Effect of host plant diet on fitness, population parameters, and gut microbiota of grape berry moth (GBM) Paralobesia vietana
Restricted (Penn State Only)
- Author:
- Laiton Jimenez, Laura
- Graduate Program:
- Entomology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 15, 2022
- Committee Members:
- Gary Felton, Program Head/Chair
Flor E Acevedo, Thesis Advisor/Co-Advisor
Kelli Hoover, Committee Member
Istvan Albert, Committee Member - Keywords:
- Bacterial microbiota
fungal microbiota
fruit-feeding insect
amplicon metagenomic sequencing
Vitis.Bacterial microbiota
Vitis.
Amplicon metagenomic sequencing
Vitis
grape cultivar
microbiome
life cycle - Abstract:
- Grape berry moth (GBM) Paralobesia vietana, is an important pest of cultivated grapes in eastern North America. The larvae of this insect damage grape clusters by direct feeding and by increasing susceptibility to fungal and bacterial pathogens. This pest feeds on various grape cultivars at all ripening stages. Currently, growing degree-day models are the most effective methods in predicting seasonal GBM activity for timing control strategies; however, the model parameters have been estimated for GBM populations grown exclusively on the Concord cultivar. Despite the economic importance of this insect, the effect of different grape cultivars and grape phenological stages on GBM development, reproduction, demography, and gut-associated microbiome -bacterial and fungal communities are unknown. In this study, we built age-stage two-sex life tables of GBM fed on five different grape cultivars: Concord, Niagara, Riesling, Chambourcin, and Vidal, to elucidate the effects of different diets on insect population development, survival, reproduction, and demographic parameters. Cohort life tables were constructed for GBM fed on each grape cultivar and analyzed using the computer program TWOSEX-MSChart. Immature developmental times, adult longevity, pupal weight, fecundity (including intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0)), and mean generation time (T) were some of the parameters estimated. We also sequenced the V3-V4 region of the 16S rRNA and V4 region of 18S rRNA to compare the composition and diversity of GBM gut bacteria and fungi communities between larvae fed on immature and mature Concord grapes. The data were analyzed with QIIME2 through command line. Downstream analyses included taxonomic composition, differential abundance, phylogenetic, alpha/beta-diversity, and functional analyses with PICRUSt2. The results of life table analyses show that grape cultivar has a significant influence on larval developmental time, adult and female longevity, pupal weight, adult preoviposition period (APOP), oviposition period, and mean generation time (T) of P. viteana. Diet type did not influence the total fecundity per female or the remaining demographic population parameters. The higher female reproductive value (vxj) across all cultivars was achieved at 30 to 40 days of age (from the egg oviposition), suggesting that application of control tactics within this time frame would have the greatest impact on the reduction of population increase. These results provide basic information for improving the degree-day models currently used for the management of this insect in vineyards. Our sequencing results from the 16S rRNA gene show that gut-associated bacteria did not differ between larvae fed on immature and mature grapes. Ninety-six percent of the bacterial communities belonged to the Proteobacteria, and some may play roles in amino acid and carbohydrate (cellulose and hemicellulose) metabolism in the insect gut. Analyses of 18S rRNA showed significant differences in fungal communities between larvae grown at different grape ripening stages. Ascomycota (99%) was the dominant phylum present in the gut of larvae fed on mature grapes, while larvae fed on immature grapes mainly contained fungi in the Cryptomycota (51%). Larvae fed on ripe grapes had a higher abundance of yeasts (Saccharomycetales) compared with those fed on immature grapes. Several gut-associated fungal genera identified are commonly found in rotten grapes, which suggests that some yeasts might be transient insect residents that are ingested with the diet. In conclusion, diet type affects GBM population parameters and gut-associated microbial communities. The results of this study may help improve GBM management practices and contribute to basic knowledge of gut-associated microbes of fruit-feeding insects.