Selectivity of Metarhizium anisopliae and Beauveria bassiana to adults of Telenomus podisi (Hymenoptera: Scelionidae)

The selectivity of entomopathogenic fungi to non-target organisms needs to be considered in Integrated Pest Management (IPM), because even though they are biological control agents, if used incorrectly, they can negatively alter the functioning of agroecosystems. Therefore, studies that assess the selectivity of these fungi to beneficial organisms are extremely important. The objective of this work was to evaluate the selectivity of Metarhizium anisopliae (Metarril®) and Beauveria bassiana (Boveril®) to adults of Telenomus podisi Ashmead (Hymenoptera: Scelionidae), under laboratory conditions. The products were evaluated on adult females of T. podisi, at the concentrations recommended by the manufacturer. To this, 0.2 mL of suspensions of each product and control (treatments) were applied to the inner surface of glass tubes, and then a female T. podisi was placed in it (≤ 48 h of emergence). After 24 h of contact, cards with 25 eggs of Euschistus heros Fabricius (Hemiptera: Pentatomidae) were offered for 24 h (COF24). After this period, the COF24 were withdrawn. After 72 h of contact of the female with the tube surface, new E. heros egg cards were made available (COF72) for 24 h for T. podisi ovipositioning. The mortality of T. podisi females was evaluated daily to determine longevity, percentage of parasitism and emergence, sex ratio, and egg-adult period of the T. podisi offspring. Metarril® and Boveril®, considered selective for adult females of T. podisi, did not negatively affect most of the parameters evaluated.

Aislamiento y caracterización de Metarhizium spp. de cultivos de caña de azúcar y su patogenicidad contra Mahanarva andigena (Hemiptera: Cercopidae)

Metarhizium anisopliae es uno de los hongos entomopatógenos más comercializados para la regulación de poblaciones de insectos plagas. Las cepas nativas de este hongo ejercen un importante rol en el control natural. Sin embargo, se desconoce su efectividad en condiciones amazónicas ecuatorianas. Es por ello que esta investigación tuvo como objetivos aislar y caracterizar cepas nativas de M. anisopliae con potencial para el control de Mahanarva andigena (Jacobi) en el cultivo de caña de azúcar (Saccharum officinarum L.). Se realizaron las colectas para el aislamiento y caracterización de los hongos, obteniendo un total de 20 aislados (quince de muestras de suelo y cinco de ninfas de M. andigena micosadas). Todos los aislados se caracterizaron con base en sus caracteres morfológicos y fisiológicos. En diez de ellos se evaluó la patogenicidad contra ninfas de M. andigena en condiciones de laboratorio. Los resultados obtenidos de la caracterización de los aislados fueron variables, tanto para el diámetro y tasa de crecimiento, como para el largo y ancho de conidios, germinación, esporulación y mortalidad corregida. El análisis de estas características demostró que los aislados DSA5401 y TI6301 presentaron los mejores valores para la mayoría de las variables evaluadas, en especial el diámetro, la tasa de crecimiento y la producción de conidios. Respecto a la efectividad en el control, los aislados DAS5401, TI6301, TS6304, PS5003, SJS5104 y SJS5102 presentaron una alta mortalidad corregida. Estos resultados indican la efectividad de aislados nativos de M. anisopliae para su uso en programas de control biológico de M. andigena.

Effect of storage conditions on the shelf-life extension of fungus-colonized substrates based on Metarhizium anisopliae using modified atmosphere packaging

Metarhizium anisopliae is a promising alternative to chemical pesticides against pine wilt disease caused by Bursaphelenchus xylophilus. Herein, we investigated the efficacy of modified atmosphere packaging (MAP) to prolong the shelf-life of the M. anisopliae conidia. The effects of various conditions on its stability were also examined. M. anisopliae-inoculated millet grains were treated in a MAP system with different packaging materials (polypropylene, PP; polyethylene terephthalate, PET; ethylene vinyl alcohol, EVOH), gas compositions (high CO2 atmosphere, ≈ 90%; high O2 atmosphere, > 95%; high N2 atmosphere, > 95%; 30% CO2 + 70% N2; 50% CO2 + 50% N2; 70% CO2 + 30% N2), and storage temperatures (4 and 25 °C). Results revealed EVOH film as the best for the preservation of gases at all concentrations for 28 days. MAP treatment in the high-barrier EVOH film under an atmosphere of 30% CO2 + 70% N2 achieved 80.5% viability of dried conidia (7.4% moisture content), with 44.2–64.9% viability recorded with the other treatments. Cold storage for technical concentrates formulation promoted extension of shelf-life of MAP-treated conidia. These results imply that MAP under optimized conditions could enhance the shelf-life of fungus-based biopesticides in fungus-colonized substrates formulations.

Characterization and Evaluation of Metarhizium spp. (Metsch.) Sorokin Isolates for Their Temperature Tolerance

A field survey was done in teak (Tectona grandis F.) forests in South India to explore the entomopathogenic effect of Metarhizium anisopliae (Ascomycota: Sordariomycetes) against teak defoliator, Hyblaea puera (Lepidoptera: Hyblaeidae). About 300 soils and infected insect samples were collected during the survey and thirty-six fungal isolates were isolated from soil and insect samples and characterized. The fungi were cultured on PDAY with dodine and antibiotics. Generally, the EPF culture was incubated at 27 °C in darkness for 15 days. Virulence of the Entomopathogenic Fungi (EPF) ability to germinate under cold and heat temperatures was assessed in a culture impregnated with conidia. In the experiment, it was found that for the first time Metarhizium quizhouense, Metarhizium robertsii, and Metarhizium majus species caused significantly higher mortality to hosts. These isolates of M. anisopliae, M. robertsii, M. majus, and M. quizhouense were all considered to be effective virulent and environmentally adaptive. The Metarhizium isolates were recommended as effective bio-control agents through the field investigation of teak defoliator Hyblaea puera from South India forest. This study paves the way to utilize the indigenous isolates of EPF for the control of teak defoliator and to combat the pests thatare resistant to insecticide.

Effect of Beauveria bassiana and Metarhizium anisopliae on different stages of Phlebotomus papatasi (Diptera: Psychodidae)

The sand fly, Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae), is the main vector of Leishmania major Yakimoff and Schokhor, 1914, the causative agent of zoonotic cutaneous leishmaniasis North Africa, the Middle East, and North Sinai. The purpose of this study was to determine the effect of fungi on P. papatasi larvae, pupae, and adults using light microscopic analysis, scanning electron microscope (SEM), and histopathological studies. Specifically, larvae, pupae, and adult P. papatasi were infected with the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae. Scanning electron microscope and histopathological methods were used to investigate the destructive impact of the fungi on the external and internal structures of P. papatasi. The results revealed propagation of the conidia on the cuticles of all P. papatasi life stages, including on the compound eyes, leg setae, thorax, wings, and abdomen of the adults. Histological sections of the control and treated larvae, pupae, and adults showed many alterations and malformations in the body and tissues of all life stages after 72 h. These results demonstrated that B. bassiana was more effective than M. anisopliae as a biological control of phlebotomine sand flies. Further studies to determine the best methods for delivery and application in the diverse ecological settings of the various leishmaniasis vectors are recommended.

SCREENING THE ABILITY TO CONTROL MESOMORPHUS VILLIGER (BLACK BEAN BEETLE) OF SIX METARHIZIUM ANISOPLIAE STRAINS ISOLATED IN BINH DUONG, VIET NAM

Three types of bio-preparations of six different Metarhizium anisopliae strains (Ma-SD, Ma-SAT, Ma-ST, Ma-RS, Ma-RN, and Ma-RM) isolated from soil in Binh Dương province, Viet Nam, including conidia, LIMs and MIXs, were evaluated the acaricidal effects on Mesomorphus villager (Black bean beetle). The results of conidia studies showed the high efficacies of Ma-SAT and Ma-ST at 98.64 ± 1.25 percent and 95.23 ± 3.15 percent, in turn. The times to kill half of the studied beetles were observed from the 9th day to the 12th day of the 15-day study process seemed indifferent and late, also without signs of mycosis at the end of the studies. LIMs had low efficacies in the studies, though the LIM of Ma-SAT continued to perform the efficacy at 57.14 ± 3.45 percent among the studied groups after the 15-day study process, moreover, its LIM was the only one killing half of the beetles on day 13th of the study process. The efficacies of MIXs were all higher than 91 percent, among them, Ma-ST, Ma-SAT, and Ma-RS showed their outstanding performance at 96.94 ± 2.49, 98.08 ± 1.21, 98.18 ± 1.38, respectively. Interestingly, all strains were observed to kill half of the studied beetles on day 5th of study time, the soonest one was recorded from the Ma-SAT experiment on day 3rd.

Synthesis of Metarhizium anisopliae–Chitosan Nanoparticles and Their Pathogenicity against Plutella xylostella (Linnaeus)

Nanotechnology is increasingly being used in areas of pesticide production and pest management. This study reports the isolation and virulence of a new Metarhizium anisopliae isolate SM036, along with the synthesis and characterization of M. anisopliae–chitosan nanoparticles followed by studies on the efficacy of nanoparticles against Plutella xylostella. The newly identified strain proved pathogenic to P. xylostella under laboratory conditions. The characterization of M. anisopliae–chitosan nanoparticles through different analytical techniques showed the successful synthesis of nanoparticles. SEM and HRTEM images confirmed the synthesis of spherical-shaped nanoparticles; X-ray diffractogram showed strong peaks between 2θ values of 16–30°; and atomic force microscopy (AFM) analysis revealed a particle size of 75.83 nm for M. anisopliae–chitosan nanoparticles, respectively. The bioassay studies demonstrated that different concentrations of M. anisopliae–chitosan nanoparticles were highly effective against second instar P. xylostella under laboratory and semi-field conditions. These findings suggest that M. anisopliae–chitosan nanoparticles can potentially be used in biorational P. xylostella management programs.