scholarly journals Effects of sublethal doses of chlorfluazuron on the testicular biochemical constituents of Spodoptera litura (Lepidoptera: Noctuidae)

2011 ◽  
Vol 10 (44) ◽  
pp. 8956-8964
Author(s):  
Perveen Farzana
Keyword(s):  
Spodoptera Litura ◽  
Biochemical Constituents ◽  
Sublethal Doses ◽  
Lepidoptera Noctuidae

Effects of sublethal doses of chlorfluazuron on the biochemical constituents of eggs of Spodoptera litura (Lepidoptera: Noctuidae)

2011 ◽  
Vol 143 (2) ◽  
pp. 178-184
Author(s):  
F. Perveen
Keyword(s):  
Embryonic Development ◽  
Spodoptera Litura ◽  
Treated Male ◽  
Biochemical Constituents ◽  
Tobacco Cutworm ◽  
Sublethal Doses ◽  
Lepidoptera Noctuidae

AbstractThe effects of sublethal doses (LD10: 1.00 ng/larva; LD30: 3.75 ng/larva) of chlorfluazuron on the biochemical constituents of eggs of the tobacco cutworm, Spodoptera litura (F.), are described. Chlorfluazuron was applied topically to fifth-instar larvae and the subsequent adults were allowed to mate according to larval treatment (LD10-treated female × LD10-treated male and LD30-treated female × LD30-treated male). Biochemical constituents of eggs resulting from these pairings were analyzed at various stages of embryonic development. Compared with controls, LD10 or LD30 reduced egg constituents as follows: protein (min.–max.) by 32.8%–34.5% or 62.0%–67.3%, lipid by 33%–34% or 62%–67%, carbohydrates by 30%–39% or 60%–67%, DNA by 33%–40% or 60%–69%, RNA by 31%–34% or 59%–67%, and ecdysteroid by 22%–83% or 28%–92%, respectively. The relative proportions of constituents in control eggs were as follows: protein > lipid > carbohydrate, and RNA > DNA. Three low and three high peaks in ecdysteroid titres were observed. Compared with controls, all peaks were reduced in LD10 or LD30 eggs as follows: low peaks: 1st (at 8 h): 32% or 66%; 2nd (at 16 h): 33% or 67%; 3rd (at 52 h): 35% or 65%; high peaks: 1st (at 32 h): 83% or 92%; 2nd (at 64 h): 65% or 82%; 3rd (at 84 h): 84 h, 36% or 63%, respectively. In addition, the first two high peaks were delayed by 4 h in LD10 eggs and by 8 h in LD30 eggs compared with controls. Sublethal doses of chlorfluazuron reduced the amounts of biochemical constituents of eggs during embryogenesis in S. litura.

scholarly journals Pathogenicity of Metarhizium rileyi (Farlow) Kepler, S.A. Rehner and Humber isolates against Spodoptera litura (Fabricius) and their extracellular enzymatic activities

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Gurmehar Kaur Grewal ◽  
Neelam Joshi ◽  
Yadhu Suneja
Keyword(s):  
Spodoptera Litura ◽  
Larval Mortality ◽  
Screening Methods ◽  
Metarhizium Rileyi ◽  
Percent Mortality ◽  
Commercially Important ◽  
Extracellular Enzymatic Activities ◽  
Chemical Pesticides ◽  
Lepidoptera Noctuidae

Abstract Background Spodoptera litura (Fab.) (Lepidoptera: Noctuidae) is a serious agricultural pest that infests many commercially important crops of Southeast Asian countries. Indiscriminate use of chemical pesticides has led to various health hazards as well as insecticide resistance. Entomopathogenic fungi (EPF) provide an important alternative as biological control agents. Metarhizium rileyi is an EPF with a specific host range for lepidopteran pests. The present study aimed to identify virulent M. rileyi isolate against S. litura larvae and analyse their extracellular cuticle-degrading enzyme activities. Results Three M. rileyi isolates viz M. rileyi NIPHM, M. rileyi MTCC 4254 and M. rileyi MTCC 10395 formulations were evaluated at different concentrations against 2nd instar larvae of S. litura. A maximum percent mortality of 63.33% was recorded in M. rileyi NIPHM (12 g/l), followed by M. rileyi MTCC 4254 (58.33%) at the same concentration, 10 days post-treatment. Maximum means of chitinase, protease and lipase activities (0.44, 1.58 and 2.95 U/ml, respectively) were recorded in the case of M. rileyi NIPHM. Correlation analysis was positive between enzyme activity and larval mortality. Conclusions Metarhizium rileyi NIPHM recorded the highest enzymatic activity and exhibited the maximum mortality rate against 2nd instar larvae of S. litura, suggesting the possible role of these enzymes in the pathogenicity of the fungus. Further knowledge in this regard may help in the development of enzyme-based screening methods for selecting virulent fungal isolates for the eco-friendly management of crop pests.

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