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1.
Nephila spider male aggregation : preference for optimal female size and web clustering
Matjaž Kuntner, Maj Kuntner, Eva Kuntner, Alexandra Bogožalec Košir, Irena Kuntner, Viktorija Tomič, Jana Faganeli Pucer, Erik Štrumbelj, Daiqin Li, 2024, original scientific article

Abstract: Sexual size dimorphism theory predicts biased operational sex ratios (OSRs) and an uneven distribution of males among certain females. We studied this phenomenon through a field census of the giant wood spider Nephila pilipes (family Nephilidae) in Singapore, a species where females are, on average, 6.9 times larger than males. Specifically, we tested two hypotheses concerning male distribution, given their tendency to aggregate in certain female webs. The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females. The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart. Our snapshot census revealed a female-biased OSR (females: males = 1.85) with an uneven distribution of males in female webs. Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis. Proximity among female webs was indicative of male presence, lending support to the web clustering hypothesis. While our study's limited sample size warrants caution, we conclude that in N. pilipes, male occupation of female webs is facilitated by the clustering of webs, and males prefer to cohabit with optimally sized, receptive females.
Keywords: sexual size dimorphism, operational sex ratios (OSRs), male distribution, optimal female size hypothesis, web clustering hypothesis, female-biased OSR, intermediate-sized females, proximity of webs, male aggregation, arachnology, behavioral ecology, environmental zoology
Published in DiRROS: 03.09.2024; Views: 71; Downloads: 46
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2.
Why do only males of Mawia benovici (Pelagiidae: Semaeostomeae: Scyphozoa) seem to onhabit the Northern Adriatic sea
Valentina Tirelli, Tjaša Kogovšek, Manja Rogelja, Paolo Paliaga, Massimo Avian, Alenka Malej, 2021, other scientific articles

Abstract: This manuscript presents four new observations of the jellyfish Mawia benovici in the Adriatic Sea. This new species was recently identified as Pelagia benovici by Piraino et al. (2014) and then placed in the new genus Mawia by Avian et al. 2016. This species is rare and is almost exclusively observed in the Adriatic Sea. Interestingly, the majority of observations refer to males only. Few studies have addressed the issue of sex determination in Syphozoa in particular, as sex identity can only be determined at the medusa stage. Unfortunately, the rarity of M. benovici and the lack of female specimens have so far prevented indispensable laboratory studies to clarify its life cycle. Still, we tried to propose an explanation for our field observations.
Keywords: jellyfish, sex ratio, Mediterranean Sea
Published in DiRROS: 06.08.2024; Views: 188; Downloads: 144
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3.
cis-vaccenyl acetate, a female-produced sex pheromone component of Ortholeptura valida, a longhorned beetle in the subfamily Lepturinae
Ann M. Ray, Alenka Žunič Kosi, Ronald L. Alten, J. Steven McElfresh, Lawrence M. Hanks, Jocelyn G. Millar, 2011, original scientific article

Abstract: We report the identification, synthesis, and field bioassays of a female-produced sex attractant pheromone component of the cerambycid beetle Ortholeptura valida (LeConte). Headspace volatiles from females contained a female-specific compound, (Z)-11-octadecen-1-yl acetate, which elicited a strong response from antennae of adult males in coupled gas chromatography-electroantennogram analyses. In field bioassays, significant numbers of males were collected by traps baited with this compound. The pheromone represents a new structural class of cerambycid pheromones, and is the first pheromone identified for a cerambycid species in the subfamily Lepturinae.
Keywords: sex pheromone, (Z)-11-octadecen-1-yl ac, cis-vaccenyl acetate, woodborer
Published in DiRROS: 05.08.2024; Views: 205; Downloads: 129
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4.
Transcriptional deregulation of stress-growth balance in Nicotiana benthamiana biofactories producing insect sex pheromones
Mojca Juteršek, Marko Petek, Živa Ramšak, Elena Moreno Gimenéz, Silvia Gianoglio, Rubèn Mateos Fernández, Diego Orzaez, Kristina Gruden, Špela Baebler, 2022, original scientific article

Abstract: Plant biofactories are a promising platform for sustainable production of high-value compounds, among which are insect sex pheromones, a green alternative to conventional insecticides in agriculture. Recently, we have constructed transgenic Nicotiana benthamiana plants (“Sexy Plants”, SxP) that successfully produce a blend of moth (Lepidoptera) sex pheromone compounds (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate. However, efficient biosynthesis of sex pheromones resulted in growth and developmental penalty, diminishing the potential for commercial use of SxP in biomanufacturing. To gain insight into the underlying molecular responses, we analysed the whole-genome transcriptome and evaluated it in relation to growth and pheromone production in low- and high-producing transgenic plants of v1.0 and v1.2 SxP lines. In our study, high-producing SxPv1.2 plants accumulated the highest amounts of pheromones but still maintained better growth compared to v1.0 high producers. For an in-depth biological interpretation of the transcriptomic data, we have prepared a comprehensive functional N. benthamiana genome annotation as well as gene translations to Arabidopsis thaliana, enabling functional information transfer by using Arabidopsis knowledge networks. Differential gene expression analysis, contrasting pheromone producers to wild-type plants, revealed that while only a few genes were differentially regulated in low-producing plants, high-producing plants exhibited vast transcriptional reprogramming. They showed signs of stress-like response, manifested as downregulation of photosynthesis-related genes and significant differences in expression of hormonal signalling and secondary metabolism-related genes, the latter presumably leading to previously reported volatilome changes. Further network analyses confirmed stress-like response with activation of jasmonic acid and downregulation of gibberellic acid signalling, illuminating the possibility that the observed growth penalty was not solely a consequence of a higher metabolic burden imposed upon constitutive expression of a heterologous biosynthetic pathway, but rather the result of signalling pathway perturbation. Our work presents an example of comprehensive transcriptomic analyses of disadvantageous stress signalling in N. benthamiana biofactory that could be applied to other bioproduction systems.
Keywords: transcriptomics, plant biotechnology, jasmonic acid, growthstress tradeoffs, network analysis, growth penalty, insect sex pheromone
Published in DiRROS: 17.07.2024; Views: 255; Downloads: 173
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