scholarly journals Suppression of Rice Planthopper Populations by the Entomopathogenic Fungus Metarhizium anisopliae without Affecting the Rice Microbiota

2020 ◽  
Vol 86 (21) ◽  
Author(s):  
Yifan Peng ◽  
Jifeng Tang ◽  
Mingsheng Hong ◽  
Jiaqin Xie

ABSTRACT Entomopathogenic fungi can regulate insect populations and function as crucial biological control agents against insect pests, but their impacts on nontarget microorganisms are poorly understood. In this study, we investigated the potential of the fungal strain Metarhizium anisopliae CQMa421 to control rice planthoppers under field conditions and its effects on rice microbiota. This fungus suppressed rice planthoppers during this period, and its control efficiency was more than 60% 7 days after application and did not significantly differ from that of the chemical treatment except in 2019. Both treatments showed a smaller population of rice planthoppers than the controls. After application, M. anisopliae was maintained on rice plants for approximately 14 days, showing a decreasing trend over time. Furthermore, the results showed that the bacterial and fungal richness (operational taxonomic units) and diversity (Shannon index) did not significantly differ between the fungal treatment and the controls after application. The major bacterial taxa of Proteobacteria (including Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria), Actinobacteria, Bacteroidetes, and Cyanobacteria accounted for more than 80% of the bacterial community after fungal application, and the major fungal taxa Ascomycota (including Eurotiomycetes, Dothideomycetes, and Sordariomycetes) and Basidiomycota (including Ustilaginomycetes) represented more than 90% of the fungal community. However, the microbial communities of the rice phyllosphere did not significantly change after entomopathogenic-agent application, indicating that the indigenous microbial communities may adapt to fungal insecticide application. Taken together, the results suggest that this fungal agent has good potential for rice planthopper control with no substantial effects on rice microbial communities. IMPORTANCE Entomopathogenic fungi may be used as crucial biocontrol agents for the control of insect pests, but few effective fungal strains have been reported for the control of the rice planthopper, a major pest of rice. More importantly, the impacts of fungal insecticide application on nontarget microorganisms have not been well evaluated, especially under field conditions. Therefore, in this study, we investigated the effects of the fungal strain M. anisopliae CQMa421 on rice planthopper populations from 2017 to 2019 and evaluated its potential impacts on the microbiota of rice plants after application. The results suggested that this fungal agent has good potential for use in the control of rice planthoppers with no significant effects on rice microbial communities, representing an alternative strategy for the control of rice pests.

2018 ◽  
Vol 64 (3) ◽  
pp. 191-200 ◽  
Author(s):  
Cynthia Barbosa Rustiguel ◽  
María Fernández-Bravo ◽  
Luis Henrique Souza Guimarães ◽  
Enrique Quesada-Moraga

Studies conducted over the last decades have shown the potential of entomopathogenic fungi for the biocontrol of some insect pests. Entomopathogenic fungi infect their host through the cuticle, so they do not need to be ingested to be effective. These fungi also secrete secondary metabolites and proteins that are toxic to insect pests. In this context, we analyzed the pathogenicity of Metarhizium anisopliae (Metschn.) strains IBCB 384 and IBCB 425 and Beauveria bassiana (Bals.-Criv.) Vuill. strains E 1764 and E 3158 against Galleria mellonella (Linn.) larvae, during pre-invasion and post-invasion phases. The results showed M. anisopliae, especially strain IBCB 384, was most virulent in the pre-invasion phase against G. mellonella, whereas B. bassiana, especially strain E 1764, was most virulent in the post-invasion phase. During in vivo development and in the production of toxic serum, B. bassiana E 3158 was the most virulent. Different fungal growth (or toxin) strategies were observed for studied strains. Metarhizium anisopliae IBCB 425 prioritizes the growth strategy, whereas strain IBCB 384 and B. bassiana strains E 1764 and E 3158 have a toxic strategy. All strains have pathogenicity against G. mellonella, indicating their possible use for biocontrol.


2018 ◽  
Vol 19 (6) ◽  
pp. 2365-2373 ◽  
Author(s):  
AYU SAFITRI ◽  
SITI HERLINDA ◽  
ARUM SETIAWAN

Safitri A, Herlinda S, Setiawan A. 2018. Entomopathogenic fungi of soils of freshwater swamps, tidal lowlands, peatlands, and highlands of South Sumatra, Indonesia. Biodiversitas 19: 2365-2373. Ecosystems of lowlands and highlands in South Sumatra have specific characteristics of soils and vegetations that can affect the availability of entomopathogenic fungi. This study aimed to explore and identify species and to determine inoculum potentials of the entomopathogenic fungi from soils of freshwater swamps, tidal lowlands, peatlands, and highlands. Baiting of entomopathogenic fungi on soil samples used the larvae of Tenebrio molitor. The entomopathogenic fungi species found in this research were Beauveria bassiana and Metarhizium anisopliae. The number of the fungal isolates were 30 isolates consisting of nine isolates of B. bassiana and 21 isolates of M. anisopliae.The highest number of isolates was found in the highland ecosystem (11 isolates) and the lowest was found in peatland ecosystem (4 isolates). The highest percentage average of inoculum potentials of the fungi was found in the high land ecosystem (4.04%) and the lowest one was found in freshwater swamps ecosystem (2.11%). Based on the vegetation type, the soil planted with mustard in Talang Patai-Pagaralam (highland ecosystem) had the highest inoculum potentials (9.33%). These fungi will make an important contribution to the biological control for insect pests in lowland to highland ecosystems in Indonesia.


Insects ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 36 ◽  
Author(s):  
Wuji Jiang ◽  
Yifan Peng ◽  
Jiayi Ye ◽  
Yiyi Wen ◽  
Gexin Liu ◽  
...  

Entomopathogenic fungi are the key regulators of insect populations and some of them are important biological agents used in integrated pest management strategies. Compared with their ability to become resistant to insecticides, insect pests do not easily become resistant to the infection by entomopathogenic fungi. In this study, we evaluated the mortality and immune response of the serious crop pest Locusta migratoria manilensis after exposure to a new entomopathogenic fungus strain, Metarhizium anisopliae CQMa421. M. anisopliae CQMa421 could effectively infect and kill the L. migratoria adults and nymphs. The locust LT50 under 1 × 108 conidia/mL concentration of M. anisopliae was much lower than that under conidial concentration 1 × 105 conidia/mL (i.e., 6.0 vs. 11.2 and 5.0 vs. 13.8 for adults and nymphs, respectively). The LC50 (log10) of M. anisopliae against locust adults and nymphs after 10 days was 5.2 and 5.6, respectively. Although the number of hemocytes in L. migratoria after exposure to M. anisopliae did not differ with that in the controls, the enzymatic activity of superoxide dismutase (SOD) and prophenoloxidase (ProPO) did differ between the two treatments. The activities of both SOD and ProPO under the M. anisopliae treatment were lower than that in the controls, except for the ProPO activity at 72 h and the SOD activity at 96 h. Further, the expression of the L. migratoria immune-related genes defensin, spaetzle, and attacin differed after exposure to M. anisopliae for 24 h to 96 h. Taken together, this study indicated that infection with M. anisopliae CQMa421 could cause the death of L. migratoria by interacting with the immune responses of the host, demonstrating that this fungal strain of M. anisopliae can be an efficient biocontrol agent against L. migratoria.


2021 ◽  
Vol 911 (1) ◽  
pp. 012061
Author(s):  
Elisurya Ibrahim ◽  
Firmansyah Firmansyah ◽  
Sumarni Panikkai

Abstract Green leafhopper (Nephotettix virescens) is one of the major pests on rice plants that can be a vector of tungro disease. Current pest control using insecticides by farmers is very worrying because in general it is not as recommended which can cause disturbances in the balance of the ecosystem, so it is necessary to use more environmentally friendly control alternatives, one of which is the use of entomopathogenic fungi that are targeted and do not cause the death of natural enemies. The potential of entomopathogenic fungi as biological control agents needs to be continuously developed to reduce the use of insecticides, one of which is the fungus Metarhizium anisopliae which is a type of entomopathogenic fungus that can kill insect pests. The purpose of this study was to determine the effect of several concentration and application method of M. anisopliae on the mortality of the green leafhopper (Nephotettix virescens). The study was conducted in the Laboratory and Greenhouse of the Tungro Disease Research Station starting from February - April 2020 using a two-factor factorial design in a completely randomized design (CRD). The first factor was the application method consisting of two treatments, namely the spray method (A1) and dip method (A2) while the second factor was the conidia density of Metarhizium anisopliae with 4 levels, namely 0 (C0) as control, conidia density 106 (C1) conidia density 107 (C2) conidia density 108(C3). Each treatment was repeated three times. The results showed that the concentration of 106 by dipping application showed the fastest average death time of green leafhopper imago, which occured after 4 days of application, while the fastest average death time of green leafhopper nymph was 3.67 days after application at a concentration of 10 7 by dipping applications.


2018 ◽  
Vol 17 ◽  
pp. 82-91 ◽  
Author(s):  
Dipak Khanal

Soil insect pests are the major productivity constrains of different crops among which white grubs (Coleoptera: Scarabaeidae), both adult and larval stages, are extremely destructive in nature. Laboratory studies were conducted to evaluate the virulence of an indigenous and a commercial strain of the entomopathogenic fungi, Metarhizium anisopliae (Metsch.) Sorokin, against white grubs species Chiloloba acuta by applying the dipping method at Entomology Division, NARC, Nepal. Third instars larvae of C. acuta were dipped in suspensions of indigenous and commercial strains (Pacer) of M. anisopliae at different concentrations ranging from 3.33×104 to 1.04×108 spores/ml for 3-5 seconds which resulted in 97.8% and 89% mortalities with the highest dose of 1.04×108 spores/ml 40 days after inoculation (DAI), respectively. The LC50 values for indigenous and commercial strain were 3.5×105 and 1.88×106 spores/ml, respectively, with the potency of 1:0.28 at 40 DAI. Bioassays were conducted in completely randomized design. From results it is concluded that the tested strains of entomopathogenic fungi have potential as microbial control agents in managing white grubs in laboratory and it is suggested to be tested under farmers field condition.


Author(s):  
Atef M M Sayed ◽  
Christopher A Dunlap

Abstract Six fungal isolates of Beauveria bassiana (Balsamo) Vuillemin and one isolate of Metarhizium anisopliae (Metschnikoff) Sorokin were isolated and evaluated for their pathogenicity to Icerya seychellarum (Westwood) and Aulacaspis tubercularis Newstead. There is a positive correlation between the concentration of the fungal blastospore concentrations and the percentage of mortality. Bio-efficacy increased significantly after inoculation with increasing concentration of blastospores and elapsed time up to 12 d after inoculation. The mortality of nymphs exposed to fungal isolates at various concentrations varied between 2.5 and 88.8%. Probit analysis of data at 95% confidence limits of LC50 and LT50s showed significant differences in the susceptibility of nymphs of I. seychellarum and A. tubercularis to the tested fungal isolates. The fungal isolates of Egy-6 and Egy-9 were the most effective against I. seychellarum and A. tubercularis, respectively. They had the lowest LC50 (4.20 × 105 and 5.71 × 103 blastospore ml−1) and LT50 (ranged from 4.61 to 9.79 and 4.84 to 8.71 d), respectively. The current study showed that all the fungal isolates yielded moderate mortality rates of nymphs and adult female populations of both the tested insect pests. To our knowledge, this is the first report of bio-efficacy of Beauveria and Metarhizium isolates against members of the Diaspidadae and Monophlebidae family insects. These results establish that the use of these native entomopathogenic fungi isolates of B. bassiana (Egy-3, Egy-4, Egy-6, Egy-7, Egy-9, and Egy-10) and M. anisopliae (Egy-5) could be considered for further development as microbial control agents of the mealybug and scale insects as a potential biological agent for use in an IPM program.


2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Quratul Ain ◽  
Ata Ul Mohsin ◽  
Muhammad Naeem ◽  
Ghulam Shabbir

Abstract Background Thrips tabaci Lindeman (Thysanoptera: Thripidae) is the key pest of onions that causes economic yield losses in commercial onion production in Pakistan. In this study, potential of the entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisopliae, as a bio agent was evaluated to manage buildup of thrips population on onion crop. Results Efficacy tests for EPF were conducted against T. tabaci infesting 3 different onion varieties (Phulkara, Swat 1, and Virio 7). Commercial formulations of B. bassiana strain GHA and M. anisopilae strain ESC-1, were evaluated at 4 different concentrations (108, 109, 1010, and 1011 conidia/ml) under field conditions for 2 years. The efficacy was assessed 3, 5, 7, and 10 days after spray application of the whole onion plant. Efficacy expressed as T. tabaci (nymphs and adults) percent population reduction in comparison to controls. Maximum corrected percent population reduction was observed in onion plants treated with B. bassiana 1011 conidia/ml, i.e., 86.62, 84.59, and 86% in Phulkara, Swat 1, and Virio 7 onion varieties respectively, after 10 days of spray application. While onion plants treated with M. anisopliae 108 conidia/ml showed minimum corrected percent population reduction, i.e., 69.42, 68.45, and 69.11% in Phulkara, Swat 1, and Virio 7 onion varieties respectively, after 10 days of spray. Conclusions Beauveria bassiana could significantly reduce thrips population and could provide a better long-term management of T. tabaci on onion. B. bassiana had a high toxic effect against offspring production of the T. tabaci under field conditions than M. anisopliae.


2020 ◽  
Vol 56 (No. 2) ◽  
pp. 92-100
Author(s):  
Marek Seidenglanz ◽  
Jaroslav Šafář ◽  
Nikoleta Rubil ◽  
Miriama Ruseňáková ◽  
Veronika Roskóová

Over the course of three years (2016–2018), the effects of insecticides on stem-mining weevils [(Ceutorhynchus pallidactylus (Marsham, 1802), Ceutorhynchus napi (Gyllenhal, 1837)] were assessed under field conditions. The dates for spraying were determined on the basis of the recorded percentages of weevil females carrying mature eggs in their ovaries (timing I: the first females with mature eggs present in yellow water traps; timing II: more than 50% of the females with mature eggs present). Delaying the first spring insecticide application till timing II made it possible to combine the control of the stem weevil along with the control of the pollen beetle, Brassicogethes aeneus (Fabricius, 1775). However, the poor effectiveness of the tested insecticides on the stem-mining weevils, regardless of the date they were sprayed, indicates it is impossible to successfully control the insect pests with one insecticide application during the seasons with prolonged egg-laying periods.


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