Genetic diversity analysis of the invasive gall pest Leptocybe invasa (Hymenoptera: Apodemidae) from China

Abstract

Leptocybe invasa Fisher et LaSalle is a global invasive pest that seriously damages Eucalyptus plants. Studying the genetic diversity, genetic structure and introgression hybridization of L. invasa in China is of great significance for clarifying the breeding strategy, future invasion and diffusion trends of L. invasa in China and developing scientific prevention and control measures. Genetic diversity and phylogenetic analyses of 320 L. invasa female adults from 14 geographic populations in China were conducted using 10 polymorphic microsatellite loci (SSRs) and mitochondrial DNA cytochrome oxidase I gene sequences (COIs). (1) The Bayesian phylogenetic tree and haplotype network diagram showed that only haplotype Hap3 existed in L. invasa lineage B in China, while haplotypes Hap1 and Hap2 existed in lineage A, among which haplotype Hap2 was found for the first time. The nucleotide and haplotype diversities of lineage A were higher than those of lineage B. (2) The SSR genetic diversity of the Wuzhou Guangxi, Ganzhou Jiangxi and Panzhihua Sichuan populations was higher than that of the other 11 populations, and the SSR genetic diversity of lineage A was higher than that of lineage B. (3) The AMOVA analysis of mitochondrial COI data showed that 75.55% of the variation was among populations, and 99.86% of the variation was between lineages, while the AMOVA analysis of nuclear SSR data showed that 35.26% of the variation was among populations, and 47.04% of the variation was between lineages. There were obvious differences in the sources of variation between the COI and SSR data. (4) The optimal K value of COI and SSR data in structure analysis was 2, and PCoA analysis also divided the dataset into two obvious categories. The UPMGA phylogenetic tree based on SSR data clustered 14 geographic species into two groups. The results of genetic structure analysis supported the existence of two lineages, A and B, in China. (5) Structural analysis showed that there was obvious introgressive hybridization in Wuzhou Guangxi, Ganzhou Jiangxi, Panzhihua Sichuan and other populations. These results suggest that lineage introgressive hybridization has occurred in the L. invasa population in China. The introgressive hybridization degree and genetic diversity of lineage A are obviously higher than those of lineage B. Lineage introgressive hybridization may be the driving force for further L. invasa invasion and diffusion in China in the future.

Identification and Validation of Reference Genes for Expression Analysis Using RT-qPCR in Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae)

“…The presence of large numbers of galls in Eucalyptus plantations and young forest nurseries not only raises concerns about the quality of damaged Eucalyptus trees but also increases the likelihood of significant economic damage to the region’s Eucalyptus forests [ 5 ]. Although many studies were performed on the pattern of L. invasa proliferation, genetic diversity, and in vivo bacterial diversity [ 4 , 6 , 7 ], little is known about the molecular processes in L. invasa gene expression. Recently, by analyzing the transcriptome of L. invasa , we identified a significant number of heat shock protein genes and some resistance genes.…”

Differences in Male-Killing Rickettsia Bacteria between Lineages of the Invasive Gall-Causing Pest Leptocybe invasa

“…Dittrich-Schröder et al [ 15 ] studied the population genetics of L. invasa around the world and found introgressive hybridization between L. invasa lineages A and B in Vietnam. Peng et al [ 27 ] conducted population genetic research on 14 geographical populations of L. invasa in China and found that 7 geographical populations included both lineages A and B. Of these, there was obvious introgressive hybridization between lineages in Wuzhou, Guangxi, and Panzhihua, Sichuan.…”

“…Mitochondrial COI sequence data have shown that L. invasa has three lineages, A, B (B1 and B2), and C, of which lineages B2 and C only appear in Australia, while lineages A and B1 are widely distributed in areas invaded by L. invasa . L. invasa lineages A and B1 coexist in China, Laos, Vietnam, Thailand, and South Africa (lineage B in this paper refers to lineage B1) [ 15 , 25 , 26 , 27 ].…”