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

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3505 ◽  
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.

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

2017 ◽  
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. The conditions that reduce penetrance of the parthenogenesis phenotype are not well understood. We hypothesize that more ecologically relevant conditions of limited host access will sustain female-biased sex ratios. By restricting access to host eggs, we see a strong relationship between reproductive rate and sex ratio. We show that reproductive output in the first 24 hours is critical to the total sex ratio of the entire brood, and limiting oviposition in that period results in near-complete parthenogenesis that can be sustained for long periods, without any significant impact on total fecundity. Our data suggest that this phenomenon may be due to the depletion of Wolbachia when oviposition occurs relatively constantly, and that 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.

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

2017 ◽  
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. The conditions that reduce penetrance of the parthenogenesis phenotype are not well understood. We hypothesize that more ecologically relevant conditions of limited host access will sustain female-biased sex ratios. By restricting access to host eggs, we see a strong relationship between reproductive rate and sex ratio. We show that reproductive output in the first 24 hours is critical to the total sex ratio of the entire brood, and limiting oviposition in that period results in near-complete parthenogenesis that can be sustained for long periods, without any significant impact on total fecundity. Our data suggest that this phenomenon may be due to the depletion of Wolbachia when oviposition occurs relatively constantly, and that 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.

scholarly journals Reproductive efficiency of the bethylid waspCephalonomia tarsalis:the influences of spatial structure and host density

2016 ◽  
Vol 107 (2) ◽  
pp. 139-147 ◽  
Author(s):  
P.A. Eliopoulos ◽  
A. Kapranas ◽  
E.G. Givropoulou ◽  
I.C.W. Hardy
Keyword(s):  
Spatial Structure ◽  
Host Density ◽  
Parasitoid Wasp ◽  
Mass Rearing ◽  
Mutual Interference ◽  
Host Population ◽  
Biological Pest Control ◽  
Offspring Production ◽  
Chemical Studies ◽  
High Degree

AbstractThe parasitoid waspCephalonomia tarsalis(Ashmead) (Hymenoptera: Bethylidae) is commonly present in stored product facilities. While beneficial, it does not provide a high degree of biological pest control against its host, the saw-toothed beetleOryzaephilus surinamensis(L.) (Coleoptera: Silvanidae). A candidate explanation for poor host population suppression is that adult females interfere with each other's foraging and reproductive behavior. We used simple laboratory microcosms to evaluate such mutual interference in terms of its overall effects on offspring production. We varied the density of the hosts and also the spatial structure of the environment, via the extent of population sub-division and the provision of different substrates. Production ofC. tarsalisoffspring was positively influenced by host density and by the isolation of females. With incomplete sub-division within microcosms offspring production was, in contrast, low and even zero. The provision of corrugated paper as a substrate enhanced offspring production and partially mitigated the effects of mutual interference. We recommend simple improvements to mass rearing practice and identify promising areas for further behavioral and chemical studies towards a better understanding of the mechanisms of mutual interference.

Host size-dependent sex allocation behaviour in a parasitoid: implications forCatolaccus grandis(Hymenoptera: Pteromalidae) mass rearing programmes

1998 ◽  
Vol 88 (1) ◽  
pp. 37-45 ◽  
Author(s):  
K.M. Heinz
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Boll Weevil ◽  
Mass Rearing ◽  
Host Size ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Control Programmes

AbstractAn often encountered problem associated with augmentative and inundative biological control programmes is the high cost of producing sufficient numbers of natural enemies necessary to suppress pest populations within the time constraints imposed by ephemeral agroecosystems. In many arrhenotokous parasitoids, overproduction of males in mass-rearing cultures inflates costs (per female) and thus limits the economic feasibility of these biological control programmes. Within the context of existing production technologies, experiments were conducted to determine if the sex ratio ofCatolaccus grandis(Burks), an ectoparasitoid of the boll weevilAnthonomous grandisBoheman, varied as a function of boll weevil larval size. Results from natural and manipulative experiments demonstrate the following behavioural characteristics associated with C.grandissex allocation behaviour: (i) femaleC. grandisoffspring are produced on large size hosts and male offspring are produced on small hosts; (ii) whether a host is considered large or small depends upon the overall distribution of host sizes encountered by a female parasitoid; and (iii) female parasitoids exhibit a greater rate of increase in body size with host size than do male parasitoids. The observed patterns cannot be explained by sex-specific mortality of immature parasitoids developing on the different host size categories. In subsequent experiments, laboratory cultures ofC. grandisexposed daily to successively larger sizes ofA. grandislarvae produced successively greater female biased offspring sex ratios, cultures exposed daily to successively smaller sizes of host larvae produced successively greater male biased offspring sex ratios, and cultures exposed daily to equivalent host size distributions over time maintained a uniform offspring sex ratio. By increasing the average size ofA. grandislarval hosts exposed toC. grandisby 2.5 mg per day in mass rearing cultures, the percentage of male progeny can be reduced from 33% to 23% over a period of four consecutive exposure days.

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

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.

scholarly journals Bracon wasps for ecological pest control–a laboratory experiment

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11540
Author(s):  
Jessica Lettmann ◽  
Karsten Mody ◽  
Tore-Aliocha Kursch-Metz ◽  
Nico Blüthgen ◽  
Katja Wehner
Keyword(s):  
Biological Control ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Laboratory Experiment ◽  
Pest Control ◽  
Insect Pests ◽  
Parasitoid Wasp ◽  
Host Larva ◽  
Wasp Species ◽  
Single Host

Biological control of pest insects by natural enemies may be an effective, cheap and environmentally friendly alternative to synthetic pesticides. The cosmopolitan parasitoid wasp species Bracon brevicornis Wesmael and B. hebetor Say (Hymenoptera: Braconidae) use lepidopteran species as hosts, including insect pests like Ephestia kuehniella or Ostrinia nubilalis. Here, we compare the reproductive success of both Bracon species on E. kuehniella in a laboratory experiment. We asked (1) how the reproductive success on a single host larva changes with temperature, (2) how it changes with temperature when more host larvae are present and (3) how temperature and availability of host larvae influence the efficacy of Bracon species as biological control agents. In general, differences between B. brevicornis and B. hebetor have been small. For rearing both Bracon species in the laboratory on one host larva, a temperature between 20–27 °C seems appropriate to obtain the highest number of offspring with a female-biased sex ratio. Rearing the braconid wasps on more than one host larva revealed a higher number of total offspring but less offspring per host larva on average. Again, highest numbers of offspring hatched at 27 °C and the sex ratio was independent from temperature. Although no parasitoids hatched at 12 °C and only few at 36 °C, host larvae were still paralyzed. The efficacy of B. brevicornis was higher than 80% at all numbers of host larvae presented at all temperatures while the efficacy of B. hebetor was less than 80% at 12 °C and 27 °C at low numbers of host larvae presented. In conclusion, practitioners can use either B. brevicornis or B. hebetor at low and high temperatures and at varying host densities to achieve high pest control efficacy.

Caloric restriction extends lifespan of mothers at the expense of offspring survival in a predatory mite (Neoseiulus cucumeris)

2020 ◽  
Vol 25 (11) ◽  
pp. 1948-1962
Author(s):  
Ming Hui Lee ◽  
Qing-Hai Fan ◽  
Lichen Yu ◽  
Zhi-Qiang Zhang
Keyword(s):  
Sex Ratio ◽  
Caloric Restriction ◽  
Predatory Mite ◽  
Reproductive Rate ◽  
Offspring Survival ◽  
Tyrophagus Putrescentiae ◽  
Neoseiulus Cucumeris ◽  
Trade Offs ◽  
Total Fecundity ◽  
Al Treatment

The extension of lifespan by means of calorie restriction (CR) is one of the most replicable mechanisms across a range of different taxa. However, the effects of this on the next generation are less studied due to the complexities associated with such an experiment. In this study, the effects of CR and ad libitum (AL) feeding on lifespan, duration of ovipositional stages, and fecundity of a predatory mite, Neoseiulus cucumeris were investigated. The egg volume, sex ratio, and survival rate of the offspring were then compared across the different treatments. The three treatments were: (1) 40 prey Tyrophagus putrescentiae eggs per day representing the AL treatment; (2) 10 eggs per day representing medium CR; and (3) 5 eggs per day being high CR. To assess for transgenerational effects, the eggs produced under the three different treatments were fed AL and reared until adulthood or death. Mothers under the medium CR treatment had a lifespan that almost doubled the lifespan of mothers fed AL. Contrastingly, a higher reproductive rate was seen in mothers under AL, which also had a significantly higher total fecundity when compared with both CR treatments. The AL mothers had a shorter gestational period and produced larger eggs. There was no difference between the sex ratio of offspring for the medium CR and AL treatments. These results indicate the different effects of the two levels of CR and highlight the trade-offs that are accompanied with a longer lifespan due to caloric restriction.

scholarly journals How long-term mass rearing affects the quality of the Trichogramma embryophagum (Hartig) (Hymenoptera: Trichogrammatidae) reared on Sitotroga cerealella (Olivier) eggs

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Farzaneh Sadat ◽  
Alireza Nazari ◽  
Shahriar Jafari ◽  
Zahra Rafiei Karahroudi
Keyword(s):  
Biological Control ◽  
Mass Rearing ◽  
Reproductive Rate ◽  
Adult Longevity ◽  
Biological Traits ◽  
Sitotroga Cerealella ◽  
Net Reproductive Rate ◽  
Significant Difference

Abstract Background Maintaining the quality and efficacy of biological control agents during long-term mass rearing plays a crucial role in the success of a biological control program. In this study, the biological traits of a local population colony of Trichogramma embryophagum (Hartig) with rearing on Sitotroga cerealella (Olivier) eggs for over 40 generations (G) were assessed. Results Female adult longevity was significantly different among generations, ranging from 7.98 d in G5 to 5.19 d in G40. The reared wasps showed highest fecundity (60.50 eggs/female) in G5 compared to the other generations. The female sex ratio varied from 63.16% in G5 to 49.31% in G40. Significant differences were observed in population growth parameters and the highest gross reproductive rate (GRR) (40.96 eggs/individual) and net reproductive rate (R0) (38.21 eggs/individual) were found in G5. However, a non-significant difference was found in the intrinsic rate of natural increase (r) until the 10th generation, but its values significantly declined with increasing the generation numbers. The finite parasitism rate (ω) ranged from 0.468 host/parasitoid/day in G5 to 0.274 host/parasitoid/day in G40. Conclusions The results showed that the quality of T. embryophagum reared under continuous laboratory conditions declined after 10 generations, and for use of them in biological control programs under field conditions, the reared population should be refreshed by adding wild individuals from time to time.

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

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.

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