scholarly journals Evaluation of Metarhizium rileyi Farlow (Samson) impregnated with azadirachtin and indoxacarb against Helicoverpa armigera (Hubner)

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Bhisham Dev ◽  
Subhash Chander Verma ◽  
Prem Lal Sharma ◽  
Rajeshwar Singh Chandel ◽  
Mahesh Balaso Gaikwad ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Helicoverpa Armigera ◽  
Developmental Stages ◽  
Management Program ◽  
Median Lethal Concentration ◽  
Larval Instars ◽  
Metarhizium Rileyi ◽  
Mortality Response ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae

Abstract Background Entomopathogenic fungi are the most versatile having a wide host range, capable of infecting insects at different developmental stages. In the present study, Metarhizium rileyi, at the concentrations of 102, 103, 104, 105, 106, 107 and 108 conidia/ml and sub-lethal concentrations of azadirachtin (1.02 and 1.53 ppm) and indoxacarb (0.72 ppm) were evaluated against the 1st, 2nd, 3rd, 4th and 5th larval instars of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) under laboratory conditions. Results M. rileyi applied at 106 conidia/ml caused a maximum mortality of 83.33 and 80.00% of 1st and 2nd larval instars of H. armigera, respectively. The maximum mortality of 3rd, 4th and 5th larval instars of H. armigera with 108 conidia/ml of M. rileyi was 83.33, 76.67 and 53.33%, respectively. When M. rileyi blended with azadirachtin at 1.02 ppm, the highest mortality rate of 86.21% at 106 conidia/ml against 2nd instar larvae was resulted. Similarly, M. rileyi applied at 108 conidia /ml mixed with azadirachtin (1.53 ppm) showed 89.66% mortality of 3rd instar larvae. The 2nd instar larvae treated with M. rileyi at 106 conidia/ml, mixed with indoxacarb (0.72 ppm), the corrected mortality rate was 82.14%. Concentration mortality response of 3rd instar larvae to M. rileyi blended with indoxacarb (0.72 ppm) was 85.71% at 108 conidia/ml. The median lethal concentration (LC50) values were 5.51 × 103, 1.86 × 104, 2.81 × 105 and 5.55 × 105 conidia/ml for 1st, 2nd, 3rd and 4th larval instars, respectively, after 7 days of treatment. M. rileyi when mixed with sub-lethal concentrations of azadirachtin (1.02 ppm) and indoxacarb (0.72 ppm) resulted LC50 values of 1.09 × 104 conidia/ml and 1.37 × 104 conidia/ml against 2nd instar larvae, respectively, after 24 hours. Similarly, M. rileyi mixed with sub-lethal concentrations of azadirachtin (1.53 ppm) and indoxacarb (0.72 ppm) resulted LC50 values of 3.12 × 108 and 3.06 × 105 conidia/ml against 3rd instar larvae, respectively, after 24 hours. The study revealed that the susceptibility of larvae decreased in case of large larval instars. Conclusions M. rileyi can be utilized as one of the component of Integrated Pest Management Program for the eco-friendly management of H. armigera. As the application of M. rileyi @ 107 conidia/ml alone or in combination with azadirachtin (1.02 and 1.53 ppm) or indoxacarb (0.72 ppm) resulted to the highest mortality.

scholarly journals Fluctuation patterns of different developmental stages of Helicoverpa armigera (Lepidoptera: Noctuidae) on chickpea (Cicer arietinum) and their relationship with the environment

2005 ◽  
Vol 16 (4) ◽  
Author(s):  
Zahid Ali Shah ◽  
Muhammad Shahzad
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Helicoverpa Armigera ◽  
Relative Frequency ◽  
Developmental Stages ◽  
Frequency Of Occurrence ◽  
Pod Borer ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae ◽  
Eggs And Larvae

The relative frequency of occurrence of different developmental stages of gram pod borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), and the dependence of its developmental stages on environmental factors, are crucial in the population management. The densities of eggs and larvae were low from December to mid-February due to prevailing cold. Owing to optimum environmental conditions, increasing densities were observed throughout March and they droppped again during the first week of April. The densities of eggs and different larval instars of H. armigera were significantly positively correlated with temperature, and significantly negatively correlated with the average morning relative humidity (RH;%) but not with the average evening RH (%).

scholarly journals Determination of Helicoverpa armigera (Lepidoptera: Noctuidae) larval instars and age based on head capsule width and larval weight

2017 ◽  
Vol 15 ◽  
pp. 53 ◽  
Author(s):  
D. G. Stavridis ◽  
C. G. Ipsilandis ◽  
P. C. Katarachias ◽  
P. G. Milonas ◽  
A. A. Ifoulis ◽  
...  
Keyword(s):  
Body Weight ◽  
Helicoverpa Armigera ◽  
Larval Instar ◽  
Head Capsule ◽  
Head Width ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Helicoverpa Armígera ◽  
L1 And L2 ◽  
Lepidoptera Noctuidae

Larνae of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) were reared in laboratory conditions (26°C, 16:8 L:D) and measurements of larval head capsule width, and body weight, were used in order to determine the boundaries of larval instars. Larvae of Η. armigera completed development in 5 to 7 instars. Head capsule width could predict the larval instar only for Ll. The upper boundary of head width for L1 was 0.4mm. Body weight could predict both L1 and L2 larval instars. Boundaries between L1-L2 instars were found to be 1 mg and for L2-L3 5,5 mg. Correlation and regression analysis suggest that a combination of head capsule width and body weight can predict both larval instars and chronological age under constant conditions in the laboratory.

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.

Effect of ultrasound on acetylcholinesterase activity in Helicoverpa armigera (Lepidoptera: Noctuidae)

2008 ◽  
Vol 140 (5) ◽  
pp. 563-568 ◽  
Author(s):  
Yu-Ping Zha ◽  
Fen Xu ◽  
Qi-Cai Chen ◽  
Chao-Liang Lei
Keyword(s):  
Enzyme Activity ◽  
Helicoverpa Armigera ◽  
Cholinergic System ◽  
Developmental Stages ◽  
Acetylcholinesterase Activity ◽  
Behavioral Effects ◽  
Stress Effects ◽  
Helicoverpa Armígera ◽  
Commercial Device ◽  
Lepidoptera Noctuidae

AbstractIt is well known that noctuid moths respond to ultrasound frequencies produced by insectivorous bats performing a series of evasive maneuvers such as loops, dives, rolls, and turns. Certain ultrasound frequencies may be considered an environmental stress factor for these moths, causing physiological and behavioral effects. We investigated changes in acetylcholinesterase activity of Helicoverpa armigera (Hübner) exposed to ultrasound produced from a commercial device (LHC20). Our results indicated that stress effects on acetylcholinesterase activity resulting from exposure to ultrasound do not differ according to sex, but effects on different developmental stages of H. armigera differ significantly depending on duration of exposure. Enzyme activity increased in adults after 20 min exposure to ultrasound and decreased in pupae after 30 and 50 min exposure. Enzyme activity in larvae was reduced after 20 min and increased after 40 and 60 min. The results of this study also indicate that stress caused by exposure to ultrasound could modulate the cholinergic system in H. armigera.

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