scholarly journals Virulence of the entomopathogenic fungus, Nomuraea rileyi, to various larval stages of the corn earworm, Helicoverpa armigera (Lepidoptera : Noctuidae)

1999 ◽  
Vol 34 (3) ◽  
pp. 399-403 ◽  
Author(s):  
Li-Chang Tang ◽  
Dor-Jih Cheng ◽  
Roger Feng-nan Hou
Keyword(s):  
Helicoverpa Armigera ◽  
Entomopathogenic Fungus ◽  
Corn Earworm ◽  
Nomuraea Rileyi ◽  
Larval Stages ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae

scholarly journals Comparative Toxicity of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) to Selected Insecticides

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 431 ◽  
Author(s):  
Fernando R. da Silva ◽  
Dario Trujillo ◽  
Oderlei Bernardi ◽  
Jose Carlos Verle Rodrigues ◽  
Woodward D. Bailey ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Acute Toxicity ◽  
Insecticide Resistance ◽  
Helicoverpa Armigera ◽  
Helicoverpa Zea ◽  
Corn Earworm ◽  
Median Lethal Concentration ◽  
Helicoverpa Armígera ◽  
Old World Bollworm ◽  
Lepidoptera Noctuidae

Until recently, the Old World bollworm (OWB) Helicoverpa armigera (Hübner) and the corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) were geographically isolated. Both species are major pests of agricultural commodities that are known to develop insecticide resistance, and they now coexist in areas where H. armigera invaded the Americas. This is the first study to compare the susceptibility of the two species to conventional insecticides. The susceptibility of third instar H. armigera and H. zea larvae to indoxacarb, methomyl, spinetoram, and spinosad was determined using a diet-overlay bioassay in a quarantine laboratory in Puerto Rico. Mortality was assessed at 48 h after exposure for up to eight concentrations per insecticide. Spinetoram exhibited the highest acute toxicity against H. armigera, with a median lethal concentration (LC50) of 0.11 µg a.i./cm2, followed by indoxacarb and spinosad (0.17 µg a.i./cm2 for both) and methomyl (0.32 µg a.i./cm2). Spinetoram was also the most toxic to H. zea (LC50 of 0.08 µg a.i./cm2), followed by spinosad (0.17 µg a.i./cm2) and methomyl (0.18 µg a.i./cm2). Indoxacarb was the least toxic to H. zea, with an LC50 of 0.21 µg a.i./cm2. These findings could serve as a comparative reference for monitoring the susceptibility of H. armigera and H. zea to indoxacarb, methomyl, spinetoram, and spinosad in Puerto Rico, and may facilitate the detection of field-selected resistance for these two species and their potential hybrids in areas recently invaded by H. armigera.

scholarly journals Pathogenicity of Native Entomopathogenic Fungus Nomuraea rileyi Against Spodoptera litura

2009 ◽  
Vol 10 (1) ◽  
pp. 11 ◽  
Author(s):  
Mahesh S. Padanad ◽  
P. U. Krishnaraj
Keyword(s):  
Topical Application ◽  
Helicoverpa Armigera ◽  
Entomopathogenic Fungus ◽  
Spodoptera Litura ◽  
Nomuraea Rileyi ◽  
Spore Concentration ◽  
Helicoverpa Armígera ◽  
Lethal Time ◽  
Geographical Locations

The entomopathogenic fungus Nomuraea rileyi was isolated from Spodoptera litura and Helicoverpa armigera insect cadavers collected from different sampling sites. Pathogenicity of ten N. rileyi isolates against Spodoptera litura was studied by exposing third instars to topical application of a spore concentration of 108 conidia/ml. All ten isolates of N rileyi were active against third instars of S. litura, resulting in 85 to 97% mortality. However, there were statistically no significant differences among the isolates with respect to the pathogenicity levels. Median lethal time (LT50) values of N. rileyi isolates against third instars of S. litura ranged from 5.5 to 6.6 days, which were not statistically different. This strongly suggests that the isolates from different geographical locations are equally pathogenic against S. litura. Accepted for publication 29 June 2009. Published 7 August 2009.

scholarly journals Effectiveness of Bacillus thuringiensis-Transgenic Chickpeas and the Entomopathogenic Fungus Metarhizium anisopliae in Controlling Helicoverpa armigera (Lepidoptera: Noctuidae)

2008 ◽  
Vol 74 (14) ◽  
pp. 4381-4389 ◽  
Author(s):  
N. C. Lawo ◽  
R. J. Mahon ◽  
R. J. Milner ◽  
B. K. Sarmah ◽  
T. J. V. Higgins ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Metarhizium Anisopliae ◽  
Entomopathogenic Fungus ◽  
Fitness Costs ◽  
Cry Proteins ◽  
Bt Crops ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae ◽  
Increased Susceptibility

ABSTRACT The use of genetically modified (Bt) crops expressing lepidopteran-specific Cry proteins derived from the soil bacterium Bacillus thuringiensis is an effective method to control the polyphagous pest Helicoverpa armigera. As H. armigera potentially develops resistance to Cry proteins, Bt crops should be regarded as one tool in integrated pest management. Therefore, they should be compatible with biological control. Bioassays were conducted to understand the interactions between a Cry2Aa-expressing chickpea line, either a susceptible or a Cry2A-resistant H. armigera strain, and the entomopathogenic fungus Metarhizium anisopliae. In a first concentration-response assay, Cry2A-resistant larvae were more tolerant of M. anisopliae than susceptible larvae, while in a second bioassay, the fungus caused similar mortalities in the two strains fed control chickpea leaves. Thus, resistance to Cry2A did not cause any fitness costs that became visible as increased susceptibility to the fungus. On Bt chickpea leaves, susceptible H. armigera larvae were more sensitive to M. anisopliae than on control leaves. It appeared that sublethal damage induced by the B. thuringiensis toxin enhanced the effectiveness of M. anisopliae. For Cry2A-resistant larvae, the mortalities caused by the fungus were similar when they were fed either food source. To examine which strain would be more likely to be exposed to the fungus, their movements on control and Bt chickpea plants were compared. Movement did not appear to differ among larvae on Bt or conventional chickpeas, as indicated by the number of leaflets damaged per leaf. The findings suggest that Bt chickpeas and M. anisopliae are compatible to control H. armigera.

scholarly journals PATOGENISITAS DUA ISOLAT LOKAL JAMUR Nomuraea rileyi (FARLOW) SAMSON TERHADAP Helicoverpa armigera HUBNER (LEPIDOPTERA: NOCTUIDAE)

2020 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
IGAA. INDRAYANI ◽  
HERI PRABOWO ◽  
SRI MULYANINGSIH
Keyword(s):  
Helicoverpa Armigera ◽  
Block Design ◽  
Larval Mortality ◽  
Host Population ◽  
Cotton Leaf ◽  
Nomuraea Rileyi ◽  
Larval Weight ◽  
Randomized Block Design ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae

<p>ABSTRAK<br />Epizootik Nomuraea rileyi telah berkembang secara alami dalam<br />populasi lebih dari 30 spesies serangga inang, termasuk H. armigera.<br />Penelitian ini dilakukan di Laboratorium Patologi Serangga Balai<br />Penelitian Tanaman Pemanis dan Serat Malang mulai Januari hingga<br />Desember 2011, tujuannya untuk mengetahui patogenisitas dua isolat lokal<br />jamur entomopatogen N. rileyi terhadap larva H. armigera. Penelitian<br />terdiri atas dua faktor perlakuan, faktor 1 adalah dua isolat lokal N. rileyi,<br />yaitu ML 01 dan LG 02, dan faktor 2 adalah konsentrasi konidia, yaitu: 2,2<br />x 10 5 ; 4,5 x 10 5 ; 2,2 x 10 6 ; 4,5 x 10 6 ; 2,2 x 10 7 ; 4,5 x 10 7 ; 2,2 x 10 8 ; 4,5 x<br />10 8 konidia/ml, dan kontrol. Setiap perlakuan disusun dalam Rancangan<br />Acak Kelompok Faktorial dengan tiga kali ulangan. Aplikasi jamur pada<br />larva H. armigera dilakukan dengan metode kontaminasi permukaan<br />media yang berupa daun kapas muda (1cm 2 ) di dalam ruangan bersuhu<br />25±1⁰C dan kelembapan 75-80%. Parameter yang diamati adalah<br />mortalitas larva, LC 50 dan LT 50 , serta bobot larva. Hasil penelitian<br />menunjukkan bahwa tingkat patogenisitas isolat ML 01 terhadap larva H.<br />armigera lebih tinggi dibandingkan dengan isolat LG 02. Isolat ML 01<br />menyebabkan mortalitas larva H. armigera antara 51,13-85,56% (LC 50  =<br />2,5 x 10 2  Konidia/ml) dan isolat LG 02 antara 43,36-78,90%, (LC 50  =<br />5x10 6  Konidia/ml). LT 50 isolat ML 01 antara 5,2-5,5 hari, sedangkan isolat<br />LG 02 antara 6,8-7,0 hari, terutama pada konsentrasi 2,2-4,5 x 10 8<br />konidia/ml. Terdapat korelasi positif yang erat antara konsentrasi konidia<br />dan mortalitas larva baik pada isolat ML 01 (r=0,975) maupun LG 02<br />(r=0,980), demikian pula antara konsentrasi konidia dan kehilangan bobot<br />larva pada isolat ML 01 (r=0,982) dan LG 02 (r=0,972).<br />Kata kunci: Helicoverpa armigera, Nomuraea rileyi, patogenisitas, isolat,<br />mortalitas</p><p>ABSTRACT<br />The epizootic of the fungi Nomuraea rileyi has naturally developed<br />in more than 30 species of insect host population, including cotton<br />bollworm, H. armigera. A study on pathogenicity of two local isolates of<br />Nomuraea rileyi (Farlow) Samson fungi against Helicoverpa armigera<br />(Hubner) (Lepidoptera: Noctuidae) was conducted at Insect Pathology<br />Laboratory of Indonesian Sweeteners and Fibers Crops Research Institute<br />(ISFCRI) in Malang from January to December 2011 in order to find out<br />the pathogenicity of the isolates against H. armigera larvae. This study<br />consists of two factors as treatment. The first factor was N. rileyi isolates,<br />e.g. ML 01 and LG 02, and the second factor were eight conidia<br />concentrations, viz. 2.2 x 10 5 ; 4.5 x 10 5 ; 2.2 x 10 6 ; 4.5 x 10 6 ; 2.2 x 10 7 ; 4.5<br />x 10 7 ; 2.2 x 10 8 ; 4.5 x 10 8 conidia/ml, and one untreated control.<br />Treatments were arranged in Factorial Randomized Block Design with<br />three replications. Suspense of conidia was applied by surface<br />contamination method of cotton leaf as medium at 25±1⁰C of temperature<br />and 75-80% of humidity. Parameter observed were larval mortality, LC 50 ,<br />LT 50 , and larval weight. Result showed that ML 01 isolate was more<br />pathogenic against H. armigera larvae than LG 02 isolate based on larval<br />mortality, LC 50 , and LT 50 . Percentage of mortality of H. armigera larvae<br />due to ML 01 and LG 02 infection were 51.1- 85.56% and 43.36-78.90%,<br />respectively. The LC 50 of ML 01 and LG 02 isolates was 5.2-5.5 days and<br />6.8-7.0 days, respectively.There are closest positive correlation between<br />conidia concentration and percentage of mortality on ML 01 (r = 0.975)<br />and LG 02 (r = 0.980) isolates as well as between conidia concentration<br />and larval weight loss on ML 01 (r = 0.982) and LG 02 (r = 0.972)<br />isolates.<br />Key words: Helicoverpa armigera, Nomuraea rileyi, pathogenicity,<br />isolate, mortality</p>

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