The Discovery of Potential Repellent Compounds for Zeugodacus cucuribitae (Coquillett) from Six Non-Favored Hosts

Abstract

Zeugodacus cucuribitae (Coquillett) (Z. cucuribitae) is a global extremely invasive quarantine pest which has a wide host range of fruits and vegetables. At present, there are a few control measures for Z. cucuribitae, and deltamethrin and avermectin are commonly used. Among the hosts of Z. cucuribitae, Luffa acutangular, Luffa cylindrica, Sechium edule, Brassica oleracea var. botrytis, Musa nana, and Fragaria × ananassa are non-favored hosts. However, it is still not clear why these hosts are non-favored and whether there are any repellent components of Z. cucuribitae in these hosts. In this study, the components of these six hosts were collected from the literature, and the genes of odor and chemical sensation were determined from the genome of Z. cucuribitae. After the potential relationships between these components and genes were determined by molecular docking methods, the KEGG and GO enrichment analysis of these genes was conducted, and a complex network of genes vs. components vs. Kegg pathway vs. GO terms was constructed and used to select the key components for experiments. The results show that oleanolic acid (1 mg/mL, 0.1 mg/mL, and 0.01 mg/mL), rotenone (1 mg/mL, 0.1 mg/mL, and 0.01 mg/mL), and beta-caryophyllene oxide (1 mg/mL, 0.1 mg/mL, and 0.01 mg/mL) had a significant repellent effect on Z. cucuribitae, and three components, rotenone (1 mg/mL and 0.1 mg/mL), echinocystic acid (1 mg/mL, 0.1 mg/mL, and 0.01 mg/mL), and beta-caryophyllene oxide (1 mg/mL, and 0.1 mg/mL) had significant stomach toxicity in Z. cucuribitae. Furthermore, a complex signaling pathway was built and used to predict the effect of these components on Z. cucuribitae. These components probably play roles in the neuroactive ligand-receptor interaction (ko04080) and calcium signaling (ko04020) pathways. This study provides a reference for the prevention and control of Z. cucuribitae and a scientific reference for the rapid screening and development of new pest control drugs.

Keywords: Zeugodacus cucuribitae (Coquillett); insect repellent; molecular docking; network pharmacology; olfactory genes.

Figure 1

Construction of phylogenetic analysis of IR genes based on gene sequences of Z. cucuribitae and several Diptera insects. Genes from Z. cucuribitae are marked in blue. Notes: Acer: Apis Cerana, Zcuc: Zeugodacus Cucurbitae, Bdor: Bactrocera Dorsalis, Bole: Bactrocera Oleae, Dmel: Drosophila Melanogaster, Mdom: Musca Domestica, Dana: Drosophila Ananassae, Dsim: Drosophila Simulans.

Figure 2

KEGG and GO enrichment. (A) KEGG enrichment; (B) GO enrichment.

Figure 3

A visualization of the docking of olfactory sensory genes with the compounds of hosts. (A) The numbers of compounds with different affinities between −5 kcal/mol and 18 kcal/mol were counted. (B) The numbers of genes with different affinities between −5 kcal/mol and −18 kcal/mol were counted. (C) The prediction results of molecular docking between maslinic acid 3-O-b-D-glucoside and the LOC105217972 gene of Luffa cylindrica. (D) The prediction of the combination of the metabolic compound echinocystic acid and the gene LOC105218953 of Luffa cylindrica. (E) The prediction of the combination of isorhoifolin and the gene LOC105215418. (F) The prediction of the combination of kaempferol, a metabolic compound of banana, and the gene LOC105209256. (G) The prediction of the combination of rutin, a metabolic compound of cauliflower, and the gene LOC105209182. (H) The prediction of the combination of damascenone, a metabolic compound of strawberry, and the gene LOC105217972. Notes: The molecular docking of Ligand X with Protein Receptor Y is shown. The figure illustrates the binding mode of Ligand X (shown in stick representation, colored by atom type, with carbon shown in blue and oxygen shown in red) within the active site of Protein Receptor Y (shown in cartoon representation, colored by secondary structure). Ligand X (stick representation) is shown interacting with key residues (labeled) of the receptor (cartoon representation). Hydrogen bonds are depicted as dashed lines.

Figure 4

A complex network node diagram of the compounds of L. acutangular, L. cylindrica, S. edule, B. oleracea, M. nana, and F. ananassa vs. Z. cucuribitae olfactory sensory genes vs. Kegg pathway vs. GO term. The core compounds are presented in blue, the Z. cucuribitae olfactory sensory genes are presented in yellow, the kegg pathway is presented in green, and the GO term is presented in red. The metabolites selected for the two-way selection test and gastric toxicity test are shown in dark blue.

Figure 5

Avoidance rate and mortality rate of Z. cucuribitae under different concentrations of five metabolic compounds. (A) Avoidance rate of rotenone. (B) Avoidance rate of diosmin. (C) Avoidance rate of beta-caryophyllene oxide. (D) Avoidance rate of oleanolic acid. (E) Avoidance rate of echinocystic acid. (F) Mortality rate of rotenone. (G) Mortality rate of diosmin. (H) Mortality rate of beta-caryophyllene oxide. (I) Mortality rate of oleanolic acid. (J) Mortality rate of echinocystic acid. Note: ck means control check; ns means no significance between two compared groups. * represents significant difference at p < 0.05; ** represents significant difference at p < 0.01; *** represents significant difference at p < 0.001 compared to model group.

Figure 6

Mechanism deduction of effect of effective compounds on odor recognition of Z. cucurbitae. Red nodes represent activated genes. Notes: GRIN: glutamate receptor ionotropic; GRI: glutamate receptor 1; ROC: nicotinic acetylcholine receptor alpha-7; CALN: calmodulin; TFEB: transcription factor EB; NFAT: nuclear factor of activated T-cells, cytoplasmic 1; NOS: nitric-oxide synthase, brain; FAK2: focal adhesion kinase 2; IP3 3K: 1D-myo-inositol-triphosphate 3-kinase; PKC: classical protein kinase C alpha type.