1. Introduction
Conogethes punctiferalis (Guenée), is an important agricultural pest of chestnut (Castanea mollissima ), peach (Amygdalus persica ), apple (Malus pumila ), maize (Zea mays ), and sunflower (Helianthus annuus ) (Luo and Honda, 2015). In some regions of China, it has become the main pest of corn, causing more significant damage thanOstrinia furnacalis (Guenée), the most prevalent corn pest in China (Wang et al., 2006). C. pinicolalis (Lepidoptera: Crambidae) is a sibling species of C. punctiferalis , even though it is considered the same species at the early stage. Koizumi first identified and classified the C. pinicolalis as another type ofC. punctiferalis and identified and classified the C. pinicolalis as another type of C. punctiferalis commonly known Pinaceae-feeding type in 1963 (Koizumi, 1963). Honda and Mitsuhashi identified and distinguished the difference between them in the adults, larvae and pupal stages (Honda and Mitsuhashi, 1989); Konno et al. tested and reported that they were different species from their response to different spectra of host-plant constituents (Konno et al., 1981); In the end, the pinaceae-feeding type was named C. pinicolalis in 2006 (Inoue et al., 1982).
The two sibling species,C. punctiferalis and C.pinicolalis,are important pest species in China. These two insects are similar in morphologically, almost indistinguishable at the egg, larval and pupal stages, and only well-trained entomologists can identify them by some morphological characteristics in the adult stage. Moreover, they are so similar that they both use (E)-10-hexadecenal (E10-16:Ald) and (Z)-10-hexadecenal (Z10-16:Ald) as their main sex pheromone components, but their foraging ranges are widely differentiated. C. punctiferalis is a polyphagous species posing a major threat to over 100 essential plant species (Lu et al., 2010), while C. pinicolalis is an oligophagous insect, mainly fed on few pine trees, especially for Pinus massoniana (Masson pine). Their feeding preferences may be associated with olfactory and gustatory system or digestive system, and this preference ultimately must manifest as the result of the regulation of proteins, genes, and their pathways. Therefore, it was of great interest to unveil the difference in some function genes or proteins between the two species.
In this study, we applied a proteomic technique, the isobaric tags for relative and absolute quantification (iTRAQ), and RNA sequencing-based transcriptome technique. The transcripts with new exons were identified from an alternative splicing database to understand further the related proteins and transcripts involved in feeding preferences. At the same time, metabolomics was used to detect the difference between the two species. Our result provided a profound understanding of the functions of the different genes about polyphagous and oligophagous.