to study their systemic effect, i.e., mortality by ingestion on sharpshooter adults. Thiamethoxam and imidacloprid effectively controlled the vectors at all concentrations tested...

Mitochondrial DNA variation among populations of the glassy-winged sharpshooter, Homalodisca coagulata

Smith, Paul T.
Fonte: University of Arizona Library Publicador: University of Arizona Library
Tipo: Artigo de Revista Científica
Publicado em 22/12/2005 Português
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57.52%
The glassy-winged sharpshooter, Homalodisca coagulata (Homoptera: Cicadellidae), is a highly polyphagous insect species that is distributed throughout most of the southern regions of the United States. In the last 10 years, H. coagualta has become established in California and represents a significant threat to the state's $35 billion wine and table grape industries. DNA sequencing analysis was used to characterize a portion of the mitochondrial cytochrome oxidase I gene from a single population of the smoke tree sharpshooter, Homalodisca liturata, in California and from 20 natural populations of H. coagulata distributed in Tahiti, California, Texas, Louisiana, Mississippi, Alabama, and Florida. The results indicate that H. liturata and H. coagulata are genetically distinct, suggesting that they do not hybridize. Populations of H. coagulata are geographically structured into two groups of haplotypes; a group of populations from east of the Mississippi River including Louisiana, Mississippi, Alabama and Florida and a group comprised of populations west of the Mississippi River from Texas and California, and from Tahiti. There was no genetic structure among haplotypes within the eastern and western groups, respectively. The data also indicates that H. coagulata in California most likely originated from a source in Texas and not from any of the populations east of the Mississippi River.

Genetic differentiation among geographic populations of Gonatocerus ashmeadi, the predominant egg parasitoid of the glassy-winged sharpshooter, Homalodisca coagulata

de León, Jesse H.; Jones, Walker A.
Fonte: University of Arizona Library Publicador: University of Arizona Library
Tipo: Artigo de Revista Científica
Publicado em 08/02/2005 Português
Relevância na Pesquisa
47.11%
The aim of genetically comparing different populations of the same species of natural enemies is to identify the strain that is most adapted to the environment where it will be released. In the present study, Inter-Simple Sequence Repeat-Polymerase Chain Reaction (ISSR–PCR) was utilized to estimate the population genetic structure of Gonatocerus ashmeadi (Girault) (Hymenoptera: Mymaridae), the predominant egg parasitoid of Homalodisca coagulata (Say) (Homoptera:Cicadellidae), the glassy-winged sharpshooter. Six populations from throughout the U.S. and a population from Argentina identified as near G. ashmeadi were analyzed. Four populations (California; San Antonio, Texas; Weslaco, Texas [WTX-2]; and Florida) were field collected and two (Louisiana and Weslaco, Texas [WTX-1]) were reared. Three ISSR–PCR reactions were pooled to generate 41 polymorphic markers among the six U.S. populations. Nei's expected heterozygosity values (h), including the reared population from Louisiana, were high (9.01–14.3%) for all populations, except for a reared population from WTX-1 (2.9%). The total genetic diversity value (Ht) for the field populations was high (23%). Interestingly, the Florida population that was collected from one egg mass (siblings) generated the greatest number of polymorphic markers (20) and was observed with the highest gene diversity value (14.3%). All populations...