Evaluation of toxicity assay of the methanolic extract of oleander leaves against fall armyworm

Abstract

Oleander (Nerium oleander L.) is a shrubbery plant with various functions as an ornamental, medicinal, bio-fungicide, and bio-insecticide. The study aimed to investigate the acute toxicity assay of methanolic extract of oleander leaves on fall armyworm (Spodoptera frugiperda J.E. Smith). The study was conducted in a Complete Randomized Design (CRD) for upper and lower concentrations. The upper and lower concentrations’ results were calculated to find the intervals and then used to determine the Lethal Concentration (LC) with four repetitions using probit analysis. In addition, the mortality, food, and weight were calculated using Analysis of Variance (ANOVA). The results showed that concentration interval values from the lower limit to the high of the extract of methanol oleander leaves were: 0.23%; 0.32%; 0.45%; 0.63%; and 0.88%. The probit analysis showed that the toxicity of oleander extract concentrations at 48 Hours after Treatment (HAT) was LC50 by 0.86% and LC95 by 2.42%. The lethal concentration on the last day (D-20) of LC50 and LC95 was 0.54% and 1.76%, respectively. During the 20 days of the observation period, fall armyworm larvae only consumed 162.36±13.48 mg of baby corn at the highest concentration (0.88%), compared to 665.47±22.60 mg at the control. The oleander extract also affected the larvae’s weight and time consumption. The resulting concentration of extracts of oleander methanol can be used to control fall armyworm larvae.

The Lethal Effect of Some Natural Plants Extracts on Tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae) and their Relative Toxicity

“…The extract of M. azedarach fruits recorded the lowest value for Lc 50, amounting to 0.251, followed by the N.oleander extract, which had a value of 0.533, which indicates its relatively high toxicity compared to the rest of the extracts, which indicates an increase in acute toxicity after 48 hours, while the value was relatively high with the extracts of Mentha arvensis and oleander. The results were close to what was indicated by the researcher [25] that the Lc50 values of the N.oleander extract against fall armyworm larvae, S. frugiperda, reached 0.86 after 48 hours of treatment. The results also agreed with the findings of the researcher [26] As for the M. azedarach fruits, they continued to maintain their lead in the lowest values of LC50 that were obtained among the plant extracts, which was 0.075, while O. basilicum continued to obtain the highest value of LC50, 0.685, which indicates weak toxicity of O. basilicum on the larvae of tobacco leaves cutworm, but it may cause different biological effects on the stages of insects.…”