Variation in sex ratio of the leafminerPhytomyza plantaginisGoureau (Diptera: Agromyzidae) from Australia

Abstract

Parthenogenetic reproduction has only previously been demonstrated in two species of agromyzid leafminer flies (Diptera: Agromyzidae), both from the genus Phytomyza. The plantain leafminer, Phytomyza plantaginis, is Palaearctic in origin, and bisexual populations have been observed in this region. However, historically, only females had been collected in the Australasian, Nearctic, Neotropical and Oceanian regions. Here, we show that southern Australian samples of this species from Plantago spp. can be composed of both parthenogenic and bisexual populations. In sites around Melbourne, males were present, although the sex ratio was female biased, with females comprising 75% of sampled individuals. In contrast, males were absent from collections in western and northern Victoria, Australian Capital Territory, New South Wales and Western Australia. Female P. plantaginis flies were reared from three Plantago host plants (Plantago lanceolata, Plantago major and Plantago coronopus), although females were particularly common from Pl. lanceolata. Insect cages set up with leafminers from sites where only females occurred produced only females, while cages with leafminers from sites where males occurred produced both sexes and mating was observed. Individuals from all populations were infected by Wolbachia endosymbionts, suggesting that the presence/absence of Wolbachia is not directly responsible for the parthenogenesis. However, there was an association between a mtDNA variant (PP.02) and sexual reproduction, in that this variant was absent in areas where only females were collected but present in all males and some females from areas with sexual populations. The mechanism responsible for parthenogenesis in P. plantaginis remains unknown but is linked to maternal factors.

Identification of two leafminer parasitoids (Hymenoptera: Eulophidae),Neochrysocharis formosaandProacriassp. from Australia, with both showing thelytoky and infection byRickettsia

“…We collected plant leaves showing signs of leafmining from field sites at Flemington Bridge, Victoria, Australia (37.788 S, 144.939 E) between 2018 and 2021, which have been used previously in leafminer surveys (Coquilleau et al . 2021; Xu et al . 2021) and where suspect N. formosa had been found (Coquilleau 2020).…”

“…We collected plant leaves showing signs of leafmining from field sites at Flemington Bridge, Victoria,Australia (37.788 S,144.939 E) between 2018 and 2021, which have been used previously in leafminer surveys (Coquilleau et al 2021;Xu et al 2021) and where suspect N. formosa had been found (Coquilleau 2020). We sampled Brassica fruticulosa infested by Liriomyza brassicae, Stellaria media infested by Liriomyza chenopodii, Plantago lanceolata infested by Phytomyza plantaginis and Sonchus oleraceus infested by Phytomyza syngenesiae.…”

Genome‐wide SNPs of vegetable leafminer, Liriomyza sativae: Insights into the recent Australian invasion

“…As species of Liriomyza have similar external morphology, taxonomic identification of L. sativae samples was confirmed by both morphological identification (by Dr. Mallik Malipatil, Agriculture Victoria, AgriBio, La Trobe University, Bundoora, Australia) and barcodes based on mitochondrial cytochrome c oxidase subunit I (CO1). For barcoding, legs of flies were taken from specimens for Chelex DNA extraction with protocols following previous work except in 70 μl of 5% Chelex 100 resin (Bio‐Rad Laboratories, Gladesville, NSW, Australia) (Coquilleau et al, 2021 ; Xu, Coquilleau et al, 2021 ; Xu, Ridland et al, 2021 ). The criteria for assigning CO1 haplotypes were based on BLAST similarity in NCBI (Johnson et al, 2008 ) with 100% similarity being used to link to existing haplotypes, and assignment to L. sativae clades defined by a similarity threshold of <2.5% (Scheffer & Lewis, 2005 ).…”

“…Liriomyza sativae field samples were obtained from 24 populations from eight countries between July 2016 and May 2020 through active sampling (Figure 1, Table 1), which depended on the good- Laboratories, Gladesville, NSW, Australia) (Coquilleau et al, 2021;Xu, Coquilleau et al, 2021;. The criteria for assigning CO1 haplotypes were based on BLAST similarity in NCBI (Johnson et al, 2008) with 100% similarity being used to link to existing haplotypes, and assignment to L. sativae clades defined by a similarity threshold of <2.5% (Scheffer & Lewis, 2005).…”

High Incidence of Related Wolbachia across Unrelated Leaf-Mining Diptera

“…For instance, in the phytophagous leaf-mining moth, Phyllonorycter blancardella (Lepidoptera: Gracillariidae) Wolbachia affects host plant physiology, producing the 'green-island' phenotype (photosynthetically active green patches) that enhances larval fitness [49]. In addition, Wolbachia can alter mtDNA haplotypes and potentially cause reproductive isolation in leafminers, as recently documented in Phytomyza plantaginis Goureau (Diptera: Agromyzidae) where two mtDNA haplotypes separate parthenogenic and bisexual populations both infected by Wolbachia [50].…”