Compatibility between entomopathogenic fungi and biorational insecticides in toxicity against Ronderosia bergi under laboratory conditions

Our aim was to evaluate the efficacy of combinations between two biorational insecticides (luphenuron, methoxyfenozide), a new synthetic chemical pesticide (rynaxypyr), and three entomopathogenic fungi strains (Beauveria bassianaLPSc 1067, LPSc1082), and Metarhizium anisopliae (LPSc 907) in the biocontrol of the pest grasshopper Ronderosia bergi (Stål) under laboratory conditions. The insecticides were tested at three concentrations: the average concentration recommended for application in the field (100%) and 50% and finally 25% of that level. The fungal strains used were adjusted to 1×108, 1×106, and 1×104conidia ml-1. The combinations of those insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to R. bergi nymphs than any of the individual agents used alone. The three insecticides tested did not affect the isolates of the two species of entomopathogenic fungi employed. In conclusion, the use of these biorational insecticides in an IPM program aimed at control of the grasshopper R. bergicould be of value

Virulence and enzymatic activity of three new isolates of Beauveria bassiana (Ascomycota: Hypocreales) from the South American locust Schistocerca cancellata (Orthoptera: Acrididae)

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

Effect of entomopathogenic fungi introduced as corn endophytes on the development, reproduction, and food preference of the invasive fall armyworm Spodoptera frugiperda

Fall armyworm (FAW), Spodoptera frugiperda, is a migratory polyphagous pest that causes major damage to economically important cultivated grasses, such as corn. Native to the neotropics in America but recently reported as an invasive pest in Africa and Asia, FAW imposes a serious threat to food security and sustainable crop productivity due to lack of efective management. In this study, the introduction of entomopathogenic fungi as endophytes was explored as an alternative more sustainable management strategy against FAW in corn. The study determined (1) the efect of isolates and inoculation methods on the ability of entomopathogenic fungi to colonize corn plants, and (2) the efect of colonized plants on S. frugiperda survival, development, reproduction, and food preference. Although all tested isolates (twelve of Beauveria bassiana and one each of Metarhizium anisopliae and Metarhizium robertsii) colonized inoculated plants, there was a highly signifcant interaction between isolates and inoculation methods. Highest plant colonization was obtained by Beauveria bassiana isolate (LPSc 1098) using foliar spray. Endophytic B. bassiana caused signifcant reductions in larval and pupal survival, length of diferent developmental stages, total S. frugiperda lifespan, and leaf area consumed by third instar larvae. Plant colonization also signifcantly reduced female longevity, fecundity, and fertility. This is the frst report for the negative efects of endophytic B. bassiana on S. frugiperda growth, reproduction, and food preference. Our results highlight the promising potential of incorporating entomopathogenic fungi as endophytes in integrated pest management practices to protect corn against FAW if their efcacy is also confrmed under feld conditions

Effects of endophytic Beauveria bassiana (Ascomycota: Hypocreales) on biological and reproductive parameters and food preference of the soybean pest Helicoverpa gelotopoeon

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 managemen

Nuevos registros de hongos entomopatógenos en acridios (Orthoptera: Acridoidea) de la República Argentina New records of entomopathogenic fungi from grasshoppers (Orthoptera: Acridoidea) in Argentina

Los acridios (tucuras y langostas) continúan ocasionando pérdidas económicas en la agricultura a nivel mundial. En Argentina, la importancia de estos insectos ha sido reconocida desde mediados del siglo XIX, dependiendo de la región considerada y en relación al progresivo desarrollo agropecuario en el país. Los hongos son los microorganismos parásitos de insectos más frecuentemente encontrados en la naturaleza y la mayoría de las investigaciones con hongos entomopatógenos se ha centrado en su desarrollo como bioplaguicidas. En el presente trabajo se dan a conocer cinco registros nuevos de Beauveria bassiana (Bals.-Criv.) Vuill., y dos de Entomophaga grylli (Fresen.) A. Batko que se encontraron afectando distintas especies de acridios; se amplía así la distribución geográfica y el espectro hospedador para estas especies fúngicas. Cabe destacar que con el aporte de estos siete registros nuevos, el número total de hongos entomopatógenos de acridios citados para la República Argentina se eleva de 22 a 29.Grasshoppers and locusts continue causing serious economic losses in agriculture worldwide. In Argentina, the importance of these insects has been recognized since the mid-nineteenth century, depending on the region considered and in relation to the progressive development of agriculture. Fungi are the most frequently found microorganisms parasitizing insects in nature, and most of the entomopathogenic fungi investigations have been focused on their development as biopesticides. In this study five new records of Beauveria bassiana (Bals.-Criv.) Vuill., and two new records of Entomophaga grylli (Fresen.) A. Batko, are presented, extending the geographical distribution and the host range for these fungal species. With these seven new records, the total number of grasshopper entomopathogenic fungi cited for Argentina is raised from 22 to 29

Nuevos registros de hongos entomopatógenos en acridios (Orthoptera: Acridoidea) de la República Argentina

Los acridios (tucuras y langostas) continúan ocasionando pérdidas económicas en la agricultura a nivel mundial. En Argentina, la importancia de estos insectos ha sido reconocida desde mediados del siglo XIX, dependiendo de la región considerada y en relación al progresivo desarrollo agropecuario en el país. Los hongos son los microorganismos parásitos de insectos más frecuentemente encontrados en la naturaleza y la mayoría de las investigaciones con hongos entomopatógenos se ha centrado en su desarrollo como bioplaguicidas. En el presente trabajo se dan a conocer cinco registros nuevos de Beauveria bassiana (Bals.-Criv.) Vuill., y dos de Entomophaga grylli (Fresen.) A. Batko que se encontraron afectando distintas especies de acridios; se amplía así la distribución geográfica y el espectro hospedador para estas especies fúngicas. Cabe destacar que con el aporte de estos siete registros nuevos, el número total de hongos entomopatógenos de acridios citados para la República Argentina se eleva de 22 a 29

Efecto de la calidad del agua de criaderos de mosquitos (Diptera: Culicidae) sobre la patogenicidad e infectividad de las zoosporas del hongo Leptolegnia chapmanii (Straminipila: Peronosporomycetes)

Effect of water quality in mosquito breeding sites on the pathogenicity and infectivity of zoospores from the fungus Leptolegnia chapmanii (Straminipila: Peronosporomycetes). The fungus Leptolegnia chapmanii is highly pathogenic to mosquito larvae in Argentina. We studied if physical and chemical characteristics of the water from mosquito breeding sites affect pathogenicity, and the infectivity of zoospores of L. chapmanii. Water samples were taken from pools filled by rains, urban ditches with domestic waste water, pools filled by overflow from Río de la Plata, and flower vases from the Cemetery of La Plata city. Sub-samples of water were analyzed for physical and chemical characteristics, while other sub-samples were used for laboratory bioassays. Containers with 150 ml of water samples, 25 Aedes aegypti larvae, and 2.8 x 105 zoospores of L. chapmanii, were incubated under controlled environment, and larval mortality was recorded after 48 h. There were highly significant differences among mortalities in water from cemetery vases (70.2%), rain pools water (99.5%), and pools with water from Rio de la Plata (95%). There were no significant differences among larval mortalities in water from ditches, rain pools and Río de la Plata pools. Leptolegnia chapmanii was successful as a biological control agent in all kinds of tested water qualities, producing high larval mortality. Rev. Biol. Trop. 57 (1-2): 371-380. Epub 2009 June 30