Bioefficacy and mode of action of rocaglamide from Aglaia elaeagnoidea (syn. A. roxburghiana) against gram pod borer, Helicoverpa armigera (Hübner)

Abstract

Rocaglamide, a highly substituted benzofuran, was isolated and identified as the main biologically active component in Aglaia elaeagnoidea (syn. A. roxburghiana) for gram pod borer Helicoverpa armigera (Hu¨bner). Addition of rocaglamide to an artificial diet retarded the growth of neonate larvae in a dose-dependent manner with EC 50 values of 0.76 p.p.m. These values compared favourably with azadirachtin (EC 50 ¼ 0.23 p.p.m.). However, azadirachtin was apparently more potent than rocaglamide in inducing growth inhibition via oral administration to these first stadium larvae. The candidate compound was found to have LD 50 and LD 95 values of 0.40 and 1.02 lg per larva, respectively, in topical application against third instar larvae 96 h post-treatment. However, these values for azadirachtin were 8.16 and 25.8 lg per larva for the same period. This shows that azadirachtin was less effective against third instar H. armigera larvae in inducing acute toxicity via topical treatment in comparison with rocaglamide. However, severe morphological larval deformities were observed in such azadirachtin-treated larvae during the process of ecdysis. The cytotoxic nature of rocaglamide was established by evaluating dietary utilization and the results did not implicate any antifeedant effect but the toxicity-mediated effect due to reduced efficiency of conversion of ingested food. It was obvious that feeding deterrence is not the primary mode of action but a centrally mediated effect, which could be due to the induced cytotoxicity at non-specific cellular levels.

Larvicidal, nematicidal, antifeedant and antifungal, antioxidant activities of <i>Mentha spicata</i> (Lamiaceae) root extracts

“…The second stage larvae were collected at the tip of a pasture pipette and placed in cotton bud to remove excess water and transferred to the test vial. The larval mortality was observed using various concentrations of Mentha spicata root extract (10,20,30 and 40 mg/mL).…”

“…Assay system was prepared with 2 mL Milli Q water containing different concentrations of Mentha spicata root extract (10,20,30 and 40 mg / mL) in glass tubes. The different concentrations of solutions are prepared treated and control nematodes were held under the same conditions as used for colony maintenance.…”

Antifeedant and Toxic Effect of Crude Extract from <i>Flourensia oolepis</i> and their Impact on Nutritional Parameters of <i>Helicoverpa gelotopoeon</i>

“…A similar response was recorded by Wheeler and Isman, (2001) using Meliaceae extract on larvae of S. littura. In contrast, other crude extracts generated a marked increase in this index for different species of lepidoptera moths (Koul et al, 2002;Nathan et al, 2005;Nathan, 2006). Reduced AD values were observed by Sadek, (2003), Pavela et al, (2008) and Shekari et al, (2008) and have been attributed to the insects using a greater proportion of the food to detoxify the extract and less for its own growth, causing a reduction in ECI and ECD (Shekari et al, 2008).…”

HumanMelia azedarachpoisoning

“…Multiple limonoid tetranotriterpenes have been isolated from various parts of this plant (6,7,9,11-15). Well-characterized limonoids include toosendanin from the bark and meliatoxin from the fruit (6,7,9,15,16). In animal studies (2-5,10), toosendanin caused abdominal distension, anorexia, and respiratory depression in rats; severe vomiting and shock in dogs; and transaminitis and muscle weakness in monkeys.…”