Sublethal effects and reproductive hormesis of emamectin benzoate on Plutella xylostella

Abstract

The diamondback moth (DBM), Plutella xylostella L., is an important pest of cruciferous vegetables, and population control mainly depends on chemical pesticides. Emamectin benzoate is a highly effective insecticide used for controlling DBM. However, it is unknown how the sublethal effects of low concentration residues of emamectin benzoate on DBM. So the population development sublethal effects of emamectin benzoate, at LC5, LC10, and LC20 with concentrations of 0.014 mg/L, 0.024 mg/L and 0.047 mg/L, respectively, on adult DBM and their progeny were investigated in this study. The pupal weight, pupal period, female fecundity, and vitellin content of the F0 DBM generation increased significantly compared to the control. And the single female oviposition number of DBM was increased by 20.21% with LC20 treatment. The pupation rate, adult longevity and ovariole length of the treatment groups decreased significantly. The fecundity of DBM in the treatment groups increased, and this increased the population by a presumptive 13.84%. Treatment also led to the shortening of ovarioles and the reduction of egg hatching, and increased pupal weight in the F1 generation. We concluded that the effects of sublethal/low concentration emamectin benzoate on the different life stages of DBM were variable, and the reproductive hormesis on DBM adults were attractive findings.

Sublethal Effects of Emamectin Benzoate on Development and Reproduction and RNAi of the Vitellogenin Gene in Spodoptera frugiperda

“…EB degrades rapidly in the field over time and under numerous environmental conditions, and its residues may produce sublethal effects on continuously exposed insects in space and time, including physiological parameters such as developmental time, fecundity, behavior, and longevity, without directly causing death. , In the present study, sublethal concentrations of EB were detrimental to the development and fecundity of PFT, with a particular emphasis on Vg, which indicated the high sensitivity of S. frugiperda to EB.…”

Bionomic responses of Spodoptera frugiperda (J. E. Smith) to lethal and sublethal concentrations of selected insecticides

“…Emamectin benzoate showed high toxicity to Lepidopterans such as the diamondback moth (Plutella xylostella, Plutellidae), the tomato leafminer (Phthorimaea absoluta, Gelechiidae), and Spodoptera sp. [31,[41][42][43][44]. For instance, [31] and [41] found 0.0051 mg/L (expressed in ppm) and 0.0023-3.303 mg/L as LC 50 for emamectin benzoate on first and second early instar larvae of S. frugiperda in a leaf-dip bioassay, respectively, while [40] found 0.0014 mg/L for neonate larvae of S. littoralis at 48 h post-exposure.…”