Life History ofChrysodeixis includens(Lepidoptera: Noctuidae) on Positively Charged Zein Nanoparticles

Abstract

Research indicates that nanoparticles can be an effective agricultural pest management tool, though unintended effects on the insect must be evaluated before their use in agroecosystems. Chrysodeixis includens (Walker) was used as a model to evaluate chronic parental and generational exposure to empty, positively charged zein nanoparticles ((+)ZNP) and methoxyfenozide-loaded zein nanoparticles (+)ZNP(MFZ) at low-lethal concentrations. To determine concentration limits, an acute toxic response test on meridic diet evaluated (+)ZNP(MFZ) and technical grade methoxyfenozide using two diet assay techniques. No differences in acute toxicity were observed between the two treatments within their respective bioassays. With these results, population dynamics following chronic exposure to low-lethal concentrations were evaluated. Parental lifetables evaluated cohorts of C. includens reared on diet treated with LC5 equivalents of (+)ZNP, (+)ZNP(MFZ), or technical grade methoxyfenozide. Compared to technical grade methoxyfenozide, (+)ZNP(MFZ) lowered both the net reproductive rate and intrinsic rate of increase, and was more deleterious to C. includens throughout its lifespan. This was contrasted to (+)ZNP, which showed no differences in population dynamics when compared with the control. To evaluate chronic exposure to (+)ZNP, generational lifetables reared cohorts of C. includens on LC5 equivalent values of (+)ZNP and then took the resulting offspring to be reared on either (+)ZNP or untreated diet. No differences in lifetable statistics were observed between the two treatments, suggesting that (+)ZNP at low ppm do not induce toxic generational effects. This study provides evidence into the effects of nanodelivered methoxyfenozide and the generational impact of (+)ZNP.

Impact of zein and lignin‐PLGA biopolymer nanoparticles used as pesticide nanocarriers on soybean growth and yield under field conditions

“…The creation of zein biopolymer nanoparticles for spray followed standards prescribed in Bonser et al. (2022). Empty positively charged zein biopolymer nanoparticles, (+)ZNP, were formed by the emulsion‐diffusion method.…”

“…Insect larval weights and mortality were assessed 7 days following placement. Larval weights were measured using a Mettler‐Toledo XS105 scale and mortality was assessed following procedures described in (Bonser et al., 2022), in which the specimen would be considered dead upon failure to respond from prodding using a small nylon paintbrush.…”

“…The following experiments used an in-house colony of Chrysodeixis includens (Walker), LSU1, which has been maintained since 1976, when it was originally collected from south Louisiana (Newsom et al, 1980). The colony was maintained as described in Bonser et al (2022). In summary, C. includens larvae were reared at 26˚C with 50% Relative humidity (RH) and 14:10 (L:D) h photophase on artificial meridic diet (Southland Products Inc.), made following manufacture's protocols.…”

“…However, prior to large-scale use in agriculture, biopolymer nanoparticles need to be field tested. Bonser et al (2022) showed that zein biopolymer nanoparticles do not have generational effects on Chrysodeixis includens (Walker) (Lepidoptera:Noctuidae) in the laboratory; similarly, lignin nanoparticle STs had no adverse impact on soybean (Glycine max [L.] Merr.) (Fabales:Fabaceae) and insect growth under laboratory settings (Kacsó et al, 2022).…”

A Nano-Delivery System Enhances the Stomach Toxicity of Methoxyfenozide against Spodoptera litura by Suppressing the Synthesis of Insect Cuticle Protein

“…It has been approved for use on a variety of crops in over 50 countries, including vegetables and specialty forestry productions . Methoxyfenozide can bind to the larval ecdysone receptor, arrest larval feeding and induce a premature lethal moult, and kill the insects within a few days. , Meanwhile, methoxyfenozide is highly specific against lepidopteran larvae, which is considered to be a green alternative due to its safety toward mammals, birds, fish, and beneficial insects. ,− However, methoxyfenozide requires ingestion to be fully effective and acts slowly, which leads to low control efficacy in actual production …”