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

Ziyan Nangong,Ping Song,Qinying Wang,Tianhui Li,Weikang Zhang

doi:10.1186/s41938-021-00492-5

Ziyan Nangong, Ping Song + Show 3 more

Open Access

https://doi.org/10.1186/s41938-021-00492-5

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Abstract

BackgroundEntomopathogenic 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.ResultsAn 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 × 104 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%.ConclusionEPNs-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

Entomopathogenic nematodes (EPNs) have long been used for controlling soil-dwelling insects
We developed an improved capsule formulation named as Capsule-C supplemented with glucose, which can obviously increase the larva feeding amount of Agrotis ipsilon
Steinernema carpocapsae HB310 was obtained from the Pest Biocontrol Laboratory (PBL) at the College of Plant Protection, Hebei Agricultural University

Summary

Introduction

Entomopathogenic nematodes (EPNs) have long been used for controlling soil-dwelling insects. The nematodes suspension was added to the alginate mixture in 2 × 104 IJs/mL; Solution II: 18% glycerol, 0.075% formaldehyde, 0.5% calcium chloride, 0.5% potassium sorbate, with the remainder being distilled water. 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. Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis, as important candidates, are used as friendly biological pesticides for pest insects in different farming systems, including fruit orchards, turf grass, and greenhouses (Katumanyane et al 2018). Other works on the formulation of EPNs were focused on above-ground applications by adding surfactants and absorbents (Hiltpold 2015), or mixing EPNs with a surfactant, polymer or insecticide (Guo et al, 2017)

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