EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 121: 134-145, 2024 | DOI: 10.14411/eje.2024.016

Use of powdered immunized insects for inhibiting Pectobacterium carotovorum infestation and promoting growth in lettuceOriginal article

Youngwoo CHO^{1, 2}, Jun Ho LEE², Jangwoo PARK³, Ki-Byung PARK¹, Mijeong KIM¹, Sung Su PARK¹, Sejung HWANG¹, Saeyoull CHO^{1, 2, *}

¹ Department of Applied Biology, College of Agriculture and Life Science, Kangwon National University, Chuncheon, Republic of Korea; e-mails: 5120057@kangwon.ac.kr (Y.C.), parkki01@naver.com (K.B.P.), mjkim@k-insect.com (M.K.), bug216@hanmail.net (S.S.P.), tpwjd321@korea.kr (S.H.), saeyoullcho@kangwon.ac.kr (S.C.)

² Department of Interdisciplinary Program in Smart Agriculture, College of Agriculture and Life Science, Environment Friendly Agriculture Center, Kangwon National University, Chuncheon, Republic of Korea, e-mail: john1232817@kangwon.ac.kr (J.H.L.)

³ Osang Kinsect Co., Guri, Republic of Korea; e-mail: pjw@k-insect.com (J.P.)

We induced immune activation in mass rearing experiments in three insect species, i.e., Gryllus bimaculatus De Geer, 1773 (Orthoptera: Gryllidae), Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae), and Protaetia brevitarsis seulensis (Kolbe, 1886) (Coleoptera: Scarabaeidae). Lysosomal staining of immune cells was a little over 6% in the control group insects, whereas it ranged from 17-35% in insects immunized with Escherichia coli K12 or Bacillus thuringiensis (Bt). The expression of attacin-like protein and defensin-like protein was also found to be upregulated at least 10-fold, and even up to 30-fold, from the third day of rearing in insects immunized with E. coli K12 or Bt. Non-immunized or immunized G. bimaculatus, H. illucens, and P. brevitarsis seulensis were freeze-dried and powdered, and these powders were then tested for protection against Pectobacterium carotovorum infestation. No inhibitory effects on P. carotovorum were observed when using all non-immunized insect powders or PBS. However, in the clear zone test treated with H. illucens powder at 10,000 ppm, an average size of 21.67 mm was observed. In a test using potato slices infected with P. carotovorum, we observed severe disease occurrence and potato weight loss in all non-immunized insect powders or PBS-treated groups. However, the group treated with H. illucens powder had the least potato weight loss. When tested on lettuce, the H. illucens powder-treated group revealed an approximately 10% increase in the fresh weight of lettuce, with both the dry weight and leaf area of lettuce increasing in comparison with those in the control group. Thus, our study proposes a novel method for the use of freeze-dried and powdered forms of insects immunized in mass rearing as effective functional fertilizers on a large scale that can also be effective in inhibiting microbial infections, overcoming the limitation of high production costs of such insect fertilizers using conventional methods.

Keywords: Hermetia illucens, insect immunization, plant pathogen, insect-based fertilizers

Received: September 19, 2023; Revised: March 20, 2024; Accepted: March 20, 2024; Published online: April 8, 2024  Show citation