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Citrus crop in Chlef valley showed many cases of decline and other typical symptoms of tristeza disease in old and young trees grafted on various rootstock and seedlings acquired from multiple origins in the valley. In order to decipher the reasons of the this citrus quick decline syndrome, a large scale survey of citrus tristeza virus (CTV) and its aphid vectors was carried out from the spring of 2016 to the autumn of 2019 in order to evaluate its current situation in term of distribution and strains. Samples collected from 93 orchards located in 21 localities were tested by DTBIA/DAS-ELISA. The analyses have confirmed the presence of CTV in 54 samples through the study area. Some of the CTV sources were chosen for further molecular genotype characterization associated with the CTV isolates now spreading in the Chlef area. Characterization with multiple molecular markers M.M.M.s and CP gene sequencing showed the presence of the T30 and VT genotypes. This result allowed confirmation of the presence of a virulent strain belonging to the VT genotype. The other CTV isolates were close to those recorded in Mitidja region, with nucleotide identity of 98,6 to 99,1% with the worldwide T30 mild CTV isolates. This early finding of a strain belonging to the severe VT genotype beside to efficient aphid vectors is an issue for Algerian citrus producers and needs rapid actions to be taken by the National phytosanitary services, extending the surveillance to other citrus production regions and uprooting the infected trees. [ABSTRACT FROM AUTHOR]

This study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the efficacy of different bio-rational insecticides against B. tabaci under greenhouse conditions. The results exhibited a special significance in B. tabaci infestation suitability between the two tomato varieties with a high infestation significance found in the Shifa F1 hybrid tomato variety compared to the Savera F1 hybrid tomato variety in the first plantation period. Subsequently, in the second plantation period, there was a significant difference between the two tomato varieties. Bemisia tabaci showed a preference for the Shifa F1 hybrid over the Savera F1 hybrid tomato variety. These differences occurred during the 1st, 2nd, 4th, 6th, 7th, 8th, and 10th weeks. In the experimental trial for the efficacy of eco-friendly biorational insecticides, spinosad, azadirachtin, Beauveria bassiana and Metarhizium anisopliae, there were significant differences between the treated and untreated plants during the two plantation periods. A high efficacy of spinosad on the B. tabaci population was found. Bemisia tabaci infestation under all the applications was reduced from 50 to 94.61% for the two plantation periods. This obvious decrease in B. tabaci population increase attention to benefits of the different bio-rational insecticides.

A small-scale survey was conducted on 12 beehives located in the Gharb region of Morocco in order to assess for the first time the presence of honey bee-infecting viruses in the country. A total of 240 individual bee samples were screened for seven honey bee viruses using reverse transcription (RT)-PCR. Among the infected samples, 41.7% contained one virus, 15% showed mixed infection with two viruses while 3.3% contained three. Deformed wing virus (DWV), was the most prevalent one, detected in 38.3% of the samples, followed by acute bee paralysis virus (ABPV), sacbrood virus (SBV) and chronic bee paralysis virus (CBPV) (20%, 14.2% and 9.2% of infection rate, respectively). Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV) and black queen cell virus (BQCV) were not detected. Nucleotide sequences of PCR amplicons obtained from detected viruses shared 98.5-99.4% identity with isolates reported in the GenBank. Although bee viruses usually persist as asymptomatic infections and persist in the colonies as covert infections, they can dramatically affect honey bee health and shorten the lives of infected bees under certain conditions. To the best of our knowledge, this study represents the first detection of ABPV, CBPV and SBV in honey bees in Morocco. [ABSTRACT FROM AUTHOR]

Strengthening Plant Health research is a major challenge for Mediterranean countries. The diversity and fragmentation of the research landscape in this region have weakened the impacts of national efforts. Mediterranean countries can benefit from coordination of research activities to increase efficiency and impacts. The initiative 'Plant health research priorities for the Mediterranean region', led by the International Centre for Advanced Mediterranean Agronomic Studies (CIHEAM Bari)1 and the Euphresco network for phytosanitary research coordination and funding2 can promote convergence of national programmes and optimize the use of the scarce funding available to plant health, thus strengthening international cooperation and increasing the excellence and relevance of research. [ABSTRACT FROM AUTHOR]

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This study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the efficacy of different bio-rational insecticides against B. tabaci under greenhouse conditions. The results exhibited a special significance in B. tabaci infestation suitability between the two tomato varieties with a high infestation significance found in the Shifa F1 hybrid tomato variety compared to the Savera F1 hybrid tomato variety in the first plantation period. Subsequently, in the second plantation period, there was a significant difference between the two tomato varieties. Bemisia tabaci showed a preference for the Shifa F1 hybrid over the Savera F1 hybrid tomato variety. These differences occurred during the 1st, 2nd, 4th, 6th, 7th, 8th, and 10th weeks. In the experimental trial for the efficacy of eco-friendly biorational insecticides, spinosad, azadirachtin, Beauveria bassiana and Metarhizium anisopliae, there were significant differences between the treated and untreated plants during the two plantation periods. A high efficacy of spinosad on the B. tabaci population was found. Bemisia tabaci infestation under all the applications was reduced from 50 to 94.61% for the two plantation periods. This obvious decrease in B. tabaci population increase attention to benefits of the different bio-rational insecticides. [ABSTRACT FROM AUTHOR]

Citrus tristeza virus (CTV) is the causal agent of the most important virus disease of citrus. CTV isolates differing in biological and molecular characteristics have been reported worldwide. Recently, CTV was detected in Syria in citrus groves from two Governorates (Lattakia and Tartous) and several CTV outbreaks have been reported in Apulia (southern Italy) since 2003. To molecularly characterize the CTV populations spreading in Syria and Italy, a number of isolates from each region was selected and examined by different molecular approaches including: Multiple Molecular Markers analysis (MMM), real time RT-(q)PCR, single strand conformation polymorphism (SSCP) of the major coat protein (CP) gene (P25), and sequence analysis of the CP (P25), P18, P20 and RdRp genes. SSCP analysis of CP25 yielded two distinct simple patterns among the Syrian isolates and three different patterns in the Italian isolates. Based on MMM analysis, all Syrian CTV isolates were categorized as VT-like genotype, whereas the Italian isolates reacted only with the markers specific for the T30 genotype. These findings were also confirmed by RT-qPCR and by sequencing analysis of four genomic regions. The Italian isolates had nucleotide identities which varied: from 99.5 to 99.8 for the CP gene; from 97.4% to 98.3% for the P18 gene; from 98.6% to 99.8% for the P20 and from 97.8% to 99.1% for the partial RdRp sequenced. High sequence identity was found for all genomic regions analyzed between the Syrian isolates (from 98.9% to 99.6%). These results show that the CTV populations spreading in Apulia and Syria are associated with different genotypes, indicating different potential impacts on the citrus trees in the field. Since in both areas the introduction of the virus is relatively recent, infected plants resulted to contain a single and common genotype, suggesting that CTV is spreading from the first outbreaks by aphids or local movement of autochthonous infected plant material. [ABSTRACT FROM AUTHOR]

Abstract: Citrus tristeza virus (CTV) is the most destructive viral pathogen of citrus and displays a high level of genetic and phenotypic diversity. In this study the biological characterization of monophyletic CTV-isolates based on p25 gene (Gp 1, Gp 2, Gp 3a, Gp 4, Gp 5, Gp M) was analyzed for the first time on the set of standard indicator plants and unde r the same environmental conditions, in order to compare the phenotypic characteristics of p25 genomic variants. The results showed that tested CTV-isolates varied in their ability to induced symptoms as well as in severity of symptoms e.g. pathogenicity. [Copyright &y& Elsevier]