Insecticide Toxicity, Synergism and Resistance in Plutella xylostella (Lepidoptera: Plutellidae)

Abstract

Plutella xylostella has become particularly notorious for its resistance to various insecticides. The toxicities of abamectin, hexaflumuron and indoxacarb to third instar larvae of the pest were assayed using the leaf-dipping method. The results showed that abamectin and indoxacarb with the lowest LC50 values exhibited stronger toxicity to larvae than hexaflumuron. To determine the synergism of PBO, DEM, DEF and TPP on the toxicity of tested insecticides and demonstrating possible biochemical mechanisms, an abamectin-, a hexaflumuron-and an indoxacarb-resistant strain of P. xylostella were selected under laboratory conditions. After 10 generations of selection, the selected strains developed 14.21, 7.08, and 32.36-fold higher resistance to these insecticides, respectively. Abamectin resistance in abamectin-selected strain was suppressed with the synergists such as DEM and PBO, suggesting the involvement of monooxygeneses and glutathione S-transferase in the development of resistance in P. xylostella. Treatment with PBO and DEF significantly decreased the toxicity of hexaflumuron in the hexaflumuron-selected strain. Also, in indoxacarb-selected strain, the maximum synergism was occurred using PBO and DEF, followed by DEM and TPP. Hexaflumuron and indoxacarb synergism studies indicated in hexaflumuron resistance, monooxygenases and esterases, and in indoxacarb resistance, monooxygenases, esterases and glutathione S-transferae may be involved in the resistance mechanisms

Indoxacarb-Loaded Anionic Polyurethane Blend with Sodium Alginate Improves pH Sensitivity and Ecological Security for Potential Application in Agriculture

“…Insecticidal activity: bioassays were performed with the third instars of S. litura with a series of indoxacarb concentrations via the leaf dip method [32]. Mortality was investigated at 48 and 72 h. First, the clean cabbage leaves were cut into discs with 2 cm diameter by using a puncher, dipped in desired concentrations for 30 s, dried and placed in a bioassay culture dish.…”

Unraveling the Mode of Action of Cordyceps fumosorosea: Potential Biocontrol Agent against Plutella xylostella (Lepidoptera: Plutellidae)

“…The diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) is a major destructive pest of cruciferous plants worldwide [ 1 ]. Current control methods are based on the frequent application of chemical insecticides [ 2 ]. However, the populations of P. xylostella have shown resistance to synthetic insecticides in certain parts of the world [ 3 , 4 , 5 ].…”