Wolbachiainfection in Argentinean populations ofAnastrepha fraterculus sp1: preliminary evidence of sex ratio distortion by one of two strains

Abstract

Background: Wolbachia, one of the most abundant taxa of intracellular Alphaproteobacteria, is widespread among arthropods and filarial nematodes. The presence of these maternally inherited bacteria is associated with modifications of host fitness, including a variety of reproductive abnormalities, such as cytoplasmic incompatibility, thelytokous parthenogenesis, host feminization and male-killing. Wolbachia has attracted much interest for its role in biological, ecological and evolutionary processes as well as for its potential use in novel and environmentally-friendly strategies for the control of insect pests and disease vectors including a major agricultural pest, the South American fruit fly, Anastrepha fraterculus Wiedemann (Diptera: Tephritidae). Results:We used wsp, 16S rRNA and a multilocus sequence typing (MLST) scheme including gatB, coxA, hcpA, fbpA, and ftsZ genes to detect and characterize the Wolbachia infection in laboratory strains and wild populations of A. fraterculus from Argentina. Wolbachia was found in all A. fraterculus individuals studied. Nucleotide sequences analysis of wsp gene allowed the identification of two Wolbachia nucleotide variants (named wAfraCast1_A and wAfraCast2_A). After the analysis of 76 individuals, a high prevalence of the wAfraCast2_A variant was found both, in laboratory (82%) and wild populations (95%). MLST analysis identified both Wolbachia genetic variants as sequence type 13. Phylogenetic analysis of concatenated MLST datasets clustered wAfraCast1/2_A in the supergroup A. Paired-crossing experiments among single infected laboratory strains showed a phenotype specifically associated to wAfraCast1_A that includes slight detrimental effects on larval survival, a female-biased sex ratio; suggesting the induction of male-killing phenomena, and a decreased proportion of females producing descendants that appears attributable to the lack of sperm in their spermathecae. Conclusions:We detected and characterized at the molecular level two wsp gene sequence variants of Wolbachia both in laboratory and wild populations of A. fraterculus sp.1 from Argentina. Crossing experiments on singly-infected A. fraterculus strains showed evidence of a male killing-like mechanism potentially associated to the wAfraCast1_A -A. fraterculus interactions. Further mating experiments including antibiotic treatments and the analysis of early and late immature stages of descendants will contribute to our understanding of the phenotypes elicited by the Wolbachia variant wAfraCast1_A in A. fraterculus sp.1.

Geographic distribution of sex chromosome polymorphism in Anastrepha fraterculus sp. 1 from Argentina

“…These two A. fraterculus lines were also purified from the A. fraterculus IGEAF strain, considering the Wolbachia strain they harbor (wAfraCast1_A and wAfraCast2_ A, respectively) [72]. Each strain was maintained for 70 generations under laboratory conditions.…”

Attractiveness and Sexual Competitiveness of Anastrepha obliqua Males (Diptera: Tephritidae) Fed on a Diet Enriched With Providencia rettgeri

“…Early studies in the Mexican fruit fly, Anastrepha ludens (Loew) were carried out to evaluate resistance or sensitivity to a variety of antibiotics in bacteria isolated from this same species ( Kuzina et al, 2001 ) and to test the attractive effect of metabolites produced by bacteria on A. ludens ( Martínez et al, 1994 ). In addition, studies have determined the presence of Wolbachia in Anastrepha species ( Mateos et al, 2020 ), including guava fruit fly, A. striata ( Martínez et al, 2012 ), West Indian fruit fly, A. obliqua ( Mascarenhas et al, 2016 ), South American fruit fly, A. fraterculus ( Conte et al, 2019 ) and sapote fruit fruit fly, A. serpentina ( Coscrato et al, 2009 ). On the other hand, studies have revealed that the gut bacterial community in flies consists mainly of species of the Enterobacteriaceae family ( Noman et al, 2020 ), and that these microorganisms may be involved in nitrogen fixation, nutrition and insect fitness, including mating behavior and sexual competitiveness, reproductive success, longevity, improve the males fitnnes ( Gavriel et al, 2011 ; Hamden et al, 2013 ; Andongma et al, 2015 ; Khaeso et al, 2017 ; Yuval, 2017 ; Juárez et al, 2019 ), protection against pathogens and detoxification ( Ben-Yosef et al, 2015 ; Guo et al, 2017 ).…”

Efeitos da bactéria Wolbachia em parâmetros reprodutivos de Anastrepha sp. 1affinis fraterculus (Diptera: Tephritidae)

“…Apesar da incompatibilidade citoplasmática (IC), descrita por Laven (1967) ser uma das alterações reprodutivas causadas pela Wolbachia mais frequente entre os insetos (BOURTZIS et al, 2003) sua ocorrência parece estar vinculada tanto a certas características da linhagem da Wolbachia quanto também de seu hospedeiro ou, em outras palavras, não é possível assumir-se que a simples presença da bactéria produza o efeito IC. Linhagens de Wolbachia presentes em amostras de A. sp.1 da Argentina, diferentes da aqui descrita mostraram causar o fenótipo morte dos machos (male killing), enquanto outras mostraram causar o fenótipo IC em diferentes morfotipos do complexo fraterculus (CONTE et al, 2019;DEVESCOVI et al, 2019). Além disso, a incidência da IC é possivelmente também dependente do tempo da associação de uma dada linhagem com seu hospedeiro (TURELLI, 1994).…”

“…fraterculus na Argentina. Os resultados de cruzamentos sugeriram que a linhagem wAfraCast1 poderia estar induzindo a morte de machos (CONTE et al, 2019). Em outro estudo, IC intraespecífica (unidirecional) foi demonstrada em A. sp.1 aff.…”