Carposina sasakii (peach fruit moth).

C. sasakii is a pest of rosaceous fruits in eastern Asia, and does not spread easily to the non-native areas and countries. C. sasakii has the potential to fly long distances, but usually flies only within and between canopies of fruit trees. Aerial dispersal to non-native areas has not been recorded. International trade of rosaceous fruits is a possible cause of spread of C. sasakii, but it is difficult for it to enter non-native countries under quarantine inspection. Even if C. sasakii enters non-native countries by international trade, it is not easy to establish a population, probably because the larvae in fruits cannot find a cocooning site near rosaceous plants after escaping from the fruits. However, C. sasakii has a strong impact on the management of rosaceous fruit orchards once a population is established. Damage to fruits can reach 100% in some cases in pears [Pyrus spp.] and 40-100% in apples [Malus spp.] if not controlled.

Selection and Validation of Reference Genes for Quantitative Real-Time PCR Expression Analysis of Candidate Genes in Carposina sasakii (Lepidoptera: Carposinidae)

Carposina sasakii is one of the most important pests on the quality of stone and pome fruits. Investigation of a gene expression level in the species is hampered because of the gap of validated reference genes. The expression variation in the transcription levels of eight candidate reference genes, Actin (ACT), Tubulinbeta-1 (TUB), Ribosomal protein 49 (RP49), Elongation factor1-alpha (EF-1a), Elongation factor1-b (EF-1b), Elongation factor1-d (EF-1d), Ribosomal proteinL13 (RPL13) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were analyzed by quantitative real-time PCR (qPCR). The stability and ranking of these gene expression profiles in three organ types (head, thorax and abdomen), three developmental stages (larva, pupa and moth), and five diapause states (non-diapause, pre-diapause, diapause 0 d, diapause 20 d and diapause 60 d) were assessed using two algorithm-based methods, geNorm and NormFinder. EF-1a, ACT and GAPDH were evaluated to be the three stable reference genes based on the important observations and comprehensive analysis, whereas TUB and EF-1b showed low expression stability. Best gene combinations for different qPCR analysis in C. sasakii could be chosen from the three stable reference genes, the using of two reference genes is sufficient to effectively normalize qPCR data in C. sasakii. The study laid the foundation for gene expression analysis in C. sasakii and provided new information for the selection of reference genes.

Similar Gut Bacterial Microbiota in Two Fruit-Feeding Moth Pests Collected from Different Host Species and Locations

Numerous gut microbes are associated with insects, but their composition remains largely unknown for many insect groups, along with factors influencing their composition. Here, we compared gut bacterial microbiota of two co-occurring agricultural pests, the peach fruit moth (PFM), Carposina sasakii, and the oriental fruit moth (OFM), Grapholita molesta, collected from different orchards and host plant species. Gut microbiota of both species was mainly composed of bacteria from Proteobacteria, followed by Firmicutes. The two species shared bacteria from the genera Pseudomonas, Gluconobacter, Acetobacter, and Pantoea. When we compared two pairs of PFM and OFM populations collected from the same host species and the same orchard, there is no difference in alpha and beta diversity in gut microbiota. When we compared gut microbiota of the same species and host plant from different orchards, alpha and beta diversity was different in populations of PFM collected from two pear orchards but not in other comparisons. Our study suggests that the two pests share many features of gut microbiota and environment in orchards is a main factor influencing their gut microbiota.