NOR activity and repeat sequences of the paternal sex ratio chromosome of the parasitoid wasp Trichogramma kaykai

This study uses molecular and cytogenetic methods to determine the origin of a B chromosome in some males of the wasp Trichogramma kaykai . This so-called paternal sex ratio (PSR) chromosome transmits only through sperm and shortly after fertilization triggers degeneration of the paternal genome, while keeping itself intact. The resulting embryos develop into haploid B-chromosome-carrying males. Another PSR chromosome with a very similar mode of action is found in the distantly related wasp Nasonia vitripennis and its origin was traced by transposon similarity to the genus Trichomalopsis , which is closely related to Nasonia . To determine whether both PSR chromosomes have a similar origin we aimed to reveal the origin of the Trichogramma PSR chromosome. Using fluorescent in situ hybridization, we discovered a major satellite repeat on the PSR chromosome, the 45S ribosomal DNA. Analysis of the internal transcribed spacer 2 (ITS2) of this repeat showed the presence of multiple ITS2 sequences on the PSR chromosome resembling either the ITS2 of T. oleae or of T. kaykai . We therefore conclude that the Trichogramma PSR chromosome originates from T. oleae or a T. oleae -like species. Our results are consistent with different origins for the PSR chromosomes in Trichogramma and Nasonia .

Download Full-text

The paternal sex ratio chromosome in the parasitic wasp Trichogramma kaykai condenses the paternal chromosomes into a dense chromatin mass

Genome ◽

10.1139/g03-044 ◽

2003 ◽

Vol 46 (4) ◽

pp. 580-587 ◽

Cited By ~ 18

Author(s):

Joke F.A van Vugt ◽

Merijn Salverda ◽

J Hans de Jong ◽

Richard Stouthamer

Keyword(s):

Sex Ratio ◽

Parasitic Wasp ◽

Parasitoid Wasp ◽

B Chromosome ◽

The Other ◽

Paternal Chromosome ◽

Paternal Genome ◽

Obvious Similarity ◽

Dense Chromatin ◽

Paternal Sex Ratio

A recently discovered B chromosome in the parasitoid wasp Trichogramma kaykai was found to be transmitted through males only. Shortly after fertilization, this chromosome eliminates the paternal chromosome set leaving the maternal chromosomes and itself intact. Consequently, the sex ratio in these wasps is changed in favour of males by modifying fertilized diploid eggs into male haploid offspring. In this study, we show that in fertilized eggs at the first mitosis the paternal sex ratio (PSR) chromosome condenses the paternal chromosomes into a so-called paternal chromatin mass (PCM). During this process, the PSR chromosome is morphologically unaffected and is incorporated into the nucleus containing the maternal chromosomes. In the first five mitotic divisions, 67% of the PCMs are associated with one of the nuclei in the embryo. Furthermore, in embryos with an unassociated PCM, all nuclei are at the same mitotic stage, whereas 68% of the PCM-associated nuclei are at a different mitotic phase than the other nuclei in the embryo. Our observations reveal an obvious similarity of the mode of action of the PSR chromosome in T. kaykai with that of the PSR-induced paternal genome loss in the unrelated wasp Nasonia vitripennis.Key words: paternal sex ratio, PSR, Trichogramma kaykai, B chromosome, paternal chromatin mass, embryogenesis.

Download Full-text

Comparative AFLP reveals paternal sex ratio chromosome specific DNA sequences in the parasitoid wasp Trichogramma kaykai

Genome ◽

10.1139/g09-024 ◽

2009 ◽

Vol 52 (5) ◽

pp. 447-455

Author(s):

Joke J.F.A. van Vugt ◽

Ron G.M. van der Hulst ◽

Andrea J.P. Pruijssers ◽

Patrick Verbaarschot ◽

Richard Stouthamer ◽

...

Keyword(s):

Sex Ratio ◽

Dna Sequences ◽

Related Species ◽

Parasitoid Wasp ◽

Specific Marker ◽

Paternal Genome ◽

Closely Related Species ◽

Repetitive Nature ◽

Aflp Fragment ◽

Paternal Sex Ratio

The parasitoid wasp Trichogramma kaykai with a haplo-diploid sex determination has a B chromosome called the paternal sex ratio (PSR) chromosome that confers paternal genome loss during early embryogenesis, resulting in male offspring. So far, it is not well known whether the PSR chromosome has unique DNA sequence characteristics. By comparative AFLP fingerprinting of genomic DNA from wasps with and without the PSR chromosome, we isolated DNA from PSR-specific bands. Fourteen of such DNA fragments were analysed to confirm their PSR specificity. Seven were sequenced and two (PT-AFLP 1 and PT-AFLP1 3) were identified as parts of retrotransposon genes based on BLAST searches. Internal primers designed from a third AFLP fragment allowed PCR amplification of a PSR chromosome specific marker, which can be used to screen for the PSR trait in male wasps. Southern analysis revealed a dispersed repetitive nature of this third sequence in the T. kaykai genome, suggesting that it is part of a transposon. A fourth AFLP fragment (PT-AFLP 5) appears to be a large repetitive sequence on the PSR chromosome. This sequence is also found in the genome of both T. kaykai and the closely related species Trichogramma deion , but its distribution on the PSR chromosome strongly resembles that of T. deion rather than that of T. kaykai. Our results provide further insight into the repetitive nature of sequences comprising B chromosomes and their similarities with their host and closely related species.

Download Full-text

Maternally Inherited Sex Ratio in the Parasitoid Wasp Nasonia vitripennis

Science ◽

10.1126/science.215.4536.1133 ◽

1982 ◽

Vol 215 (4536) ◽

pp. 1133-1134 ◽

Cited By ~ 64

Author(s):

S. W. SKINNER

Keyword(s):

Sex Ratio ◽

Parasitoid Wasp ◽

Nasonia Vitripennis

Download Full-text

Test of the adaptiveness of sex ratio manipulation in a parasitoid wasp

Behavioral Ecology and Sociobiology ◽

10.1007/s002650050117 ◽

1994 ◽

Vol 35 (6) ◽

pp. 437-443 ◽

Cited By ~ 2

Author(s):

Bethia H. King ◽

H. E. Lee

Keyword(s):

Sex Ratio ◽

Parasitoid Wasp

Download Full-text

Does time until mating affect progeny sex ratio? A manipulative experiment with the parasitoid wasp

Journal of Evolutionary Biology ◽

10.1007/s000360050109 ◽

1998 ◽

Vol 11 (5) ◽

pp. 611 ◽

Cited By ~ 1

Author(s):

X. Fauvergue ◽

K. R. Hopper ◽

M. F. Antolin ◽

D. J. Kazmer

Keyword(s):

Sex Ratio ◽

Parasitoid Wasp ◽

Manipulative Experiment

Download Full-text

Penetrance of symbiont-mediated parthenogenesis is driven by reproductive rate in a parasitoid wasp

PeerJ ◽

10.7717/peerj.3505 ◽

2017 ◽

Vol 5 ◽

pp. e3505 ◽

Cited By ~ 6

Author(s):

Amelia R.I. Lindsey ◽

Richard Stouthamer

Keyword(s):

Biological Control ◽

Sex Ratio ◽

Reproductive Output ◽

Parasitoid Wasp ◽

Strong Relationship ◽

Mass Rearing ◽

Reproductive Rate ◽

Symbiotic Relationship ◽

Offspring Production ◽

Total Fecundity

Trichogramma wasps are tiny parasitoids of lepidopteran eggs, used extensively for biological control. They are often infected with the bacterial symbiont Wolbachia, which converts Trichogramma to an asexual mode of reproduction, whereby females develop from unfertilized eggs. However, this Wolbachia-induced parthenogenesis is not always complete, and previous studies have noted that infected females will produce occasional males in the lab. The conditions that reduce penetrance of the parthenogenesis phenotype are not well understood. We hypothesized that more ecologically relevant conditions of limited host access will sustain female-biased sex ratios. After restricting access to host eggs, we found a strong relationship between reproductive rate and sex ratio. By limiting reproduction to one hour a day, wasps could sustain up to 100% effective parthenogenesis for one week, with no significant impact on total fecundity. Reproductive output in the first 24-hours appears to be critical to the total sex ratio of the entire brood. Limiting oviposition in that period resulted in more effective parthenogenesis after one week, again without any significant impact on total fecundity. Our data suggest that this phenomenon may be due to the depletion of Wolbachia when oviposition occurs continuously, whereas Wolbachia titers may recover when offspring production is limited. In addition to the potential to improve mass rearing of Trichogramma for biological control, findings from this study help elucidate the context-dependent nature of a pervasive symbiotic relationship.

Download Full-text

Absence of complementary sex determination in Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae)

10.7287/peerj.preprints.27871 ◽

2019 ◽

Author(s):

Quan-quan Liu ◽

Jin-cheng Zhou ◽

Chen Zhang ◽

Qian-jin Dong ◽

Su-fang Ning ◽

...

Keyword(s):

Sex Ratio ◽

Sex Determination ◽

Brood Size ◽

Indirect Evidence ◽

Parasitoid Wasp ◽

Mass Rearing ◽

Diploid Male ◽

Diploid Males ◽

Offspring Sex Ratio ◽

Complementary Sex Determination

Over 60 species in Hymenoptera have been reported to possess a complementary sex determination (CSD) system. Under CSD, sex is determined by allelic complementation at one or several sex loci. But this mechanism is still uninvestigated in parasitoid wasp Trichogramma dendrolimi, one of the most important biocontrol agents widely used against Lepidopteran pests. We tested CSD in this species by conducting ten consecutive generations of inbreeding, to monitor both direct evidence (diploid male production) and indirect evidence (brood size, sex ratio, mortality). In total 475 males detected from this inbreeding regime, only one was determined as diploidy. The observed proportions of diploid male offspring significantly differed from expected values under CSD model involving up to ten independent loci, allowing us to safely reject CSD in T. dendrolimi. Meanwhile, the possibility of unviable diploid males was excluded by the absence of significant differences in brood size, offspring sex ratio and offspring mortality among different generations. Our study of sex determination in T. dendrolimi provides useful information for the mass rearing conditions in a biofactory and the quality improvement of this biocontrol agent. It also brings necessary background to further study of the sex determination in Trichogramma.

Download Full-text