Low concentrations of selenium nanoparticles enhance the performance of a generalist parasitoid and its host, with no net effect on host suppression

Abstract

BACKGROUNDThe environmental and economic costs of conventional insecticides have stirred an interest in alternative management tactics, including the use of nanotechnologies. Selenium nanoparticles (SeNPs) have many applications in agriculture but may not be compatible with biological control; however, low concentrations of SeNPs may benefit natural enemies via hormesis. This study investigates the concentration‐dependent effects of SeNPs (0–1000 mg L−1) on Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), a generalist parasitoid of stored product pests.RESULTSThe LC50 of SeNPs was 1540 mg L−1 for female parasitoids and 1164 mg L−1 for males. SeNPs had a significant hormetic effect; average lifespan increased by 10% at a concentration of 4.03 mg L−1 for females and by 35% at 13.83 mg L−1 for males. In a bioassay including hosts [the azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae: Bruchinae)], a low concentration of SeNPs (25 mg L−1) enhanced the performance of female parasitoids; lifespan increased by 23% and the number of offspring increased by 88%. However, the number of emerging hosts did not significantly decrease; in the absence of parasitism, SeNPs actually improved host emergence by 17%.CONCLUSIONBecause higher concentrations of SeNPs reduced parasitoid lifespan, whereas low concentrations enhanced not only parasitoid performance but also host emergence, practitioners should exercise caution when considering SeNPs for use in integrated pest management. © 2023 Society of Chemical Industry.

Baseline Susceptibility to a Novel dsRNA-Based Insecticide across US Populations of Colorado Potato Beetle

“…It is possible that there was a hermetic effect of a low dose of ledprona that stimulated beetle voracity. Hormesis in response to pesticides is fairly common in insects (e.g., [26,27]), including the Colorado potato beetle [28]. If this is indeed the case for ledprona, it highlights the importance of using high field rates for protecting potato crops from Colorado potto beetle damage.…”

Silica and Selenium Nanoparticles Attract or Repel Scale Insects by Altering Physicochemical Leaf Traits

“…In recent studies, the application of specific concentrations of Se significantly influenced plant growth (Citrus reticulata at 150 mg/L [45]) and mitigated insect pest damage to a plant (Atractylodes macrocephala (Asteraceae) [46]). However, low concentrations of SeNPs (10-500 mg/L) can increase survival of pest insects (e.g., the azuki bean beetle, Callosobruchus chinensis, and the cowpea beetle, C. maculatus) [43,47,48], whereas higher concentrations of SeNPs or Se can inhibit the development and/or survival of both pest insects and their natural enemies (at 500-1000 mg/L, C. chinensis, C. maculatus, and the parasitoid-Anisopteromalus calandrae) [43,47,48] as well as plants such as A. macrocephala [46] and Citrus reticulata (at 200 mg/L) [45]. Therefore, the application of Se within a reasonable stoichiometric range emerges as a crucial consideration for future research.…”