Capsule-C: an improved Steinernema carpocapsae capsule formulation for controlling Agrotis ipsilon Hufnagel (Lepidoptera: Noctuidae)

• Published in: Egyptian Journal of Biological Pest Control Vol. 31; no. 1; pp. 1 - 10
• Main Authors: NanGong, Ziyan, Li, Tianhui, Zhang, Weikang, Song, Ping, Wang, Qinying
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 27.11.2021; Springer; Springer Nature B.V; SpringerOpen
• Subjects: Agrotis ipsilon; Alginic acid; Biomedical and Life Sciences; Calcium alginate capsules; Calcium chloride; Distilled water; Entomopathogenic nematodes; Feeding rates; Formaldehyde; Formulations; Fructose; Galleria mellonella; Glucose; Glycerin; Glycerol; Insects; Larvae; Lepidoptera; Life Sciences; Long-term storage; Mortality; Nematoda; Nematodes; Noctuidae; Pathogenicity; Pathogens; Pesticides; Pests; Polysaccharides; Potassium; Potassium sorbate; Rhizosphere; Seedlings; Sodium alginate; Steinernema carpocapsae; Sucrose; Survival; Virulence; Xanthan; Xanthan gum; Zoology; Calcium alginate capsules; Long-term storage
• ISSN: 2536-9342; 1110-1768; 2536-9342
• DOI: 10.1186/s41938-021-00492-5

Background Entomopathogenic nematodes (EPNs) have long been used for controlling soil-dwelling insects. Steinernema carpocapsae HB310, previously showed a high virulence against many pests including Agrotis ipsilon Hufnagel (Lepidoptera: Noctuidae). Due to the lack of durable formulations, up until now, S. carpocapsae HB310 has thus far been prevented from use in large-scale farming. The present study aimed to get a better EPNs capsule formulation suitable for long-term storage and effective application. Results An improved EPNs capsule formulation, herein named: Capsule-C was prepared by the following composition: Solution I: 18% glycerol, 0.075% formaldehyde, 1% sodium alginate, 0.2% xanthan gum, 0.5% potassium sorbate, 9% glucose, 2% fructose, 2% sucrose, and the remainder was distilled water. The nematodes suspension was added to the alginate mixture in 2 × 10 4 IJs/mL; Solution II: 18% glycerol, 0.075% formaldehyde, 0.5% calcium chloride, 0.5% potassium sorbate, with the remainder being distilled water. After storage for 180 days at 16 °C and 100% RH, the survival rate of nematodes in Capsule-C was 75.68 ± 0.48% and the nematodes caused 82.33 ± 1.45% mortality in the 5th instar larvae of Galleria mellonella. A. ipsilon larvae preferred to chew and ingest Capsule-C due to the addition of the glucose compound. The feeding rate of A. ipsilon larvae on Capsule-C reached to 100% within 24 h and the larval mortality of A. ipsilon was 90.48 ± 6.35%. Conclusion EPNs-containing capsules were as effective as sprayed EPNs in water solution at killing A. ipsilon. These results will provide ideas to acquire a stable and efficient EPNs capsule formulation and further promote the application of environmental friendly biological pesticides. Highlights We developed an improved capsule formulation named as Capsule-C supplemented with glucose, which can obviously increase the larva feeding amount of Agrotis ipsilon . The nematodes of Steinernema carpocapsae HB310 in Capsule-C survived well and maintained high pathogenicity against Galleria mellonella after storage for 180 days . Under laboratory conditions, Capsule-C could be released into the rhizosphere directly and effectively reduced maize seedlings damage by A.ipsilon .