Characterization of a new Helicoverpa armigera nucleopolyhedrovirus variant causing epizootic on a previously unreported host, Helicoverpa gelotopoeon (Lepidoptera: Noctuidae).

This paper reports the first biological and molecular characterization of a nucleopolyhedrovirus isolated from the soybean and cotton pest Helicoverpa gelotopoeon. Studies were performed following a virus outbreak in a rearing facility and in wild H. gelotopoeon populations in Córdoba, Argentina. Host identity was corroborated by partial sequencing of the COI gene. Scanning electron microscope observations of purified OBs revealed their polyhedral morphology and an average diameter of 0.89±0.14µm. Ultrathin sections of infected larvae examined by transmission electron microscopy showed the intranuclear occurrence of polyhedra and virus particles in fat body cells. Nucleocapsids were singly enveloped. Phylogenetic analysis of lef-8, lef-9, polh, orf5/5b and hr3-orf62 viral sequences identified this new NPV isolate (hereafter HegeSNPV) as a variant of Helicoverpa armigera nucleopolyhedrovirus (HearNPV). Furthermore, HegeSNPV was closely related to the so-called "HzSNPV Group" within HearNPV, although having particular characteristics.

Exploring the bacterial microbiota associated with native South American species of Aphis (Hemiptera: Aphididae).

Aphids harbor a variety of bacterial endosymbionts, including the obligate symbiont Buchnera aphidicola and diverse facultative symbionts. The former supplies its host with essential amino acids. The latter are not indispensable for insect survival, but often improve their host's fitness. To date, the study of such associations was restricted to aphids of Holarctic origin. The bacterial microbiota of seven Aphis species from Argentina was investigated. The presence of B. aphidicola was assessed by specific PCR. Additional symbionts were identified through PCR with eubacterial universal primers, cloning, and sequencing of nearly complete 16S rRNA gene, intergenic spacer region, and partial 23S rRNA gene and subjected to phylogenetic analysis. Infection with B. aphidicola was confirmed in every species analyzed. The facultative symbiont Serratia symbiotica was detected in Aphis malalhuina Mier Durante, Nieto Nafría & Ortego, 2003, Aphis senecionicoides Blanchard, 1944, and Aphis schinifoliae Blanchard, 1939, while Hamiltonella defensa was identified in Aphis mendocina Mier Durante, Ortego & Nieto Nafría, 2006. Arsenophonus sp. was found infecting Aphis melosae Mier Durante & Ortego, 1999, and a new, undescribed Aphis sp. In Aphis danielae Remaudière, 1994, no facultative symbionts could be recorded. When analyzing the highly conserved 16S rRNA gene, the phylogenetic tree grouped the S. symbiotica, H. defensa, and Arsenophonus isolates into three well-defined clusters showing little variability among clones corresponding to the same aphid host species. This article reports for the first time the endosymbionts associated with aphids native to South America. Despite their geographic origin, the qualitative composition of their microbiota revealed no evident differences from that described for aphids in the Northern Hemisphere.

Detection and kinetic analysis of Epinotia aporema granulovirus in its lepidopteran host by real-time PCR.

Epinotia aporema granulovirus (EpapGV) has attracted interest as a potential biocontrol agent of the soybean pest Epinotia aporema in Argentina. Studies on virus/host interactions conducted so far have lacked an accurate method to assess the progress of virus load during the infection process. The present paper reports the development of a real-time PCR for EpapGV and its application to describe viral kinetics following ingestion of two different virus doses by last-instar E. aporema larvae. Real-time PCR was shown to be a reliable method to detect and quantify the presence of EpapGV in the analyzed samples. The increase in virus titer (log) exhibited a sigmoidal pattern, with an exponential growth phase between 24 and 48 h postinfection for both initial doses tested.

Ultrastructural detection of an unusual intranuclear bacterium in Pentastiridius leporinus (Hemiptera: Cixiidae).

Pentastiridius leporinus is an important vector of sugar beet pathogens in eastern France. An electron microscope survey on the insect-associated microflora revealed the occurrence of intranuclear prokaryotic cells in every internal organ analysed. These bacteria, which could also be found in the cytoplasm surrounding the nucleus, had a homogeneous coccoid (ca. 0.45 microm) or rod (0.45-1 microm) shape. The presence of three membrane layers was observed, the outermost forming a kind of vacuole containing generally a single microorganism. No cytopathological abnormalities were detected in the infected cells. To our knowledge, this is the first report of a hemipteran species infected by intranuclear bacteria. The possible identity of this microorganism is discussed.

Sequencing of the bicistronic genome segments S7 and S9 of Mal de Río Cuarto virus (Fijivirus, Reoviridae) completes the genome of this virus.

The nucleotide sequences of genomic segments S7 and S9 of Mal de Río Cuarto virus (MRCV, Fijivirus group II) have been determined, thus completing the entire genome sequence of the virus. These segments showed a non-overlapping bicistronic structure, as in other members of the genus. MRCV S7 ORF-1 had a length of 1086 bp and encoded a 41.5 kDa putative polypeptide, whereas MRCV S7 ORF-2 had a length of 930 bp and encoded a 36.8 kDa putative polypeptide. Proteins of 39 and 20.5 kDa were predicted for the 1014 bp long MRCV S9 ORF-1 and the 537 bp long MRCV S9 ORF-2, respectively. The terminal 5' and 3' sequences of both segments were 5'AAGUUUUU3' and 5'CAGCUnnnGUC3', respectively. Specific imperfect inverted repeats of each segment were identified. Comparison of the predicted proteins with those of related virus genome segments counterparts in maize rough dwarf virus (MRDV) and rice black streaked dwarf virus (RBSDV), showed 64.5-44.3% identities. These values are lower than those resulting from comparisons between MRDV and RBSDV. The topology of the trees obtained using the complete nucleotide and amino acid sequences of MRCV S7 and MRCV S9 was consistent with the analysis of the other MRCV segments previously published.