- ArtículoAcceso AbiertoNew association between the mite Erythraeus sp. (Acari: Prostigmata: Parasitengona) and the psyllid Russelliana adunca (Hemiptera: Psylloidea)(2021)The association between the ectoparasitic mite, Erythraeus Latreille (Acari: Prostigmata: Parasitengona) and the psyllid Russelliana adunca Burckhardt (Hemiptera: Psylloidea) is reported for the first time. Larval erythraeid mites are not common on psyllids, therefore this first report adds a new host association and widens the distribution of the mite in South America.
- ArtículoAcceso AbiertoFirst record of Heteropsylla tenuata from Argentina (Hemiptera: Psyllidae), and additional notes on other psyllid species(2021)The Psyllidae family is the most diverse within Psylloidea, with more than 1,300 species worldwide. Some psyllid species are important pests mainly of fruit trees, forest and ornamental plants. Despite being an economically relevant group, there are few studies on its biology, geographic distribution, natural enemies or host plant associations for many Argentinean psyllid species. This work records one species from Argentina for the first time, extends the distribution of another two psyllid species and provides information on host plants.
- ArtículoAcceso AbiertoVirulence and enzymatic activity of three new isolates of Beauveria bassiana (Ascomycota: Hypocreales) from the South American locust Schistocerca cancellata (Orthoptera: Acrididae)(2020)Schistocerca cancellata is a large-sized acridid, which has historically represented the greatest agricultural problem in southern South America, causing serious economic losses. Since 2015 S. cancellata entered in a state of outbreak condition of historical proportions, producing frequent and large swarms of up to 25 km² in the north and central region of Argentina and areas of neigh boring Bolivia and Paraguay. At present, chemical insecticides are still the only means available for the control of S. cancellata. We analyzed under laboratory conditions the effectiveness of three fungal strains of Beauveria bassiana isolated from S. cancellata and also determined the relationship between chitinase, protease, and lipase levels at different temperatures of these fungi and their insecticidal activities. The pathogenicity assays were carried out by the sprayed method with concentrations of 1 × 10⁴, 1 × 10⁶ and 1 × 10⁸ conidia/ml. We observed that isolate LPSc 1227 caused the highest mortality at each dose studied, ranging from 100% at a dose of 1 × 10⁸ conidia/ml to 33.3 ± 3.2% at the lowest dose of 1 × 10⁴ conidia/ml. Moreover, in this isolate the highest values of chitinolytic and proteolytic activity were recorded (2.31 ± 0.31 and 1.78 ± 0.04), respectively.
- ArtículoAcceso AbiertoPotential of spore-forming bacteria as biocontrol agents of wheat foliar diseases under laboratory and greenhouse conditions(2000)The potential of Bacillus subtilis, Bacillus cereus, Bacillus licheniformis, Bacillus pumilus, Brevibacillus laterosporus and Paenibacillus polymyxa as biocontrol agents of four foliar necrotrophic pathogens of wheat in Argentina has been evaluated. The following assays were used: (a) effect of the bacterial antagonists on fungal growth in the central disk test with paired cultures, (b) effect of the antagonists on the germination of fungal spores in the paired suspension assay, and (c) reduction of disease severity in greenhouse experiments. The observed effects were specific for the antagonist-pathogen combination investigated. In the paired culture test, most of the bacterial antagonists inhibited the mycelial growth of the four pathogens tested at 14 days of the evaluation. B. licheniformis showed the best results for controlling Septoria tritici and Drechslera tritici-repentis whereas it was the worst against Bipolaris sorokiniana. In the case of Alternaria triticimaculans, the best were B. laterosporus, P. polymyxa and B. licheniformis. Microscopic examination of excised pieces of the fungal colony perimeters showed clear differences among treatments and controls in hyphal morphology (plasmolysis and vacuolation of hyphae, irregular texture in the cytoplasm, formation of chlamydospores). In the central disk test, mycelial necrosis of A. triticimaculans was induced by B. laterosporus, P. polymyxa and B. pumilus. Similar results were obtained with B. sorokiniana in the presence of B. licheniformis and B. subtilis and D. tritici-repentis with B. pumilus. In some combinations, the presence of inhibition haloes or bacterial chemotaxis were observed. In the paired suspension assay, all the bacteria except B. cereus, inhibited the conidial germination of S. tritici. Only P. polymyxa, B. licheniformis and B. laterosporus inhibited the conidial germination of A. triticimaculans, B. laterosporus being the most effective. Although all the bacteria inhibited the conidial germination of B. sorokiniana, the most efficient were B. licheniformis, B. cereus and B. laterosporus. In greenhouse experiments, P. polymyxa and B. cereus were the most efficient to reduce disease severities produced by S. tritici and A. triticimaculans; on the contrary, these bacteria were not effective against B. sorokiniana and D. tritici-repentis. B. laterosporus BLA 170 showed a good behaviour against all the fungal pathogens, particularly for D. tritici-repentis and B. sorokiniana. This is the first report on the efficacy of B. laterosporus against fungal wheat pathogens.
- ArtículoAcceso AbiertoEffects of endophytic Beauveria bassiana (Ascomycota: Hypocreales) on biological and reproductive parameters and food preference of the soybean pest Helicoverpa gelotopoeon(Science Direct, 2019)Objectives: We studied Beauveria bassiana ability to endophytic colonize soybean and its effects on some biological and reproductive parameters and on the food preference of Helicoverpa gelotopoeon, a polyphagous plague of several agronomic crops. Methods: A suspension of 1x108 conidia ml-1 of B. bassiana (LPSC 1098), was inoculated in soybean plants using the leaf spraying method. H. gelotopoeon survival, developement, fecundity and fertility were registered to evaluate fungal effect. Also, food preference was determined by the free-choice method. Results: B. bassiana as an endophyte adversely affected the duration of the larval stages (L1, L2, L3, L4) and of the adult stages, as well as the total duration of the life cycle. Furthermore, the oviposition period, fecundity and fertility of H. gelotopoeon decreased. This is the first report of decreased consumption of soybean leaves by H. gelotopoeon due to endophytic B. bassiana. Conclusions: This investigation shows that endophytic fungi could be considered as useful microorganisms for the integrated pest management