Meiosis in rare males in parthenogenetic Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) populations from northern Europe

Abstract

For studying meiosis in males, large samples of Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) were collected in Norway, Sweden, Finland and northwest Russia. In addition to all-female populations, males were present in 10 out of 47 populations; still, all populations were highly female-biased, the proportion of males varying from 0.1% to 9.1%. These males are thus rare or so-called spanandric males. Males in northern Norway, Finland and northwest Russia showed normal chiasmate meiosis, while complete absence of chiasmata due to asynapsis was found in males collected in Norway and northern Sweden. In asynaptic meiosis, all univalent chromosomes divided during the first meiotic division resulting in incomplete second meiotic division and formation of diploid sperms. Hence, males in these populations are nonfunctional and do not contribute to the genetic constitution of the population, but appear in every generation as reversals from apomictic parthenogenesis and the mode of parthenogenesis is of obligatory type.

Rare diploid females coexist with rare males: a novel finding in triploid parthenogenetic populations in the psyllid Cacopsylla myrtilli (W. Wagner, 1947) (Hemiptera, Psylloidea) in northern Europe

“…1b). Interestingly, diploid females displayed chiasmate bivalents irrespective of the type of male meiosis, this being chiasmate in White Sea and Paltamo or achiasmate/asynaptic in Rindhovda (Nokkala et al 2013). This indicates that the gene carrying the mutation resulting in asynapsis in males is male specific in its function.…”

“…Although it is tempting to think that diploids reproduce bisexually at Rindhovda, there is firm evidence to show this is not the case. Previously (Nokkala et al 2013), we showed that males at Rindhovda display achiasmate meiosis and are thus nonfunctional, producing only diploid sperms. Even if females produced haploid eggs, mating with males would result in triploid, not diploid offspring, Hence, diploid females and males must be produced in every generation by parthenogenetic females as reversals from triploidy by eliminating one haploid chromosome set.…”

“…Since it was expected that diploid females would be most likely found in populations showing high frequency of males (Nokkala et al 2013), diploid females were first looked for in White Sea (northwest Russia) and Rindhovda (Norway) populations and later at Abisko (Sweden) and Paltamo (Finland). The only reliable way to identify diploid bisexual females among parthenogenetic triploid females is to analyse the first metaphase from mature eggs.…”

“…Sporadic populations with males were found in Norway, Sweden, Finland and northwest Russia (Nokkala et al 2013). Chromosome number of males was 2n = 24 ?…”

Vector mediated transmission of Candidatus Liberibacter solanacearum and epidemiological consequences

“…The psyllid life cycle comprises: the egg stage, five nymphal stages and sexually reproducing adults (Hodkinson, 1974). Parthenogenetic reproduction is possible but rare and it has been documented only in few psyllid species (Hodkinson, 2009;Nokkala et al, 2013). In the sexual reproduction phase, after mating and egg maturation, females oviposit in the edges or in the underside of the host plant leaves.…”