Toxicity of Plant Secondary Metabolites Modulating Detoxification Genes Expression for Natural Red Palm Weevil Pesticide Development

Abstract

This study aimed to explore the larvicidal and growth-inhibiting activities, and underlying detoxification mechanism of red palm weevil against phenylpropanoids, an important class of plant secondary metabolites. Toxicity of α-asarone, eugenol, isoeugenol, methyl eugenol, methyl isoeugenol, coumarin, coumarin 6, coniferyl aldehyde, diniconazole, ethyl cinnamate, and rosmarinic acid was evaluated by incorporation into the artificial diet. All of the phenylpropanoids exhibited dose- and time-dependent insecticidal activity. Among all the tested phenylpropanoids, coumarin exhibited the highest toxicity by revealing the least LD50 value (0.672 g/L). In addition, the most toxic compound (coumarin) observed in the current study, deteriorated the growth resulting tremendous reduction (78.39%) in efficacy of conversion of digested food (ECD), and (ECI) efficacy of conversion of ingested food (70.04%) of tenth-instar red palm weevil larvae. The energy-deficient red palm weevil larvae through their intrinsic abilities showed enhanced response to their digestibility resulting 27.78% increase in approximate digestibility (AD) compared to control larvae. The detoxification response of Rhynchophorus ferrugineus larvae determined by the quantitative expression of cytochrome P450, esterases, and glutathione S-transferase revealed enhanced expression among moderately toxic and ineffective compounds. These genes especially cytochrome P450 and GST detoxify the target compounds by enhancing their solubility that leads rapid excretion and degradation resulting low toxicity towards red palm weevil larvae. On the other hand, the most toxic (coumarin) silenced the genes involved in the red palm weevil detoxification mechanism. Based on the toxicity, growth retarding, and masking detoxification activities, coumarin could be a useful future natural red palm weevil-controlling agent.

Toxin-Pathogen Synergy Reshaping Detoxification and Antioxidant Defense Mechanism of Oligonychus afrasiaticus (McGregor)

“…The enhanced GST activities in these combinations trigger the solubility of target compound, which ultimately promotes the degradation and excretion of compounds from the target host. Previous studies strengthened our findings and coincides with our results, which reported that lethality of the compound regulates the GST activities [ 47 , 48 ]. Furthermore, their findings suggested that less toxic compounds greatly induced target host GST activities.…”

“…However, synergistic combinations established in the current study (especially 2.24 mg/mL phytol + 4 mg/mL spores and 2.80 mg/mL phytol + 5 mg/mL spores) found to be the most lethal treatments showed the reduced activity of GST. These findings are similar to the results of AlJabr et al [ 47 ], who also reported similar GST activity of coumarin-fed red palm weevil larvae. Furthermore, their findings suggested that the most lethal treatment targeted the enzymatic activities of GST, which ultimately led towards the reduction in GST response by masking their enzymatic activities.…”

Potential Synergy between Spores of Metarhizium anisopliae and Plant Secondary Metabolite, 1-Chlorooctadecane for Effective Natural Acaricide Development

“…Fungal infection evades the host defense mechanism by triggering complex biochemical interactions in the form of series of events through cuticle adhesion, penetration, proliferation, and toxin production, which ultimately lead to the host mortality [29,[31][32][33]. On the other hand, plant secondary metabolites are known antagonists that act by interfering with the signaling of the nervous and cellular systems to overcome the target host defense mechanism [34][35][36][37][38]. Therefore, the combined application is considered as a promising approach due to the differences in their mechanism of actions.…”

Isolation and Identification of Insect Antifeedant Compound from Ethanol Extract of Hemidesmus indicus Root

“…These natural compounds have shown to be effective in agricultural pest management, as they function as antifeedant, growth inhibitors, toxic, repellent, fumigant, attractant etc. and also causes moulting disruption, respiratory inhibition, pheromone-based behavioural adaptations, oviposition deterrence and fecundity reduction against target pest populations (AlJabr et al, 2017;Koul, 2008;Nawaz et al, 2017). Majority of plant secondary metabolites are untapped and are of particular interest in insecticide development (Isman, 2006;Miresmailli and Isman, 2014).…”