Essential oil of Cymbopogon flexuosus, Vernonia polyanthes and potassium phosphite in control of bean anthracnose

Evaluation of Insecticidal activity and Genetic Expressions of some Essential Oil and Methomyl Lannate 90% against Spodoptera frugiperda [J.E. Smith]; (Lepidoptera: Noctuidae).. [DOI: 10.21203/rs.3.rs-3156489/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Fall Armyworm (FAW) Spodoptera frugiperda [J.E. Smith] (Lepidoptera: Noctuidae) is regarded as a major pest of various economic crops, their caterpillars are a highly destructive and have a wide host range. This study's goal was to assess the insecticide potency of essential oils [rosemary (Rosmarinus officinalis L.), lemongrass (Cymbopogon citratus) and Cinnamon (Cinnamomum zeylanicum)] and Methomyl Lannate 90% commerial Insecticide to control FAW and their effected on Expression of caspase-8 and Inhibitor of Apoptosis Protein (IAP) genes and Expression of Acetylcholinesterase (AChE) gene in FAW. The insecticidal activity against 2nd larval instar was evaluated with five concentrations (2.5%, 2%, 1.0%, 0.5% and 0.25%) for essential oil and four concentrations 0.4%, 0.2%,0.15% and 0.05% for Methomyl Lannate 90%. The findings indicated that raising both essential oil concentrations and Methomyl Lannate 90%, resulted in increased the larval mortality at high concentration. Lemongrass and Cinnamon oil produced about to the same estimated LC50, whereas Methomyl Lannate 90% was (0.3%). Cymbopogon citratus (1.68%) had higher Caspase-8 gene expression levels compared to the control, but at a lower level than Rosmarinus officinalis L. (2.59%) and Cinnamomum zeylanicum (1.67%). The expression levels of Ache gene in the treated by low concentration of Methomyl Lannate were increased (by 313%) significant compared with the control but without significant differences. FAW death as a result of treatment with the tested oils having an effect on the genes that the pest uses to express critical processes. As a result, using the tested essential oils as a substitute for conventional management of FAW is a brilliance option.

Detection of Voltage-Gated Sodium Channel (VGSC) Mutation in Deltamethrin-Resistant Blattella germanica L. from Indonesia

<b>Background and Objective:</b> German cockroach (<i>Blattella germanica</i> L.) is one of the most common residential pests in Indonesia. Controlling the population face obstacles due to insecticide resistance, especially to deltamethrin. This research investigated the resistance status and the possibility of a Voltage-Gated Sodium Channel (VGSC) knockdown resistance mutation (L1014F) in two field strains of German cockroaches collected from two cities in Indonesia (Bukittinggi, named RMKN-BKT and Bandung, named KRSA-BDG) with VCRU-WHO as the standard strain. <b>Materials and Methods:</b> This study started with a bioassay test to determine the lethal dose of 50% (LD<sub>50</sub>) for each strain and followed by a molecular test for mutation detection. <b>Results:</b> The results showed that the RMKN-BKT and KRSA-BDG strains were highly resistant to deltamethrin with RR50 values of 80,090 times and 73,272 times, respectively. Only the RMKN-BKT strain was shown to carry L1014F kdr mutation which lead to an amino acid replacement from leucine (TTG) to phenylalanine (TTC). Two silent mutations were also found in both field strains at codons 983 (TGC/cysteine→TGT/cysteine) and 984 (GGG/ glycine→GGA/glycine) which were suggested as polymorphism phenomena. The absence of the L1014F mutation in the Bandung strain does not exclude the possibility of the presence of the VGSC mutation at other points. <b>Conclusion:</b> It requires subsequent investigation in mutation detection at other points and the possible presence of other resistance mechanisms to get a precise solution in the population control. Bioinsecticides may stand as a breakthrough so that the strategy will no longer focus on insecticides.

Biochemical responses of common bean to white mold potentiated by phosphites

Considering that the mechanisms for phosphite-afforded disease control remain elusive, this study investigated whether zinc (Zn) and copper (Cu) phosphites could possible potentiate common bean resistance to white mold, caused by Sclerotinia sclerotiorum, through the stimulation of biochemical defence responses. Lesion area and disease severity were decreased by phosphites spray, but Zn phosphite outcompeted Cu phosphite. Histopathological observations revealed fewer fungal hyphae and less collapse of the mesophyll cells in the Zn and Cu phosphite-sprayed plants compared to water-sprayed ones. The S. sclerotiorum-triggered accumulation of reactive oxygen species, oxalic acid (a fungal secreted toxin) and malondialdehyde (an indicator of cellular damage) were constrained as a result of Zn and Cu phosphites spray. Activities of antioxidant enzymes (superoxide dismutase, peroxidase, ascorbate peroxidase and glutathione-S-transferase at 12 h after inoculation (hai) and catalase at 60 and 84 hai) were higher for Zn and Cu phosphites-sprayed plants than for water-sprayed ones. Activities of defence-related enzymes chitinase (CHI) at 12 hai, β-1,3-glucanase (GLU) and polyphenoloxidase (PPO) were higher at 12-84 hai for Zn, and Cu phosphites sprayed plants, phenylalanine ammonia-lyase at 36-84 hai for the Zn phosphite sprayed ones, CHI at 12-36 hai, GLU at 12-60 hai, PPO at 36 hai and PAL and lipoxygenase at 12 hai for the Cu phosphite sprayed ones upon inoculation with S. sclerotiorum relative to their water-sprayed counterparts. Concentrations of total soluble phenols and lignin-thioglycolic acid derivatives were not affected by Cu phosphite spray on infected plants but were higher and lower, respectively, for Zn phosphite sprayed plants at 60 hai compared to water-sprayed ones. Taken together, the findings from the present study shed light on the biochemical defence mechanisms involved in the Zn and Cu phosphites-mediated suppression of white mold in common bean.